Patent ID: 12230985

DETAILED DESCRIPTION

Overview

This document describes apparatuses, methods, and techniques for switched multi-cell battery systems for electronic devices. Generally, a switched multi-cell battery system can be utilized to power an electronic device when the electronic device is not electrically connected to (e.g., plugged into) a power source (e.g., an external or an alternating current (AC) power supply). In various aspects, the switched multi-cell battery system includes an input voltage node, an output voltage node, a ground node, a plurality of power control switches, and a plurality of rechargeable battery cells. The rechargeable battery cells may include a first rechargeable battery cell and a second rechargeable battery cell. A power management integrated controller (PMIC) can be configured to control the power control switches to selectively enable or disable the flow of current during a first phase and a second phase of a duty cycle. For example, during the first phase of the duty cycle, the PMIC enables and/or disables each of the power control switches, such that the first and the second rechargeable battery cells are connected in series between the input voltage node and the ground node, and the second rechargeable battery cell is connected between the output voltage node and the ground node. During the second phase of the duty cycle, the PMIC enables and/or disables each of the power control switches, such that the first and the second rechargeable battery cells are connected in series between the input voltage node and the ground node, and the first rechargeable battery cell is connected between the output voltage node and the ground node. As set out above, the switched multi-cell battery system may reduce or eliminate a voltage step-down conversion stage to increase a power-transfer efficiency of an electronic device. By doing so, charging times may be reduced and/or operating times on one battery charge may be increased, thereby making mobile electronic/electrical devices more useful. Further, by appropriate choice of the relative durations of the first and second phases it is possible to control the proportion of a duty cycle for which the first battery cell transfers electrical power to the components of the electronic device and the proportion of a duty cycle for which the second battery cell transfers electrical power to the components of the electronic device.

While features and concepts of the described techniques, methods, and apparatuses for a switched multi-cell battery system for electronic devices can be implemented in any number of different environments, systems, devices, and/or various configurations, aspects of techniques, methods, and apparatuses for a switched multi-cell battery system for electronic devices are described in the context of the following example devices, systems, methods, and configurations.

Example Environment

FIG.1illustrates an example environment100that includes an electronic device102, including a switched multi-cell battery system110(battery system110). In the illustrated example environment100, electrical power may flow from a power source120, through a power adapter130(e.g., external power adapter), and to the battery system110of the electronic device102. Generally, the power source120can be a single-phase 120 Volt (V)-60 Hertz (Hz) outlet120-1(e.g., in North America), a single-phase 230 V-50 Hz outlet120-2(e.g., in Europe), a direct current power source, and/or a power outlet with more than one phase (e.g., a two-phase voltage), a different voltage with a different frequency, and a different outlet-socket type (FIG.1illustrates two of many types of outlet sockets), depending on the country, state, and/or territory.

The power adapter130(e.g., alternating current (AC) adapter, alternating current to direct current (AC/DC) adapter, AC/DC converter) derives the voltage and power required by the electronic device102from a power source. Examples of a power adapter130include a wired power adapter containing an AC/DC converter and a wireless power transfer system (e.g., a Qi charger). In aspects where the power source120is a direct current power source, a power adapter130may not be utilized. The power adapter130can connect to the electronic device102at a connector116, an example of which is illustrated inFIG.2.

The electronic device102can be any suitable computing device or electronic device, including but not limited to, a smartphone102-1, a tablet102-2, a laptop102-3, a gaming system102-4, a smart speaker102-5, a security camera102-6, a smart thermostat102-7, and a desktop computer102-8. Other devices may also be used, such as home-service devices, baby monitors, routers, computing watches, computing glasses, drones, internet-of-things devices, health monitoring devices, netbooks, e-readers, home automation and control systems, and other computing devices that include rechargeable battery cell(s). The electronic device102can be wearable, non-wearable but mobile, or relatively immobile (e.g., computer desktop102-8).

The electronic device102includes the battery system110for supplying power to components104of the electronic device102. The battery system110includes a plurality of rechargeable battery cells111(e.g., a first battery cell112, a second battery cell114). As used herein, “rechargeable battery cells111” may be defined as any battery capable of supplying power to the electronic device102provided that the charge within the rechargeable battery cells111that comprise the battery can be restored by applying a voltage potential across the terminals of the battery. Such cells include, but are not limited to, Nickel-Cadmium (NiCad), Nickel-Metal-Hydride (NiMH), Lithium-Ion (Li-Ion), and Lithium-Polymer based technologies.

In various aspects, the battery system110includes a battery management system118. The battery management system118connects at each of the battery cells111(e.g., the first battery cell112and the second battery cell114) and manages the charging and discharging of the battery cells111. The battery management system118may sample voltage potentials across one or more of the battery cells111and provide measurements to the electronic device102for fuel-gauging purposes.

The components104of the electronic device102include one or more processor(s)105, a computer-readable storage media106(CRM106), a display (not illustrated), and a transceiver(s) (not illustrated). The processor(s)105may include any type of processor, such as a central processor unit or a multi-core processor, configured to execute processor-executable instructions (e.g., code) stored by the CRM106. The CRM106may include any suitable memory or storage device, such as volatile memory (e.g., random-access memory (RAM)), non-volatile memory (e.g., Flash memory), optical media, magnetic media (e.g., disk or tape), and so forth.

The CRM106may store executable instructions for the power management integrated controller108(PMIC108). Additionally or alternatively, the PMIC108or other power management entities of the electronic device102may be implemented in a whole or part as hardware logic or an integrated circuit with or separate from the components104of the electronic device102. Generally, the PMIC108controls the switching frequency of power control switches (not illustrated inFIG.1) that selectively enable and/or disable the flow of current in parts of the battery system110, as described throughout the disclosure.

During charging, electrical power may flow from the power source120, through a power adapter130, to the battery system110, and the battery system110supplies energy to (charges) the rechargeable battery cells111of the electronic device102. During discharging, electric power may flow from the battery system110(discharges) to power the components104of the electronic device102.

FIG.2illustrates a block diagram of an example environment200, which includes a power adapter130coupled to a connector116that electrically connects with a battery system110of an electronic device102. The output power (Padapter, not illustrated) of the power adapter130equals the output voltage (Vadapter202) of the power adapter130multiplied by the output current of the power adapter (Iadapter204), as is defined in Formula 1.
Padapter=Vadapter·Iadapter(1)

As is demonstrated in Formula 1, to increase the power flow from the power adapter130to the battery system110, there needs to be an increase in Vadapter202and/or an increase in Iadapter204, where Vadapter202and Iadapter204are inputs to the battery system110. In an implementation where the power adapter130supplies Vadapter202, the battery system110performs a voltage step-down of the Vadapter202and outputs a lower voltage (Vbattery206). Increasing Vadapter202translates to a higher voltage-conversion ratio, from Vadapter202to Vbattery206, occurring in the battery system110.

In a conventional battery charger, however, energy and/or power-transfer efficiency of the battery system is inversely correlated to the voltage-conversion ratio. Ideally, the input power (Padapter) to the battery system needs to equal the output power (Pbattery, not illustrated) of the battery system. Low power-transfer efficiency in the battery system often leads to a higher energy loss that, besides wasting energy, translates into heat in the battery system. In terms of power-transfer efficiency, Padapterbecomes greater than Pbattery.

As is demonstrated in Formula 1, instead of, or in addition to, increasing Vadapter202, increasing Padaptermay be accomplished by increasing Iadapter204. Nevertheless, the power adapter130may supply power to the battery system110through a power connector, such as a universal serial bus Type-C (USB-C) connector. Thus, one of many limitations of decreasing the charging time by increasing Iadapter204, is the maximum current bus rating of the USB-C connector (e.g., three (3) Amperes (A), five (5) A).

Instead of a wired power adapter, a user may also use a wireless power transfer (WPT) system (e.g., a Qi charger) to transfer power from the power adapter130to the battery system110. Typical WPT systems, however, do not output higher power than wired power adapters and may take longer to charge the rechargeable battery cells111. Therefore, increasing Iadapter204is often not feasible regardless of the type of power adapter130that the user may utilize to charge the rechargeable battery cells111inside the battery system110.

To increase the operating time of the electronic device102using the same storage capacity of the rechargeable battery cells111, the battery system110needs to transfer power to the components104of the electronic device102by not increasing Vbattery206. Note that the system voltage (Vsystem, not illustrated) is lower than Vbattery206. There is a positive correlation of energy loss to the voltage conversion ratio from the battery system110to the voltage-conversion from the battery system110to the components104of the electronic device102. The components104of the electronic device102perform a DC-to-DC power conversion that down-converts Vbattery206to a lower voltage system voltage, Vsystem(not illustrated inFIG.2). Vsystempowers the components104of the electronic device102(e.g., processor(s)105, memory, transceivers, display).

Ideally, to have zero energy loss from the power adapter130to the components104of the electronic device102, power flow needs to satisfy the set of equations in Formula 2.

{Padapter=Vadapter·IadapterPbattery=Vbattery·IbatteryPsystem=Vsystem·IsystemPadapter=Pbattery=Psystem(2)

Recapping, there are multiple stages of power conversion, such as from the power source120(illustrated inFIG.1) to the power adapter130, from the power adapter130to the battery system110, and from the battery system110to the components104of the electronic device102. When using a conventional battery charger, decreasing the voltage-conversion ratio in one stage translates to increasing the voltage-conversion ratio in another stage. Consequently, a decrease in energy loss in a first stage by decreasing the voltage-conversion ratio in the first stage results in an increase in energy loss in a second stage by increasing the voltage-conversion ratio in the second stage. Therefore, when using a conventional battery charger, increasing the conversion-voltage ratio in any stage introduces energy loss, often in the form of heat, during charging and/or discharging. To this end, in some aspects, the disclosed apparatuses, methods, and techniques for a switched multi-cell battery system decrease energy loss in the battery system without requiring a higher voltage-conversion ratio from the power adapter130to the battery system110, nor from the battery system110to the components104of the electronic device102. Furthermore, depending on the number of battery cells111used in the battery system110, the described battery system110can increase the voltage-conversion ratio from an output of the power adapter130to an output of the battery system110and still achieve high power-transfer efficiency, as described in greater detail below.

Operational Principles of a Switched Multi-Cell Battery System

FIG.3Aillustrates an example of a switched multi-cell battery system300(battery system300) comprising a first battery cell352and a second battery cell354. Iadapter304and Vadapter302are current and voltage inputs to the battery system300, while Ibattery308and Vbattery306are current and voltage outputs of the battery system300. Vadapter302is the voltage potential across an input voltage node340(node340) and a ground node390, while Vbattery306is the voltage potential across an output voltage node346(node346) and the ground node390.

The battery system300ofFIG.3Aincludes a first plurality of power control switches and a second plurality of power control switches that are used to generate a phase one (φ1) and a phase two (φ2) of a voltage and/or current digital pulse, which can have a duty cycle of (or close) to fifty percent (50%). As described herein, the duty cycle is the fraction of one period for which the pulse adopts φ1. In aspects, the first and second plurality of power control switches are field-effect transistors (FETs). More specifically, to create φ1 and φ2, the battery system300ofFIG.3Auses FET310and FET312in the first plurality of power control switches, and FET320and FET322in the second plurality of power control switches.

A power management integrated controller (PMIC) (such as the PMIC108ofFIG.1) utilizes signal310-1to control the switching of FET310, signal312-1to control the switching of FET312, signal320-1to control the switching of FET320, and signal322-1to control the switching of FET322. Generally, when signals310-1and312-1are high, signals320-1and322-1are low. Alternately, when the signals310-1and312-1are low, the signals320-1and322-1are high. In some aspects, signals310-1,312-1,320-1, and322-1enable the battery system300ofFIG.3Ato create the φ1 and φ2 of the 50% duty cycle and/or determine whether the battery system300ofFIG.3Aoperates in a first operating state380or a second operating state382.

To generate φ1 and φ2, the battery system300ofFIG.3Acan utilize various types of active circuit elements, such as the FETs (310,312,320,322). Examples of active circuit elements may include an n-type metal-oxide-semiconductor (-silicon) field-effect transistors (n-MOSFETs), p-type MOSFETs (p-MOSFETs), a combination of n-MOSFETs and p-MOSFETs, or other types of power control switches. In such a case, the PMIC108changes the signals310-1,320-1,312-1, and322-1(e.g., polarity inversion) to accommodate the type of active circuit elements that are being used to generate φ1 and φ2. Similar modifications may be made to any electrical design described herein.

The frequency of switching between the first operating state380and the second operating state382in the battery system300may be as low as a few hundred Hertz (Hz) and is independent from an operating frequency of the power adapter130(illustrated inFIG.1) and an operating frequency of the components104(illustrated inFIG.1) of the electronic device102. Compared to a conventional battery charger that often uses a capacitor to store charge temporarily, the switching frequency in the battery system300is considerably lower. A lower switching frequency in the battery system300ofFIG.3Aenables a more-efficient power transfer from the power adapter130to the components104of the electronic device102.

A switching period between the first operating state380and the second operating state382can be varied in aspects of the battery system300. For example, the switching frequency can be lowered down to a frequency level in which the components104of the electronic device102starts sensing the switching frequency in the battery system300. Then, the switching frequency can be increased by a few Hz to avoid that frequency point. By so doing, neither the power adapter130nor the components104of the electronic device102sense the battery system300switching between the first operating state380and the second operating state382.

FIG.3Billustrates an example block diagram of the first operating state380of the battery system300ofFIG.3A, with the battery cells (e.g.,352,354) connected in series. When the electronic device102is coupled to the power adapter130, the battery system300may operate in the first operating state380during φ1 that occurs when the first plurality of power control switches (FET310, FET312) enable flow of current. The second plurality of power control switches (FET320, FET322) disable flow of current, causing electrical circuit openings at certain parts of the block diagram inFIG.3A, as is illustrated by comparingFIG.3AtoFIG.3B.

As shown, Vadapter302is the voltage potential across the input voltage node340and the ground node390and equals approximately the voltage potential across FET310, plus the voltage potential across the first battery cell352, plus the voltage potential across FET312, plus the voltage potential across the second battery cell354(ignoring routing voltage-drop). Vbattery306is the voltage potential across the output voltage node346and the ground node390and equals approximately the voltage potential across the second battery cell354(ignoring routing voltage-drop). Because roughly 50% of the time the battery cells are in parallel, excess charge and/or energy in one battery cell flows to the other battery cell(s). Generally, the first battery cell352and the second battery cell354measure close to identical voltage potentials across their positive and negative terminals because the battery cells hold approximately the same charge during the first operating state380and the second operating state382. Given that the voltage potential across each battery cell is considerably larger than voltage potentials across other circuit elements in other parts of the battery system300ofFIG.3A, in some aspects, Vadapter302is slightly more than two times larger than Vbattery306in the battery system300that contains two battery cells.

The example environment illustrated inFIG.3Bhelps demonstrate the example battery system300during the first operating state380, in which the battery system300can concurrently transfer power to the battery cells (charging) and to the components104(discharging) of the electronic device102enabling the user to operate the electronic device102while charging the electronic device102. The input voltage to the components104, however, equals Vbattery306, not Vadapter302. Therefore, the example battery system300illustrated inFIGS.3A and3Bhas a voltage-conversion ratio of approximately two (2), which is similar to a conventional battery charger, but the described battery system300can transfer power more efficiently.

FIG.3Cillustrates an example block diagram of the second operating state382of the battery system300ofFIG.3A, in which the battery cells are connected in parallel. Whether the electronic device102is currently coupled to the power adapter130or not, the battery system300operates in the second operating state382during φ2 that occurs when the second plurality of power control switches (FET320, FET322) enable flow of current, while the first plurality of power control switches (FET310, FET312) disable flow of current, creating electrical circuit openings in certain parts the battery system300ofFIG.3A, which may be apparent when comparingFIG.3AtoFIG.3C.

As is illustrated inFIG.3C, during φ2 of the battery system300ofFIG.3A, the value of Vadapter302is irrelevant because during the second operating state382, the power adapter130does not transfer electrical power to the battery system300. Unlike in the first operating state380(illustrated inFIG.3B), during the second operating state382(illustrated inFIG.3C), the first battery cell352is connected in parallel with the second battery cell354. During the second operating state382, the battery cells are connected in parallel, and excess charge in the first battery cell352flows to the second battery cell354. Generally, the stored energy and/or charge in battery cells are used to transfer electrical power to the components104of the electronic device102. In addition to transferring power more efficiently, using a plurality of battery cells enables the battery system300to store more energy and/or charge than a conventional battery charger that contains one battery cell. Thus, compared to a conventional battery charger, the discharging time increases due to less energy loss during power transferring and due to increased energy storage in the battery system300ofFIGS.3A,3B, and3C.

During the first operating state380(illustrated inFIG.3B) and the second operating state382(illustrated inFIG.3C), Vbattery306may equal the voltage potential across the output voltage node346and the ground node390, equaling approximately half of Vadapter302(illustrated inFIG.3AandFIG.3B). The exact value of Vadapter302and the exact value of Vbattery306(illustrated inFIG.3A,FIG.3B, andFIG.3C) may differ depending on the state of charge (SoC) of the first battery cell352and the second battery cell354. For example, when the battery cells are fully charged, Vbattery306may be 4.45 V, but when the battery cells are almost depleted, Vbattery306may be closer to 3.5 V, because the value of Vbattery306depends on the voltage potential across each battery cell. The voltage-conversion ratio (Vadapter302divided by Vbattery306), however, remains approximately the same, regardless of how much energy is stored in the battery cells. Here, note that the voltage potential example values explain the concept of input and output voltage fluctuations and are not intended to limit an exact operating voltage of the battery system300.

The illustrated example of the battery system300ofFIG.3Acontains two battery cells. In other configurations, however, the battery system300can have more than two battery cells, which are connected in series during the first operating state380and are connected in parallel during the second operating state382. Therefore, regardless of how many battery cells are in the battery system300, Vbattery306equals approximately the voltage potential across the terminals of one battery cell (ignoring routing voltage-drop). The components104of the electronic device102sense a battery system300that outputs Vbattery306approximately equaling the voltage potential across the terminals of one battery cell. Alternately, the power adapter130senses a battery system300that requires an input Vadapter302approximately equaling the number of battery cells multiplied by the voltage potential across one battery cell (ignoring routing voltage-drop).

In some aspects, the battery system300ofFIG.3Aincludes two battery cells (the first battery cell352and the second battery cell354), and transfers power by satisfying the set of equations in Formula 3.

{Padapter=Vadapter·IadapterPbattery=Vbattery·IbatteryPadapter=PbatteryVadapter=2·VbatteryIbattery=2·Iadapter(3)

In another configuration, the battery system300may include three battery cells (not illustrated) and a third plurality of power control switches, such as two additional FETs (not illustrated) transferring power by satisfying the set of equations in Formula 4.

{Padapter=Vadapter·IadapterPbattery=Vbattery·IbatteryPadapter=PbatteryVadapter=3·VbatteryIbattery=3·Iadapter(4)

Therefore, if the battery system300contains N battery cells (not illustrated), and a fourth, a fifth, . . . , and an N-th plurality of power control switches (not illustrated), the battery system300transfers power by satisfying the set of equations in Formula 5. Note that the battery system300containing N battery cells may contain 2N power control switches.

{Padapter=Vadapter·IadapterPbattery=Vbattery·IbatteryPadapter=PbatteryVadapter=N·VbatteryIbattery=N·Iadapter(5)
Use of Discharging Power Control Switches

FIG.4Aillustrates an example switched multi-cell battery system400(battery system400) that can operate in a first operating state480and a second operating state482. Throughout this disclosure, an operating state may be referenced or labeled with a suffix of −80 for a first operating state or −82 for a second operating state. Generally, the battery system400ofFIG.4Autilizes discharging power control switches to protect the battery cells.

Similar to the example inFIG.3A, the battery system400inFIG.4Aincludes a first battery cell452and a second battery cell454that are protected using discharging power control switches (discharging FETs430,432, and434). The discharging FET430is coupled between node442and node448, the discharging FET432is coupled between an output voltage node446(node446) and node449, and the discharging FET434is also coupled between node446and node449. The discharging FET434may help with impedance matching, which will become clearer in subsequent descriptions. Signals430-1,432-1, and434-1, may turn on or activate the illustrated discharging FETs430,432, and434, respectively. Unlike the signals that control the switching of FETs410,412,420, and422, the signals430-1,432-1, and434-1, may not transition or switch between φ1 and φ2 of the operating stages.

Similar to the battery system300ofFIG.3A, the battery system400ofFIG.4Auses four FETs (e.g., FET410, FET412, FET420, and FET422) to generate φ1 and φ2 that enable the battery system400to switch between the first operating state480and the second operating state482.

FIG.4Billustrates an example block diagram of the first operating state480of the battery system400ofFIG.4A, with the battery cells connected in series, and the battery system400utilizing discharging power control switches (discharging FET430, discharging FET432, discharging FET434) to protect the battery cells in case of a short circuit. When the electronic device102(seeFIG.1) is currently coupled to the power adapter130(seeFIG.1), the battery system400may operate in the first operating state480during φ1 that occurs when a first plurality of power control switches (FET410, FET412) enable flow of current, while a second plurality of power control switches (FET420, FET422) disable flow of current, causing openings at certain parts of the block diagram inFIG.4A, which may be apparent by comparingFIG.4AtoFIG.4B.

In some cases, the discharging FETs430,432, and434protect the battery cells in the event of a short circuit between an input voltage node440(node440) and a ground node490(node490). Thus, discharging FET434offers double protection in case of a short circuit between the output voltage node446(node446) and the ground node490. Alternately or additionally, discharging FETs430,432, and434, may disable the flow of current in high-current conditions, as is in the case of a short circuit.

FIG.4Cillustrates an example block diagram of the second operating state482of the battery system400ofFIG.4A, with the first battery cell452and the second battery cell454connected in parallel. As inFIGS.4A and4B, the battery system400ofFIG.4Cutilizes discharging power control switches (discharging FET430, discharging FET432, and discharging FET434) to protect the battery cells in case of a short circuit. The second operating state482inFIG.4Cfunctions similar to the second operating state382described inFIG.3C. As the first battery cell452is connected in parallel to the second battery cell454, Vbattery406may equal the voltage across the output voltage node446(node446) and the ground node490. Generally, the voltage across the output voltage node446(node446) to the ground node390equals the voltage across FET420, plus the voltage across the discharging FET430, plus the voltage across the first battery cell452, plus the voltage across FET422(ignoring routing voltage-drop). Additionally, Vbattery406generally equals the voltage across the output voltage node446(node446) to the ground node490that equals the voltage across discharging FET432, plus the voltage across the second battery cell454, plus the voltage across the impedance-matching discharging FET434. The impedance-matching discharging FET434may serve a dual purpose; it offers double protection to the second battery cell114in the event of a short circuit, and it can provide impedance matching during the second operating state382. Alternately or additionally, instead of solely utilizing the discharging FET434to achieve impedance matching during the second operating state482, the battery system400can be modified by adding a resistive passive circuit element (not illustrated) to achieve impedance matching.

As shown, the examples of the battery system300described inFIGS.3A and3B, and the battery system400described inFIG.4AandFIG.4B, the battery cells are connected in series during the first operating state (380inFIG.3AandFIG.3B,480inFIG.4AandFIG.4B). In this state, the first battery cell (352inFIG.3AandFIG.3B,452inFIG.4AandFIG.4B) is on the top (closest to the input voltage node), and the second battery cell (354inFIG.3AandFIG.3B,454inFIG.4AandFIG.4B) is on the bottom (closest to the ground node). The examples of the battery system300described inFIG.3, and the battery system400described inFIG.4, over a lifetime of usage, may unequally use each battery cell due to a different voltage in a respective positive terminal. Also, during the first operating state (380inFIG.3AandFIG.3B,480inFIG.4AandFIG.4B), the current from the power adapter130, Iadapter304and/or Iadapter404, flows through the first battery cell (352inFIG.3AandFIG.3B,452inFIG.4AandFIG.4B) to the second battery cell (354inFIG.3AandFIG.3B,454inFIG.4AandFIG.4B).

A Balanced Switched Multi-Cell Battery System

FIG.5Aillustrates a block diagram of an example of a balanced switched multi-cell battery system500(battery system500) including a first battery cell552and a second battery cell554. The battery system500ofFIG.5Aoperates in a first operating state580and a second operating state582. The battery system500ofFIG.5Amay also utilize discharging power control switches (discharging FET530, and discharging FET532) to protect the battery cells. In this example, the battery system500ofFIG.5uses four FETs in a first plurality of power control switches and four FETs in a second plurality of power control switches to generate φ1 and φ2.

The battery system500has an input voltage node540, an output voltage node546, and a ground node590, and a first rechargeable battery cell552with a positive terminal and a negative terminal and a second rechargeable battery cell554with a positive terminal and a negative terminal. The system500further includes current control switches comprising at least: a first current control switch510having a gate terminal, a first channel terminal coupled to the input voltage node540, and a second channel terminal coupled (in this example via a discharging FET530) to the positive terminal of the first rechargeable battery cell552; a second current control switch522having a gate terminal, a first channel terminal coupled to the second channel terminal of the first current control switch510, and a second channel terminal coupled to the output voltage node546; and third and fourth current control switches514,526coupled between the second channel terminal of the second current control switch and the ground node590. In this example the third and fourth current control switches are coupled in series with one another, with the third current control switch514having a gate terminal, a first channel terminal coupled to the second channel terminal of the second current control switch522, and a second channel terminal and the fourth current control switch526having a gate terminal, a first channel terminal coupled to the second channel terminal of the third current control switch514, and a second channel terminal coupled to the ground node579. The system further includes: a fifth current control switch520having a gate terminal, a first channel terminal coupled to the input voltage node540, and a second channel terminal coupled (in this example via a discharging FET532) to the positive terminal of the second rechargeable battery cell554; a sixth current control switch512having a gate terminal, a first channel terminal coupled to the second channel terminal of the fifth current control switch520, and a second channel terminal coupled to the output voltage node546; and seventh and eighth current control switches524,516coupled between the second channel terminal of the sixth current control switch and the ground node590. In this example the seventh and eighth current control switches are coupled in series with one another, with the seventh current control switch524having a gate terminal, a first channel terminal coupled to the second channel terminal of the sixth current control switch524, and a second channel terminal, and the eighth current control switch516having a gate terminal, a first channel terminal coupled to the second channel terminal of the seventh current control switch524, and a second channel terminal coupled to the ground node590. (In modified versions, one or both of the discharging FETs530,532may be omitted or replaced by a passive circuit element as described above.)

In the first plurality of power control switches, the battery system500ofFIG.5uses FETs (e.g., n-MOSFETs)510,512,514, and516. In the second plurality of power control switches, the battery system500ofFIG.5uses FETs (e.g., n-MOSFETs)520,522,524, and526. To generate φ1 and φ2, the PMIC108(FIG.1) turns on and off the first plurality of power control switches ofFIG.5Ausing signals510-1,512-1,514-1, and516-1, and the PMIC108turns on and off the second plurality of power control switches ofFIG.5Ausing signals520-1,522-1,524-1, and526-1. For example, when the signals510-1,512-1,514-1, and516-1are high, the signals520-1,522-1,524-1, and526-1are low and vice versa. Alternately, when the signals510-1,512-1,514-1, and516-1are low, the signals520-1,522-1,524-1, and526-1are high. Signals530-1and532-1may turn on or activate the illustrated discharging FETs530,532, respectively. Unlike the signals that control the switching of FETs510,512,514,516,520,522,524and526, the signals530-1and532-1may not transition or switch between φ1 and φ2 of operating stage so that the discharging FETs530,532may be closed in both the first operating state580(FIG.5B) and the second operating state582(FIG.5C).

When the power adapter130(FIG.1) is coupled to the electronic device102(FIG.1), during φ1, the battery system500ofFIG.5Aoperates in the first operating state580by charging the first battery cell552and the second battery cell554and by discharging the second battery cell554. Alternately, during φ2, the battery system500ofFIG.5Aoperates in the second operating state582by charging the first battery cell552and the second battery cell554and by discharging the first battery cell552. Thus, the battery system500ofFIG.5alternates which battery cell transfers electrical power (discharges) to the components104of the electronic device102depending on whether the battery system500ofFIG.5Ais operating in the first operating state580or in the second operating state582. Thus, by appropriate choice of 1 and (2 it is possible to control the proportion of time for which the first battery cell552transfers electrical power to the components104of the electronic device102and the proportion of time for which the second battery cell554transfers electrical power to the components104of the electronic device102. As one non-limiting example, if ω1 and φ2 are chosen to provide a 50% duty ratio, each of the first battery cell552and the second battery cell554transfers electrical power to the components104of the electronic device102for 50% of the time.

In some aspects, discharging FET530and discharging FET532provide short-circuit protection in the event that the first and second plurality of power control switches that generate φ1 and φ2 fail at the same time. For example, discharging FET530and/or discharging FET532open the circuit during a high-current condition, protecting the battery system500ofFIG.5A, the first battery cell552, the second battery cell554, and the electronic device102.

FIG.5Billustrates an example block diagram of the first operating state580of the battery system500ofFIG.5A. During the first operating state580, signals510-1,512-1,514-1, and516-1turn on the first plurality of power control switches (FETs510,512,514, and516). Alternately, during the first operating state580, signals520-1,522-1,524-1, and526-1turn off the second plurality of power control switches (FETs520,522,524, and526), creating circuit openings in certain parts of the battery system500, which may be apparent by comparingFIG.5AtoFIG.5B.

Generally, when the power adapter130is coupled to the electronic device102, during the first operating state580, the power adapter130transfers electrical power to the first battery cell552, the second battery cell554, and the components104of the electronic device102, concurrently. Iadapter504enters an output voltage node546(node546), through the first battery cell552, and exits the output voltage node546(node546) satisfying Kirchhoffs Current Law (KCL), as is illustrated in Formula 6:
Iadapter=Ibattery+I554(6)
where I554(not illustrated) stands for the current exiting the output voltage node546(node546) and going into the second battery cell554.

In this example, Vadapter502is the voltage potential across an input voltage node (node540) and a ground node590and equals approximately the voltage potential across FET510, plus the voltage potential across the discharging FET530, plus the voltage potential across the first battery cell552, plus the voltage potential across FET514, plus the voltage potential across FET512, plus the voltage potential across the discharging FET532, plus the voltage potential across the second battery cell554, plus the voltage potential across FET516(ignoring routing voltage-drop).

When the power adapter130is not coupled to the electronic device102, there is no current flow from the power adapter130to the battery system500ofFIG.5(Iadapter404is zero). Thus, when the power adapter130is not coupled to the electronic device102, during the first operating state580, the battery system500ofFIG.5transfers energy stored in the second battery cell554into the components104of the electronic device102that are coupled to the output voltage node. Alternatively, the power management integrated controller (PMIC108) can be configured to discharge the first (552) and the second (554) battery cells is parallel by turning on FETs522,526,512, and516(not illustrated).

Regardless of whether the power adapter130is coupled or not coupled to the electronic device102, during the first operating state580, Vbattery506is the voltage potential across the output voltage node546(node546) and the ground node590and equals approximately the voltage potential across FET512, plus the voltage potential across the discharging FET532, plus the voltage potential across the second battery cell554, plus the voltage potential across FET516(ignoring routing voltage-drop). Therefore, whether the power adapter130is coupled or not coupled to the electronic device102, Vbattery506changes only by a change in the voltage potential across the second battery cell554. Recall that one reason for the change in the voltage potential across a battery cell may be due to the amount of charge stored in the battery cell (e.g., fully charged, fully depleted, partially charged).

FIG.5Cillustrates an example block diagram of the second operating state582of the battery system500ofFIG.5A. During the second operating state582, signals520-1,522-1,524-1, and526-1turn on the second plurality of power control switches (FETs520,522,524, and526). Alternately, still during the second operating state582, signals510-1,512-1,514-1, and516-1turn off the first plurality of power control switches (FETs510,512,514, and516), creating circuit openings in certain parts of the battery system500, as is illustrated by comparingFIG.5AtoFIG.5C.

When the power adapter130is coupled to the electronic device102, during the second operating state582, the power adapter130transfers electrical power to the first battery cell552, the second battery cell554, and the components104of the electronic device102, concurrently. Iadapter504enters the output voltage node546(node546), through the second battery cell554, and exits the output voltage node546(node546) satisfying KCL, as is illustrated in Formula 7:
Iadapter=Ibattery+I552(7)
where I552(not illustrated) stands for the current exiting the output voltage node546(node546) and going into the first battery cell552.

When the power adapter130is coupled to the electronic device102, recall that, during the first operating state580(FIG.5B), Iadapter504goes into the first battery cell552. In contrast, during the second operating state582(FIG.5C), Iadapter504goes into the second battery cell554.

Generally, Vadapter502is the voltage potential across the input voltage node540(node540) to the ground node590and equals approximately the voltage potential across FET520, plus the voltage potential across the discharging FET532, plus the voltage potential across second battery cell554, plus the voltage potential across the discharging FET524, plus the voltage potential across FET522, plus the voltage potential across the discharging FET530, plus the voltage potential across the first battery cell552, plus the voltage potential across FET526(ignoring routing voltage-drop).

Vbattery506is the voltage potential across the output voltage node546(node546) and the ground node590and equals approximately the voltage potential across FET522, plus the voltage potential across the discharging FET530, plus the voltage potential across the first battery cell552, plus the voltage potential across FET526(ignoring routing voltage-drop).

Therefore, the battery system500ofFIGS.5A,5B, and5C, over time exposes each battery cell to the same voltages and the same currents. In addition, the battery system500ofFIGS.5A,5B, and5Cautomatically balances the charge between the first battery cell552and the second battery cell554. Also, over time, after multiple battery charging and depleting cycles, the battery system500inFIGS.5A,5B, and5Cdegrades the battery cells equally.

Although not illustrated, the battery system500ofFIGS.5A,5B, and5Cmay include more than two battery cells. For example, the battery system500may include a third battery cell (not illustrated) and a third plurality of power control switches (not illustrated, e.g., implemented with a same topology as shown with respect to cell1or cell2). The third plurality of power control switches allows the battery system500to operate in a third operating state (not illustrated) and, overtime, automatically balances the charge between the first battery cell552and the second battery cell554and the third battery cell (not illustrated). Note that the battery system500containing three battery cells may contain twelve power control switches. Similarly, a battery system500containing N battery cells may contain 4N power control switches.

FIG.6Aillustrates a block diagram of an example regulated power adapter660coupled to a balanced switched multi-cell battery system600(battery system600). The balanced battery system600is similar to the balanced battery system500ofFIG.5A, and detailed description of the balanced battery system will not be repeated here. The voltage potential of the input voltage node540is Vadapter602. The voltage potential of the output voltage node546is Vbattery606. The voltage potential inside the components104of the electronic device102is Vsystem607. Between a battery FET674(BattFET674) and an inductance676(L) a power conversion occurs from Vbattery608to Vsystem607in the components104. Also, between the components104and the regulated power adapter660are coupled a front-porch FET670(FPF670), a power control switch672(FET672), and a power control switch678(FET678), as is illustrated inFIG.6A.

In some aspects, the regulated power adapter660may supply a high enough voltage to charge the battery cells when they are connected in series. The battery system600inFIG.6Aworks as intended (similar toFIG.5A) when the user utilizes the regulated power adapter660to charge the electronic device102. Therefore, the battery system600works as intended with numerous power adapters that can supply the proper voltage level. Although not illustrated, the battery system600inFIG.6Afunctions as intended in the first operating state580(seeFIG.5B) and the second operating state582(seeFIG.5C).

FIG.6Billustrates a block diagram of an example legacy power adapter680coupled to the battery system600, similar to the battery system500ofFIG.5A. The voltage potential of the input voltage node540is Vadapter602. The voltage potential of the output voltage node546is Vbattery606. The voltage potential inside the components104of the electronic device102is Vsystem607. Between a battery FET674(BattFET674) and an inductance676(L) occurs a power conversion from Vbattery608to Vsystem607in the components104. Also, between the components104and the regulated power adapter660are coupled a front-porch FET670(FPF670), a power control switch672(FET672), and a power control switch678(FET678), as is illustrated inFIG.6A.

The legacy power adapter680, however, may only supply 5 V, and the voltage potential across the terminals of each battery cell (first battery cell552and second battery cell554) may be 4.5 V. In this case, the legacy power adapter680cannot supply a high enough voltage potential to charge the battery cells if they are connected in series. The user, however, can still use the legacy power adapter680to charge the battery system600of the electronic device102. The PMIC108(FIG.1) configures the battery system600by coupling the battery cells in parallel during φ1 and φ2. FET526and FET516enable the flow of current during φ1 and φ2.

FIG.7illustrates a block diagram of an example of a balanced switched multi-cell battery system700(battery system700) including a battery management system770(BMS770). The battery system700ofFIG.7operates similarly to the battery system500illustrated inFIGS.5A,5B, and5C, operating in a first operating state780and a second operating state782. In addition to the descriptions inFIGS.5A,5B, and5C, by using the BMS770, the battery system700ofFIG.7can monitor the energy and/or the charge stored in each battery cell and can mitigate the effects of a floating ground node790(ground node790).

Generally, in electrical circuits a ground can be relative or different between various components or power rails. In some aspects, voltages in an isolated electrical component may reference a local ground. For example, the main apparatuses inFIG.2, such as the power adapter130, the battery system110, and the components104of the electronic device102, have their own local grounds. In the battery system700ofFIG.7, the ground node790can be considered a floating ground as the battery system700switches between φ1 and φ2, or between the first operating state780and the second operating state782. Thus, besides monitoring and reporting the energy and/or the charge stored in each battery cell, the BMS770, can also mitigate the effects of the floating ground node790.

In various aspects, the BMS770utilizes operational amplifiers (op-amps), including a first op-amp774and a second op-amp776, to generate two voltage potentials, Vaand Vb, that reference the same ground node790, as is illustrated inFIG.7. An operational amplifier is a voltage amplifier with a differential input that produces an output potential. Vaand Vbare inputs to a multiplexer772(mux772) that, depending on the value of a select (SEL) signal to the mux772, supplies two voltage potentials to a third op-amp778that outputs a voltage potential VW.

The SEL signal to the mux772is zero (0) during φ1, or during the first operating state780, satisfying the set of conditions and/or equations in Formula 8:

{SEL=0Vc=Va-VbVa=V752+V754Vb=V754Vc=V752(8)
where V752stands for the voltage potential across the first battery cell752, V754stands for the voltage potential across the second battery cell754, and Vcstands for the output of the BMS770.

The SEL signal to the mux772is one (1) during φ2, or during the second operating state782, satisfying the set of conditions and/or equations in Formula 9:

{SEL=1Vc=Vb-VaVb=V752+V754Va=V752Vc=V754.(9)

Generally, the BMS770may sample the voltages across the first battery cell752and across the second battery cell754and sends the V752and V754values of to the components104of the electronic device102for fuel-gauging purposes. These values of V752and V754are also useful to notify the user on the charging status of the battery system110(e.g., 30% battery charge, low battery, and so forth). When one battery cell has more charge compared to the other battery cell(s), then the battery cell having more charge is used longer during discharging until it measures the same voltage potential as the other battery cell(s). When the battery cells have approximately the same amount of stored charge then, the battery system700ofFIG.7alternates the charging and/or discharging of the battery cells.

Example Methods

An example method800is described with reference toFIG.8in accordance with one or more aspects of managing a switched multi-cell battery system. Generally, any of the components, modules, methods, and operations described herein can be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Some operations of the example methods may be described in the general context of executable instructions stored on computer-readable storage memory that is local and/or remote to a computer processing system, and implementations can include software applications, programs, functions, and the like. Alternatively, or in addition, any of the functionality described herein can be performed, at least in part, by one or more hardware logic components, such as, and without limitation, Field-Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application-Specific Standard Products (ASSPs), System-on-a-Chip systems (SoCs), Complex Programmable Logic Devices (CPLDs), and the like.

FIG.8depicts example method800for managing a switched multi-cell battery system (e.g.,500,700). Method800illustrates sets of operations (or acts) performed in, but not necessarily limited to, the order or combinations in which the operations are shown herein. Further, any of one or more of the operations may be repeated, combined, reorganized, skipped, or linked to provide a wide array of additional and/or alternate methods. The techniques described in this specification are not limited to performance by one entity or multiple entities operating on one device.

At802, during φ1, each of the first plurality of power control switches (e.g.,510,710,512,712,514,714,516,716) are closed to enable flow of current and each of the second plurality of power control switches (e.g.,520,720,522,722,524,724,526,726) are opened to disable flow of current.

At804, during φ1, a first operating state (e.g.,580,780,880) is established, and electrical power from a power adapter130charges a first battery cell (e.g.,552,752) and a second battery cell (e.g.,554,754), and charge stored in the second battery cell (e.g.,554,754) flows to components104of an electronic device102.

At806, during φ2, each of the second plurality of power control switches (e.g.,520,720,522,722,524,724,526,726) is closed to enable flow of current and each of the first plurality of power control switches is opened (e.g.,510,710,512,712,514,714,516,716) to disable flow of current.

At808, during φ2, a second operating state is established (e.g.,582,782,882), and electrical power from a power adapter130charges the second battery cell (e.g.,554,754) and the first battery cell (e.g.,552,752), and charge stored in the first battery cell (e.g.,552,752) flows to the components104of the electronic device102.

FIG.9depicts example method900for utilizing the battery management system770(BMS770) of the balanced switched multi-cell battery system700(battery system700). Method900illustrates sets of operations (or acts) performed in, but not necessarily limited to, the order or combinations in which the operations are shown herein. Further, any of one or more of the operations may be repeated, combined, reorganized, skipped, or linked to provide a wide array of additional and/or alternate methods. The techniques described in this specification are not limited to performance by one entity or multiple entities operating on one device.

At902, the BMS770compares the amount of charge stored in the first rechargeable battery cell (e.g.,752) to the amount of charge stored in the second rechargeable battery cell (e.g.,754).

At904, a power management integrated controller108(FIG.1) selects the first (e.g.,780) or the second (e.g.,782) operating state depending on which battery cell has a higher amount of charge stored.

At906, current from the rechargeable battery cell with the higher amount of charge stored is discharged to the components104of the electronic device102.

At908, the respective amounts of charge stored in the first and second rechargeable battery cells (e.g.,752,754) is balanced by operating in the operating state (first or second) that allows for the discharging of the battery cell with the higher amount of charge stored. For example, if the second battery cell (e.g.,754) has a higher amount of charge stored than the first battery cell (e.g.,752), then the battery system700operates in the first operating state (e.g.,780) until there is an approximately equal amount of charge stored in the first (e.g.,752) and second (e.g.,754) battery cells. Alternately, if the first battery cell (e.g.,752) has a higher amount of charge stored than the second battery cell (e.g.,754), then the battery system (e.g.,700) operates in the second operating state (e.g.,782) until there is an approximately equal amount of charge stored in the first and second battery cells (e.g.,752,754).

Although aspects of switched multi-cell battery systems for electronic devices have been described in language specific to features and/or methods, the subject of the appended claims is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as example implementations of switched multi-cell battery systems for electronic devices, and other equivalent features and methods are intended to be within the scope of the appended claims. Further, various different aspects are described, and it is to be appreciated that each described aspect can be implemented independently or in connection with one or more other described aspects.

Unless context dictates otherwise, use herein of the word “or” may be considered use of an “inclusive or,” or a term that permits inclusion or application of one or more items that are linked by the word “or” (e.g., a phrase “A or B” may be interpreted as permitting just “A,” as permitting just “B,” or as permitting both “A” and “B”). Further, items represented in the accompanying figures and terms discussed herein may be indicative of one or more items or terms, and thus reference may be made interchangeably to single or plural forms of the items and terms in this written description. Finally, although subject matter has been described in language specific to structural features or methodological operations, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or operations described above, including not necessarily being limited to the organizations in which features are arranged or the orders in which operations are performed.

The following are additional examples of the described apparatuses, methods, and techniques for a switched multi-cell battery system for an electronic device.

Example 1. A switched multi-cell battery system for an electronic device, the switched multi-cell battery system comprising: an input voltage node; an output voltage node; a ground node; a plurality of rechargeable battery cells comprising at least a first rechargeable battery cell with a positive terminal and a negative terminal and a second rechargeable battery cell with a positive terminal and a negative terminal; and a plurality of power control switches comprising at least: a first power control switch having a gate terminal, a first channel terminal coupled to the input voltage node, and a second channel terminal coupled to the positive terminal of the first rechargeable battery cell; a second power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the first power control switch, and a second channel terminal coupled to the output voltage node; a third power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the second power control switch, and a second channel terminal; a fourth power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the third power control switch, and a second channel terminal coupled to the ground node; a fifth power control switch having a gate terminal, a first channel terminal coupled to the input voltage node, and a second channel terminal coupled to the positive terminal of the second rechargeable battery cell; a sixth power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the fifth power control switch, and a second channel terminal coupled to the output voltage node; a seventh power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the sixth power control switch, and a second channel terminal; and an eighth power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the seventh power control switch, and a second channel terminal coupled to the ground node.

Example 2. The switched multi-cell battery system of example 1, wherein: the first channel terminal of the third power control switch is coupled to the output voltage node; and the second channel terminal of the third power control switch is coupled to the negative terminal of the first rechargeable battery cell.

Example 3. The switched multi-cell battery system of example 1, wherein: the first channel terminal of the seventh power control switch is coupled to the output voltage node; and the second channel terminal of the seventh power control switch is coupled to the negative terminal of the second rechargeable battery cell.

Example 4. The switched multi-cell battery system of example 1, further comprising a ninth power control switch having a gate terminal, a first channel terminal coupled to the positive terminal of the first rechargeable battery cell, and a second channel terminal coupled to the second channel terminal of the first power control switch and the first channel terminal of the second power control switch.

Example 5. The switched multi-cell battery system of example 4, further comprising a tenth power control switch having a gate terminal, a first channel terminal coupled to the positive terminal of the second rechargeable battery cell, and a second channel terminal coupled to the second channel terminal of the fifth power control switch and the first channel terminal of the sixth power control switch.

Example 6. The switched multi-cell battery system of example 4 or example 5, wherein the ninth power control switch or the tenth power control switch is implemented as a discharge power control switch to enable or prevent respective current to discharge from the first rechargeable battery cell or the second rechargeable battery cell.

Example 7. The switched multi-cell battery system of example 1, wherein the input voltage node and the output voltage node of the switched multi-cell battery system electrically reference the ground node.

Example 8. The switched multi-cell battery system of example 1, wherein any of the first power control switch through the eighth power control switch are implemented as a transistor, a field-effect transistor (FET), an N-channel (N-FET), or a P-channel FET (P-FET), an n-type metal-oxide-semiconductor (-silicon) field-effect transistor (n-MOSFET), a p-type MOSFET (p-MOSFET), a bipolar junction transistor (BJT), a heterojunction bipolar transistor (HBT), or a junction field-effect transistor (JFET).

Example 9. The switched multi-cell battery system of example 1, further comprising a battery management system, the battery management system comprising: a first operational amplifier having a non-inverting input coupled to the positive terminal of the second rechargeable battery cell, an inverting input coupled to the ground node, and an output coupled to a first input of a multiplexer; a second operational amplifier having a non-inverting input coupled to the positive terminal of the first rechargeable battery cell, an inverting input coupled to the ground node, and an output coupled to a second input of the multiplexer; and a third operational amplifier having a non-inverting input coupled to a first output of the multiplexer, an inverting input coupled to a second output of the multiplexer; and an output coupled to a power management entity of the electronic device.

Example 9a. The switched multi-cell battery system of any one of examples 1 to 9 may further comprise a power management controller, the power management controller configured to: during a first phase of a duty cycle, control the plurality of current control switches effective to (i) couple the first and second rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the second rechargeable battery cell between the output voltage node and the ground node; and during a second phase of the duty cycle, control the plurality of current control switches effective to (i) couple the first and second rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the first rechargeable battery cell between the output voltage node and the ground node.

Example 10. A switched multi-cell battery system for an electronic device, the switched multi-cell battery system comprising: an input voltage node; an output voltage node; a ground node; a plurality of rechargeable battery cells comprising at least a first rechargeable battery cell with a positive terminal and a negative terminal and a second rechargeable battery cell with a positive terminal and a negative terminal; a plurality of power control switches comprising at least: a first power control switch having a gate terminal, a first channel terminal coupled to the input voltage node, and a second channel terminal coupled to the positive terminal of the first rechargeable battery cell; a second power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the first power control switch, and a second channel terminal coupled to the output voltage node; third and fourth power control switches coupled between the second channel terminal of the second power control switch and the ground node; a fifth power control switch having a gate terminal, a first channel terminal coupled to the input voltage node, and a second channel terminal coupled to the positive terminal of the second rechargeable battery cell; a sixth power control switch having a gate terminal, a first channel terminal coupled to the second channel terminal of the fifth power control switch, and a second channel terminal coupled to the output voltage node; seventh and eighth power control switches coupled between the second channel terminal of the sixth power control switch and the ground node. The switched multi-cell battery system of this example may optionally further include a power management integrated controller, the power management integrated controller configured to: during a first phase of a duty cycle, control the plurality of power control switches effective to (i) couple the first and second rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the second rechargeable battery cell between the output voltage node and the ground node; and during a second phase of the duty cycle, control the plurality of power control switches effective to (i) couple the first and second rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the first rechargeable battery cell between the output voltage node and the ground node.

Example 11. The switched multi-cell battery system of example 10, wherein: the third power control switch includes a gate terminal, a first channel terminal coupled to the second channel terminal of the second power control switch, and a second channel terminal; the fourth power control switch includes a gate terminal, a first channel terminal coupled to the second channel terminal of the third power control switch, and a second channel terminal coupled to the ground node; the seventh power control switch includes a gate terminal, a first channel terminal coupled to the second channel terminal of the sixth power control switch, and a second channel terminal; and the eighth power control switch includes a gate terminal, a first channel terminal coupled to the second channel terminal of the seventh power control switch, and a second channel terminal coupled to the ground node.

Example 12. The switched multi-cell battery system of example 10, wherein the input voltage node and the output voltage node of the switched multi-cell battery system electrically reference the ground node.

Example 13. The switched multi-cell battery system of example 10, wherein the first phase of the duty cycle establishes a first operating state in which: when the switched multi-cell battery system is coupled to an external power adapter, the external power adapter charges the first and second rechargeable battery cells, and the second rechargeable battery cell discharges to components of the electronic device that are coupled to the output voltage node; and when the switched multi-cell battery system is not coupled to the external power adapter, the second rechargeable battery cell discharges to the components of the electronic device.

Example 14. The switched multi-cell battery system of example 10, wherein the second phase of the duty cycle establishes a second operating state in which: when the switched multi-cell battery system is coupled to the external power adapter, the external power adapter charges the first and second rechargeable battery cells, and the first rechargeable battery cell discharges to the components of the electronic device that are coupled to the output voltage node; and when the switched multi-cell battery system is not coupled to the external power adapter, the first rechargeable battery cell discharges to the components of the electronic device.

Example 15. The switched multi-cell battery system of example 10, further comprising: a ninth power control switch having a gate terminal, a first channel terminal coupled to the positive terminal of the first rechargeable battery cell, and a second channel terminal coupled to the second channel terminal of the first power control switch and the first channel terminal of the second power control switch; and a tenth power control switch having a gate terminal, a first channel terminal coupled to the positive terminal of the second rechargeable battery cell, and a second channel terminal coupled to the second channel terminal of the fifth power control switch and the first channel terminal of the sixth power control switch.

Example 16. The switched multi-cell battery system of example 10, further comprising a battery management system comprising: a first operational amplifier configured to reference the positive terminal of the second rechargeable battery cell to the ground node to produce a first voltage potential Va; a second operational amplifier configured to reference the positive terminal of the first rechargeable battery cell to the ground node to produce a second voltage potential Vb; a multiplexer configured to select between the first voltage potential Va produced by the first operating amplifier and the second voltage potential Vb produced by the second operational amplifier to produce a first multiplexer output and a second multiplexer output; and a third operational amplifier configured to reference the first multiplexer output to the second multiplexer output to produce a third voltage potential Vc.

Example 17. The switched multi-cell battery system of example 10, wherein: the plurality of rechargeable battery cells further comprises a third rechargeable battery cell; the plurality of power control switches includes at least four additional power control switches by which the third rechargeable battery cell is coupled to the input voltage node, the output voltage node, and the ground node; and the power management integrated controller is further configured to: during the first phase of the duty cycle, control the plurality of power control switches effective to (i) couple the plurality of the rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the third rechargeable battery cell between the output voltage node and the ground node; and during the second phase of the duty cycle, control the plurality of power control switches effective to (i) couple the plurality of the rechargeable battery cells in series between the input voltage node and the ground node and (ii) couple the first or the second rechargeable battery cell between the output voltage node and the ground node.

Example 18. A method for charging and discharging a switched multi-cell battery system, the method comprising: closing, based on a first phase of a duty cycle, each of a first plurality of power control switches to enable flow of current as part of establishing a first operating state; opening, based on the first phase of the duty cycle, each of a second plurality of power control switches to disable flow of current as part of establishing the first operating state in which: electrical power from an external power adapter charges a first rechargeable battery cell and a second rechargeable battery cell that are connected, by at least one of the first plurality of power control switches, in series between an input voltage node and a ground node, and charge stored in the second battery rechargeable cell flows, through at least one of the first plurality of power control switches, to components of an electronic device; closing, based on a second phase of the duty cycle, each of the second plurality of power control switches to enable flow of current as part of establishing a second operating state; opening, based on a second phase of the duty cycle, each of the first plurality of power control switches to disable flow of current as part of establishing the second operating state in which: electrical power from the external power adapter charges the second rechargeable battery cell and the first rechargeable battery cell that are connected, by at least one of the second plurality of power control switches, in series between the input voltage node and the ground node, and charge stored in the first rechargeable battery cell flows, through at least one of the second plurality of power control switches, to the components of the electronic device.

Example 19. The method of example 18, further comprising: comparing, with a battery management system, an amount of charge stored in the first rechargeable battery cell to an amount of charge stored in the second rechargeable battery cell; selecting, using a power management integrated controller, the first operating state or the second operating state; discharging, to the components of the electronic device, the rechargeable battery cell with a higher amount of charge stored; and balancing the respective amounts of charge stored in the first rechargeable battery cell and the second rechargeable battery cell.

Example 20. The method of example 18, wherein establishing the first operating state and the second operating state is effective to down-convert an input voltage received by the switched multi-cell battery system to an output voltage out of the switched multi-cell battery system and creating an input-to-output voltage conversion ratio such that: the input-to-output voltage conversion ratio is approximately equal to the number rechargeable battery cells in a plurality of rechargeable battery cells; and the plurality of rechargeable battery cells may comprise two or more rechargeable battery cells.