Multimode battery charger

A multimode battery charger circuit supporting switch mode and linear mode charging operations. In various embodiments, the multimode battery charging circuit includes mode control circuitry, a linear gate driver, a pulse width modulation (PWM) control circuit, a programmable constant current control loop circuit, and a programmable constant voltage control loop circuit. In operation, the mode control circuitry receives a charge mode indication signal corresponding to a desired charge mode. Based on this signal, the mode control circuitry enables either the linear gate driver or PWM control circuit to provide control signals to output transistors coupled between an adapter power port and a battery pack, thereby supporting a plurality of charging modes. In some embodiments, one or more of the output transistors are formed on a common substrate with the multimode battery charger circuit.

BACKGROUND

1. Technical Field

The disclosure relates generally to battery powered devices and, more particularly, it relates to multimode battery charger circuitry for use in such devices.

2. Description of Related Art

Battery-powered electronic devices, such as smart phones, tablet computing devices and laptop computers, typically include a power management unit (PMU) having a battery charger for charging an internal battery. In general, there are two principal types of battery charger designs, switching (or switch) chargers and linear chargers. Each type may utilize a variety of topologies, especially in complex mobile and tablet devices with Charge and Play (CnP) or similar options.

In such systems, the battery charger is designed to operate as either a switching charger or a linear charger, and the complex current and voltage control blocks used in one charger type typically will not work in a different type. Further, changes in a system's requirements often require a new battery charger design. For example, if a system requires additional power, external (to an integrated circuit) power transistors may become necessary, thereby requiring design modifications to the battery charger architecture.

DETAILED DESCRIPTION

In various embodiments of the battery charger technology described herein, systems and methodologies are provided to support a plurality of operating/charging modes. In application, multimode charging architectures according to the disclosure permit design optimization and adaptability to support different battery configurations and charging modes of operation (e.g., switch modes and linear modes). In some embodiments, operating modes may be changed in real time or near real time. Further, through sharing of common circuitry, a reduction in semiconductor die area and power consumption can be achieved.

FIG. 1illustrates an example system100having devices with multimode battery charger circuitry in accordance with embodiments of the present disclosure. The illustrated system includes one or more communications network(s)102, one or more smartphones104, one or more tablet devices106and/or other battery-powered mobile devices (e.g., laptop computers)108, wireless LAN (WLAN) devices110, and servers/computers112. In the illustrated system100, a home gateway/set top box (STB)116is also provided, and includes processing118, storage120, and communication interface122resources. The home gateway/STB116may service, for example, a coupled entertainment system. Servers/computers112may support various local, distributed and/or cloud-based services and processing operations. The servers/computers112may store media and advertising content, user data, profile information, etc.

The communication network(s)102may include one or more of the Internet, the World Wide Web (WWW), one or more Local Area Networks (LANs), one or more Wide Area Networks (WANs), one or more Personal Area Networks (PANs), one or more cellular communication networks, one or more Metropolitan Area Networks, Heterogeneous Networks (HetNets), and/or other types of networks. These network(s)102may service one or both of wired and/or wireless communications, and serve to support communications among various system components.

Referring more specifically to the mobile devices104-108, such battery-powered devices are manufactured using integrated circuits, which typically include a power management unit (PMU) having battery charger circuitry. The batteries in these devices may be charged by internal battery charging circuitry through the use of external adapters (such as a wall adapter) and other devices. For example, certain devices may incorporate the ability to receive power through a Universal Serial Bus (USB) connection coupled to USB port(s)114of servers/computers112or other devices.

As noted, the power requirements and battery technology of mobile devices104-108may vary greatly. In order to overcome related design challenges and/or for other reasons, multimode battery charger circuitry according to one or more embodiments of the present disclosure (described in more detail with reference toFIGS. 2-5) is incorporated in such devices.

In addition, while certain embodiments of the disclosure presented herein are described for use in mobile communication devices, various aspects and principles, and their equivalents, can also be extended generally to other types of devices that are designed to rely, at least in part, on battery power. In some instances, structures and components described herein are illustrated in block diagram form in order to avoid obscuring the concepts of the subject technology.

Referring now toFIG. 2, a functional block diagram representation200of a mobile device202incorporating exemplary multimode battery charger circuitry is shown. In this embodiment, the mobile device202(e.g., a smartphone, tablet device, portable navigation device, personal media player, handheld game console, etc.) includes multimode battery charger circuitry204for charging an internal battery206. The multimode battery charger circuitry204may be integrated in a device such as a

PMU208, formed from one or more standalone integrated circuit devices, or various combinations thereof. As described in greater detail below, the multimode battery charger circuitry204may utilize various combinations of integrated or discrete output components such as transistors, capacitors and inductors.

The mobile device202may include a wide range of additional components and functionality, some or all of which may receive power from the battery206during mobile operation. By way of example and without limitation, communication circuitry210, a baseband processor212, and a mobile multi-media processor214are provided to enable communications and other functionality of the illustrated mobile device202.

The mobile device further includes one or more proprietary or standardized power ports (or general purpose ports capable of supporting charging operations) for coupling to a power source to provide power for use by the multimode battery charger circuit204. In some embodiments, such power sources include an AC power adapter216that plugs into a wall outlet and provides a regulated DC output voltage. A standardized connection, such as a USB-compliant link218, may be utilized in lieu of or in addition to other power sources.

FIG. 3is a schematic block diagram of an exemplary multimode battery charger circuit300. In the illustrated embodiment, mode control circuitry (or module)302operates to selectively enable/disable circuit elements necessary to operate in either a switch mode or linear mode of charging when performing charging operations on a battery pack304. The mode control circuitry302may comprise, for example, a plurality of switches responsive to one or more charge mode indication signals. As will be appreciated, the charge mode indication signals can change in real-time or near real-time to support adaptive charge mode transitions.

The illustrated multimode battery charger circuit300further includes a configurable constant current control loop circuit310and a configurable constant voltage control loop circuit312, each of which may be coupled to a linear gate driver314and a pulse width modulation (PWM) control circuit316. The currents and voltages produced by the configurable constant current control loop circuit310and configurable constant voltage control loop circuit312are utilized in generating (via linear gate driver314and PWM control circuit316) the desired control signals at the gates of output transistors318-322, and are configurable to support a plurality of linear modes of operation and a plurality of switch modes of operation. In some alternate embodiments, the constant current control loop310and constant voltage control loop312may be fixed to support specific modes of operation.

In various embodiments, the output transistors318-322may be implemented utilizing n-channel field effect transistors (NFETs) and p-channel field effect transistors (PFETs) manufactured in a complementary metal oxide semiconductor (CMOS) process. For example, output (or pass) transistor318and output transistor320are shown as a PFETs, while output transistor322is an NFET. In alternate embodiments, and in view of cost and/or power considerations, one or more of the output transistors may be bipolar transistors and/or external to an integrated circuit device containing other charger elements.

When the multimode battery charger circuit300is configured to operate in a linear mode (as described in greater detail below in conjunction withFIG. 4), the linear gate driver314generates an output voltage that is provided to the gate of pass transistor318, which is coupled between a system load308and a terminal (V—BATTERY) of the battery pack304. In the illustrated embodiment, system load308is powered by a system level supply (V—SYSTEM).

When the multimode battery charger circuit300is configured to operate in a pulse mode (as described in greater detail below in conjunction withFIG. 5), the PWM control circuit316generates at least one output to control power provided by output transistors320and322. The output transistors320and322of this embodiment are coupled in series between an adapter power port (V—IN) and ground, while the common drain/source is coupled to a battery terminal (V—BATTERY) for charging and receiving power from the battery pack304, as well as powering other system components represented by load306, via an external or internal inductor324. A capacitor326is coupled between V—BATTERYand ground and, in conjunction with inductor324, forms a passive low-pass LC filter that attenuates switching harmonics and passes DC voltages.

The battery pack304may have a variety of configurations and include a variety of battery types. For example, the rechargeable battery pack304may be comprised of a single cell battery, a series dual-cell battery, etc., and utilize different types of batteries, such as lithium-ion batteries, thin film lithium-ion batteries, lithium-polymer batteries, etc. Selection of charging modes may, in some cases, depend on the type of battery that is utilized.

Further, the configurable constant current control loop circuit310and configurable constant voltage control loop circuit312may be implemented using a variety of architectures. In one exemplary embodiment, the configurable constant current control loop circuit310utilizes a current reference and sensing circuit (with additional components in the case of an external pass transistor), a programmable gain stage and a programmable output filter. Likewise, the constant voltage control loop circuit312may utilize a voltage reference and sensing circuit, a programmable gain stage and a programmable output filter. Depending on the selected mode of operation, one or more of such elements may be selectively enabled or disabled by the mode control circuitry302.

FIG. 4illustrates the exemplary multimode battery charger circuit ofFIG. 3configured to operate as a linear charger400. In this embodiment, the mode control circuitry402enables the signal path of the internal/external pass transistor418for charging of battery pack404. In particular, and in accordance with one or more charge mode indication signals, the mode control circuitry402enables (e.g., by closing and/or opening one or more switches) charging control voltages from the linear gate driver414to be received at the gate of the pass transistor418.

Further, the mode control circuitry402may configure (e.g., by generating appropriate gate control voltages for a plurality of additional switches) the configurable constant current control loop circuit410and configurable constant voltage control loop circuit412such that the currents and voltages generated by these circuits are able to effectively control the linear gate driver414and pass transistor418. In the illustrated embodiment, the PWM control circuit and related output transistors (not shown) are disabled. The remaining illustrated elements406,408,424and426generally function in a like manner to the corresponding elements described in conjunction withFIG. 3.

FIG. 5illustrates the exemplary multimode battery charger circuit ofFIG. 3configured to operate as a switch mode charger500. In this embodiment, the mode control circuitry502enables the signal path of the internal/external output transistors520and522for charging of battery pack504and/or provision of power to a system load506. In particular, and in accordance with one or more charge mode indication signals, the mode control circuitry502enables (e.g., by closing one or more switches) charging control voltages from the PWM control circuit516to be received at the gates of output transistors520and522.

Further, the mode control circuitry502may configure (e.g., by generating appropriate gate control voltages for a plurality of additional switches) the configurable constant current control loop circuit510and configurable constant voltage control loop circuit512such that one or more control voltages generated by these circuits are able to effectively control the PWM control circuit516and output transistors520and522. In the illustrated embodiment, the linear gate driver and pass transistor (not shown) used in the linear mode are disabled. As previously described, the inductor524and capacitor526act as a filter between the charging circuitry and battery pack504.

Although not separately illustrated, a variety of additional circuitry and features may be included in battery charger circuitry according to the present disclosure. As noted, the disclosed multimode battery charger circuitry may be part of a PMU that integrates most or all of the key portable power components and functionality. Such components and functionality might include, by way of example, wall and USB charging for the main battery(ies), automatic charger source switchover, battery presence detection circuitry, battery temperature monitoring, a die temperature regulation loop, high-efficiency synchronous buck regulators, high-performance programmable Low Dropout (LDO)regulators, a backup battery charger, an RTC, programmable current sources for driving signal LEDs, GPIO ports, a fuel gauge, etc. The PMU functions can be controlled through a serial bus interface or the like, whereby an external host controller can access desired registers to read or program the internal blocks.

FIG. 6is a circuit diagram illustrating details of an exemplary multimode battery charger600. In the illustrated embodiment, a plurality of switches (controlled by one or more charge mode indication signals or “CMI”) and other configurable circuit elements operate to support switch modes and linear modes of charging. Various such elements may be incorporated, for example, in the mode control circuitry302.

Referring first to a linear mode of operation, the linear gate driver602generates an output voltage that is provided to the gate of pass transistor606, which is coupled between a system level supply (V—SYSTEM) and battery(ies) (not shown). When enabled, a charging current I—CHARGEflows through pass transistor606. In the illustrated embodiment, the linear gate driver602may be enabled and disabled through a switch652coupled between V—SYSTEMand a first end of resistor608, the switch being controlled by a charge mode indication signal. In operation, the switch652is open when a linear charge mode is enabled. The second end of the resistor608is coupled to the drain of transistor610, as well as the gate of the pass transistor606. The source of the transistor610is coupled to the drain of transistor612, while the source of transistor612is coupled to ground. When transistors610and612are enabled by control voltages V—CIand V—CVat their respective gates, the voltage at the gate of pass transistor606is pulled low, enabling the desired charging current I—CHARGE.

When the multimode battery charger600is configured for switch mode charging operations, the switch mode output stage604operates as generally described above. In the illustrated embodiment, output transistors614and616are coupled in series between an adapter power port (providing a voltage V—IN) and ground. The common node between these transistors establishes a voltage V—SWITCHthat (through a low pass filter) governs battery charging.

Linear/switching current sense circuitry618is coupled to both the linear gate driver602and the switch mode output stage604to monitor charging currents under various modes of operation. In embodiments that utilize an external pass transistor, external FET current sense circuitry620may also be provided. Such circuitry may utilize an external sense resistor (not shown) to sense charge current.

In operation, the linear/switching current sense circuitry618provides an output voltage that is proportional to a dc charge current in the relevant mode of operation. This voltage is provided at the positive input of a transconductance amplifier624. In the illustrated embodiment, the output of a constant current (CC) loop programmable reference generator622is coupled to the negative input of the transconductance amplifier624. The voltage level at the output of the CC loop programmable reference generator622may be set, for example, to correspond to a charge current limit. The transconductance amplifier624produces an output current that is proportional to the difference between the voltages at its input.

The output of the transconductance amplifier624is provided to a CC loop output filter626comprised of a variable resistor or potentiometer628coupled in series with a capacitor630. A capacitor632is coupled between the output of the transconductance amplifier624and ground in parallel with the potentiometer628and capacitor630. Current provided by the output of the transconductance amplifier624is thereby utilized to generate the control voltage V—CIat the output of the CC loop output filter626.

Similarly, the output of a constant voltage (CV) loop programmable reference generator636is coupled to the positive input of a transconductance amplifier640, while the negative input of the transconductance amplifier640is coupled to the output of a battery voltage sense circuit638which monitors the voltage at the charging terminal of a battery coupled to the multimode battery charger600. The CV loop programmable reference generator636may be programmed, for example, to reflect the type and/or number of battery cells coupled to the multimode battery charger600. The output of the transconductance amplifier640is provided to a CV loop output filter642comprised of a variable resistor or potentiometer644coupled in series with a capacitor646. A capacitor648is coupled between the output of the transconductance amplifier640and ground in parallel with the potentiometer644and capacitor646. Current provided by the output of the transconductance amplifier640is thereby utilized to generate the control voltage V—CVat the output of the CV loop output filter642.

During switch mode charging operations, the outputs (V—CIand V—CV) of the CC loop output filter626and CV loop output filter642are coupled to the inputs of a PWM comparator634, which produces a series of pulses having pulse widths that are modulated over time to control battery charging rate. In particular, the output of the PWM comparator634is coupled to ramp and driver logic650for use in driving the gate voltages of output transistors614and616.

In the illustrated embodiment, various components of the exemplary multimode battery charger600are configurable via one or more charge mode indication signals to support a plurality of linear modes of operation and a plurality of switch modes of operation. In one exemplary embodiment in which Li-ion battery charging is performed, a two-phase approach may be utilized. In a first phase typically referred to as the constant current phase, the battery may be charged at a maximum recommended (or “fast”) charging rate. When the battery reaches a specified voltage, charging is switched to a second phase, or constant voltage phase, in which only enough current is provided to maintain the voltage of the battery at the specified voltage. Typically, there is a gradual decay in the charge current profile during this phase as the battery approaches maximum charge.

FIG. 7is an operational flow diagram illustrating an exemplary method700for multimode-enabled charging of a battery. The method may be performed through use of a circuit having both linear mode and pulse mode charging capabilities and a power port for receiving power from an external source. The method commences following receipt of a charge mode indication signal(s) identifying linear mode or pulse mode charging (702). In various exemplary embodiments, a charge mode indication signal may be fixed at the time of manufacture, generated by sensing or like circuitry, etc. If linear mode is indicated (704), a linear gate driver coupled to a pass transistor is activated (706) (e.g., by mode control circuitry). Programmable constant current and constant voltage control loops may also be configured for use in a desired linear mode of charging.

If pulse mode charging is indicated (708), a PWM control circuit coupled to one or more output transistors is activated (710) (e.g., by mode control circuitry).

Programmable constant current and constant voltage control loops may also be configured for use in a desired pulse mode of charging. Further, the state of the charge mode indication signal(s) may be continuously monitored to enable real-time or near real-time modifications to desired charge modes.

The term “module” is used in the description of one or more of the embodiments. A module includes a processing module, a processor, a functional block, hardware, and/or memory that stores operational instructions for performing one or more functions as may be described herein. Note that, if the module is implemented via hardware, the hardware may operate independently and/or in conjunction with software and/or firmware. As also used herein, a module may contain one or more sub-modules, each of which may be one or more modules.

The one or more embodiments are used herein to illustrate one or more aspects, one or more features, one or more concepts, and/or one or more examples of the claimed subject matter. A physical embodiment of an apparatus, an article of manufacture, a machine, and/or of a process may include one or more of the aspects, features, concepts, examples, etc. described with reference to one or more of the embodiments discussed herein. Further, from figure to figure, the embodiments may incorporate the same or similarly named functions, steps, modules, etc. that may use the same or different reference numbers and, as such, the functions, steps, modules, etc. may be the same or similar functions, steps, modules, etc. or different ones. While the transistors in the above described figure(s) is/are shown as field effect transistors (FETs), as one of ordinary skill in the art will appreciate, the transistors may be implemented using any type of transistor structure including, but not limited to, bipolar, metal oxide semiconductor field effect transistors (MOSFET), N-well transistors, P-well transistors, enhancement mode, depletion mode, and zero voltage threshold (VT) transistors.