Patent Description:
A buck-boost circuit can effectively reduce system power consumption by regulating an output voltage. With the starting of the age of <NUM> communication, a circuit capable of boosting and bucking a voltage quickly is needed to ensure a smooth communication and facilitate reduction of the system power consumption.

The existing buck-boost structure takes a too long time to realize buck-boost switching. As a result, a voltage stabilization time is relatively long when regulating the output voltage, especially when switching from a bucking mode to a boosting mode, an intermediate switching process is time-consuming, and thus the voltage stabilization time is too long to meet a communication requirement of a system, which reduces signal sensitivity when using the system, thereby causing a communication failure. <CIT> refers to a power converter. The power converter comprises a voltage level increasing circuit which receives a DC-input voltage between first and second power converter inputs, and which has an output to supply an adapted input voltage having either a higher level than the input voltage or a polarity opposite to the input voltage. A down-converter has first and second down-converter inputs, a control switch with a main current path arranged between a first node and the first downconverter input, an inductor arranged between the first node and a load, and a sync switch arranged between the first node and the second down-converter input. A controller controls the control switch, and switches of the voltage level increasing circuit for either coupling the input voltage or the adapted input voltage to the first node or to the first or second downconverter inputs. <CIT> refers to a direct current voltage conversion circuit which can operate as a step-up circuit, a step-down circuit, or operate as a step-up or step-down circuit depending on the modes of operation.

Therefore, how to reduce the voltage stabilization time of the buck-boost circuit during voltage regulation and regulate the voltage quickly has become a big problem to be solved.

In view of the above, the present disclosure provides a buck-boost circuit according to independent device claim <NUM> or <NUM>, so that a voltage can be regulated quickly and stably.

According to an aspect of the present disclosure, a buck-boost circuit is provided. The buck-boost circuit includes a first switch, a second switch, a third switch, a fourth switch, a first inductor, a first capacitor, a second capacitor, a sixth switch connected in parallel with the first capacitor, and a control module configured to control switches based on a relationship between a target voltage Vtar and an input voltage VBAT. A first terminal of the first switch is connected to an anode of an input power supply. A first terminal of the second switch is connected to the anode of the input power supply. A first terminal of the third switch and a first terminal of the first capacitor are connected to a second terminal of the first switch. A second terminal of the third switch is connected to a cathode of the input power supply. A first terminal of the fourth switch, a second terminal of the first capacitor, and a first terminal of the first inductor are connected to a second terminal of the second switch. A second terminal of the fourth switch is connected to the cathode of the input power supply. A second terminal of the first inductor is connected to an anode of an output power supply. The second capacitor is connected in parallel between the anode and a cathode of the output power supply.

In an embodiment, the buck-boost circuit further includes a seventh switch connected in parallel with the first inductor.

In an embodiment, the control module is configured to:.

In an embodiment, the control module is further configured to turn on the sixth switch and the third switch to perform in response to Vout>Vtar+ΔV being satisfied and to turn off the sixth switch and the third switch in response to Vout=Vtar+ΔV being satisfied.

A buck-boost circuit includes a first switch, a second switch, a third switch, a fourth switch, a first inductor, a first capacitor, a second capacitor, a seventh switch connected in parallel with the first inductor, and a control module configured to control switches based on a relationship between a target voltage Vtar and an input voltage VBAT. A first terminal of the first switch is connected to an anode of an input power supply. A first terminal of the second switch is connected to the anode of the input power supply. A first terminal of the third switch and a first terminal of the first capacitor are connected to a second terminal of the first switch. A second terminal of the third switch is connected to a cathode of the input power supply. A first terminal of the fourth switch, a second terminal of the first capacitor, and a first terminal of the first inductor are connected to a second terminal of the second switch. A second terminal of the fourth switch is connected to the cathode of the input power supply. A second terminal of the first inductor is connected to an anode of an output power supply. The second capacitor is connected in parallel between the anode and a cathode of the output power supply.

In an embodiment, the buck-boost circuit further includes a fifth switch connected between the second terminal of the first capacitor and the second terminal of the second switch.

In an embodiment, the buck-boost circuit includes a sixth switch connected in parallel with the first capacitor, and the control module is configured to:.

In an embodiment, the buck-boost circuit includes a sixth switch connected in parallel with the first capacitor, and the control module is further configured to turn on the fifth switch in response to both Vout<Vtar-ΔV and Vtar>VBAT being satisfied and to turn off the fifth switch in response to Vout=VBAT being satisfied.

In an embodiment, the buck-boost circuit includes a sixth switch connected in parallel with the first capacitor, and the control module is further configured to turn on the sixth switch and the third switch to perform in response to Vout>Vtar+ΔV being satisfied and to turn off the sixth switch and the third switch in response to Vout=Vtar+ΔV being satisfied.

Twice an input supply voltage is generated on one terminal of the inductor when the capacitor and the switch work cooperate to operate, so that the buck-boost circuit in the present disclosure can quickly boost an output voltage in a boosting mode. In this way, a voltage stabilization time can be reduced when the buck-boost circuit regulates the output voltage, and the voltage are regulated quickly and stably.

According to the following detailed description of exemplary embodiments with reference to the accompanying drawings, other features and aspects of the present disclosure will become clear.

The accompanying drawings included in this specification and constituting a part of this specification, together with this specification, illustrate exemplary embodiments, features, and aspects of the present disclosure, and are used to explain the principle of the present disclosure.

Various exemplary embodiments, features, and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, unless otherwise noted, the accompanying drawings are not necessarily drawn to scale.

The dedicated word "exemplary" herein means "serving as an example, embodiment, or illustration". Any embodiment described herein as "exemplary" need not be construed as being superior to or better than other embodiments.

In addition, to better illustrate the present disclosure, numerous specific details are given in the following specific implementations. Those skilled in the art should understand that the present disclosure can also be implemented without certain specific details. In some examples, the methods, means, elements, and circuits well-known to those skilled in the art are not described in detail in order to highlight the subject matter of the present disclosure.

<FIG> is a structural diagram of a buck-boost circuit according to an embodiment of the present disclosure. As shown in <FIG>, the buck-boost circuit includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first inductor L1, a first capacitor C1, and a second capacitor C2.

A first terminal of the first switch S <NUM> is connected to an anode of an input power supply VBAT, a first terminal of the second switch S2 is connected to the anode of the input power supply VBAT, a first terminal of the third switch S3 and a first terminal of the first capacitor C1 are connected to a second terminal of the first switch S1, a second terminal of the third switch S3 is connected to a cathode of the input power supply VBAT (for example, for grounding), a first terminal of the fourth switch S4, a second terminal of the first capacitor C1, and a first terminal of the first inductor L1 are connected to a second terminal of the second switch S2, a second terminal of the fourth switch S4 is connected to the cathode of the input power supply VBAT (for example, for grounding), a second terminal of the first inductor L1 is connected to an anode of an output power supply Vout, and the second capacitor C2 is connected in parallel between the anode and a cathode of the output power supply Vout.

A control module can be provided to control a status of each switch based on a relationship between a target voltage Vtar and an input voltage VBAT, to realize bucking and boosting modes of the circuit. The control module can be implemented in the buck-boost circuit, or can be independent from the buck-boost circuit, and can execute, according to a preset program or an external instruction, control methods provided in some embodiments of the present disclosure to control the switch. The switch not mentioned in the control methods is in an off state by default.

A control method of the buck-boost circuit in <FIG> includes:.

In other words, when Vtar<VBAT-ΔV, the circuit operates in the bucking mode. ΔV represents the set voltage difference. It is defined as required, and for example, can be <NUM> mV, <NUM> mV, or the like. Referring to a switch status diagram shown in <FIG>, the first switch S1 and the third switch S3 are turned off, so that both S1 and S3 are in an off state, and the second switch S2 and the fourth switch S4 are complementarily tuned on. When the second switch S2 is turned on, a voltage at LX is VBAT, and an inductive current of the first inductor L1 increases linearly. When the second switch S2 is turned off and the fourth switch S4 is turned on, the voltage at the LX is <NUM>. Because the inductive current cannot change suddenly, a circuit is formed through the fourth switch S4 to charge the second capacitor C2. Each switch has an initial state of an off state by default.

According to the volt-second principle, it can be learned that a calculation formula of an output voltage is <MAT> where ton represents a turn-on time of the second switch, and ton/T represents a duty cycle of a control voltage of the second switch.

When VBAT-ΔV ≤Vtar≤VBAT+ΔV, the circuit operates in a bypass mode. Referring to a switch status diagram shown in <FIG>, the first switch S1 and the third switch S3 are in the off state, the second switch S2 is in a normally-open state (namely, the second switch S2 is in an ON state continuously), and the fourth switch S4 is in a normally-closed state. The second switch S4 is always turned on, and the voltage at LX is always VBAT. Therefore, Vout=VBAT.

When Vtar>VBAT+ΔV, the circuit operates in a boosting mode. Referring to a switch status diagram shown in <FIG>, the fourth switch S4 is in the off state, the second switch S2 and the third switch S3 operate simultaneously, and the second switch S2 and the first switch S <NUM> are complementarily turned on, in other words, the third switch S3 and the first switch S <NUM> are also complementarily turned on. When the second switch S2 and the third switch S3 are turned on, the voltage at LX is VBAT, and the inductive current of the first inductor L1 increases linearly. When the second switch S2 and the third switch S3 are turned off, and the first switch S <NUM> is turned on, the first inductor L1 charges the first capacitor C1 to enable the voltage at LX to reach 2VBAT.

According to the volt-second principle, it can be learned that the calculation formula of the output voltage is: <MAT>.

Twice the input supply voltage is generated on one terminal of the inductor when the capacitor and the switch cooperate to operate, so that the buck-boost circuit in this embodiment can quickly boost the output voltage in the boosting mode. In this way, a voltage stabilization time can be reduced when the buck-boost circuit regulates the output voltage, and the voltage can be regulated quickly and stably.

It should be noted that each switch provided in the embodiments of the present disclosure can be a semiconductor transistor, such as a bipolar transistor, a field effect transistor, or a switch of any other type.

<FIG> is a structural diagram of a buck-boost circuit according to an embodiment of the present disclosure. As shown in <FIG>, compared with the buck-boost circuit in <FIG>, the buck-boost circuit further includes a fifth switch S5. The fifth switch S5 is connected in series with the first capacitor C1, and is connected between the second terminal of the first capacitor C1 and the second terminal of the second switch, in other words, between being connected between the second terminal of the first capacitor C1 and the first terminal of the first inductor L1.

When the fifth switch S5 is in the normally-open state, an operation status of the buck-boost circuit is the same as that in <FIG>. S5 can be appropriately regulated based on an application scenario, so that the circuit can be applied more flexibly.

A first control method of the buck-boost circuit in <FIG> includes:.

In other words, when Vtar<VBAT-ΔV, the circuit operates in a bucking mode. Referring to a switch status diagram shown in <FIG>, the fifth switch S5 is in the off state, the second switch S2 and the fourth switch S4 are complementarily turned on, and the first switch S1 and the third switch S3 have opposite statuses or are both in an off state, in other words, S1 is turned on and S3 is turned off, S3 is turned on and S1 is turned off, or both S1 and S3 are turned off. When the second switch S2 is turned on, the voltage at LX is VBAT, and the inductive current of the first inductor L1 increases linearly. When the second switch S2 is turned off and the fourth switch S4 is turned on, the voltage at LX is <NUM>. Because the inductive current cannot change suddenly, the circuit is formed through the fourth switch S4 to charge the second capacitor C2.

When VBAT-ΔV ≤Vtar≤VBAT+ΔV, the circuit operates in a bucking and boosting mode, and a control method can be referred to <FIG>. The first switch S1 and the third switch S3 are complementarily turned on, the fourth switch S4 and the fifth switch S5 are complementarily turned on, and the second switch S2 is turned on from turning off of the first switch S1 to turning on of the fourth switch S4. When both the first switch S1 and the fifth switch S5 are turned on, the voltage at LX is 2VBAT, and a turn-on time of the first switch S1 is ton1, in other words, a time during which both the first switch S1 and the fifth switch S5 are turned on is ton1. When the first switch S1 is turned off and the second switch S2 is turned on, the voltage at LX is VBAT, and a turn-on time of the second switch S2 is ton2. When the fourth switch S4 is turned on, the voltage at LX is <NUM>. A desired output voltage is obtained by controlling ton1 and ton2. The calculation formula of the output voltage is: <MAT>.

When Vtar>VBAT+ΔV, the circuit operates in the boosting mode. Referring to a switch status diagram shown in <FIG>, the fifth switch S5 is turned on, the fourth switch S4 is turned off, the second switch S2 and the third switch S3 operates simultaneously, and the second switch S2 and the first switch S1 are complementarily turned on. The operation mode is the same as the boosting mode in <FIG>.

A second control method of the buck-boost circuit in <FIG> includes:.

The control method is different from the first control method only when VBAT-ΔV≤Vtar≤VBAT+ΔV.

When VBAT-ΔV ≤Vtar≤VBAT+ΔV, the circuit operates in a bucking and boosting mode. A control method can be referred to <FIG>. The first switch S1 and the third switch S3 are complementarily turned on, the fourth switch S4 and the fifth switch S5 are complementarily turned on, and the second switch S2 is turned on from turning-off of the fourth switch S4 to turning-on of the first switch S1. When the fourth switch S4 is turned on, the voltage at LX is <NUM>. When the fourth switch S4 is turned off and the second switch S2 is turned on, the voltage at LX is VBAT, and a turning-on time of the second switch S2 is ton2. When the first switch S1 is turned on, the voltage at LX is 2VBAT, and a turning-on time of the first switch S1 is ton1. Similarly, a desired output voltage is obtained by controlling ton1 and ton2. The calculation formula of the output voltage is the same as the formula (<NUM>).

<FIG> is a structural diagram of a buck-boost circuit according to an embodiment of the present disclosure. As shown in <FIG>, compared with the buck-boost circuit in <FIG>, the buck-boost circuit further includes a sixth switch S6. The sixth switch S6 is connected in parallel to the first capacitor C1, and is connected between the second terminal of the first switch S1 and the first terminal of the first inductor.

When the sixth switch S6 is in the normally-closed state (in other words, is always turned off), an operation status of the buck-boost circuit is the same as that in <FIG>.

In other words, when Vtar<VBAT-ΔV, the circuit operates in the bucking mode. Referring to a switch status diagram shown in <FIG>, the sixth switch S6 is turned on, the first switch S1 and the second switch S2 operate simultaneously, the third switch S3 and the fourth switch S4 operate simultaneously, and the first switch S1 and the third switch S3 are complementarily turned on. When the first switch S1 and the second switch S2 are turned on, the voltage at LX is VBAT. When the first switch S1 and the second switch S2 are turned off, and the third switch and the fourth switch S4 are turned on, the voltage at LX is <NUM>.

When VBAT-ΔV ≤Vtar≤VBAT+ΔV, the circuit operates in the bypass mode. Referring to a switch status diagram shown in <FIG>, the first switch S1, the third switch S3, and the fourth switch S4 are turned off, and the second switch S2 and the sixth switch S6 are turned on.

When Vtar>VBAT+ΔV, the circuit operates in the boosting mode. Referring to a switch status diagram shown in <FIG>, the fourth switch S4 and the sixth switch S6 are turned off, the second switch S2 and the third switch S3 operate simultaneously, and the second switch S2 and the first switch S1 are complementarily turned on. When the first switch S1 is turned on, the voltage at LX is 2VBAT. When the first switch S1 is turned off, and the second switch S2 and the third switch S3 are turned on, the voltage at LX is VBAT. In other words, the sixth switch is in the normally-closed state, which is the same as that in the boosting mode in <FIG>.

<FIG> is a structural diagram of a buck-boost circuit according to an embodiment of the present disclosure. As shown in <FIG>, compared with the buck-boost circuit in <FIG>, the buck-boost circuit further includes a seventh switch S7. The seventh switch S7 is connected in parallel with the first inductor L1, and is connected between the second terminal of the second switch S1 and the anode of the output power supply.

When the seventh switch S7 is in the normally-closed state, the circuit is the same as that in <FIG>. When the output voltage of the circuit is required to be regulated, the seventh switch S7 is turned on to charge or discharge the output capacitor quickly, so that the output voltage can be quickly regulated to the target voltage.

The control module controls the switches based on the relationship between the output voltage Vout and the target voltage Vtar and the relationship between the target voltage Vtar and the input voltage VBAT, and such controlling includes:.

<FIG> shows an output voltage and a switch status in a boosting process of the buck-boost circuit in this embodiment. When Vout<Vtar-ΔV and Vtar≤VBAT, as represented by the first half of an output voltage curve in <FIG>, the circuit is essentially a bucking circuit, and the actual output voltage is smaller than the target voltage, and needs to be boosted to reach the target voltage, in other words, the output voltage is in a boosting state.

At an initial stage, the supply voltage VBAT is higher than the output voltage. Firstly, the fourth switch S4 is turned off, and the second switch S2 and the seventh switch S7 are turned on to quickly charge the second capacitor C2 connected to the output terminal of the buck-boost circuit. The output voltage is boosted quickly. When the output voltage is smaller than the target voltage by ΔV, namely, Vout=Vtar-ΔV, the seventh switch S7 is turned off to stop quick charging. The circuit is restored to the structure in <FIG>, and enters a control process of the buck-boost circuit in <FIG>, in other words, entering the first operation mode. The output voltage is gradually regulated to the target voltage Vtar, and Vtar is stably output.

When Vtar>VBAT, as represented by the last half of the output voltage curve in <FIG>, the circuit is essentially a boosting circuit, and the actual output voltage needs to be boosted to reach the target voltage, in other words, the output voltage is in the boosting state. Firstly, the second switch S2, the third switch S3, and the seventh switch S7 are turned on. When the output voltage reaches VBAT, the second switch S2 and the third switch S3 are turned off, and the first switch S1 is turned on to continue to quickly charge the second capacitor C2 through the first capacitor C1. When the output voltage is smaller than the target voltage by ΔV, the first switch S1 and the seventh switch S7 are turned off. The circuit is restored to the structure in <FIG>, and enters the control process of the buck-boost circuit in <FIG>, in other words, entering the first operation mode.

<FIG> shows an output voltage and a switch status in a bucking process of the buck-boost circuit in this embodiment. When Vout>Vtar+ΔV, as represented by an output voltage curve in <FIG>, the actual output voltage is greater than the target voltage, and needs to be bucked to reach the target voltage, in other words, the output voltage is in a bucking state.

Firstly, the seventh switch S7 and the fourth switch S4 are turned on to discharge the second capacitor C2 connected to the output terminal. When the voltage is greater than the target voltage by ΔV, namely, Vout=Vtar+ΔV, the seventh switch S7 and the fourth switch S4 are turned off. The circuit is restored to the structure in <FIG>, and enters the control process of the buck-boost circuit in <FIG>, in other words, entering the first operation mode.

When the seventh switch S7 is in the normally-closed state, the circuit is the same as that in <FIG>. When the fifth switch S7 is in the normally-open state, the operation status is similar to that of the buck-boost circuit in <FIG>, and a difference is that the control module is further configured to turn on the fifth switch S5 when Vout<Vtar-ΔV and Vtar>VBAT, and to turn off the fifth switch S5 when Vout=VBAT.

In other words, in a boosting process, when Vout>VBAT, the fifth switch S5 needs to be turned on. A control method is shown in <FIG>. Control methods of the first switch S1, the second switch S2, the third switch S3, and the seventh switch S7 are the same as those in the boosting process of the buck-boost circuit in <FIG>.

When the seventh switch S7 is in the normally-closed state, the circuit is the same as that in <FIG>. When the sixth switch S6 is in the off state, the operation status is similar to that of the buck-boost circuit in <FIG>, and a difference is that the control module is further configured to turn on the sixth switch S6 and the third switch S3 to perform discharging when Vout>Vtar+ΔV, and to turn off the sixth switch S6 and the third switch S3 when Vout=Vtar+ΔV.

Claim 1:
A buck-boost circuit, comprising a first switch (S1), a second switch (S2), a third switch (S3), a fourth switch (S4), a first inductor (L1), a first capacitor (C1), a second capacitor (C2), and a control module configured to control switches based on a relationship between a target voltage Vtar and an input voltage VBAT;
wherein a first terminal of the first switch (S1) is connected to an anode of an input power supply (VBAT); a first terminal of the second switch (S2) is connected to the anode of the input power supply (VBAT); a first terminal of the third switch (S3) and a first terminal of the first capacitor (C1) are connected to a second terminal of the first switch (S1); a second terminal of the third switch (S3) is connected to a cathode of the input power supply (VBAT); a first terminal of the fourth switch (S4), a second terminal of the first capacitor (C1), and a first terminal of the first inductor (L1) are connected to a second terminal of the second switch (S2); a second terminal of the fourth switch (S4) is connected to the cathode of the input power supply (VBAT); a second terminal of the first inductor (L1) is connected to an anode of an output power supply (Vout); and the second capacitor (C2) is connected in parallel between the anode and a cathode of the output power supply (Vout),
the buck-boost circuit is characterised by
a sixth switch (S6) connected in parallel with the first capacitor (C1).