TWI777736B - Buck-boost switching regulator having bypass mode and control method thereof - Google Patents

Abstract

The present invention discloses a buck-boost switching regulator, including: a power switch circuit including an input switch unit and an output switch unit which switch a first terminal and a second terminal of an inductor for buck-boost conversion; at least one low dropout regulator correspondingly coupled to at least one output high side switch in the output switch unit to correspondingly convert the at least one low dropout voltage into at least one output voltage; and a bypass control circuit configured to operably generate a bypass control signal according to a conversion voltage difference between the input voltage and the corresponding low dropout voltage; wherein when the corresponding conversion voltage difference is below a reference voltage, the bypass control signal controls a corresponding bypass switch to electrically connect the input voltage with the corresponding low dropout node.

Description

Buck-boost switching power supply circuit with bypass mode and control method thereof

The present invention relates to a buck-boost switching power supply circuit, in particular to a buck-boost switching power supply circuit with a bypass mode. The present invention also relates to a control method of a buck-boost switching power supply circuit.

Please refer to FIG. 1, which shows a conventional single-input multiple-output buck-boost switching power converter. The low dropout voltages VINLDO[1], VINLDO[2] and VINLDO[3] of the conventional single-input multiple-output buck-boost switching power converter are respectively converted into an output voltage VOUT[ 1], VOUT[2], and VOUT[3]. When the input voltage VIN is close to the low dropout voltages VINLDO[1], VINLDO[2] and VINLDO[3], the switching loss of the single-input multiple-output buck-boost switching power converter is relatively increased, resulting in a low overall power conversion efficiency .

In view of this, the present invention addresses the above-mentioned shortcomings of the prior art, and provides a buck-boost switching power supply circuit that can reduce switching losses in a bypass mode when the input voltage is close to the low dropout voltage to improve efficiency.

In one aspect, the present invention provides a buck-boost switching power supply circuit for converting an input voltage into at least an output voltage, comprising: a power switch circuit including an input switch unit and an output switch unit, wherein The input switch unit is used for switching a first terminal of an inductor between the input voltage and a ground potential, and the output switch unit is used for switching a second terminal of the inductor between at least a low dropout node and the ground potential, to convert the input voltage into at least one corresponding low dropout voltage at the at least one low dropout node, and the at least one low dropout node is correspondingly coupled with at least one output high-bridge switch in the output switch unit; at least one low dropout voltage A low dropout regulator (LDO) is correspondingly coupled with the at least one output high-bridge switch, so as to convert the at least one low dropout voltage into the at least one output voltage correspondingly; a bypass control circuit is used for to generate a bypass control signal according to a switching voltage difference between the input voltage and the corresponding low dropout voltage; and a bypass switching circuit, wherein the bypass control signal corresponds to the switching voltage difference lower than a reference voltage , controlling the bypass switching circuit to electrically connect the input voltage with the corresponding low-dropout node, so that the buck-boost switching power supply circuit operates in a bypass mode.

In one embodiment, the bypass switching circuit includes the corresponding output high-bridge switch and an input high-bridge switch in the input switch unit, and the bypass control circuit corresponds to when the switching voltage difference is lower than the reference voltage. generating the corresponding bypass control signal to control both the output high-bridge switch and the input high-bridge switch to be turned on, so as to electrically connect the input voltage and the corresponding low-dropout node through the inductor.

In one embodiment, the bypass switching circuit includes at least one bypass switch, and the at least one bypass switch is directly electrically connected between the input voltage and the corresponding low-dropout node, so that the corresponding switching voltage difference is lower than the When the reference voltage is used, the corresponding bypass switch is controlled to be turned on, so as to directly electrically connect the input voltage with the corresponding low-dropout node.

In one embodiment, the converted voltage difference is the absolute value of the difference between the input voltage and the corresponding low dropout voltage.

In one embodiment, the reference voltage includes a first reference voltage and a second reference voltage, wherein when the difference between the corresponding low dropout voltage minus the input voltage is lower than the first reference voltage, and the input voltage When the difference value minus the corresponding low dropout voltage is lower than the second reference voltage, the corresponding bypass control signal is enabled, wherein the first reference voltage and the second reference voltage have one of the following relationships: ( 1) the first reference voltage is equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is zero; (2) the first reference voltage is equal to zero, and the second reference voltage is not zero; (3) the second reference voltage is equal to zero, and the first reference voltage is not zero; or (4) the first reference voltage is not equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is equal to zero.

In one embodiment, the bypass control circuit includes: a threshold control circuit for generating an upper threshold and a lower threshold according to the reference voltage; and a comparison circuit for comparing a signal to be compared with the upper limit a threshold and the lower threshold, when the signal to be compared is between the upper threshold and the lower threshold, the corresponding bypass control signal is enabled to electrically connect the input voltage with the corresponding low dropout node, wherein The signal to be compared, the upper threshold and the lower threshold have one of the following relationships: (1) the signal to be compared is the corresponding conversion voltage difference, the upper threshold is the first reference voltage, and the lower threshold is the second a reference voltage; (2) the signal to be compared is the corresponding low dropout voltage, the upper threshold is the sum of the input voltage and the first reference voltage, and the lower threshold is the difference between the input voltage and the second reference voltage; (3) The signal to be compared is the input voltage, the upper threshold is the sum of the corresponding low dropout voltage and the second reference voltage, and the lower threshold is the difference between the corresponding low dropout voltage and the first reference voltage.

In one embodiment, the input switch unit includes: an input high bridge switch coupled between the input voltage and the first end of the inductor; and an input low bridge switch or an input low bridge diode, is coupled between the ground potential and the first end of the inductor; wherein the input is bridged The switch, and the input low-bridge switch or the input low-bridge diode, are used for switching the first end of the inductor between the input voltage and the ground potential.

In one embodiment, the output switch unit includes: an output lower bridge switch, coupled between the ground potential and the second end of the inductor; and the at least one output upper bridge switch, respectively coupled to the between at least one low dropout node and the second end of the inductor; wherein the output lower bridge switch and the at least one output upper bridge switch are used to switch the second end of the inductor between the at least one low dropout node and the The ground potential, thereby generating the corresponding at least one low dropout voltage at the at least one low dropout node.

In one embodiment, when the corresponding conversion voltage difference is greater than or equal to the reference voltage, the buck-boost switching power supply circuit is further operated in a buck (buck) according to the input voltage and the corresponding low-dropout voltage, respectively. ) mode and a boost mode.

In one embodiment, the buck-boost switching power supply circuit operates in the boost mode when the difference between the corresponding low dropout voltage and the input voltage is greater than or equal to the first reference voltage, and the input When the difference between the voltage minus the corresponding low dropout voltage is greater than or equal to the second reference voltage, the step-down mode is operated.

In one embodiment, when the corresponding conversion voltage difference is greater than or equal to the reference voltage, the buck-boost switching power circuit is further operated in a buck boost according to the input voltage and the corresponding low-dropout voltage. )model.

In an embodiment, the conversion voltage difference is from large to small, and the corresponding mode is operated according to one of the following sequences: (1) the boost mode, the buck-boost mode, the bypass mode, the buck mode ; (2) the boost mode, the bypass mode, the buck-boost mode, the buck mode; (3) the boost mode, the buck-boost mode, the bypass mode, the buck-boost mode, the buck model.

In one embodiment, at least one of the low dropout voltage regulators is a negative voltage generating circuit, wherein the negative voltage generating circuit includes: a negative charge pump coupled to the corresponding low dropout node for using converting the corresponding low dropout voltage into a negative low dropout voltage; and at least one negative low dropout voltage regulator coupled to the negative charge pump for converting the negative low dropout voltage into a corresponding at least one negative low dropout voltage The output voltage.

In another aspect, the present invention provides a control method for controlling a buck-boost switching power supply circuit for converting an input voltage into at least one output voltage, the buck-boost switching power supply circuit comprising a power switch circuit , the power switch circuit includes an input switch unit and an output switch unit, wherein the input switch unit is used for switching a first end of an inductor between the input voltage and a ground potential, and the output switch unit is used for the inductor A second terminal is switched between at least one low dropout node and the ground potential to convert the input voltage at the at least one low dropout node to a corresponding at least one low dropout voltage, and the at least one low dropout node and the output At least one output high-bridge switch in the switch unit is correspondingly coupled; the control method includes: using at least one low dropout voltage regulator to correspondingly convert the at least one low dropout voltage into the at least one output voltage; according to the input voltage and the corresponding A switching voltage difference between the low dropout voltages generates a bypass control signal; and when the corresponding switching voltage difference is lower than a reference voltage, the bypass control signal controls the input voltage and the corresponding low dropout node The electrical connection enables the buck-boost switching power supply circuit to operate in a bypass mode.

In one embodiment, when the corresponding conversion voltage difference is lower than the reference voltage, the bypass control signal controls both the output high-bridge switch and the input high-bridge switch to be turned on, so that the input voltage and the corresponding input high-bridge switch are both turned on. The low dropout node is electrically connected via the inductor.

In one embodiment, when the corresponding conversion voltage difference is lower than the reference voltage, the corresponding one of the at least one bypass switch is controlled to be turned on, so that the input voltage is directly connected to the corresponding low dropout node. connection, wherein the at least one bypass switch is directly electrically connected between the input voltage and the corresponding low dropout node.

In one embodiment, the converted voltage difference is the absolute value of the difference between the input voltage and the corresponding low dropout voltage.

In one embodiment, the reference voltage includes a first reference voltage and a second reference voltage, wherein when the difference between the low dropout voltage minus the input voltage is lower than the first reference voltage, and the input voltage minus When the difference between the low dropout voltages is lower than the second reference voltage, the corresponding bypass control signal is enabled, wherein the first reference voltage and the second reference voltage have one of the following relationships: (1) the first reference voltage A reference voltage is equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is zero; (2) the first reference voltage is equal to zero, and the second reference voltage is not zero; (3) the The second reference voltage is equal to zero, and the first reference voltage is not zero; or (4) the first reference voltage is not equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is zero.

In one embodiment, the step of generating the bypass control signal includes: generating an upper threshold and a lower threshold according to the reference voltage; and comparing a signal to be compared with the upper threshold and the lower threshold, when the When the comparison signal is between the upper threshold and the lower threshold, the corresponding bypass control signal is enabled to electrically connect the input voltage with the corresponding low dropout node, wherein the signal to be compared, the upper threshold and The lower threshold has one of the following relationships: (1) the signal to be compared is the corresponding conversion voltage difference, the upper threshold is the first reference voltage, and the lower threshold is the second reference voltage; (2) the to-be-compared The signal is the corresponding low dropout voltage, the upper threshold is the sum of the input voltage and the first reference voltage, and the lower threshold is the difference between the input voltage and the second reference voltage; (3) the signal to be compared is the For the input voltage, the upper threshold is the sum of the corresponding low dropout voltage and the second reference voltage, and the lower threshold is the difference between the corresponding low dropout voltage and the first reference voltage.

In one embodiment, when the corresponding conversion voltage difference is greater than or equal to the reference voltage, the buck-boost switching power supply circuit is further operated in a buck according to the input voltage and the corresponding low dropout voltage, respectively. mode and a boost mode.

In an embodiment, when the difference between the corresponding low dropout voltage and the input voltage is greater than or equal to the first reference voltage, the buck-boost switching power supply circuit is controlled to operate in the boost mode, and the input When the difference between the voltage minus the corresponding low dropout voltage is greater than or equal to the second reference voltage, the buck-boost switching power supply circuit is controlled to operate in the buck mode.

In one embodiment, when the corresponding conversion voltage difference is greater than or equal to the reference voltage, according to the input voltage and the corresponding low dropout voltage, the buck-boost switching power supply circuit is further operated in a buck boost (buck boost) )model.

In one embodiment, the conversion voltage difference is from large to small, and the buck-boost switching power supply circuit is operated in a corresponding mode according to one of the following sequences: (1) the boost mode, the buck-boost mode, the Bypass mode, the buck mode; (2) the boost mode, the bypass mode, the buck-boost mode, the buck mode; (3) the boost mode, the buck-boost mode, the bypass mode, The buck-boost mode, the buck mode.

In one embodiment, the control method for controlling a buck-boost switching power supply circuit of the present invention further comprises: converting the corresponding low dropout voltage into a negative low dropout voltage; and converting the negative low dropout voltage into a corresponding low dropout voltage of the at least one negative output voltage.

One advantage of the present invention is that the present invention can have higher efficiency and lower switching loss when the input voltage is close to the low dropout voltage.

Another advantage of the present invention is that because the present invention directly bypasses the input voltage to the input terminal of the low dropout voltage regulator, more voltage drop space of the low dropout voltage regulator can be obtained.

Another advantage of the present invention is that the present invention can save the layout area of the bypass switch.

The following describes in detail with specific embodiments, when it is easier to understand the purpose, technical content, characteristics and effects of the present invention.

10, 20, 30, 40, 50, 60, 70, 80, 90: Buck-Boost switching power supply circuit

100: Control method of buck-boost switching power supply circuit

101, 201, 301, 401, 501, 601, 701, 801, 901: Power Switch Circuits

1001, 10011, 10012, 1002, 1003, 10031a, 10031b: Steps

1011, 2011, 3011, 4011, 5011, 6011, 7011, 8011, 9011: Input switch unit

1012, 2012, 3012, 4012, 5012, 6012, 7012, 8012, 9012: Output switch unit

102[1:n],202[1]~202[n],302[1]~302[n],402[1],402[2],502[1],502[2],602[1 ],602[2],702,902[1]: Low dropout regulator

103, 203, 203', 303, 403, 503, 603, 703, 803, 903: Bypass control circuit

104[1:n], 204[1:n], 304[1:n], 404[1:n], 504[1:n], 604[1:n], 704, 804, 904: Low dropout nodes

2031[k], 3031[k]: Threshold control circuit

2032[k], 2032'a[k], 2032'b[k], 3032[k]: Comparison circuit

2033a[k], 2033b[k], 3033a[k], 3033b[k]: switch

2034’[k]: Reverse and gate

305, 405, 505, 605, 705, 805, 905: Conversion Control Circuits

402[n], 502[n-x+1], 502[n], 602[n], 802, 902[2]: Negative pressure generating circuit

406,506[1]~506[x],606,806,906: negative charge pump

407,507[1]~507[x],607[1]~607[x],807,907: Negative Low Dropout Regulator

408, 508, 608, 708, 808, 908: Bypass Switching Circuits

A: Input bridge switch

B: Input lower bridge switch

C: Output lower bridge switch

CPOL[k], CPOU[k]: Comparison result

Cs1[k], Cs2[k]: Control signal

D[1:n], D[1]~D[n]: output bridge switch

E[1:n], E[1]~E[n]: Bypass switch

L: Inductance

LX1: first end

LX2: second end

NVINLDO, NVINLDO[1]~NVINLDO[x]: Negative low dropout voltage

NVOUT,NVOUT[1]~NVOUT[x]: Negative output voltage

VA,VB,VC,VD[1:n]: Control signal

VE[1:n],VE[k],VE[1],VE[2]~VE[n]: Bypass control signal

VIN: input voltage

VIN_S: Input voltage sensing signal

VINLDO, VINLDO[1:n], VINLDO[1], VINLDO[2], VINLDO[3], VINLDO[n-x+1], VINLDO[n]: Low dropout voltage

VINLDO[1:n]_S, VINLDO[k]_S: Low dropout voltage sensing signal

Vref1: The first reference voltage

Vref2: The second reference voltage

VTC,VTC[k]: Signal to be compared

VthL, VthL[k]: lower threshold

VthM1: First Mediation Threshold

VthM2: Second Mediation Threshold

VthU, VthU[k]: upper threshold

VOUT[1:n],VOUT[1],VOUT[2],VOUT[3]: output voltage

FIG. 1 is a schematic diagram showing a conventional single-input multiple-output buck-boost switching power converter.

FIG. 2 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to an embodiment of the present invention.

3A is a schematic circuit diagram showing a buck-boost switching power supply circuit according to another embodiment of the present invention.

3B is a comparison table showing the signals in the bypass control circuit of the buck-boost switching power supply circuit according to an embodiment of the present invention.

3C is a schematic circuit diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention.

3D is a schematic circuit diagram showing another embodiment of the bypass control circuit of the buck-boost switching power supply circuit of FIGS. 3A and 3C according to an embodiment of the present invention.

FIG. 4 is a characteristic diagram showing an operation mode of a buck-boost switching power supply circuit according to an embodiment of the present invention.

FIG. 5 is a schematic diagram showing signal waveforms of the circuit of FIG. 3A .

6 is a circuit schematic diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

FIG. 7 is a circuit schematic diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention.

FIG. 8 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

FIG. 9 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention.

FIG. 10 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

FIG. 11 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

FIG. 12A is a characteristic diagram showing the operation mode of a buck-boost switching power supply circuit according to an embodiment of the present invention.

12B is a characteristic diagram showing an operation mode of a buck-boost switching power supply circuit according to another embodiment of the present invention.

FIG. 12C is a characteristic diagram showing an operation mode of a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

13 is a schematic diagram showing signal waveforms of the circuit of FIG. 3C operating in the operation mode of FIG. 12A according to an embodiment of the present invention.

FIG. 14 shows a control method of a buck-boost switching power supply circuit according to yet another embodiment of the present invention.

FIG. 15 shows a control method of a buck-boost switching power supply circuit according to another embodiment of the present invention.

The drawings in the invention are schematic, mainly intended to represent the coupling relationship between the circuits and the relationship between the signal waveforms, and the circuits, signal waveforms and frequencies are not drawn to scale.

FIG. 2 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to an embodiment of the present invention. The buck-boost switching power supply circuit 10 of the present invention includes a power switch circuit 101 , a low dropout voltage regulator 102 [1:n], a bypass switching circuit 105 and a bypass control circuit 103 . where n is a positive integer greater than or equal to 1.

The power switch circuit 101 includes an input switch unit 1011 and an output switch unit 1012, wherein the input switch unit 1011 is used to switch the first end of the inductor L (eg, LX1 shown in FIG. 2 ) between the input voltage VIN and the ground potential, and the output switch The unit 1012 is used to switch the second terminal of the inductor L (eg, LX2 shown in FIG. 2 ) between the low dropout node 104 [1:n] and the ground potential. The low dropout nodes 104[1:n] have corresponding low dropout voltages VINLDO[1:n], respectively. From one point of view, the power switch circuit 101 and the inductor L together form a buck-boost switching power supply circuit for converting the input voltage VIN into a low dropout voltage VINLDO[1:n], wherein the input voltage VIN can be greater than, equal to or Less than the low dropout voltage VINLDO[1:n].

Please continue to refer to FIG. 2 , at least one low dropout regulator (LDO) 102[1:n] is coupled to the output switch unit 1012 for correspondingly converting the low dropout voltages VINLDO[1:n] is the output voltage VOUT[1:n]. The bypass control circuit 103 is used for generating the bypass control signal VE[1:n] according to the conversion voltage difference between the input voltage VIN and the corresponding low dropout voltage VINLDO[1:n], wherein the conversion voltage difference refers to the input voltage The difference between VIN and the corresponding low dropout voltage VINLDO[1:n]. The bypass control signal VE[1:n] controls the bypass switching circuit 105 when the corresponding conversion voltage difference is lower than the reference voltage, so as to switch the input voltage VIN to the corresponding low dropout node 104[1:n] respectively. connected so that the buck-boost switching power supply circuit operates in a bypass mode.

Please also refer to FIG. 4 . FIG. 4 is a characteristic diagram showing the operation mode of the buck-boost switching power supply circuit according to an embodiment of the present invention. In one embodiment, the buck-boost switching power supply circuit of the present invention can operate in a bypass mode. The buck-boost switching power supply circuit of the present invention operates in a bypass mode when the conversion voltage difference is lower than the reference voltage.

Taking FIG. 4 as an example, the above-mentioned reference voltages may include a first reference voltage Vref1 and a second reference voltage Vref2. In this embodiment, when VINLDO-VIN<Vref1 and VIN-VINLDO<Vref2, the bypass mode is operated.

Please continue to refer to FIG. 2 . In one embodiment, as shown in FIG. 2 , the bypass switching circuit 105 includes bypass switches E[1:n], and the bypass control signals VE[1:n] correspond to the corresponding switching voltage differences When the voltage is lower than the reference voltage, the corresponding bypass switches E[1:n] are respectively controlled to electrically connect the input voltage VIN to the corresponding low-dropout node 104[1:n]. In the embodiment shown in FIG. 2 , the bypass switch E[1:n] is directly electrically connected between the input voltage VIN and the corresponding low dropout node 104[1:n], so that the corresponding conversion voltage difference is low At the reference voltage, the corresponding bypass switches E[1:n] are controlled to directly electrically connect the input voltage VIN and the corresponding low-dropout nodes 104[1:n]. In one embodiment, the conversion voltage difference is the absolute value of the difference between the input voltage VIN and the corresponding low dropout voltage VINLDO[1:n].

3A is a schematic circuit diagram showing a buck-boost switching power supply circuit with a single input and at least one output according to another embodiment of the present invention. In this embodiment, the inductor L, the power switch circuit 201, the low dropout voltage regulator 202[1:n], and the bypass switch E[1:n] are similar to the inductor L, the power switch circuit 101, and the low dropout switch in FIG. 2 . The voltage regulator 102[1:n] and the bypass switch E[1:n] are omitted. As shown in FIG. 3A , the input switch unit 2011 includes an input high-bridge switch A and an input low-bridge switch B (or, in one embodiment, an input low-bridge diode). The input high bridge switch A is coupled between the input voltage VIN and the first terminal LX1 of the inductor L, and the input low bridge switch B is coupled between the ground potential and the first terminal LX1 of the inductor L. The control signals VA and VB are used to control the input high-bridge switch A, or control the input high-bridge switch A and the input low-bridge switch B to switch the first terminal LX1 of the inductor L between the input voltage VIN and ground potential. The output switch unit 2012 includes an output lower bridge switch C and at least one output upper bridge switch D[1:n]. The output lower bridge switch C is coupled between the ground potential and the second terminal LX2 of the inductor L, and the output upper bridge switches D[1:n] are respectively coupled to the low dropout voltage VINLDO[1:n] and the inductor L respectively between the second end LX2. The control signals VC and VD[1:n] are used to control the output lower bridge switch C and the output upper bridge switch D[1:n], so as to switch the second end LX2 of the inductor L to the corresponding low dropout voltage VINLDO[1 :n] and ground potential, thereby converting the input voltage VIN into the corresponding low dropout voltage VINLDO[1:n]. The low dropout node 204[1:n] is correspondingly coupled to the output high-bridge switch D[1:n] in the output switch unit 2012 . where n is a positive integer greater than or equal to 1.

As shown in FIG. 3A , the bypass control circuit 203 includes a threshold control circuit 2031[k] and a comparison circuit 2032[k]. The threshold control circuit 2031[k] is used for generating an upper threshold VthU[k], a lower threshold VthL[k] and complex control signals Cs1[k], Cs2[k] according to the reference voltage. The complex control signals Cs1[k] and Cs2[k] are used to control the switches 2033a[k] and 2033b[k] respectively, so that the lower threshold VthL[k] and the upper threshold VthU[k] are respectively input to the comparison circuit 2032 [ k]. The comparison circuit 2032[k] is used for comparing a to-be-compared signal VTC[k] with the upper threshold VthU[k] and the lower threshold VthL[k]. When the signal to be compared VTC[k] is between the upper threshold VthU[k] and the lower threshold VthL[k], the bypass control signal VE[k] is enabled, and the bypass switch E[k] is turned on to enter the bypass Bypass mode is used to electrically connect the input voltage VIN to the corresponding low dropout node 204[k]. It should be noted that, in the embodiment shown in FIG. 3A, in the embodiment where n is greater than 1, only one or more of the n channels may enter the bypass mode, and the other channels still maintain the normal operation mode. Such as boost mode or buck mode. It should be noted that the aforementioned sequence number k is any one of 1 to n. In addition, it should be noted that the bypass control circuit 203 of the buck-boost switching power supply circuit 20 of the present invention is not limited to the structure shown in FIG. 3A, and any other feasible structure can also be used. The structure shown in FIG. to illustrate the present invention, but not to limit the scope of the present invention.

3B is a comparison table of the signals in the bypass control circuit of the buck-boost switching power supply circuit according to an embodiment of the present invention, which lists the signal to be compared VTC[k], the upper threshold VthU[k] and the lower threshold Example of VthL[k]. In one embodiment, the signal to be compared VTC[k], the upper threshold VthU[k] and the lower threshold VthL[k] have one of the following relationships: (1) The signal to be compared VTC[k] is the conversion voltage difference VINLDO[ k]-VIN, the upper threshold VthU[k] is the first reference voltage Vref1, and the lower threshold VthL[k] is the second reference voltage Vref2; (2) the signal to be compared VTC[k] is the low dropout voltage VINLDO[k], The upper threshold VthU[k] is the sum of the input voltage VIN and the first reference voltage Vref1, and the lower threshold VthL[k] is the difference between the input voltage VIN and the second reference voltage Vref2; (3) the signal to be compared VTC[k] is the input voltage VIN, the upper threshold VthU[k] is the sum of the low dropout voltage VINLDO[k] and the second reference voltage Vref2, and the lower threshold VthL[k] is the low dropout voltage VINLDO[k] and the first reference voltage Vref1 Difference.

Specifically, in one embodiment, when the signal to be compared VTC[k] is the input voltage sensing signal VIN_S, the upper threshold VthU[k] is the low dropout voltage sensing signal VINLDO[k]_S plus the second reference The value of the voltage Vref2 and the lower threshold VthL[k] are the value of the low dropout voltage sensing signal VINLDO[k]_S minus the first reference voltage Vref1. In another embodiment, when the signal to be compared VTC[k] is the low dropout voltage sensing signal VINLDO[k]_S, the upper threshold VthU[k] is the input voltage sensing signal VIN_S plus the first reference voltage Vref1. The lower threshold VthL[k] is the value of the input voltage sensing signal VIN_S minus the second reference voltage Vref2. In yet another embodiment, when the signal to be compared VTC[k] is the value of the low dropout voltage sensing signal VINLDO[k]_S minus the input voltage sensing signal VIN_S, the upper threshold VthU[k] is the first reference voltage Vref1, the lower threshold VthL[k] is the second reference voltage Vref2. The input voltage sensing signal VIN_S is a sensing signal corresponding to the input voltage VIN, and the low dropout voltage sensing signal VINLDO[k]_S is a sensing signal corresponding to the low dropout voltage VINLDO[k].

3C is a schematic circuit diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention. The inductor L, the power switch circuit 301, and the low dropout voltage regulator 302[1:n] in this embodiment are similar to the inductor L, the power switch circuit 101, and the low dropout voltage regulator 102[1:n] in FIG. 2. The input switch unit 3011 , the output switch unit 3012 , and the bypass control circuit 303 in this embodiment are similar to the input switch unit 2011 , the output switch unit 2012 , and the bypass control circuit 203 in FIG. 3A , so their descriptions are omitted. The difference between this embodiment and the embodiment of FIG. 3A is that the bypass mode of this embodiment controls the input high-bridge switch A and the output high-bridge switch D[1:n] to be turned on, that is, the bypass mode in this embodiment The switching circuit 308 includes the corresponding output high-bridge switch D[1:n] and one input high-bridge switch A in the input switch unit, so this embodiment does not need an additional bypass switch, which can save the layout of the additional bypass switch (layout) area. The bypass control circuit 303 generates a bypass control signal VE[1:n] to the conversion control circuit 305 when the switching voltage difference is lower than the reference voltage. The conversion control circuit 305 generates control signals VA, VB, VC and VD[1:n] according to the bypass control signals VE[1:n] to control the corresponding output high-bridge switches D[1:n] and input high-bridge switches A, to electrically connect the input voltage VIN and the corresponding low dropout node 304[1:n] through the inductor L. In one embodiment, the conversion control circuit 305 is also used to control the aforementioned switches in other modes (eg, a buck mode or a boost mode) to perform corresponding power conversion. It should be noted that, in the bypass mode in this embodiment, all n channels enter the bypass mode at the same time. It should be noted that the bypass control circuit 303 of the buck-boost switching power supply circuit 30 of the present invention is not limited to the structure shown in FIG. 3C, and any other feasible structure can also be used, and the structure shown in FIG. 3C is only for illustration. The present invention is not intended to limit the scope of the present invention. where n is a positive integer greater than or equal to 1.

3D is a schematic circuit diagram showing another embodiment of the bypass control circuit of the buck-boost switching power supply circuit of FIGS. 3A and 3C according to an embodiment of the present invention. The to-be-compared signal VTC[k], the upper threshold VthU[k] and the lower threshold VthL[k] of this embodiment can also use the embodiment listed in FIG. 3B . The bypass control circuit 203' includes a threshold control circuit 2031[k] and comparison circuits 2032'a[k] and 2032'b[k]. The threshold control circuit 2031[k] is used to generate an upper limit according to the reference voltage Threshold VthU[k] and lower threshold VthL[k]. The comparison circuit 2032'a[k] is used for comparing the to-be-compared signal VTC[k] with the upper threshold VthU[k] to generate a comparison result CPOU[k], and the comparison circuit 2032'b[k] is used to compare the to-be-compared signal VTC [k] and the lower threshold VthL[k] to generate the comparison result CPOL[k]. When the signal to be compared VTC[k] is less than the upper threshold VthU[k], and the signal to be compared VTC[k] is greater than the lower threshold VthL[k], the bypass control signal VE[ is enabled through the inversion gate 2034'[k] k], and enter the bypass mode (Bypass mode).

Please continue to refer to Figure 4. In one embodiment, the buck-boost switching power supply circuit of the present invention can operate in a boost mode, a bypass mode or a buck mode. The buck-boost switching power supply circuit of the present invention operates in the bypass mode when the corresponding conversion voltage difference is lower than the reference voltage, and when the corresponding conversion voltage difference is greater than or equal to the reference voltage, according to the input voltage VIN and the corresponding The low dropout voltage VINLDO operates in a buck mode and a boost mode, respectively.

In one embodiment, the reference voltage may include a first reference voltage and a second reference voltage. As shown in FIG. 4 , the first reference voltage is Vref1, the second reference voltage is Vref2, the upper threshold is VthU, and the lower threshold is VthL. When the difference between the low dropout voltage VINLDO[k] and the input voltage VIN is lower than the first reference voltage Vref1, and the difference between the input voltage VIN and the low dropout voltage VINLDO[k] is lower than the second reference voltage Vref2, the side The communication control signal VE[k] is enabled, so that the buck-boost switching power supply circuit of the present invention operates in the bypass mode. In one embodiment, the buck-boost switching power supply circuit of the present invention operates in the boost mode when the difference between the low dropout voltage VINLDO[k] minus the input voltage VIN is greater than or equal to the first reference voltage Vref1, and operates at a low voltage When the difference between the difference voltage VINLDO[k] minus the input voltage VIN is greater than or equal to the second reference voltage Vref2, the operation is in the step-down mode. In one embodiment, the first reference voltage Vref1 and the second reference voltage Vref2 have one of the following relationships: (1) the first reference voltage Vref1 is equal to the second reference voltage Vref2, and the first reference voltage Vref1 and the second reference voltage Vref2 are not zero; (2) the first reference voltage Vref1 is equal to zero, and the second reference voltage voltage Vref2 is not zero; (3) the second reference voltage Vref2 is equal to zero, and the first reference voltage Vref1 is not zero; or (4) the first reference voltage Vref1 is not equal to the second reference voltage Vref2, and the first reference voltage Vref1 and the first reference voltage Vref1 are not equal to zero; Both reference voltages Vref2 are not zero.

FIG. 5 is a schematic diagram showing signal waveforms of the circuit of FIG. 3A . The input voltage VIN, low dropout voltage VINLDO[1], VINLDO[2], VINLDO[n], bypass control signals VE[1], VE[2], VE[n] are shown in Figure 5. It should be noted that, FIG. 5 shows an embodiment in which the first reference voltage Vref1 is zero and the second reference voltage Vref2 is not zero, but it is not intended to limit the scope of the present invention. As shown in Figure 5, only one or more channels may enter bypass mode, while the other channels operate normally.

6 is a circuit schematic diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention. The power switch circuit 401, the input switch unit 4011, the output switch unit 4012, the low dropout voltage regulators 402[1], 402[2], the inductor L, the bypass control circuit 403, the conversion control circuit 405 and the bypass in this embodiment The switching circuit 408 is similar to the power switching circuit 301 in FIG. 3C, the input switching unit 3011, the output switching unit 3012, the low dropout voltage regulators 302[1]~302[n], the inductor L, the bypass control circuit 303, the switching control The circuit 305 and the bypass switching circuit 308 are not described in detail. The bypass control circuit 403 of this embodiment can also use the embodiment of FIG. 3D , and the bypass switching circuit 408 of this embodiment can also use the embodiment of FIG. 3A . The difference between this embodiment and the embodiment of FIG. 3C is that a low dropout voltage regulator of the buck-boost switching power supply circuit 40 of this embodiment corresponds to a negative voltage generating circuit 402[n], which is used to convert the low dropout voltage VINLDO[ n] is converted into a negative output voltage NVOUT (corresponding to the output voltage VOUT[n]), wherein the negative voltage generating circuit 402[n] includes a negative charge pump 406 and a negative low dropout voltage regulator 407 . The negative charge pump 406 is coupled to the low dropout node 404[n] for converting the low dropout voltage VINLDO[n] into a negative low dropout voltage NVINLDO. The negative low dropout voltage regulator 407 is coupled to the negative charge pump 406 for converting the negative low dropout voltage NVINLDO into a negative output voltage NVOUT. In this embodiment, n is a positive integer greater than or equal to 2.

FIG. 7 is a circuit schematic diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention. The power switch circuit 501, the input switch unit 5011, the output switch unit 5012, the low dropout voltage regulators 502[1], 502[2], the inductor L, the bypass control circuit 503, the conversion control circuit 505 and the bypass in this embodiment The switching circuit 508 is similar to the power switching circuit 301 in FIG. 3C, the input switching unit 3011, the output switching unit 3012, the low dropout voltage regulators 302[1]~302[n], the inductor L, the bypass control circuit 303, the switching control The circuit 305 and the bypass switching circuit 308 are not described in detail. The bypass control circuit 503 of this embodiment can also use the embodiment of FIG. 3D , and the bypass switching circuit 508 of this embodiment can also use the embodiment of FIG. 3A . The difference between this embodiment and the embodiment of FIG. 3C is that in the buck-boost switching power supply circuit 50 of this embodiment, some of the plurality of low-dropout voltage regulators correspond to negative voltage generating circuits 502 [n−x+1]˜502 [n], used to convert the low dropout voltages VINLDO[n-x+1]~VINLDO[n] into negative output voltages NVOUT[1]~NVOUT[x] (corresponding to the output voltages VOUT[n-x+ 1]~VOUT[n]), the negative voltage generating circuits 502[n-x+1]~502[n] respectively include negative charge pumps 506[1]~506[x] and a plurality of negative low dropout voltage regulators 507[1]~507[x]. The complex negative charge pumps 506[1]~506[x] are respectively coupled to the corresponding low-dropout nodes 504[n-x+1]~504[n], and are used to convert the corresponding low-dropout voltages VINLDO[n- x+1]~VINLDO[n] are converted into corresponding negative low dropout voltages NVINLDO[1]~NVINLDO[x]. The complex negative low dropout voltage regulators 507[1]˜507[x] are respectively coupled to the complex negative charge pumps 506[1]˜506[x], respectively, and are used to respectively convert the corresponding negative low dropout voltage NVINLDO[1] ~NVINLDO[x] is converted to the corresponding negative output voltage NVOUT[1]~NVOUT[x]. where x is a positive integer greater than or equal to 1. In this embodiment, n is a positive integer greater than or equal to 3.

FIG. 8 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention. The power switch circuit 601, the input switch unit 6011, the output switch unit 6012, the low dropout voltage regulators 602[1], 602[2], the inductor L, the bypass control circuit 603, the conversion control circuit 605 and the bypass in this embodiment The switching circuit 608 is similar to the power switching circuit 301 of FIG. The input switch unit 3011, the output switch unit 3012, the low dropout voltage regulators 302[1]~302[n], the inductor L, the bypass control circuit 303, the conversion control circuit 305 and the bypass switch circuit 308 are not described in detail. The bypass control circuit 603 of this embodiment can also use the embodiment of FIG. 3D , and the bypass switching circuit 608 of this embodiment can also use the embodiment of FIG. 3A . The difference between this embodiment and the embodiment of FIG. 3C is that a low dropout voltage regulator in the buck-boost switching power supply circuit 60 of this embodiment corresponds to a negative voltage generating circuit 602[n], which is used to convert the low dropout voltage VINLDO[ n] is converted into at least one negative output voltage NVOUT[1]~NVOUT[x] (corresponding to the output voltage VOUT[n]). The negative voltage generating circuit 602[n] includes a negative charge pump 606 and at least one negative low dropout voltage Voltage regulators 607[1]~607[x]. The negative charge pump 606 is coupled to the low dropout node 604[n] for converting the low dropout voltage VINLDO[n] into a negative low dropout voltage NVINLDO. The plurality of negative low dropout voltage regulators 607[1]~607[x] are respectively coupled to the negative charge pump 606 for converting the negative low dropout voltage NVINLDO to the corresponding negative output voltage NVOUT[1]~NVOUT[x, respectively ]. In this embodiment, n is a positive integer greater than or equal to 2.

FIG. 9 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to still another embodiment of the present invention. The difference between this embodiment and FIG. 3C is that this embodiment only includes a single output high-bridge switch D and a single low dropout voltage regulator 702 . The input switch unit 7011, the output low-bridge switch C, the low-dropout regulator 702, and the conversion control circuit 705 in this embodiment are similar to the input switch unit 3011, the output low-bridge switch C, and the low-dropout regulator 302 in FIG. 3C [ 1:n], the conversion control circuit 305, but n is 1 in this embodiment, so the detailed description is omitted. The bypass control circuit 703 of this embodiment can use the embodiment of FIG. 3C or FIG. 3D . The bypass control circuit 703 generates the bypass control signal VE to the switching control circuit 705 . The conversion control circuit 705 generates control signals VA, VB, VC and VD according to the bypass control signal VE to control the output high-bridge switch D and the input high-bridge switch A to electrically connect the input voltage VIN and the low dropout node 704 through the inductor L .

FIG. 10 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention. The difference between this embodiment and the embodiment of FIG. 6 is that this embodiment only includes A single output high-bridge switch D, and the single low dropout voltage regulator of this embodiment corresponds to a negative voltage generating circuit 802 . The input switch unit 8011 , the output low-bridge switch C, the conversion control circuit 805 , the bypass control circuit 803 , the negative voltage generating circuit 802 , the negative charge pump 806 , and the negative low dropout voltage regulator 807 in this embodiment are similar to those shown in FIG. 6 The input switch unit 4011, the output lower bridge switch C, the conversion control circuit 405, the bypass control circuit 403, the negative voltage generation circuit 402[n], the negative charge pump 406, and the negative low dropout voltage regulator 407 are omitted in detail. narrative. The bypass control circuit 803 of this embodiment can use the embodiment of FIG. 3C or FIG. 3D . The bypass control circuit 803 generates the bypass control signal VE to the switching control circuit 805 . The conversion control circuit 805 generates control signals VA, VB, VC and VD according to the bypass control signal VE to control the output high-bridge switch D and the input high-bridge switch A to electrically connect the input voltage VIN and the low dropout node 804 through the inductor L .

FIG. 11 is a schematic circuit diagram showing a buck-boost switching power supply circuit according to yet another embodiment of the present invention. The difference between this embodiment and the embodiment of FIG. 6 is that this embodiment only includes a single output high-bridge switch D, and this embodiment only includes a low dropout voltage regulator 902[1], and another low dropout voltage regulator (corresponding to the negative pressure generating circuit 902[2]). The bypass control circuit 903 of this embodiment can use the embodiment of FIG. 3C or FIG. 3D . In this embodiment, the input switch unit 9011 , the output lower bridge switch C, the conversion control circuit 905 , the bypass control circuit 903 , the low dropout voltage regulator 902[1], the negative voltage generation circuit 902[2], and the negative charge pump 906 The negative low dropout voltage regulator 907 is similar to the input switch unit 4011 of FIG. 6 , the output lower bridge switch C, the conversion control circuit 405 , the bypass control circuit 403 , the low dropout voltage regulator 402 [1], and the negative voltage generation circuit 402[n], the negative charge pump 406, and the negative low dropout voltage regulator 407, so the detailed description thereof is omitted. The bypass control circuit 903 generates the bypass control signal VE to the switching control circuit 905 . The conversion control circuit 905 generates control signals VA, VB, VC and VD according to the bypass control signal VE to control the output high-bridge switch D and the input high-bridge switch A to electrically connect the input voltage VIN and the low dropout node 904 through the inductor L .

12A-12C are characteristic diagrams illustrating operation modes of a buck-boost switching power supply circuit according to several embodiments of the present invention. It should be noted that FIG. 12A , FIG. 12B or FIG. 12C may be applicable to any one of the embodiments of FIG. 3A , FIG. 3C , and FIGS. 6-11 . Similarly, FIG. 4 can also be applied to any one of the embodiments of FIGS. 3A , 3C and 6 to 11 . As shown in FIG. 12A , the first reference voltage is Vref1, the second reference voltage is Vref2, the upper threshold is VthU, the lower threshold is VthL, the first intermediate threshold is VthM1, and the second intermediate threshold is VthM2. The difference between the present embodiment and FIG. 4 is that the buck-boost switching power supply circuit of the present embodiment operates more according to the input voltage VIN and the corresponding low dropout voltage VINLDO when the corresponding conversion voltage difference is greater than or equal to the reference voltage. in a buck boost mode. As shown in FIG. 12A, the conversion voltage difference (taking VINLDO-VIN as an example) increases from large to small, and operates in the corresponding mode according to the following sequence: boost mode, buck-boost mode, bypass mode, buck-boost mode, Buck mode.

As shown in FIG. 12B , the first reference voltage is Vref1, the second reference voltage is Vref2, the upper threshold is VthU, the lower threshold is VthL, and the first intermediate threshold is VthM1. The difference between this embodiment and FIG. 12A is that this embodiment only has a buck boost mode above the bypass mode. As shown in FIG. 12B , the conversion voltage difference increases from large to small (taking VINLDO-VIN as an example), and operates in corresponding modes according to the following sequence: boost mode, buck-boost mode, bypass mode, and buck mode.

FIG. 12C is a characteristic diagram showing an operation mode of a buck-boost switching power supply circuit according to yet another embodiment of the present invention. As shown in FIG. 12C , the first reference voltage is Vref1, the second reference voltage is Vref2, the upper threshold is VthU, the lower threshold is VthL, and the second intermediate threshold is VthM2. The difference between this embodiment and FIG. 12A is that this embodiment only has a buck boost mode below the bypass mode. As shown in FIG. 12C , the conversion voltage difference increases from large to small, and operates in the corresponding mode according to one of the following sequences: boost mode, bypass mode, buck-boost mode, and buck mode.

13 is a schematic diagram showing signal waveforms of the circuit of FIG. 3C operating in the operation mode of FIG. 12A according to an embodiment of the present invention. Input voltage VIN, low dropout voltage VINLDO[k], The control signals VA and VD[k] are shown in FIG. 13 . It should be noted that FIG. 13 shows an embodiment in which the first reference voltage Vref1 is zero and the second reference voltage Vref2 is not zero, but it is not intended to limit the scope of the present invention. Specifically, in the step-down mode, the corresponding output high-bridge switch D[k] is always on, that is, the corresponding control signal VD[k] in the figure is always at a high level, and the input high-bridge switch A is switched to perform Buck conversion. In the buck-boost mode, the corresponding output high-bridge switch D[k] and the input high-bridge switch A are switched to perform buck-boost conversion. In the bypass mode, the corresponding output high-bridge switch D[k] and the input high-bridge switch A are both in constant conduction, so that the input voltage VIN and the corresponding low dropout voltage VINLDO[k] are electrically connected through the inductor L. In the boost mode, the input high-bridge switch A is in constant conduction, and the corresponding output high-bridge switch D[k] is switched for boost conversion.

FIG. 14 shows a control method of a buck-boost switching power supply circuit according to yet another embodiment of the present invention. The control method 100 of the buck-boost switching power supply circuit of the present invention includes in step 1001 , at least one low-dropout voltage regulator is correspondingly coupled to the at least one output high-bridge switch, and the at least one low-dropout voltage VINLDO is correspondingly converted is the at least one output voltage VOUT. Then, in step 1002, a bypass control signal is generated according to a conversion voltage difference between the input voltage VIN and the corresponding low dropout voltage VINLDO. Then, in step 1003, when the corresponding conversion voltage difference is lower than a reference voltage, the bypass control signal controls the input voltage VIN to be electrically connected to the corresponding low dropout node. In one embodiment, step 1003 may include step 10031a or step 10031b. In step 10031a, when the corresponding conversion voltage difference is lower than the reference voltage, the bypass control signal controls the corresponding output high-bridge switch and the input high-bridge switch, so that the input voltage VIN corresponds to the corresponding low voltage difference The nodes are electrically connected via an inductor. In step 10031b, when the corresponding conversion voltage difference is lower than the reference voltage, control the corresponding bypass switch of at least one bypass switch to be turned on, so as to directly electrically connect the input voltage VIN and the corresponding low dropout node.

FIG. 15 shows a control method of a buck-boost switching power supply circuit according to another embodiment of the present invention. In one embodiment, step 1001 may include step 10011 and step 10012. In step 10011, an upper threshold VthU and a lower threshold VthL are generated according to the reference voltage. In step 10012, a to-be-compared signal VTC is compared with the upper threshold VthU and the lower threshold VthL, and when the to-be-compared signal VTC is between the upper threshold VthU and the lower threshold VthL, the corresponding bypass control signal is enabled to change the input voltage VIN is electrically connected to the corresponding low-dropout node, wherein the signal to be compared VTC, the upper threshold VthU and the lower threshold VthL have one of the following relationships: (1) The signal to be compared VTC is the corresponding conversion voltage difference, and the upper threshold VthU is the first reference The voltage Vref1, the lower threshold VthL is the second reference voltage Vref2; (2) the signal to be compared VTC is the corresponding low dropout voltage VINLDO, the upper threshold VthU is the sum of the input voltage VIN and the first reference voltage Vref1, and the lower threshold VthL is the input voltage The difference between VIN and the second reference voltage Vref2; (3) the signal to be compared VTC is the input voltage VIN, the upper threshold VthU is the sum of the corresponding low dropout voltage VINLDO and the second reference voltage Vref2, and the lower threshold VthL is the corresponding low dropout voltage The difference between VINLDO and the first reference voltage Vref1.

As mentioned above, the present invention provides a buck-boost switching power supply circuit and a control method thereof, which can have lower switching loss and higher efficiency when the input voltage is similar to the low dropout voltage by the bypass mode, and due to the input The voltage is directly bypassed to the input of the low dropout regulator to obtain more headroom for the voltage drop of the low dropout regulator. In addition, the present invention can also save the layout area of the bypass switch through the bypass mode in which the input high-bridge switch and the output high-bridge switch are constantly turned on.

The present invention has been described above with respect to the preferred embodiments, but the above descriptions are only intended to make the content of the present invention easy for those skilled in the art to understand, and are not intended to limit the broadest scope of rights of the present invention. The described embodiments are not limited to be used alone, but can also be used in combination. For example, two or more embodiments can be used in combination, and some components in one embodiment can also be used to replace those in another embodiment. corresponding components. In addition, under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations. According to the text of the signal It also includes, when necessary, performing voltage-to-current conversion, current-to-voltage conversion, and/or ratio conversion, etc. on the signal, and then performing processing or operation on the converted signal to generate an output result. It can be seen from this that under the same spirit of the present invention, those skilled in the art can think of various equivalent changes and various combinations, and there are many combinations, which are not listed and described here. Accordingly, the scope of the present invention should cover the above and all other equivalent changes.

10: Buck-boost switching power supply circuit 101: Power switch circuit 1011: Input switch unit 1012: Output switch unit 102[1:n]: Low dropout regulator 103: Bypass Control Circuit 104[1:n]: Low dropout node 105: Bypass switching circuit E[1:n]: Bypass switch L: Inductance LX1: first end LX2: second end VE[1:n]: Bypass control signal VIN: input voltage VIN_S: Input voltage sensing signal VINLDO[1:n]: Low dropout voltage VINLDO[1:n]_S: Low dropout voltage sensing signal VOUT[1:n]: output voltage

Claims (24)

A buck-boost switching power supply circuit is used to convert an input voltage into at least one output voltage, comprising: a power switch circuit, including an input switch unit and an output switch unit, wherein the input switch unit is used to convert an A first end of the inductor is switched between the input voltage and a ground potential, and the output switch unit is used for switching a second end of the inductor between at least one low-dropout node and the ground potential, so that the input voltage is connected to the ground potential. at least one low dropout node is converted into corresponding at least one low dropout voltage, and the at least one low dropout node is correspondingly coupled with at least one output high-bridge switch in the output switch unit; at least one low dropout regulator , LDO), correspondingly coupled with the at least one output high-bridge switch, so as to convert the at least one low dropout voltage into the at least one output voltage correspondingly; a bypass control circuit is used to correspond to the input voltage and the corresponding A switching voltage difference between the low dropout voltages generates a bypass control signal; and a bypass switching circuit, wherein the bypass control signal controls the bypass switching circuit when the corresponding switching voltage difference is lower than a reference voltage, The input voltage is electrically connected to the corresponding low-dropout node, so that the buck-boost switching power supply circuit operates in a bypass mode. The buck-boost switching power supply circuit as claimed in claim 1, wherein the bypass switching circuit comprises the corresponding output high-bridge switch and an input high-bridge switch in the input switch unit, and the bypass control circuit corresponds to the corresponding output high-bridge switch. When the conversion voltage difference is lower than the reference voltage, the corresponding bypass control signal is generated to control both the output high-bridge switch and the input high-bridge switch to be turned on, so that the input voltage and the corresponding low-dropout node pass through the Inductive electrical connection. The buck-boost switching power supply circuit as claimed in claim 1, wherein the bypass switching circuit comprises at least one bypass switch, and the at least one bypass switch is directly electrically connected between the input voltage and the corresponding low dropout node, so as to When the corresponding conversion voltage difference is lower than the reference voltage, the corresponding bypass switch is controlled to be turned on, so as to directly electrically connect the input voltage to the corresponding low-dropout node. The buck-boost switching power supply circuit as claimed in claim 1, wherein the conversion voltage difference is the absolute value of the difference between the input voltage and the corresponding low dropout voltage. The buck-boost switching power supply circuit as claimed in claim 1, wherein the reference voltage comprises a first reference voltage and a second reference voltage, wherein when the difference between the corresponding low dropout voltage minus the input voltage is lower than the the first reference voltage, and when the difference between the input voltage and the corresponding low dropout voltage is lower than the second reference voltage, the corresponding bypass control signal is enabled, wherein the first reference voltage and the second reference voltage are The reference voltage has one of the following relationships: (1) the first reference voltage is equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is zero; (2) the first reference voltage is equal to zero, The second reference voltage is not zero; (3) the second reference voltage is equal to zero, and the first reference voltage is not zero; or (4) the first reference voltage is not equal to the second reference voltage, and the first reference Neither the voltage nor the second reference voltage is zero. The buck-boost switching power supply circuit as claimed in claim 5, wherein the bypass control circuit comprises: a threshold control circuit for generating an upper threshold and a lower threshold according to the reference voltage; and a comparison circuit for using to compare a signal to be compared with the upper threshold and the lower threshold, and when the signal to be compared is between the upper threshold and the lower threshold, enable the corresponding Bypassing the control signal to electrically connect the input voltage with the corresponding low-dropout node, wherein the signal to be compared, the upper threshold and the lower threshold have one of the following relationships: (1) The signal to be compared is the corresponding Convert the voltage difference, the upper threshold is the first reference voltage, the lower threshold is the second reference voltage; (2) the signal to be compared is the corresponding low dropout voltage, the upper threshold is the input voltage and the first The sum of reference voltages, the lower threshold is the difference between the input voltage and the second reference voltage; (3) the signal to be compared is the input voltage, and the upper threshold is the corresponding sum of the low dropout voltage and the second reference voltage and, the lower threshold is the corresponding difference between the low dropout voltage and the first reference voltage. The buck-boost switching power supply circuit of claim 1, wherein the input switch unit comprises: an input high-bridge switch coupled between the input voltage and the first end of the inductor; and an input low-bridge switch or an input lower bridge diode, coupled between the ground potential and the first end of the inductor; wherein the input upper bridge switch, and the input lower bridge switch or the input lower bridge diode are used for The first terminal of the inductor is switched between the input voltage and the ground potential. The buck-boost switching power supply circuit as claimed in claim 1, wherein the output switch unit comprises: an output lower bridge switch coupled between the ground potential and the second end of the inductor; and the at least one output switch bridge switches, respectively coupled between the at least one low dropout node and the second end of the inductor; The output low-bridge switch and the at least one output high-bridge switch are used for switching the second end of the inductor between the at least one low-dropout node and the ground potential, thereby generating a corresponding voltage at the at least one low-dropout node. the at least one low dropout voltage. The buck-boost switching power supply circuit as claimed in claim 5, wherein the buck-boost switching power supply circuit is further based on the input voltage and the corresponding low dropout voltage when the corresponding conversion voltage difference is greater than or equal to the reference voltage , respectively operate in a buck (buck) mode and a boost (boost) mode. The buck-boost switching power supply circuit as claimed in claim 9, wherein the buck-boost switching power supply circuit operates in the corresponding low dropout voltage minus the input voltage when the difference is greater than or equal to the first reference voltage The step-up mode operates in the step-down mode when the difference between the input voltage and the corresponding low dropout voltage is greater than or equal to the second reference voltage. The buck-boost switching power supply circuit as claimed in claim 9, wherein the buck-boost switching power supply circuit, when the corresponding conversion voltage difference is greater than or equal to the reference voltage, according to the input voltage and the corresponding low dropout voltage, It is further operated in a buck boost mode. The buck-boost switching power supply circuit as claimed in claim 11, wherein the conversion voltage difference increases from large to small, and operates in a corresponding mode according to one of the following sequences: (1) the boost mode, the buck-boost mode, The bypass mode, the buck mode; (2) the boost mode, the bypass mode, the buck-boost mode, the buck mode; (3) the boost mode, the buck-boost mode, the bypass mode , the buck-boost mode, the buck mode. The buck-boost switching power supply circuit as claimed in claim 1, wherein at least one of the low dropout voltage regulators is a negative voltage generating circuit, wherein the negative voltage generating circuit comprises: a negative charge pump coupled to the corresponding a low dropout node for converting the corresponding low dropout voltage into a negative low dropout voltage; and At least one negative low dropout voltage regulator, coupled to the negative charge pump, is used for converting the negative low dropout voltage into a corresponding at least one negative output voltage. A control method for controlling a buck-boost switching power supply circuit is used to convert an input voltage into at least one output voltage, the buck-boost switching power supply circuit includes a power switch circuit, and the power switch circuit includes an input switch unit and an output switch unit, wherein the input switch unit is used to switch a first end of an inductor between the input voltage and a ground potential, the output switch unit is used to switch a second end of the inductor to at least one a low dropout node and the ground potential, so that the input voltage is converted into a corresponding at least one low dropout voltage at the at least one low dropout node, and the at least one low dropout node is bridged with at least one output in the output switch unit The switches are correspondingly coupled; the control method includes: using at least one low dropout voltage regulator to correspondingly convert the at least one low dropout voltage into the at least one output voltage; according to a conversion between the input voltage and the corresponding low dropout voltage voltage difference to generate a bypass control signal; and when the corresponding conversion voltage difference is lower than a reference voltage, the bypass control signal controls the input voltage to be electrically connected to the corresponding low-dropout node, so that the buck-boost switching type The power circuit operates in a bypass mode. The control method of claim 14, wherein when the corresponding conversion voltage difference is lower than the reference voltage, the bypass control signal controls both the output high-bridge switch and the input high-bridge switch to be turned on, so as to turn on The input voltage and the corresponding low dropout node are electrically connected via the inductor. The control method of claim 14, wherein when the corresponding conversion voltage difference is lower than the reference voltage, the corresponding one of the at least one bypass switch is controlled to be turned on, so as to The input voltage is directly electrically connected to the corresponding low dropout node, wherein the at least one bypass switch is directly electrically connected between the input voltage and the corresponding low dropout node. The control method of claim 14, wherein the conversion voltage difference is the absolute value of the difference between the input voltage and the corresponding low dropout voltage. The control method of claim 14, wherein the reference voltage includes a first reference voltage and a second reference voltage, wherein when the difference between the low dropout voltage minus the input voltage is lower than the first reference voltage, and When the difference between the input voltage and the low dropout voltage is lower than the second reference voltage, the corresponding bypass control signal is enabled, wherein the first reference voltage and the second reference voltage have one of the following relationships: (1) The first reference voltage is equal to the second reference voltage, and neither the first reference voltage nor the second reference voltage is zero; (2) The first reference voltage is equal to zero, and the second reference voltage is not zero (3) the second reference voltage is equal to zero, and the first reference voltage is not zero; or (4) the first reference voltage is not equal to the second reference voltage, and both the first reference voltage and the second reference voltage are not zero. The control method of claim 18, wherein the step of generating the bypass control signal comprises: generating an upper threshold and a lower threshold according to the reference voltage; and comparing a signal to be compared with the upper threshold and the lower threshold a threshold, when the signal to be compared is between the upper threshold and the lower threshold, the corresponding bypass control signal is enabled to electrically connect the input voltage with the corresponding low-dropout node, wherein the signal to be compared is , the upper threshold and the lower threshold have one of the following relationships: (1) the signal to be compared is the corresponding conversion voltage difference, the upper threshold is the first reference voltage, and the lower threshold is the second reference voltage; (2) The signal to be compared is the corresponding low dropout voltage, the upper threshold is the sum of the input voltage and the first reference voltage, and the lower threshold is the difference between the input voltage and the second reference voltage; (3) The signal to be compared is the input voltage, the upper threshold is the sum of the corresponding low dropout voltage and the second reference voltage, and the lower threshold is the difference between the corresponding low dropout voltage and the first reference voltage. The control method as claimed in claim 14, wherein when the corresponding conversion voltage difference is greater than or equal to the reference voltage, the buck-boost switching power supply circuit is further operated in one of the input voltage and the corresponding low dropout voltage, respectively Buck (buck) mode and a boost (boost) mode. The control method of claim 20, wherein when the difference between the corresponding low dropout voltage minus the input voltage is greater than or equal to the first reference voltage, the buck-boost switching power supply circuit is controlled to operate in the boost mode , and when the difference between the input voltage and the corresponding low dropout voltage is greater than or equal to the second reference voltage, the buck-boost switching power supply circuit is controlled to operate in the buck mode. The control method of claim 20, wherein when the corresponding conversion voltage difference is greater than or equal to the reference voltage, according to the input voltage and the corresponding low dropout voltage, the buck-boost switching power supply circuit is further operated in a Buck boost mode. The control method as claimed in claim 22, wherein the conversion voltage difference is from large to small, and the buck-boost switching power supply circuit is operated in a corresponding mode according to one of the following sequences: (1) the boost mode, the The buck-boost mode, the bypass mode, the buck mode; (2) the boost mode, the bypass mode, the buck-boost mode, the buck mode; (3) the boost mode, the buck-boost mode, The bypass mode, the buck-boost mode, the buck mode. The control method of claim 14, wherein the at least one output voltage includes at least one negative output voltage, the control method further comprising: converting the corresponding low dropout voltage into a negative low dropout voltage; and the negative low dropout voltage The voltage is converted into the corresponding at least one negative output voltage.

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