Bridge type switching converter and controller thereof

Abstract

The invention discloses a bridge switching converter and a controller thereof. The bridge-type switching converter comprises a transformer and a bridge-type switching circuit. A first input end of the bridge switch circuit is coupled to an input voltage end, a second input end is coupled to an output voltage end, a first bridge arm end is coupled to a first end of a primary winding of the transformer, a second bridge arm end is coupled to a second end of the primary winding of the transformer, and a center tap of a secondary winding of the transformer is coupled to the output voltage end. The first switch tube is coupled between the first bridge arm end and the output voltage end, and the second switch tube is coupled between the input voltage end and the first bridge arm end. The controller controls the first switch control signal to conduct the first switch tube according to the output voltage, and controls the second switch control signal to conduct the second switch tube according to the output voltage when the first switch control signal controls the first switch tube to keep off. According to the invention, the transient response performance and the output voltage precision are good.

Description

Technical Field

[0001] The embodiments of the present invention relate to an electronic circuit, and more particularly, to a bridge switching converter and a controller thereof. Background Art

[0002] A bridge switching converter is an electronic circuit that converts an input voltage into an adjustable output voltage. The output voltage of a step-down bridge switching converter is lower than the input voltage, while the output voltage of a step-up bridge switching converter is higher than the input voltage. Bridge switching converters can be used in a variety of devices, including computers, smartphones, etc. With the push for more energy-efficient and smaller devices, there is a need for higher efficiency and lower cost bridge switching converters that allow for high printed circuit board (PCB) density. Bridge switching converters can use a transformer to regulate or isolate the voltage on the primary winding of the transformer. Summary of the invention

[0003] The invention provides a bridge switch converter and a controller thereof.

[0004] According to an embodiment of the present invention, a bridge switching converter is proposed, comprising: an input voltage terminal for receiving an input voltage, and an output voltage terminal for providing an output voltage; a transformer, comprising a primary winding and a secondary winding, wherein the secondary winding comprises a first terminal, a second terminal, and a center tap located between the first terminal and the second terminal, and the center tap is coupled to the output voltage terminal of the bridge switching converter; a first switch tube, comprising a first terminal and a second terminal, the first terminal of the first switch tube being coupled to the input voltage terminal of the bridge switching converter, and the second terminal of the first switch tube being coupled to the first terminal of the primary winding; a second switch tube, comprising a first terminal and a second terminal, the first terminal of the second switch tube being coupled to the second terminal of the primary winding; The second end of the first switch tube and the first end of the primary winding, and the second end of the second switch tube are coupled to the center tap of the secondary winding, and the second switch tube and the first switch tube form a first bridge arm; the third switch tube includes a first end and a second end, the first end of the third switch tube is coupled to the input voltage end of the bridge switching converter, and the second end of the third switch tube is coupled to the second end of the primary winding; the fourth switch tube includes a first end and a second end, the first end of the fourth switch tube is coupled to the second end of the third switch tube and the second end of the primary winding, and the second end of the fourth switch tube is coupled to the center tap of the secondary winding, and the fourth switch tube and the third switch tube form a second bridge arm; the fifth switch a fifth switch tube, comprising a first end and a second end, the first end of the fifth switch tube being coupled to the first end of the secondary winding, and the second end of the fifth switch tube being coupled to the reference end; a sixth switch tube, comprising a first end and a second end, the first end of the sixth switch tube being coupled to the second end of the secondary winding, and the second end of the sixth switch tube being coupled to the reference end; and a controller, providing a first switch control signal for controlling the second switch tube and the third switch tube, a second switch control signal for controlling the first switch tube and the fourth switch tube, a third switch control signal for controlling the fifth switch tube, and a fourth switch control signal for controlling the sixth switch tube; wherein when the second switch control signal controls the first switch tube and the fourth switch tube When the switch tube remains turned off, the controller controls the first switch control signal according to the output voltage to turn on the second switch tube and the third switch tube until the turn-on time of the second switch tube or the third switch tube is equal to the first time, and the controller controls the second switch tube and the third switch tube to turn off through the first switch control signal; and when the first switch control signal controls the second switch tube and the third switch tube to remain turned off, the controller controls the second switch control signal according to the output voltage to turn on the first switch tube and the fourth switch tube until the turn-on time of the first switch tube or the fourth switch tube is equal to the second time, and the controller controls the first switch tube and the fourth switch tube to turn off through the second switch control signal.

[0005] According to an embodiment of the present invention, a bridge switching converter is proposed, comprising: an input voltage terminal, an output voltage terminal, and a reference terminal, wherein the voltage between the input voltage terminal and the reference terminal is the input voltage, and the voltage between the output voltage terminal and the reference terminal is the output voltage; a transformer, comprising a primary winding and a secondary winding, wherein the secondary winding comprises a first terminal, a second terminal, and a center tap located between the first terminal and the second terminal; a bridge switching circuit, comprising a first input terminal, a second input terminal, a first bridge arm terminal, a second bridge arm terminal, a first switch tube, and a second switch tube, wherein the first input terminal of the bridge switching circuit is coupled to the input voltage terminal, the second input terminal of the bridge switching circuit is coupled to the output voltage terminal, the first bridge arm terminal of the bridge switching circuit is coupled to the first end of the primary winding, and the second bridge arm terminal of the bridge switching circuit is coupled to the first end of the primary winding. The bridge arm end is coupled to the second end of the primary winding, the center tap of the secondary winding is coupled to the second input end of the bridge switching circuit, the first switch tube is coupled between the first bridge arm end and the output voltage end, and the second switch tube is coupled between the input voltage end and the first bridge arm end; and a controller provides a first switch control signal according to the output voltage to control the first switch tube in the bridge switching circuit, and provides a second switch control signal to control the second switch tube in the bridge switching circuit, wherein when the second switch control signal controls the second switch tube to remain turned off, the controller controls the first switch control signal according to the output voltage to turn on the first switch tube, and when the first switch control signal controls the first switch tube to remain turned off, the controller controls the second switch control signal according to the output voltage to turn on the second switch tube.

[0006] According to an embodiment of the present invention, a controller for a bridge switching converter is proposed, wherein the bridge switching converter includes a transformer, a primary switching circuit coupled to a primary winding of the transformer, and a secondary switching circuit coupled to a secondary winding of the transformer, wherein the controller includes: an output voltage sampling pin for receiving an output voltage sampling signal representing an output voltage of the bridge switching converter; an input voltage sampling pin for receiving an input voltage sampling signal representing an input voltage of the bridge switching converter; a first control signal output pin for providing a first switch control signal to control a first switch tube in the primary switching circuit; a second control signal output pin for providing a second switch control signal to control a second switch tube in the primary switching circuit; and a third control signal output pin for for providing a third switch control signal to control the third switch tube in the secondary switch circuit; and a fourth control signal output pin, for providing a fourth switch control signal to control the fourth switch tube in the secondary switch circuit; wherein when the second switch control signal controls the second switch tube to remain turned off, the controller controls the first switch control signal according to the output voltage to turn on the first switch tube until the turn-on time of the first switch tube is equal to the first time, and the controller controls the first switch control signal to turn off the first switch tube; and when the first switch control signal controls the first switch tube to turn off, the controller controls the second switch control signal according to the output voltage to turn on the second switch tube until the turn-on time of the second switch tube is equal to the second time, and the controller controls the second switch control signal to turn off the second switch tube.

[0007] The bridge switch converter of the present invention can realize the output of large current and low voltage, and has good transient response performance and output voltage accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to better understand the present invention, the present invention will be described in detail according to the following drawings, wherein the same or similar elements have the same reference numerals.

[0009] Figure 1A FIG. 4 shows a circuit structure diagram of a bridge switching converter 100A according to an embodiment of the present invention.

[0010] Figure 1B FIG. 4 shows a circuit structure diagram of a bridge switching converter 100B according to an embodiment of the present invention.

[0011] Figure 2 FIG. 4 shows a circuit structure diagram of a controller 30 according to an embodiment of the present invention.

[0012] Figure 3A FIG. 2 shows a circuit structure diagram of the conduction duration unit 22A according to an embodiment of the present invention.

[0013] Figure 3BFIG. 2 shows a circuit structure diagram of the conduction duration unit 22B according to an embodiment of the present invention.

[0014] Figure 4 FIG. 2 shows a circuit structure diagram of the switch control unit 23 according to an embodiment of the present invention.

[0015] Figure 5 A signal waveform diagram 50 of the switch control unit 23 according to an embodiment of the present invention is shown.

[0016] Figure 6 FIG. 2 shows a structural diagram of a bridge switching converter 200 according to an embodiment of the present invention.

[0017] Figure 7 FIG. 4 shows a structural diagram of a bridge switching converter 300 according to an embodiment of the present invention.

[0018] Figure 8 FIG. 4 shows a structural diagram of a controller 30B according to an embodiment of the present invention.

[0019] Fig. 9 FIG. 4 is a structural diagram of a bridge switching converter 400 according to an embodiment of the present invention.

[0020] Fig.10 FIG. 4 shows a structural diagram of a controller 30C according to an embodiment of the present invention.

[0021] Fig.11 A method 500 for controlling a bridge switching converter according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0022] Specific embodiments of the present invention will be described in detail below. It should be noted that the embodiments described here are only used for illustration and are not intended to limit the present invention. In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details do not have to be adopted to implement the present invention. In other examples, in order to avoid confusing the present invention, known circuits, materials or methods are not specifically described. Terms such as "connection" and "coupling" described herein are defined as coupling directly or indirectly in an electrical or non-electrical manner. Terms such as "one", "the" and "said" include plural. The phrase "in one embodiment" used in this article does not necessarily refer to the same embodiment, but may also be the same embodiment.

[0023] Figure 1A1 shows a circuit structure diagram of a bridge switching converter 100A according to an embodiment of the present invention. The bridge switching converter 100A receives an input voltage Vin at an input voltage terminal 101 and provides an output voltage Vo at an output voltage terminal 102. The bridge switching converter 100A includes a transformer T1, a primary switching circuit 10A coupled to a primary winding of the transformer T1, a secondary switching circuit 20 coupled to a secondary winding of the transformer T1, and a controller 30. The primary switching circuit 10A includes, for example, a bridge switching circuit. Figure 1A In the illustrated embodiment, the primary switch circuit 10A is described by taking a full-bridge switch circuit as an example. It can be understood by those skilled in the art that the primary switch circuit 10A can also include a half-bridge switch circuit. The bridge switching converter 100A further includes a reference terminal 110. The input capacitor Cin is coupled between the input voltage terminal 101 and the reference terminal 110, and the voltage across the two terminals is the input voltage Vin. In one embodiment, the reference terminal 110 is coupled to a reference ground.

[0024] exist Figure 1A In the illustrated embodiment, the input voltage terminal 101 serves as one input terminal of the primary switch circuit 10A, and the output voltage terminal 102 serves as another input terminal of the primary switch circuit 10A. The primary switch circuit 10A further comprises a bridge arm terminal 103 coupled to a first terminal 105 of the primary winding, and a bridge arm terminal 104 coupled to a second terminal 106 of the primary winding. A center tap 107 of the secondary winding of the transformer T1 is coupled to the output voltage terminal 102 of the primary switch circuit 10A, and the center tap 107 is located between a first terminal 108 and a second terminal 109 of the secondary winding. Figure 1AIn the illustrated embodiment, the primary switch circuit 10A includes switch tubes Q1-Q4, wherein the switch tubes Q1-Q2 are coupled in series between the input voltage terminal 101 and the output voltage terminal 102 to form a switch bridge arm, and the switch tubes Q3-Q4 are coupled in series between the input voltage terminal 101 and the output voltage terminal 102 to form another switch bridge arm. The switch tube Q1 includes a first end coupled to the input voltage terminal 101 and a second end coupled to the bridge arm end 103. The switch tube Q2 includes a first end and a second end, wherein the first end is coupled to the second end of the switch tube Q1 and the first end of the bridge arm end 103, and the second end is coupled to the secondary winding center tap 107. The switch tube Q3 includes a first end coupled to the input voltage terminal 101 and a second end coupled to the bridge arm end 104. The switch tube Q4 includes a first end and a second end, wherein the first end is coupled to the second end of the switch tube Q3 and the first end of the bridge arm end 104, and the second end is coupled to the secondary winding center tap 107. The secondary switch circuit 20 includes switch tubes S1 and S2. The first end of the switch tube S1 is coupled to the first end 108 of the secondary winding, and the second end of the switch tube S1 is coupled to the reference end 110. The first end of the switch tube S2 is coupled to the second end 109 of the secondary winding, and the second end of the switch tube S2 is coupled to the reference end 110. In one embodiment, the switch tubes Q1-Q4 and S1-S2 include, for example, metal oxide semiconductor field effect transistors (MOSFETs). Those skilled in the art can understand that the switch tubes Q1-Q4 and S1-S2 can also include any other suitable transistors, such as junction field effect transistors (JFETs), laterally diffused metal oxide field effect transistors (LDMOS), etc.

[0025] The controller 30 includes an output voltage sampling pin P1, an input voltage sampling pin P2, and control signal output pins P5-P8. The output voltage sampling pin P1 receives an output voltage sampling signal Vosen representing an output voltage Vo, the input voltage sampling pin P2 receives an input voltage sampling signal Vinsen representing an input voltage Vin, the control signal output pin P5 provides a switch control signal PWM1, the control signal output pin P6 provides a switch control signal PWM2, the control signal output pin P7 provides a switch control signal PWMS1, and the control signal output pin P8 provides a switch control signal PWMS2. In one embodiment, the switch control signal PWM1 is used to control the on and off of the switches Q3 and Q2, the switch control signal PWM2 is used to control the on and off of the switches Q1 and Q4, the switch control signal PWMS1 is used to control the on and off of the switch S1, and the switch control signal PWMS2 is used to control the on and off of the switch S2.

[0026] The controller 30 controls the switch control signal PWM1 to change to the first state to turn on the switch tubes Q3 and Q2 according to the output voltage Vo and the switch control signal PWM2, controls the switch control signal PWMS2 to change to the second state to turn off the switch tube S2, and controls the switch control signal PWM2 to change to the first state to turn on the switch tubes Q1 and Q4 according to the output voltage Vo and the switch control signal PWM1, and controls the switch control signal PWMS1 to change to the second state to turn off the switch tube S1. The first state includes, for example, a high level, and the second state includes, for example, a low level. In one embodiment, the controller 30 provides the switch control signal PWMS2 according to the switch control signal PWM1, and provides the switch control signal PWMS1 according to the switch control signal PWM2. For example, after the switch control signal PWM1 changes to the second state, after a delay time, the switch control signal PWMS2 is controlled to change to the first state to turn on the switch tube S2, and after the switch control signal PWM2 changes to the second state, after a delay time, the switch control signal PWMS1 is controlled to change to the first state to turn on the switch tube S1. In one embodiment, when the duration of the switch control signal PWM1 being in the first state is equal to the duration Ton1, or when the conduction duration of the switch tube Q2 or Q3 is equal to the duration Ton1, the controller 30 controls the switch control signal PWM1 to change to the second state to turn off the switch tubes Q2 and Q3, and when the duration of the switch control signal PWM2 being in the first state is equal to the duration Ton2, or when the conduction duration of the switch tube Q1 or Q4 is equal to the duration Ton2, the controller 30 controls the switch control signal PWM2 to change to the second state to turn off the switch tubes Q1 and Q4. In one embodiment, the controller 30 controls the duration Ton1 of the switch control signal PWM1 being in the first state and the duration Ton2 of the switch control signal PWM2 being in the first state according to the input voltage sampling signal Vinsen, for example, the control durations Ton1 and Ton2 change with the change of the input voltage Vin.

[0027] In one embodiment, the controller 30 further includes current sampling pins P3-P4. The current sampling pin P3 receives the current sampling signal CS1, and the current sampling pin P4 receives the current sampling signal CS2. In one embodiment, the current sampling signal CS1 represents the current flowing through the switch tube Q2, and the current sampling signal CS2 represents the current flowing through the switch tube Q4. The controller 30 adjusts at least one of the durations Ton1 and Ton2 to balance the current flowing through the switch tube Q2 and the current flowing through the switch tube Q4, that is, to balance the current flowing through the two switch bridge arms. In another embodiment, the current sampling signal CS1 represents the current flowing through the switch tube S1, and the current sampling signal CS2 represents the current flowing through the switch tube S2. The controller 30 adjusts at least one of the durations Ton1 and Ton2 to balance the current flowing through the switch tube S1 and the current flowing through the switch tube S2, that is, to balance the current flowing through the first end 108 of the secondary winding and the current flowing through the second end 109 of the secondary winding.

[0028] In one embodiment, the controller 30 further includes a remote return pin P0. The remote return pin P0 and the output voltage sampling pin P1 together implement remote voltage sampling of the output voltage Vo. Figure 1A As shown, the output voltage sampling pin P1 is coupled to one end of the output capacitor Co, the remote return pin P0 is coupled to the other end of the output capacitor Co, and the voltage between the output capacitor sampling terminal P1 and the remote return pin P0 is the output voltage sampling signal Vosen. In another embodiment, the output voltage sampling pin P1 can also be coupled to one end of the output capacitor Co through a voltage divider resistor, and the remote return pin P0 is coupled to the other end of the output capacitor Co. In another embodiment, the controller 30 can also adopt remote voltage sampling (not shown in the figure) for the input voltage Vin.

[0029] The bridge switching converter 100A according to the embodiment of the present invention can achieve high current and low voltage output while having good transient response performance and output voltage accuracy. On the other hand, it can also achieve balanced distribution of current and heat in a relatively simple manner.

[0030] Figure 1B FIG. 1 shows a circuit structure diagram of a bridge switching converter 100B according to an embodiment of the present invention. Figure 1A The bridge switching converter 100A shown is different in that Figure 1B In the illustrated embodiment, the input capacitor Cin is coupled between the input voltage terminal 101 and the output voltage terminal 102 , and the voltage across the input capacitor Cin is the difference (Vin−Vo) between the output voltage Vin and the output voltage Vo.

[0031] Figure 2 FIG. 2 shows a circuit structure diagram of a controller 30 according to an embodiment of the present invention. Figure 2 As shown, the controller 30 includes a comparison unit 21 , a conduction time unit 22 , and a switch control unit 23 .

[0032] The comparison unit 21 provides a comparison signal SC according to a voltage feedback signal Vfb representing the output voltage Vo and a reference signal Vref. In one implementation, the controller 30 provides a voltage feedback signal Vfb according to the output voltage sampling signal Vosen. In one embodiment, when the voltage feedback signal Vfb is less than the reference signal Vref, the comparison signal SC becomes a high level. In another embodiment, when the voltage feedback signal Vfb is less than the sum of the reference signal Vref and the slope compensation signal Vramp (Vref+Vramp), the comparison signal SC becomes a high level. In yet another embodiment, when the sum of the feedback signal Vfb and the bias signal Vfb (Vfb+Vtrim) is less than the reference signal Vref, the comparison signal SC becomes a high level. In yet another embodiment, when the sum of the feedback signal Vfb and the bias signal Vfb (Vfb+Vtrim) is less than the sum of the reference signal Vref and the slope compensation signal Vramp (Vref+Vramp), the comparison signal SC becomes a high level. The bias signal Vtrim is used to adjust the static error between the output voltage Vo and the target value of the output voltage Vo. The slope compensation signal Vramp may be, for example, a periodically changing slope, whose period is equal to half of the switching period, for example, the duration from the rising edge of the switch control signal PWM1 to the rising edge of the switch control signal PWM2. Figure 2 In the illustrated embodiment, the controller 30 further includes a differential amplifier 24, the two ends of which are coupled to the output voltage sampling pin P1 and the remote return pin P0 to receive the output voltage sampling signal Vosen, and provide a differential signal Vdiff after differential amplification. The controller 30 provides a voltage feedback signal Vfb according to the differential signal Vdiff, for example, the voltage feedback signal Vfb is equal to the differential signal Vdiff, or is equal to the sum Vdiff+Vdroop of the differential signal Vdiff and the drop signal Vdroop. The drop signal Vdroop represents the voltage drop of the output voltage Vo when the output current Io increases. The reference signal Vref can be set according to the target value of the output voltage Vo, for example, it can be set through the pin of the controller 30, according to the initial data stored in the controller 30, or by the user through the communication bus.

[0033] The conduction duration unit 22 provides duration control signals CTon1 and CTon2 according to the input voltage sampling signal Vinsen, the current sampling signals CS1 and CS2, the reference signal Vref, and the target frequency signal Fstgt. The duration control signal CTon1 is used to control the duration Ton1 of the switch control signal PWM1 in the first state, and the duration control signal CTon2 is used to control the duration Ton2 of the switch control signal PWM2 in the first state. The target frequency signal Fstgt represents the target value of the switching frequency fs of the bridge switching converter 100A and 100B, for example, the expected value of the switching frequency of the switch tubes Q1-Q4 when the bridge switching converter 100A and 100B are in steady-state operation. The target frequency signal Fstgt can be set, for example, through the pin of the controller 30, according to the initial data stored in the controller 30, or by the user through the communication bus. In one embodiment, the on-time unit 22 controls the duration Ton1 and the duration Ton2 to change with the change of the input voltage Vin, and further adjusts at least one of the durations Ton1 and Ton2 according to the current sampling signal CS1 and the current sampling signal CS2. In one embodiment, the on-time unit 22 controls the duration Ton1 and the duration Ton2 to change with the change of the reference signal Vref, that is, the target value of the output voltage Vo. In one embodiment, the on-time unit 22 further controls the durations Ton1 and Ton2 to change with the change of the target value of the switching frequency fs of the bridge switching converters 100A and 100B.

[0034] The switch control unit 23 provides the switch control signals PWM1, PWM2, PWMS1, and PWMS2 according to the comparison signal SC and the duration control signals CTon1 and CTon2. In one embodiment, the switch control unit 23 sequentially controls the switch control signals PWM1 and PWM2 to alternately change to the first state according to the comparison signal SC, and sequentially controls the switch control signals PWMS1 and PWMS2 to alternately change to the second state. In one embodiment, the switch control unit 23 controls the switch control signal PWM1 to change to the second state according to the duration control signal CTon1, controls the switch control signal PWMS2 to change to the first state, and controls the switch control signal PWM2 to change to the second state according to the duration control signal CTon2, and controls the switch control signal PWMS1 to change to the first state.

[0035] Figure 3A The circuit structure diagram of the conduction duration unit 22A according to an embodiment of the present invention is shown. The conduction duration unit 22A obtains the basic duration Tonb according to the input voltage sampling signal Vinsen, the reference signal Vref, and the target frequency signal Fstgt to control the duration Ton1 and the duration Ton2. In one embodiment, the basic duration Tonb is shown in the following formula (1), where k is a proportionality coefficient.

[0036]

[0037] Further, the conduction duration unit 22A generates an adjustment duration DltaT according to the difference (CS2-CS1) between the current sampling signal CS2 and the current sampling signal CS1 to adjust at least one of the duration Ton1 and the duration Ton2, wherein the adjustment duration DltaT can be a positive value, zero, or a negative value. In one embodiment, the duration Ton1 is equal to the basic duration Tonb, and the duration Ton2 is equal to the basic duration Tonb plus the adjustment duration DltaT.

[0038] exist Figure 3A In the illustrated embodiment, the conduction duration unit 22A includes a calculation unit 231 and an adjustment unit 232. The calculation unit 231 obtains the basic duration Tonb according to the above formula (1), and provides a duration control signal CTon1 according to the basic duration Tonb to control the duration Ton1. The adjustment unit 232 generates an adjustment duration DltaT according to the difference (CS2-CS1) between the current sampling signal CS2 and the current sampling signal CS1, and provides a duration control signal CTon2 according to the sum (Tonb+DltaT) of the basic duration Tonb and the adjustment duration DltaT to control the duration Ton2.

[0039] Figure 3B The circuit structure diagram of the conduction duration unit 22B according to an embodiment of the present invention is shown. The conduction duration unit 22B includes a calculation unit 231, an adjustment unit 233, and an adjustment unit 234. The adjustment unit 233 generates an adjustment duration DltaT1 according to the difference (CS1-Iref) between the current sampling signal CS1 and the current reference signal Iref, and provides a duration control signal CTon1 to control the duration Ton1 according to the sum (Tonb+Dlta1) of the basic duration Tonb and the adjustment duration DltaT1. The adjustment unit 234 generates an adjustment duration DltaT2 according to the difference (CS2-Iref) between the current sampling signal CS2 and the current reference signal Iref, and provides a duration control signal CTon2 to control the duration Ton2 according to the sum (Tonb+DltaT2) of the basic duration Tonb and the adjustment duration DltaT2. In one embodiment, the current reference signal Iref may be equal to an average value (CS1+CS2) / 2 of the current sampling signal CS1 and the current sampling signal CS2, or equal to a preset value.

[0040] Figure 4 FIG. 2 shows a circuit structure diagram of a switch control unit 23 according to an embodiment of the present invention. Figure 4In the illustrated embodiment, the switch control unit 23 includes a frequency dividing unit 231 , logic units 233_1 , 233_2 , and control signal generating units 232_1 , 232_2 .

[0041] The frequency division unit 231 provides the frequency division signals SC1 and SC2 according to the comparison signal SC. In one embodiment, the frequency division unit 231 distributes the pulses of the comparison signal SC to the frequency division signal SC1 and the frequency division signal SC2 in sequence. The logic unit 233_1 provides the set signal SET1 according to the frequency division signal SC1 and the switch control signal PWM2 to control the moment when the switch control signal PWM1 changes to the first state, and the moment when the switch control signal PWMS2 changes to the second state. For example, when the switch control signal PWM2 is in the second state, the switch control signal PWMS2 is controlled to change to the second state according to the output voltage Vo, and then after the delay time, the switch control signal PWM1 is controlled to change to the first state. The logic unit 233_2 provides the set signal SET2 according to the frequency division signal SC2 and the switch control signal PWM1 to control the moment when the switch control signal PWM2 changes to the first state, and the moment when the switch control signal PWMS1 changes to the second state. For example, when the switch control signal PWM1 is in the second state, the switch control signal PWMS1 is controlled to change to the second state according to the output voltage Vo, and then after the delay time, the switch control signal PWM2 is controlled to change to the first state.

[0042] The control signal generating unit 232_1 generates a switch control signal PWM1 and a switch control signal PWMS2 according to the set signal SET1 and the on-time signal CTon1. The control signal generating unit 232_2 generates a switch control signal PWM2 and a switch control signal PWMS1 according to the set signal SET2 and the on-time signal CTon2. In one embodiment, the control signal generating unit 232_1 controls the switch control signal PWM1 to change to the second state according to the on-time signal CTon1, and controls the switch control signal PWMS2 to change to the first state. In one embodiment, the control signal generating unit 232_2 controls the switch control signal PWM2 to change to the second state according to the on-time signal CTon2, and controls the switch control signal PWMS1 to change to the first state.

[0043] exist Figure 4In the illustrated embodiment, the control signal generating unit 232_1 includes an RS trigger 41_1, a shutdown control unit 42_1, and an output unit 43_1. The RS trigger 41_1 includes a set terminal S for receiving a set signal SET1, a reset terminal R for receiving a reset signal COT1, and an output terminal Q. The shutdown control unit 42_1 provides a reset signal COT1 according to the on-time signal CTon1. The output unit 43_1 is coupled to the output terminal Q of the RS trigger 41_1 and outputs the switch control signals PWM1 and PWMS2. The control signal generating unit 232_2 includes an RS trigger 41_2, a shutdown control unit 42_2, and an output unit 43_2. The RS trigger 41_2 includes a set terminal S for receiving a set signal SET2, a reset terminal R for receiving a reset signal COT2, and an output terminal Q. The shutdown control unit 42_2 provides a reset signal COT2 according to the on-time signal CTon2. The output unit 43_2 is coupled to the output terminal Q of the RS flip-flop 41_2 and outputs the switch control signals PWM2 and PWMS1 .

[0044] Figure 5 A signal waveform diagram 50 of the switch control unit 23 according to an embodiment of the present invention is shown. Figure 5 The waveform diagram shown is, from top to bottom, a comparison signal SC, a frequency division signal SC1, a switch control signal PWM1, a switch control signal PWMS2, a frequency division signal SC2, a switch control signal PWM2, and a switch control signal PWMS1. Figure 5 In the illustrated embodiment, when the switch control signals PWM1, PWM2, PWMS1, and PWMS2 are at a high level, the corresponding switch tubes are turned on, and when the switch control signals PWM1, PWM2, PWMS1, and PWMS2 are at a low level, the corresponding switch tubes are turned off.

[0045] The comparison signal SC changes to a high level according to the output voltage Vo. For example, when the voltage feedback signal Vfb or the sum of the voltage feedback signal Vfb and the bias signal Vtrim (Vfb+Vtrim) is less than the reference signal Vref or the sum of the reference signal Vref and the slope compensation signal Vramp (Vref+Vramp), the comparison signal SC changes to a high level. The comparison signal SC sequentially controls the switch control signal PWM1 and the switch control signal PWM2 to change to a high level, and sequentially controls the switch control signal PWMS2 and the switch control signal PWMS1 to change to a low level. Figure 5As shown, the pulses of the comparison signal SC are sequentially distributed to the frequency-divided signals SC1 and SC2. For example, the pulses of the comparison signal SC labeled "1" are distributed to the frequency-divided signal SC1, and the pulses of the comparison signal SC labeled "2" are distributed to the frequency-divided signal SC2. When the switch control signal PWM2 is at a low level, the switch control unit 23 controls the switch control signal PWMS2 to become a low level and controls the switch control signal PWM1 to become a high level according to the frequency-divided signal SC1. When the switch control signal PWM1 is at a low level, the switch control unit 23 controls the switch control signal PWMS1 to become a low level and controls the switch control signal PWM2 to become a high level according to the frequency-divided signal SC2.

[0046] like Figure 5 As shown, at time t1, the switch control signal PWM2 is at a low level, and the frequency division signal SC1 becomes a high level according to the output voltage Vo. In response to the low-level switch control signal PWM2 and the high-level frequency division signal SC1, the switch control signal PWMS2 becomes a low level, and after the delay time, the switch control signal PWM1 becomes a high level. When the duration of the switch control signal PWM1 at a high level reaches the duration Ton1, the switch control unit 23 controls the switch control signal PWM1 to become a low level, and after the delay time, controls the switch control signal PWMS2 to become a high level. At time t2, the switch control signal PWM1 is at a low level, and the frequency division signal SC2 becomes a high level according to the output voltage Vo. In response to the low-level switch control signal PWM1 and the high-level frequency division signal SC2, the switch control signal PWMS1 becomes a low level, and after the delay time, the switch control signal PWM2 becomes a high level. When the duration of the switch control signal PWM2 being at a high level reaches the duration Ton2, the switch control unit 23 controls the switch control signal PWM2 to become a low level, and after a delay time, controls the switch control signal PWMS1 to become a high level. In one embodiment, when the current sampling signal CS1 and the current sampling signal CS2 are equal, the duration Ton2 of the switch control signal PWM2 being at a high level is equal to the duration Ton1 of the switch control signal PWM1 being at a high level, and both are equal to the basic duration Tonb.

[0047] continue Figure 5Description. At time t3, the frequency division signal SC1 becomes a high level, but at this time the switch control signal PWM2 is still a high level, the switch control signal PWM1 maintains a low level and the switch control signal PWMS2 maintains a high level. Until time t4, the switch control signal PWM2 becomes a low level, and the switch control unit 23 responds to the high level frequency division signal SC1, controls the switch control signal PWMS2 to become a low level, and after a delay time, controls the switch control signal PWM1 to become a high level. In one embodiment, when the current sampling signal CS2 and the current sampling signal CS1 are not equal, the time length Ton2 that the switch control signal PWM2 is at a high level is equal to the basic time length Tonb plus the adjustment time length DltaT. At time t5, the frequency division signal SC2 becomes a high level, but at this time the switch control signal PWM1 is still a high level, the switch control signal PWM2 maintains a low level and the switch control signal PWMS1 maintains a high level. Until time t6, the switch control signal PWM1 becomes low level, the switch control unit 23 responds to the high level frequency division signal SC2, controls the switch control signal PWMS1 to become low level, and after a delay time, controls the switch control signal PWM2 to become high level.

[0048] Figure 6 FIG. 2 shows a structural diagram of a bridge switching converter 200 according to an embodiment of the present invention. Figure 1A The bridge switching converter 100A shown is different in that Figure 6 In the illustrated embodiment, the primary switch circuit 10B includes a half-bridge switch circuit composed of a capacitor Cin1, a capacitor Cin2, a switch tube Q1, and a switch tube Q2. The capacitor Cin1 and the capacitor Cin2 are coupled in series between the input voltage terminal 101 and the output voltage terminal 102. The first end of the capacitor Cin1 is coupled to the input voltage terminal 101, the first end of the capacitor Cin2 is coupled to the second end of the capacitor Cin1, forming a bridge arm terminal 104, and the second end of the capacitor Cin2 is coupled to the output voltage terminal 102. The input voltage terminal 101 serves as the first input terminal of the primary switch circuit 10B, and the output voltage terminal 102 serves as the second input terminal of the primary switch circuit 10B.

[0049] Figure 7 FIG. 2 shows a structural diagram of a bridge switching converter 300 according to an embodiment of the present invention. Figure 7 In the illustrated embodiment, the controller 30B further includes communication pins P9-P10 for communicating with a host computer to receive user settings. Figure 7 In the embodiment shown, the communication pin P9 is coupled to the clock bus SCL, and the communication pin P10 is coupled to the data bus SDA. Figure 7In the illustrated embodiment, the bridge switching converter 300 further includes drivers 40_1 to 40_4. Driver 40_1 receives a switch control signal PWM1, and outputs a drive signal Drp1 to drive switch tubes Q1 and Q4 according to the switch control signal PWM1. Driver 40_2 receives a switch control signal PWM2, and outputs a drive signal Drp2 to drive switch tubes Q2 and Q3 according to the switch control signal PWM2. Driver 40_3 receives a switch control signal PWMS1, and outputs a drive signal Drs1 to drive switch tube S1 according to the switch control signal PWMS1. Driver 40_4 receives a switch control signal PWMS2, and outputs a drive signal Drs2 to drive switch tube S2 according to the switch control signal PWMS2. In one embodiment, drivers 40_1 to 40_4 are respectively integrated on different chips. In another embodiment, driver 40_1 and driver 40_2 can be integrated on the same chip, and driver 40_3 and driver 40_4 can be integrated on the same chip.

[0050] Figure 8 FIG. 4 shows a structural diagram of a controller 30B according to an embodiment of the present invention. Figure 8 In the illustrated embodiment, the controller 30B further includes an interface circuit 25 and a memory 26. The controller 30B receives data sent by the host computer through the communication pins P9 and P10, and the memory 26 is used to store the data received from the communication pins P9 and P10, and to store initial data. The initial data can be written before the controller 30B leaves the factory. The controller 30B provides a reference signal Vref and a target frequency signal Fstgt according to the data received from the communication pins P9 and P10 or according to the initial data stored in the memory 26.

[0051] Fig. 9 FIG. 4 shows a structural diagram of a bridge switching converter 400 according to an embodiment of the present invention. Fig. 9 In the illustrated embodiment, the bridge switching converter 400 includes a primary switch circuit 10D, a transformer T1, a secondary switch circuit 20C, and a controller 30C. The primary switch circuit 10D includes switch tubes Q1 to Q4, wherein the second end of the switch tube Q2 and the second end of the switch tube Q4 are coupled to the reference terminal 110, which is different from the primary switch circuit 10C. The center tap 107 of the secondary winding of the transformer T1 is coupled to the reference terminal 111. The reference terminal 111 can also be coupled to the reference terminal 110. The secondary switch circuit 20C is different from the secondary switch circuit 20B in that the second end of the switch tube S1 and the second end of the switch tube S2 are coupled to the output terminal 102.

[0052] Fig.10 FIG. 4 shows a structural diagram of a controller 30C according to an embodiment of the present invention. Fig.10As shown, the controller 30C further includes an isolation circuit 61 coupled between the switch control unit 23 and the control signal output pins P5-P6 to isolate the switch control signal PWM1 and the switch control signal PWM2 from the secondary circuit of the transformer T1. The isolation circuit 61 includes, for example, an isolation capacitor.

[0053] Fig.11 A method 500 for controlling a bridge switching converter according to an embodiment of the present invention is shown. The bridge switching converter includes a transformer, a primary switching circuit coupled to a primary winding of the transformer, and a secondary switching circuit coupled to a secondary winding of the transformer, wherein the primary switching circuit includes at least a first switching tube and a second switching tube. The method 500 includes steps S11 to S15.

[0054] In step S11, an output voltage sampling signal representing the output voltage of the bridge switching converter is received through the output voltage sampling pin. In step S12, an input voltage sampling signal representing the input voltage of the bridge switching converter is received through the input voltage sampling pin. In step S13, a first switch control signal is provided through the first control signal output pin, and a second switch control signal is provided through the second control signal output pin, the first switch control signal is used to control the conduction and shutdown of the first switch tube, and the second switch control signal is used to control the conduction and shutdown of the second switch tube. In step S14, according to the output voltage sampling signal and the second switch control signal, the first switch control signal is controlled to become a first state to turn on the first switch tube, and according to the output voltage sampling signal and the first switch control signal, the second switch control signal is controlled to become a first state to turn on the second switch tube. In step S15, when the duration that the first switch control signal is in the first state is equal to the first duration, the first switch control signal is controlled to change to the second state to turn off the first switch tube, and when the duration that the second switch control signal is in the first state is equal to the second duration, the second switch control signal is controlled to change to the second state to turn off the second switch tube.

[0055] It should be noted that the execution order of the steps in the above flowchart is not limited to Fig.11 As shown, two consecutive function blocks may be executed simultaneously, or in reverse order, for example, step S12 may be executed before step S11, or may be executed simultaneously.

[0056] Although the present invention has been described with reference to several typical embodiments, it should be understood that the terms used are illustrative and exemplary, rather than restrictive. Since the present invention can be embodied in a variety of forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims, so all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A bridge switching converter, comprising: An input voltage terminal for receiving an input voltage, and an output voltage terminal for providing an output voltage; A transformer, comprising a primary winding and a secondary winding, wherein the secondary winding comprises a first end, a second end, and a center tap located between the first end and the second end, wherein the center tap is coupled to an output voltage terminal of the bridge switching converter; A first switch tube, comprising a first end and a second end, the first end of the first switch tube being coupled to an input voltage end of the bridge switching converter, and the second end of the first switch tube being coupled to a first end of the primary winding; A second switch tube, comprising a first end and a second end, the first end of the second switch tube being coupled to the second end of the first switch tube and the first end of the primary winding, and the second end of the second switch tube being coupled to the center tap of the secondary winding, the second switch tube and the first switch tube forming a first bridge arm; A third switch tube comprises a first end and a second end, the first end of the third switch tube is coupled to the input voltage end of the bridge switching converter, and the second end of the third switch tube is coupled to the second end of the primary winding; a fourth switch tube, comprising a first end and a second end, wherein the first end of the fourth switch tube is coupled to the second end of the third switch tube and the second end of the primary winding, and the second end of the fourth switch tube is coupled to the center tap of the secondary winding, and the fourth switch tube and the third switch tube form a second bridge arm; A fifth switch tube, comprising a first end and a second end, wherein the first end of the fifth switch tube is coupled to the first end of the secondary winding, and the second end of the fifth switch tube is coupled to the reference end; a sixth switch tube, comprising a first end and a second end, the first end of the sixth switch tube being coupled to the second end of the secondary winding, and the second end of the sixth switch tube being coupled to the reference end; and A controller provides a first switch control signal for controlling the second switch tube and the third switch tube, a second switch control signal for controlling the first switch tube and the fourth switch tube, a third switch control signal for controlling the fifth switch tube, and a fourth switch control signal for controlling the sixth switch tube; wherein When the second switch control signal controls the first switch tube and the fourth switch tube to remain turned off, the controller controls the first switch control signal according to the output voltage to turn on the second switch tube and the third switch tube until the turn-on time of the second switch tube or the third switch tube is equal to the first time, and the controller controls the second switch tube and the third switch tube to turn off through the first switch control signal; as well as When the first switch control signal controls the second switch tube and the third switch tube to remain turned off, the controller controls the second switch control signal according to the output voltage to turn on the first switch tube and the fourth switch tube until the turn-on time of the first switch tube or the fourth switch tube is equal to the second time, and the controller controls the first switch tube and the fourth switch tube to turn off through the second switch control signal.

2. The bridge switching converter as claimed in claim 1, wherein the controller balances the current flowing through the first bridge arm and the current flowing through the second bridge arm by adjusting at least one of the first time length and the second time length. 3 . The bridge switching converter as claimed in claim 2 , wherein the first time duration and the second time duration vary with a change in input voltage.

4. The bridge switching converter as claimed in claim 1, wherein: The controller controls the third switch control signal according to the first switch control signal and the output voltage to turn off the fifth switch tube; as well as The controller controls the third switch control signal to turn on the fifth switch tube according to the turn-on time of the first switch tube or the fourth switch tube.

5. The bridge switching converter as claimed in claim 1, wherein: The controller controls the fourth switch control signal according to the second switch control signal and the output voltage to turn off the sixth switch tube; and The controller controls the fourth switch control signal to turn on the sixth switch tube according to the turn-on time of the second switch tube or the third switch tube.

6. The bridge switching converter as claimed in claim 1, wherein the controller comprises: A comparison unit, providing a comparison signal according to an output voltage sampling signal and a reference signal, wherein the output voltage sampling signal represents the output voltage; A conduction duration unit, providing a first duration control signal and a second duration control signal according to an input voltage, a first current sampling signal, and a second current sampling signal, wherein the first current sampling signal represents a current flowing through the first bridge arm, and the second current sampling signal represents a current flowing through the second bridge arm; as well as The switch control unit generates a first switch control signal and a fourth switch control signal according to the comparison signal, the first duration control signal, and the second switch control signal, and generates a second switch control signal and a third switch control signal according to the comparison signal, the second duration control signal, and the first switch control signal.

7. A bridge switching converter, comprising: An input voltage terminal, an output voltage terminal, and a reference terminal, wherein the voltage between the input voltage terminal and the reference terminal is the input voltage, and the voltage between the output voltage terminal and the reference terminal is the output voltage; A transformer comprising a primary winding and a secondary winding, wherein the secondary winding comprises a first end, a second end, and a center tap between the first end and the second end; A bridge switch circuit, comprising a first input terminal, a second input terminal, a first bridge arm terminal, a second bridge arm terminal, a first switch tube, and a second switch tube, wherein the first input terminal of the bridge switch circuit is coupled to an input voltage terminal, the second input terminal of the bridge switch circuit is coupled to an output voltage terminal, the first bridge arm terminal of the bridge switch circuit is coupled to a first terminal of a primary winding, the second bridge arm terminal of the bridge switch circuit is coupled to a second terminal of the primary winding, a center tap of the secondary winding is coupled to the second input terminal of the bridge switch circuit, the first switch tube is coupled between the first bridge arm terminal and the output voltage terminal, and the second switch tube is coupled between the input voltage terminal and the first bridge arm terminal; as well as A controller provides a first switch control signal according to an output voltage to control a first switch tube in a bridge switch circuit, and provides a second switch control signal to control a second switch tube in the bridge switch circuit, wherein when the second switch control signal controls the second switch tube to remain off, the controller controls the first switch control signal according to the output voltage to turn on the first switch tube, and when the first switch control signal controls the first switch tube to remain off, the controller controls the second switch control signal according to the output voltage to turn on the second switch tube.

8. The bridge switching converter as claimed in claim 7, further comprising: A third switch tube and a fourth switch tube, wherein the first end of the third switch tube is coupled to the first end of the secondary winding, the second end of the third switch tube is coupled to the reference end of the bridge switch converter, the first end of the fourth switch tube is coupled to the second end of the secondary winding, and the second end of the fourth switch tube is coupled to the reference end of the bridge switch converter.

9. The bridge switching converter as claimed in claim 8, wherein: The controller further provides a third switch control signal to control the third switch tube, and provides a fourth switch control signal to control the fourth switch tube; The controller controls the third switch control signal to turn off the third switch tube according to the first switch control signal and the output voltage, and controls the third switch control signal to turn on the third switch tube according to the second switch control signal; as well as The controller controls the fourth switch control signal to turn off the fourth switch tube according to the second switch control signal and the output voltage, and controls the fourth switch control signal to turn on the fourth switch tube according to the first switch control signal.

10. The bridge switching converter as described in claim 7, wherein when the on-time of the first switch tube is equal to the first time length, the controller turns off the first switch tube through a first switch control signal, and when the on-time of the second switch tube is equal to the second time length, the controller turns off the second switch tube through a second switch control signal.

11. The bridge switching converter of claim 10, wherein the controller balances the current flowing through the first end of the secondary winding and the current flowing through the second end of the secondary winding by adjusting at least one of the first time duration and the second time duration.

12. The bridge switching converter as claimed in claim 7, wherein the controller comprises: A comparison unit, providing a comparison signal according to an output voltage sampling signal and a reference signal, wherein the output voltage sampling signal represents the output voltage; A conduction duration unit, providing a first duration control signal and a second duration control signal according to an input voltage, a first current sampling signal, and a second current sampling signal, wherein the first current sampling signal represents a current flowing through the first end of the secondary winding, and the second current sampling signal represents a current flowing through the second end of the secondary winding; as well as The switch control unit generates a first switch control signal and a fourth switch control signal according to the comparison signal, the first duration control signal, and the second switch control signal, and generates a second switch control signal and a third switch control signal according to the comparison signal, the second duration control signal, and the first switch control signal. 13 . The bridge switching converter as claimed in claim 7 , wherein the second bridge arm end is coupled to the input voltage end through the first capacitor or the fifth switch tube, and is coupled to the output voltage end through the second capacitor or the sixth switch tube.

14. A controller for a bridge switching converter, the bridge switching converter comprising a transformer, a primary switching circuit coupled to a primary winding of the transformer, and a secondary switching circuit coupled to a secondary winding of the transformer, the controller comprising: An output voltage sampling pin, used to receive an output voltage sampling signal representing the output voltage of the bridge switching converter; An input voltage sampling pin, used to receive an input voltage sampling signal representing an input voltage of the bridge switching converter; A first control signal output pin, used to provide a first switch control signal to control a first switch tube in a primary switch circuit; A second control signal output pin, used to provide a second switch control signal to control a second switch tube in the primary switch circuit; A third control signal output pin, used to provide a third switch control signal to control a third switch tube in the secondary side switch circuit; as well as A fourth control signal output pin, used for providing a fourth switch control signal to control a fourth switch tube in the secondary side switch circuit; in When the second switch control signal controls the second switch tube to remain turned off, the controller controls the first switch control signal to turn on the first switch tube according to the output voltage until the turn-on time of the first switch tube is equal to the first time, and the controller controls the first switch control signal to turn off the first switch tube; as well as When the first switch control signal controls the first switch tube to turn off, the controller controls the second switch control signal to turn on the second switch tube according to the output voltage until the turn-on time of the second switch tube is equal to the second time, and the controller controls the second switch control signal to turn off the second switch tube.

15. The controller of claim 14, further comprising: A first current sampling pin, receiving a first current sampling signal, wherein the first current sampling signal represents a current flowing through the third switch tube; as well as A second current sampling pin, receiving a second current sampling signal, wherein the second current sampling signal represents a current flowing through the fourth switch tube; in The controller adjusts at least one of the first time length and the second time length according to the first current sampling signal and the second current sampling signal.

16. The controller of claim 15, further comprising: Communication pin, used to receive data; as well as A memory for storing data received from the communication pin and for storing initial data; in The controller obtains the first duration and the second duration according to the input voltage sampling signal, the first current sampling signal, the second current sampling signal, and the data received from the communication pin or the initial data in the memory.

17. The controller of claim 14, further comprising: A comparison unit, providing a comparison signal according to the output voltage sampling signal and the reference signal; A conduction duration unit, providing a first duration control signal and a second duration control signal according to an input voltage sampling signal, a first current sampling signal, and a second current sampling signal; as well as The switch control unit generates a first switch control signal and a fourth switch control signal according to the comparison signal, the first duration control signal, and the second switch control signal, and generates a second switch control signal and a third switch control signal according to the comparison signal, the second duration control signal, and the first switch control signal.

18. The controller of claim 14, wherein: The controller controls the third switch control signal to turn off the third switch tube according to the first switch control signal and the output voltage; and The controller controls the third switch control signal to turn on the third switch tube according to the second switch control signal.

19. The controller of claim 14, wherein: The controller controls the fourth switch control signal according to the second switch control signal and the output voltage to turn off the fourth switch tube; and The controller controls the fourth switch control signal to turn on the fourth switch tube according to the first switch control signal.

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