Single-input multiple-output power supply system and single-input multiple-output control chip thereof

Abstract

Provided are a single-input multiple-output power supply system and a single-input multiple-output control chip thereof. The power supply system includes a first power tube and a synchronous rectification tube, and further includes: a PWM control chip configured to generate a driving control signal for the first power tube based on an output voltage feedback signal; a synchronous rectification control chip configured to generate a driving control signal for the synchronous rectification tube based on a voltage between a drain and a source of the synchronous rectification tube; a SIMO control chip configured to generate an output voltage representation current based on first and second output voltages, generate first and second path control signals based on the driving control signal for the synchronous rectification tube and the second output voltage, generate a driving control signal for a first output path based on the first path control signal, and generate a driving control signal for a second output path based on the second path control signal; and an optocoupler configured to generate the output voltage feedback signal based on the output voltage representation current.

Description

Technical Field

[0001] This invention relates to the field of circuits, and more specifically to a single-input multiple-output power supply system and its single-input multiple-output control chip. Background Technology

[0002] In a traditional single-input dual-output power supply system 100, such as Figure 1 As shown, the AC input voltage VAC is rectified into a DC voltage Vbuck by an electromagnetic interference (EMI) filter and a rectifier bridge circuit; the DC voltage Vbuck is converted into a DC output voltage Vout by a transformer T1; the voltage divider resistors R1 / R2 divide the DC output voltage Vout to generate a DC output voltage divider; the DC output voltage divider is converted into an output voltage feedback signal VFB associated with the DC output voltage Vout by a TL431 and an optocoupler OPTO; the output voltage feedback signal VFB is sent to the pulse width modulation (PWM) control chip 102 via the output feedback pin (i.e., the FB pin); the PWM control chip 102 implements constant voltage control of the DC output voltage Vout based on the output voltage feedback signal VFB, and... The system output power is controlled by switching the power transistor M1 between the on and off states via the gate drive pin (i.e., the GATE pin). The synchronous rectification (SR) control chip 104 achieves high efficiency by controlling the synchronous rectifier transistor M2 to be in the on state during the demagnetization time of the transformer T1 via the GATE pin. The DC output voltage Vout is converted into the first output voltage VO1 via the power transistors MH1 and ML1, inductor L1, capacitor C1, and the first DC / DC converter chip 106-1 in the first output path. Simultaneously, the second output voltage VO2 is converted into the second output voltage VO2 via the power transistors MH2 and ML2, inductor L2, capacitor C2, and the second DC / DC converter chip 106-2 in the second output path. It should be noted that the AC input voltage VAC can be in the range of 90V to 264V. Summary of the Invention

[0003] A single-input multi-output power supply system according to an embodiment of the present invention includes a transformer, a first power transistor connected between the primary winding of the transformer and ground, a synchronous rectifier connected between the secondary winding of the transformer and ground, a first output path for outputting a first output voltage, and a second output path for outputting a second output voltage. It further includes: a pulse width modulation (PWM) control chip configured to generate a drive control signal for controlling the on / off state of the first power transistor based on an output voltage feedback signal associated with the first and second output voltages; a synchronous rectification control chip configured to generate a drive control signal for controlling the on / off state of the synchronous rectifier based on the voltage between the drain and source of the synchronous rectifier; and a single-input multi-output control chip. The chip is configured to generate an output voltage characterizing current based on a first output voltage and a second output voltage; to generate a first path control signal and a second path control signal based on a drive control signal for controlling the on and off of a synchronous rectifier diode and the second output voltage, or based on a drive control signal for controlling the on and off of a synchronous rectifier diode and the first output voltage; to generate a drive control signal for controlling the on and off of a first output path based on the first path control signal; and to generate a drive control signal for controlling the on and off of a second output path based on the second path control signal; and an optocoupler, connected between a pulse width modulation control chip and a single-input multiple-output control chip, is configured to generate an output voltage feedback signal based on the output voltage characterizing current.

[0004] According to an embodiment of the present invention, a single-input multiple-output (SIMO) control chip for use in a single-input multiple-output (SMO) power supply system includes a transformer, a first power transistor connected between the primary winding of the transformer and ground, a synchronous rectifier transistor connected between the secondary winding of the transformer and ground, a first output path for outputting a first output voltage, a second output path for outputting a second output voltage, a pulse width modulation (PWM) control chip for controlling the on and off states of the first power transistor, a synchronous rectifier control chip for controlling the on and off states of the synchronous rectifier transistor, and an optocoupler connected between the SIMO control chip and the PWM control chip. The SIMO control chip is configured to generate an output voltage meter based on the first and second output voltages. The system is configured to generate an output voltage feedback signal based on the current characterized by the output voltage, and a pulse width modulation control chip is configured to generate a drive control signal for controlling the on and off of a first power transistor based on the output voltage feedback signal. A first path control signal and a second path control signal are generated based on the drive control signal for controlling the on and off of a synchronous rectifier transistor generated by the synchronous rectifier control chip and the second output voltage, or based on the drive control signal for controlling the on and off of a synchronous rectifier transistor and the first output voltage. A drive control signal for controlling the on and off of a first output path is generated based on the first path control signal. A drive control signal for controlling the on and off of a second output path is generated based on the second path control signal. Attached Figure Description

[0005] The invention can be better understood from the following description of specific embodiments of the invention in conjunction with the accompanying drawings, wherein: Figure 1 The system architecture diagram of a traditional single-input dual-output power supply system is shown.

[0006] Figure 2 A system architecture diagram of a single-input multiple-output power supply system according to an embodiment of the present invention is shown.

[0007] Figure 3 It shows Figure 2 The diagram shows a schematic block diagram of the internal circuitry of the SIMO control chip.

[0008] Figure 4 It shows Figure 3 The circuit diagram shown is an example implementation of the ramp signal generation circuit.

[0009] Figure 5 It shows Figure 3 The circuit diagram shown is an example of a closed-loop control circuit.

[0010] Figure 6 It shows the relationship with Figure 3 The diagram shows the waveforms of several signals related to the SIMO control chip. Detailed Implementation

[0011] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a comprehensive understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific configuration and algorithm presented below, but covers any modifications, substitutions, and improvements to elements, components, and algorithms without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description in order to avoid unnecessarily obscuring the invention. Furthermore, it should be noted that the term "A connected to B" as used herein can mean "A and B are directly connected" or "A and B are indirectly connected via one or more other elements."

[0012] like Figure 1 As shown, in a traditional single-input dual-output power supply system 100, each output path includes a DC / DC converter chip and a DC / DC inductor (i.e., inductors L1 / L2), which has problems such as complex system design, high cost, low efficiency, and high temperature rise.

[0013] In view of the above, a single-input multiple-output power supply system and its single-input multiple-output (SIMO) control chip according to embodiments of the present invention are proposed, which can simplify system design, reduce system cost, improve system efficiency, and reduce system temperature rise.

[0014] Figure 2 A system architecture diagram of a single-input dual-output power supply system according to an embodiment of the present invention is shown. Figure 2As shown, in the single-input dual-output power supply system 200, the AC input voltage VAC is rectified into a DC voltage Vbuck by an EMI filter and a rectifier bridge circuit; the DC voltage Vbuck is converted into a DC output voltage Vout by a transformer T2; the PWM control chip 202 receives the output voltage feedback signal VFB associated with the first output voltage VO1 of the first output path and the second output voltage VO2 of the second output path via the FB pin, and generates a drive control signal based on the output voltage feedback signal VFB to control the on and off of the power transistor M3 connected between the primary winding of the transformer T2 and ground. The generated drive control signal is output to the gate of power transistor M3 via the GATE pin; the positive output terminal of transformer T2 is connected to diode D1 and capacitor C3, and the output terminal of capacitor C3 is connected to the chip power supply pin (i.e., VDD pin) of SIMO control chip 206; after the system is powered on, the DC output voltage Vout is generated by diode D1 and capacitor C3 to power SIMO control chip 206; synchronous rectifier M4 is connected between the secondary winding of transformer T2 and ground (specifically, between the negative output terminal of transformer T2 and ground); SR control chip 204 detects synchronous rectifier M4... The voltage between the drain and source of the transformer T2 is used to generate a drive control signal for controlling the turn-on and turn-off of the synchronous rectifier M4, and the generated drive control signal is output to the gate of the synchronous rectifier M4 via the GATE pin. When the transformer T2 is in the demagnetization period, the GATE pin of the SR control chip 204 outputs a high level to turn on the synchronous rectifier M4. When the transformer T2 is demagnetized, the GATE pin of the SR control chip 204 outputs a low level to turn off the synchronous rectifier M4. The positive output terminal of the transformer T2 is simultaneously connected to the power transistors M1L and M1R of the first output path and the power transistors M2L and M2R of the second output path.The SIMO control chip 206 detects the first output voltage VO1 via the first output voltage detection pin (i.e., VO1 pin) and the second output voltage VO2 via the second output voltage detection pin (i.e., VO2 pin). Based on the first output voltage VO1 and the second output voltage VO2, it generates an output voltage characterization current and outputs this current to the optocoupler OPTO via the optocoupler connection pin (i.e., OPTO pin). The optocoupler OPTO then generates an output voltage feedback signal VFB based on the output voltage characterization current. It receives a drive control signal for controlling the on / off state of the synchronous rectifier diode M4 via the synchronous rectification detection pin (i.e., SR pin) and generates a first path control signal and a second path control signal based on the received drive control signal and the second output voltage VO2. Based on the first path control signal... A drive control signal for controlling the on / off state of the first output path (i.e., a drive control signal for controlling the on / off state of power transistors M1L and M1R) is generated and output to the gates of power transistors M1L and M1R respectively via the first left gate drive pin (i.e., GATE1L pin) and the first right gate drive pin (i.e., GATE1R pin). Similarly, a drive control signal for controlling the on / off state of the second output path (i.e., a drive control signal for controlling the on / off state of power transistors M2L and M2R) is generated based on the second path control signal and output to the gates of power transistors M2L and M2R respectively via the second left gate drive pin (i.e., GATE2L pin) and the second right gate drive pin (i.e., GATE2R pin). It should be noted that the SIMO control chip 206 can also generate the first and second path control signals based on the drive control signal for controlling the on / off state of synchronous rectifier M4 and the first output voltage VO1. ;

[0015] Compared Figure 1 The single-input dual-output power supply system 100 shown is... Figure 2 The single-input dual-output power supply system 200 shown has the following advantages: each output path eliminates the need for a DC / DC converter chip and a DC / DC inductor (i.e., Figure 1 The L1 and L2 in the system simplify system design, reduce system cost, improve system efficiency, and reduce system temperature rise; at the same time, without a DC / DC inductor, the system is easier to miniaturize.

[0016] Figure 3 It shows Figure 2 The diagram shows a schematic block diagram of the internal circuitry of the SIMO control chip. Figure 3 As shown, in some embodiments, Figure 2The SIMO control chip 206 shown includes a boost control circuit 2062, a diode D6, a switching transistor M6, a ramp signal generation circuit 2064, a closed-loop control circuit 2066, a first drive circuit 2068-1, and a second drive circuit 2068-2. The boost control circuit 2062 is connected to the VDD pin, used to connect to the output of capacitor C3 via the VDD pin, and controls the switching transistor M6 to turn on and off based on the voltage across capacitor C3. The diode D6 is connected to the switching node pin (i.e., the SW pin), used to control the voltage across the switching transistor M6 via the SW pin. The freewheeling current of L4 generates a boosted voltage VBST to power the first drive circuit 2068-1 and the second drive circuit 2068-2. The ramp signal generation circuit 2064 is connected to the SR pin and receives drive control signals via the SR pin to control the on / off state of the power transistor M4, and generates a ramp voltage signal Vramp based on the received drive control signals. The closed-loop control circuit 2066 is connected to the VO1, VO2, and OPTO pins, and detects the first output voltage VO1 via the VO1 pin and the first output voltage VO2 via the VO2 pin. The second output voltage VO2 is measured. Based on the ramp voltage signal Vramp and the second output voltage VO2, the first path control signal Vg1 and the second path control signal Vg2 are generated. Furthermore, based on the first output voltage VO1 and the second output voltage VO2, an output voltage characterizing current is generated and output to the optocoupler OPTO via the OPTO pin. The first drive circuit 2068-1 is connected to the GATE1L and GATE1R pins and is used to generate signals based on the first path control signal Vg1 to control power transistors M1L and M1R. The first drive circuit generates the on / off drive control signal for power transistors M2L and M2R, and outputs the generated drive control signal to the gates of power transistors M1L and M1R respectively via the GATE1L and GATE1R pins; the second drive circuit 2068-2 is connected to the GATE2L and GATE2R pins, and is used to generate drive control signals for controlling the on / off of power transistors M2L and M2R based on the second path control signal Vg2, and outputs the generated drive control signals to the gates of power transistors M2L and M2R respectively via the GATE2L and GATE2R pins.

[0017] Figure 4 It shows Figure 3 The circuit diagram shown is an example implementation of the ramp signal generation circuit. Figure 4 As shown, in some embodiments, Figure 3The ramp signal generation circuit 2064 shown includes a current source I0, an inverter INV0, switching transistors PM1 and NM1, and a capacitor Cramp. The inverter INV0 is used to invert the voltage at the SR pin (i.e., the drive control signal used to control the on and off of the synchronous rectifier M4) to generate drive control signals for controlling the on and off of switching transistors PM1 and NM1. When switching transistor PM1 is on and switching transistor NM1 is off, the reference current I0 from the current source I0 charges the capacitor Cramp through the switching transistor PM1, and the voltage on the capacitor Cramp is the ramp voltage signal Vramp. When switching transistor PM1 is off and switching transistor NM1 is on, the capacitor Cramp discharges through the switching transistor NM1, and the ramp voltage signal Vramp is reset to 0. Here, when the drive control signal used to control the on and off of the synchronous rectifier M4 is at a high level, the switch PM1 is in the on state and the switch NM1 is in the off state; when the drive control signal used to control the on and off of the synchronous rectifier M4 is at a low level, the switch PM1 is in the off state and the switch NM1 is in the on state.

[0018] Figure 5 It shows Figure 3 The circuit diagram shown is an example of a closed-loop control circuit. Figure 5 As shown, in some embodiments, Figure 3 The closed-loop control circuit 2066 shown is further configured to generate a first output voltage divider by dividing the first output voltage OV1, generate a second output voltage divider by dividing the second output voltage OV2, and generate an output voltage characterizing the current based on the magnitude comparison between the first output voltage divider and the first reference voltage VREF1 and the magnitude comparison between the second output voltage divider and the second reference voltage VREF2.

[0019] like Figure 5 As shown, in some embodiments, Figure 3The closed-loop control circuit 2066 shown includes a first voltage divider network (e.g., composed of resistors Ro1 / Ro2), a second voltage divider network (e.g., composed of resistors Ro3 / Ro4), a first transconductance amplifier gm1, and a second transconductance amplifier gm2, wherein: the first voltage divider network is used to divide the first output voltage VO1 to generate a first output voltage divider; the second voltage divider network is used to divide the second output voltage VO2 to generate a second output voltage divider; the first transconductance amplifier gm1 is used to generate a first output voltage characterization signal based on the first output voltage divider and a first reference voltage VREF1; the second transconductance amplifier gm2 is used to generate a second output voltage characterization signal based on the second output voltage divider and a second reference voltage VREF2, wherein the output voltage characterization current is generated based on a first loop compensation voltage, and the first loop compensation voltage is generated based on the first output voltage characterization signal and the second output voltage characterization signal.

[0020] like Figure 5 As shown, in some embodiments, Figure 2 The SIMO control chip 206 shown includes a first loop compensation pin (i.e., the VCOMP1 pin). Figure 2 The single-input multiple-output power supply system 200 shown further includes a first RC compensation circuit (e.g., consisting of a resistor Rc1 and a capacitor Cc1) connected between the VCOMP1 pin and ground, the output of the first transconductance amplifier gm1 and the output of the second transconductance amplifier gm1 connected to the VCOMP1 pin, and the first loop compensation voltage being the voltage at the VCOMP1 pin.

[0021] like Figure 5 As shown, in some embodiments, Figure 3 The closed-loop control circuit 2066 shown further includes a switching transistor M7 and a resistor Ropto. The gate of the switching transistor M7 is connected to the VCOMP1 pin, the drain is connected to the OPTO pin, and the source is connected to the first terminal of the resistor Ropto. The second terminal of the resistor Ropto is grounded. Figure 2 The optocoupler OPTO shown is connected to the OPTO pin.

[0022] like Figure 5 As shown, in some embodiments, Figure 3The closed-loop control circuit 2066 shown further includes a third transconductance amplifier gm3, a comparator cmp1, and an inverter inv1, wherein: the third transconductance amplifier gm3 is used to generate a differential voltage characterization signal based on the second output voltage divider and the second reference voltage VREF2; the comparator cmp1 is used to generate a second path control signal Vg2 based on the ramp voltage signal Vramp and the second loop compensation voltage, wherein the second loop compensation voltage is generated based on the differential voltage characterization signal; and the inverter inv1 is used to invert the second path control signal Vg2 to generate a first path control signal Vg1. It should be noted that the third transconductance amplifier gm3 can also be used to generate a differential voltage characterization signal based on the first output voltage divider and the first reference voltage VREF1.

[0023] like Figure 5 As shown, in some embodiments, Figure 2 The SIMO control chip 206 shown further includes a second loop compensation pin (i.e., the VCOMP2 pin). Figure 2 The single-input multiple-output power supply system 200 shown further includes a second RC compensation circuit (e.g., consisting of resistor Rc2 and capacitor Cc2) connected between the VCOMP2 pin and ground, the output of a third transconductance amplifier gm3 connected to the VCOMP2 pin, and a second loop compensation voltage being the voltage at the VCOMP2 pin.

[0024] like Figure 2 , Figure 3 ,and Figure 5 As shown, in the single-input multiple-output power supply system 200 according to an embodiment of the present invention, the ramp voltage signal Vramp is input to the closed-loop control circuit 2066; the closed-loop control circuit 2066 is connected to the VO1 and VO2 pins to detect the first output voltage VO1 and the second output voltage VO2 and control them to a set voltage; the closed-loop control circuit 2066 is connected to the VCOMP1 and VCOMP2 pins to connect to loop compensation devices (i.e., the first and second RC compensation circuits); the closed-loop control circuit 2066 is also connected to the OPTO pin to input... Figure 2 The optocoupler OPTO outputs current as shown. This optocoupler OPTO is also connected to the FB pin of the PWM control chip 202 to control the total energy transferred from the primary side to the secondary side.

[0025] like Figure 5As shown, in the closed-loop control circuit 2066, the input voltage at pin VO1 is divided by voltage divider resistors Ro1 / Ro2 and then fed to the positive input terminal of the first transconductance amplifier gm1. The negative input terminal of the first transconductance amplifier gm1 is connected to the first reference voltage VREF1, and the output terminal of the first transconductance amplifier gm1 is connected to the VCOMP1 pin. The input voltage at pin VO2 is divided by voltage divider resistors Ro3 / Ro4 and then fed to the positive input terminal of the second transconductance amplifier gm2. The negative input terminal of the second transconductance amplifier gm2 is connected to the second reference voltage VREF2, and the output terminal of the second transconductance amplifier gm2 is simultaneously connected to the VCOMP1 pin. The voltage at pin VCOMP1 is converted into current by switching transistor M7 and resistor Ropto and output from pin OPTO, so that optocoupler OPTO generates an output voltage feedback signal VFB based on the current from pin VCOMP1. This process realizes the control of the total output power transmitted from the primary side to the secondary side.

[0026] like Figure 5 As shown, in the closed-loop control circuit 2066, the input voltage at pin VO2 is divided by voltage divider resistors Ro3 / Ro4 and simultaneously fed to the positive input terminal of the third transconductance amplifier gm3. The negative input terminal of the third transconductance amplifier gm3 is connected to the second reference voltage VREF2, and the output terminal of the third transconductance amplifier gm3 is connected to pin VCOMP2. The output terminal of the third transconductance amplifier gm3 is also connected to the negative input terminal of comparator cmp1, and the positive input terminal of comparator cmp1 is connected to the ramp voltage signal Vramp. The output signal of comparator cmp1 is the second path control signal Vg2. The second drive circuit 2068-2 controls the power transistors M2L and M2R to turn on and off, thereby making the second output voltage VO2 reach the set voltage (1+Ro3 / Ro4)*VREF2; the output signal of comparator cmp1 is inverted by inverter INV1 to generate the first path control signal Vg1; the first path control signal Vg1 controls the power transistors M2L and M2R to turn on and off, thereby making the first output voltage VO1 reach the set voltage (1+Ro3 / Ro4)*VREF2.

[0027] Figure 6 It shows the relationship with Figure 3The diagram shows the waveforms of several signals related to the SIMO control chip. SR represents the drive control signal generated by the SR control chip 204, used to control the on / off state of the synchronous rectifier M4; Vramp represents the ramp voltage signal generated by the ramp signal generation circuit 2064; Vg1 represents the first path control signal generated by the closed-loop control circuit 2066; Vg2 represents the second path control signal generated by the closed-loop control circuit 2066; GATE1L and GATE1R represent the drive control signals generated by the first drive circuit 2068-1, used to control the on / off state of the power transistors M1L / M1R in the first output path; GATE2L and GATE2R represent the drive control signals generated by the second drive circuit 2068-2, used to control the on / off state of the power transistors M2L / M2R in the second output path; and VCOMP2 represents the second loop compensation voltage at the VCOMP2 pin.

[0028] like Figure 6 As shown, when the drive control signal SR, used to control the on and off of the synchronous rectifier M4, is high, the ramp voltage signal Vramp begins to rise. When the ramp voltage signal Vramp rises to the second loop compensation voltage VCOMP2, the second path control signal Vg2 changes from low to high, and the first path control signal Vg1 changes from high to low. The first drive circuit 2068-1 outputs drive control signals GATE1L and GATE1R based on the first path control signal Vg1. When the first path control signal Vg1 is high, the drive control signals GATE1L and GATE1R are high, the power transistors M1L and M1R are in the on state, and the demagnetizing energy of the transformer T2 is transmitted to the first output terminal through the first output path. When the first path control signal Vg1 is low, the drive control signals GATE1L and GATE1R are low, the power transistors M1L and M1R are in the off state, and the demagnetizing energy of the transformer T2 is no longer transmitted to the first output terminal. Similarly, the second drive circuit 2068-2 outputs drive control signals GATE2L and GATE2R based on the second path control signal Vg2. When the second path control signal Vg2 is high, the drive control signals GATE2L and GATE2R are high, the power transistors M2L and M2R are in the on state, and the demagnetizing energy of transformer T2 is transmitted to the second output terminal through the second output path; when the second path control signal Vg2 is low, the drive control signals GATE2L and GATE2R are low, the power transistors M2L and M2R are in the off state, and the demagnetizing energy of transformer T2 is no longer transmitted to the second output terminal. The above process is repeated continuously, and the closed-loop control circuit 2066 controls the first output voltage VO1 and the second output voltage VO2 to the set voltage.

[0029] It should be noted that the above description uses a single-input dual-output power supply system and its SIMO control chip as an example to illustrate the circuit structure and working principle of a single-input multi-output power supply system and its SIMO control chip according to embodiments of the present invention. Those skilled in the art, after reading the above description of the single-input dual-output power supply system, can easily conceive of how to construct and / or design a single-input multi-output power supply system and its SIMO control chip according to embodiments of the present invention.

[0030] This invention can be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in a particular embodiment can be modified without departing from the basic spirit of the invention. Therefore, the present embodiments are to be regarded as exemplary rather than limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and scope of the claims and their equivalents are thus included within the scope of the invention.

Claims

1. A single-input multi-output power supply system, comprising a transformer, a first power transistor connected between the primary winding of the transformer and ground, a synchronous rectifier transistor connected between the secondary winding of the transformer and ground, a first output path for outputting a first output voltage, and a second output path for outputting a second output voltage, and further comprising: The pulse width modulation control chip is configured to generate a drive control signal for controlling the on and off of the first power transistor based on an output voltage feedback signal associated with the first output voltage and the second output voltage. The synchronous rectification control chip is configured to generate a drive control signal for controlling the turn-on and turn-off of the synchronous rectifier tube based on the voltage between the drain and source of the synchronous rectifier tube. A single-input multiple-output (SIMO) control chip is configured as follows: Based on the first and second output voltages, an output voltage characterizing the current is generated. A first path control signal and a second path control signal are generated based on the drive control signal used to control the on and off of the synchronous rectifier and the second output voltage, or based on the drive control signal used to control the on and off of the synchronous rectifier and the first output voltage. Based on the first path control signal, a drive control signal is generated to control the on and off states of the first output path, and Based on the second path control signal, a drive control signal is generated to control the on and off of the second output path; as well as An optocoupler, connected between the pulse width modulation control chip and the single-input multiple-output control chip, is configured to generate the output voltage feedback signal based on the output voltage characterizing the current.

2. The single-input multi-output power supply system as described in claim 1, wherein, The single-input multiple-output control chip includes: A ramp signal generation circuit is configured to generate a ramp voltage signal based on a drive control signal used to control the on / off state of the synchronous rectifier diode; and The closed-loop control circuit is configured to generate the first path control signal and the second path control signal based on the ramp voltage signal and the second output voltage.

3. The single-input multi-output power supply system as described in claim 2, wherein, The ramp signal generation circuit includes a current source, a first inverter, a first switching transistor, a second switching transistor, and a capacitor. The first inverter is used to invert the drive control signal used to control the on and off of the synchronous rectifier to generate drive control signals used to control the on and off of the first and second switching transistors, wherein: When the first switch is in the ON state and the second switch is in the OFF state, the reference current from the current source charges the capacitor via the first switch, and the voltage across the capacitor is the ramp voltage signal. When the first switch is in the off state and the second switch is in the on state, the capacitor discharges through the second switch, and the ramp voltage signal is reset to 0.

4. The single-input multi-output power supply system as described in claim 3, wherein: When the drive control signal used to control the switching on and off of the synchronous rectifier is at a high level, the first switch is in the on state and the second switch is in the off state, and When the drive control signal used to control the switching on and off of the synchronous rectifier is at a low level, the first switch is in the off state and the second switch is in the on state.

5. The single-input multi-output power supply system as described in claim 2, wherein, The closed-loop control circuit is further configured to generate a first output voltage divider by dividing the first output voltage, generate a second output voltage divider by dividing the second output voltage, and generate the output voltage representing the current based on the magnitude comparison between the first output voltage divider and the first reference voltage and the magnitude comparison between the second output voltage divider and the second reference voltage.

6. The single-input multi-output power supply system as described in claim 5, wherein, The closed-loop control circuit includes: The first voltage divider network is used to divide the first output voltage to generate the first output voltage. The second voltage divider network is used to divide the second output voltage to generate the second output voltage. A first transconductance amplifier is used to generate a first output voltage characterization signal based on the first output voltage divider and the first reference voltage; and The second transconductance amplifier is used to generate a second output voltage characterization signal based on the second output voltage divider and the second reference voltage, wherein the output voltage characterization current is generated based on the first loop compensation voltage, and the first loop compensation voltage is generated based on the first output voltage characterization signal and the second output voltage characterization signal.

7. The single-input multi-output power supply system as described in claim 6, wherein, The closed-loop control circuit further includes: The third transconductance amplifier is used to generate a differential voltage characterization signal based on the second output voltage divider and the second reference voltage, or to generate a differential voltage characterization signal based on the first output voltage divider and the first reference voltage. A comparator is used to generate a second path control signal based on the ramp voltage signal and a second loop compensation voltage, wherein the second loop compensation voltage is generated based on the differential voltage characterization signal; and The second inverter is used to invert the second path control signal to generate the first path control signal.

8. The single-input multi-output power supply system as described in claim 6, wherein, The single-input multiple-output control chip includes a first loop compensation pin, and the single-input multiple-output power supply system further includes a first RC compensation circuit connected between the first loop compensation pin and ground. The output terminals of the first transconductance amplifier and the second transconductance amplifier are connected to the first loop compensation pin, and the first loop compensation voltage is the voltage at the first loop compensation pin.

9. The single-input multi-output power supply system as described in claim 8, wherein, The single-input multiple-output control chip further includes an optocoupler connection pin, a third switching transistor, and a resistor. The gate of the third switching transistor is connected to the first loop compensation pin, the drain is connected to the optocoupler connection pin, the source is connected to the first end of the resistor, the second end of the resistor is grounded, and the optocoupler is connected to the optocoupler connection pin.

10. The single-input multi-output power supply system as described in claim 7, wherein, The single-input multiple-output control chip includes a second loop compensation pin, and the single-input multiple-output power supply system further includes a second RC compensation circuit connected between the second loop compensation pin and ground. The output terminal of the third transconductance amplifier is connected to the second loop compensation pin, and the second loop compensation voltage is the voltage at the second loop compensation pin.

11. A single-input multiple-output control chip for use in a single-input multiple-output power supply system, wherein, The single-input multi-output power supply system includes a transformer, a first power transistor connected between the primary winding of the transformer and ground, a synchronous rectifier transistor connected between the secondary winding of the transformer and ground, a first output path for outputting a first output voltage, a second output path for outputting a second output voltage, a pulse width modulation control chip for controlling the on and off of the first power transistor, a synchronous rectifier control chip for controlling the on and off of the synchronous rectifier transistor, and an optocoupler connected between the single-input multi-output control chip and the pulse width modulation control chip. The single-input multi-output control chip is configured as follows: Based on the first output voltage and the second output voltage, an output voltage characterizing current is generated, wherein the optocoupler is configured to generate an output voltage feedback signal based on the output voltage characterizing current, and the pulse width modulation control chip is configured to generate a drive control signal for controlling the on and off of the first power transistor based on the output voltage feedback signal. A first path control signal and a second path control signal are generated based on the drive control signal generated by the synchronous rectification control chip for controlling the on and off of the synchronous rectifier tube and the second output voltage, or based on the drive control signal for controlling the on and off of the synchronous rectifier tube and the first output voltage. Based on the first path control signal, a drive control signal is generated to control the on and off states of the first output path; and Based on the second path control signal, a drive control signal is generated to control the on and off of the second output path.

12. The single-input multiple-output control chip as described in claim 11, comprising: The ramp signal generation circuit is configured to generate a ramp voltage signal based on a drive control signal used to control the on and off states of the synchronous rectifier. as well as The closed-loop control circuit is configured to generate the first path control signal and the second path control signal based on the ramp voltage signal and the second output voltage.

13. The single-input multiple-output control chip as described in claim 12, wherein, The ramp signal generation circuit includes a current source, a first inverter, a first switching transistor, a second switching transistor, and a capacitor. The first inverter is used to invert the drive control signal used to control the on and off of the synchronous rectifier to generate drive control signals used to control the on and off of the first and second switching transistors, wherein: When the first switch is in the ON state and the second switch is in the OFF state, the reference current from the current source charges the capacitor via the first switch, and the voltage across the capacitor is the ramp voltage signal. When the first switch is in the off state and the second switch is in the on state, the capacitor discharges through the second switch, and the ramp voltage signal is reset to 0.

14. The single-input multiple-output control chip as described in claim 13, wherein: When the drive control signal used to control the switching on and off of the synchronous rectifier is at a high level, the first switch is in the on state and the second switch is in the off state, and When the drive control signal used to control the switching on and off of the synchronous rectifier is at a low level, the first switch is in the off state and the second switch is in the on state.

15. The single-input multiple-output control chip as described in claim 12, wherein, The closed-loop control circuit is further configured to generate a first output voltage divider by dividing the first output voltage, generate a second output voltage divider by dividing the second output voltage, and generate the output voltage representing the current based on the magnitude comparison between the first output voltage divider and the first reference voltage and the magnitude comparison between the second output voltage divider and the second reference voltage.

16. The single-input multiple-output control chip as described in claim 15, wherein, The closed-loop control circuit includes: The first voltage divider network is used to divide the first output voltage to generate the first output voltage. The second voltage divider network is used to divide the second output voltage to generate the second output voltage. A first transconductance amplifier is used to generate a first output voltage characterization signal based on the first output voltage divider and the first reference voltage; and The second transconductance amplifier is used to generate a second output voltage characterization signal based on the second output voltage divider and the second reference voltage, wherein the output voltage characterization current is generated based on the first loop compensation voltage, and the first loop compensation voltage is generated based on the first output voltage characterization signal and the second output voltage characterization signal.

17. The single-input multiple-output control chip as described in claim 16, wherein, The closed-loop control circuit further includes: The third transconductance amplifier is used to generate a differential voltage characterization signal based on the second output voltage divider and the second reference voltage, or to generate a differential voltage characterization signal based on the first output voltage divider and the first reference voltage. A comparator is used to generate a second path control signal based on the ramp voltage signal and a second loop compensation voltage, wherein the second loop compensation voltage is generated based on the differential voltage characterization signal; and The second inverter is used to invert the second path control signal to generate the first path control signal.

18. The single-input multiple-output control chip of claim 16, further comprising a first loop compensation pin, wherein the single-input multiple-output power supply system further comprises a first RC compensation circuit connected between the first loop compensation pin and ground, the output terminal of the first transconductance amplifier and the output terminal of the second transconductance amplifier are connected to the first loop compensation pin, and the first loop compensation voltage is the voltage at the first loop compensation pin.

19. The single-input multiple-output control chip of claim 18, further comprising an optocoupler connection pin, a third switching transistor, and a resistor, wherein the gate of the third switching transistor is connected to the first loop compensation pin, the drain is connected to the optocoupler connection pin, the source is connected to the first end of the resistor, the second end of the resistor is grounded, and the optocoupler connection pin is used to connect the optocoupler.

20. The single-input multiple-output control chip of claim 17, further comprising a second loop compensation pin, the single-input multiple-output power supply system further comprising a second RC compensation circuit connected between the second loop compensation pin and ground, the output terminal of the third transconductance amplifier being connected to the second loop compensation pin, and the second loop compensation voltage being the voltage at the second loop compensation pin.

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