On-time control circuit, circuit board and electronic equipment

Abstract

The invention discloses a turn-on time control circuit, a circuit board and electronic equipment, and belongs to the field of electronic circuits, and the turn-on time control circuit comprises a conversion module, a current mirror module, a generation module and a control module. The conversion module outputs a related first current according to an external load input voltage, and the current mirroring module mirrors the first current to generate a second current. The generation module comprises a charging unit and a charging control unit, the charging unit receives the second current for charging, and the charging control unit controls the charging process according to the voltage at the two ends of the charging unit and the external load output voltage and ensures that the charging voltage is not zero. The control module adjusts the charging time of the charging unit through the external output reference voltage and the output voltage so as to control the conduction time of the current mirror image module, the undershoot voltage of the output voltage when the load transients can be reduced, and the stability of the power supply in a high-load state is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a conduction time control circuit, a circuit board and an electronic device. Background Art

[0002] With the rapid development of the field of artificial intelligence, CPU (Central Processing Unit) and GPU (Graphics Processing Unit) often work under high load conditions, and multi-phase control power management chips must quickly handle transient changes in the load. TON (Turn-On Time) refers to the time required for a switch element (such as a transistor, MOSFET, etc.) to switch from an off state to an on state in an electronic circuit. The existing multi-phase control power management chip has a large jitter in the output voltage due to the slow feedback loop rate and the instability of the TON control algorithm. When the jitter is severe, there is a risk of damaging the CPU and GPU. TON is directly calculated and determined by the proportional relationship between the load output voltage and the output voltage, but when the load changes transiently, the adjustment speed of TON is slower than the transient change speed, resulting in a large undershoot and rebound in the output voltage. Therefore, how to reduce the undershoot voltage of the output voltage during load transients to improve the stability of the power supply under high load conditions is a technical problem that needs to be solved urgently. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a conduction time control circuit, a circuit board and an electronic device, which can reduce the undershoot voltage of the output voltage when the load changes transiently, and improve the stability of the power supply under high load conditions.

[0004] In order to achieve the above purpose, this application adopts the following technical solutions:

[0005] In a first aspect, the present application provides a conduction time control circuit, comprising:

[0006] A conversion module, the conversion module being used to output a first current related to the external load input voltage according to the external load input voltage;

[0007] a current mirror module, wherein an input end of the current mirror module is connected to an output end of the conversion module, and the current mirror module is used to mirror the first current to generate a second current related to the first current;

[0008] A generating module, the generating module comprising a charging unit and a charging control unit, the input end of the charging unit is connected to the output end of the current mirror module, the first input end of the charging control unit is connected to the input end of the charging unit, the second input end of the charging control unit is connected to the external load output voltage, the third input end of the charging control unit is connected to the external enable signal, the output end of the charging unit and the output end of the charging control unit are both connected to the ground end, and the charging control unit is used to control the charging unit to charge and control the voltage at both ends of the charging unit not to drop to zero according to the voltage at both ends of the charging unit, the external load output voltage and the external enable signal;

[0009] A control module, wherein a first input terminal of the control module is connected to an external output reference voltage, a second input terminal of the control module is connected to an external load output voltage, an output terminal of the control module is connected to an input terminal of the charging unit, and the control module is used to control the charging time of the charging unit according to the external output reference voltage and the external load output voltage, thereby controlling the conduction time of the current mirror module.

[0010] According to the on-time control circuit of the first aspect of the present application, there are at least the following beneficial effects: the external load input voltage is converted into a first current for output through a conversion module, wherein the first current is related to the external load input voltage. The first current is mirrored through a current mirror module, and a second current related to the first current is output for charging the charging unit. When the voltage at both ends of the charging unit is lower than the external load output voltage, the charging control unit controls the charging unit to charge according to an external enable signal; when the voltage at both ends of the charging unit is higher than the external load output voltage, the charging control unit controls the charging unit according to the voltage at both ends of the charging unit and the external load output voltage so that the voltage at both ends of the charging unit does not drop to zero. When the output is loaded, when the external output reference voltage is greater than the external output voltage, the control module does not work; when the external output reference voltage is less than the external output voltage, the charging time of the charging unit is controlled by the control module according to the external output reference voltage and the external load output voltage. When the external load output voltage continues to decrease, the charging time of the charging unit is shortened, thereby extending the on-time of the current mirror module. The on-time of the current mirror module is TON. Compared with the prior art, when the load changes transiently, the present application reduces the undershoot voltage of the output voltage by extending TON, thereby improving the stability of the power supply under high load conditions. Therefore, the present application solves the technical problem of how to reduce the undershoot voltage of the output voltage when the load changes transiently to improve the stability of the power supply under high load conditions.

[0011] According to some embodiments of the first aspect of the present application, the control module includes a transconductance amplifier and a diode, the positive input terminal of the transconductance amplifier is the first input terminal of the control module, and the negative output terminal of the transconductance amplifier is the second input terminal of the control module; the positive input terminal of the transconductance amplifier is connected to an external reference voltage, the negative input terminal of the transconductance amplifier is connected to an external load output voltage, the output terminal of the diode is connected to the output terminal of the transconductance amplifier, and the input terminal of the diode is connected to the input terminal of the charging unit, and the transconductance amplifier is used to control the charging time of the charging unit according to the external load output voltage and the external output reference voltage, thereby controlling the conduction time of the current mirror module.

[0012] According to some embodiments of the first aspect of the present application, the charging control unit includes a comparator, a trigger, a first resistor and a first switch tube, the positive input end of the comparator is the first input end of the charging control unit, and the negative input end of the comparator is the second input end of the charging control unit; the negative input end of the comparator is connected to the external load output voltage, the positive input end of the comparator is connected to the input end of the charging unit, the reset end of the trigger is connected to the output end of the comparator, the set end of the trigger is connected to the external enable signal, the control end of the first switch tube is connected to the inverting output end of the trigger, the first end of the first resistor is connected to the positive input end of the comparator, and the second end of the first resistor is connected to the first The input end of the switch tube and the output end of the first switch tube are both connected to the ground end, the control end of the first switch tube is used to control the conduction state of the input end and the output end of the first switch tube according to the signal output from the inverting output end, the trigger is used to control the charging of the charging unit or the conduction state of the input end and the output end of the first switch tube according to the external enable signal or the signal output by the comparator, the comparator is used to control the output signal of the inverting output end of the trigger according to the voltage across the charging unit and the external load output voltage, thereby controlling the conduction state of the input end and the output end of the first switch tube, and the first resistor is used to prevent the voltage across the charging unit from dropping to zero to compensate for the transmission delay of the comparator.

[0013] According to some embodiments of the first aspect of the present application, the charging unit includes a capacitor, a first end of the capacitor is connected to the output end of the current mirror module, and a second end of the capacitor is connected to a ground end.

[0014] According to some embodiments of the first aspect of the present application, the conversion module includes an operational amplifier, a second resistor, a third resistor, a fourth resistor and a second switch tube, the first end of the second resistor is connected to the input end of the current mirror module and is used to access the external load input voltage, the first end of the third resistor is connected to the second end of the second resistor, the second end of the third resistor is connected to the ground end, the positive input end of the operational amplifier is connected to the first end of the third resistor, the negative input end of the operational amplifier is connected to the output end of the second switch tube, the output end of the operational amplifier is connected to the control end of the second switch tube, the input end of the second switch tube is connected to the input end of the current mirror module, the first end of the third resistor is connected to the output end of the operational amplifier, and the second end of the third resistor is connected to the ground end.

[0015] According to some embodiments of the first aspect of the present application, the current mirror module includes a third switch tube and a fourth switch tube, the input end of the third switch tube and the input end of the fourth switch tube are both connected to the first end of the second resistor, the control end of the third switch tube and the control end of the fourth switch tube are both connected to the input end of the second switch tube, the output end of the third switch tube is connected to the input end of the second switch tube, and the output end of the fourth switch tube is connected to the input end of the charging unit.

[0016] According to some embodiments of the first aspect of the present application, the first switch tube is an NMOS tube.

[0017] According to some embodiments of the first aspect of the present application, the second switch tube is an NMOS tube, and the third switch tube and the fourth switch tube are both PMOS tubes.

[0018] In a second aspect, the present application provides a circuit board, comprising the conduction time control circuit described in the embodiment of the first aspect of the present application.

[0019] In a third aspect, the present application provides an electronic device, comprising the on-time control circuit described in the embodiment of the first aspect of the present application.

[0020] The present application is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of an embodiment of a conduction time control circuit of the present application;

[0022] Figure 2 A corresponding relationship diagram between the upper tube on-time and the error voltage of an embodiment of the on-time control circuit of the present application;

[0023] Figure 3The figure is a comparison diagram of the effects before and after processing using an embodiment of the conduction time control circuit of the present application.

[0024] Reference numerals:

[0025] The conversion module 100 , the current mirror module 200 , the generation module 300 , the charging unit 310 , the charging control unit 320 , and the control module 400 . DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0027] In the description of this application, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0028] The embodiments of the present application are further described below in conjunction with the accompanying drawings.

[0029] Reference Figure 1As shown in the figure, VIN is the external load input voltage, EN is the external enable signal, VOUT is the external load output voltage, I2 is the first current, and Ion is the second current. The on-time control circuit includes a conversion module 100, a current mirror module 200, a generation module 300 and a control module 400. The conversion module 100 is used to output a first current related to the external load input voltage according to the external load input voltage; the input end of the current mirror module 200 is connected to the output end of the conversion module 100, and the current mirror module 200 is used to mirror the first current to generate a second current related to the first current; the generation module 300 includes a charging unit 310 and a charging control unit 320, the input end of the charging unit 310 is connected to the output end of the current mirror module 200, the first input end of the charging control unit 320 is connected to the input end of the charging unit 310, the second input end of the charging control unit 320 is connected to the external load output voltage, the third input end of the charging control unit 320 is connected to the external enable signal, and the charging unit 3 The output end of the control module 10 and the output end of the charging control unit 320 are both connected to the ground end. The charging control unit 320 is used to control the charging of the charging unit 310 and control the voltage at both ends of the charging unit 310 not to drop to zero according to the voltage at both ends of the charging unit 310, the external load output voltage and the external enable signal; the first input end of the control module 400 is connected to the external output reference voltage, the second input end of the control module 400 is connected to the external load output voltage, the output end of the control module 400 is connected to the input end of the charging unit 310, and the control module 400 is used to control the charging time of the charging unit 310 according to the external output reference voltage and the external load output voltage, thereby controlling the conduction time of the current mirror module 200.

[0030] In the above embodiment, the external load input voltage is converted into a first current for output through the conversion module 100, wherein the first current is related to the external load input voltage. The first current is mirrored through the current mirror module 200, and a second current related to the first current is output for charging the charging unit 310. When the voltage across the charging unit 310 is lower than the external load output voltage, the charging control unit 320 controls the charging unit 310 to charge according to an external enable signal; when the voltage across the charging unit 310 is higher than the external load output voltage, the charging control unit 320 controls the charging unit 310 according to the voltage across the charging unit 310 and the external load output voltage so that the voltage across the charging unit 310 does not drop to zero. When the output is loaded, when the external output reference voltage is greater than the external output voltage, the control module 400 does not work; when the external output reference voltage is less than the external output voltage, the control module 400 controls the charging time of the charging unit 310 according to the external output reference voltage and the external load output voltage. When the external load output voltage continues to decrease, the charging time of the charging unit 310 is shortened, thereby extending the conduction time of the current mirror module 200. The conduction time of the current mirror module 200 is the conduction time of the upper tube. Compared with the prior art, when the load is transient, the present application extends the conduction time of the upper tube to reduce the undershoot voltage of the output voltage, thereby improving the stability of the power supply under high load conditions.

[0031] Understandably, referring to Figure 1 As shown, the control module 400 includes a transconductance amplifier and a diode, the positive input terminal of the transconductance amplifier is the first input terminal of the control module 400, and the negative output terminal of the transconductance amplifier is the second input terminal of the control module 400; the positive input terminal of the transconductance amplifier is connected to an external reference voltage, the negative input terminal of the transconductance amplifier is connected to an external load output voltage, the output terminal of the diode is connected to the output terminal of the transconductance amplifier, and the input terminal of the diode is connected to the input terminal of the charging unit 310. The transconductance amplifier is used to control the charging time of the charging unit 310 according to the external load output voltage and the external output reference voltage, thereby controlling the conduction time of the current mirror module 200.

[0032] The nonlinear upper tube conduction time control is achieved through the cooperation of the transconductance amplifier and the diode.

[0033] For example, Figure 1As shown, VREF is the external output reference voltage, VOUT is the external load output voltage, GM is the transconductance amplifier, D1 is a diode, Ion is the first current, and I1 is the output current. When VOUT is higher than VREF-20mV, due to the existence of D1, the path where D1 is located is cut off, and I1=0; when VOUT is lower than VREF-20mV, the transconductance is gm, and I1 is (VREF-20mV-VOUT)*gm. When the load changes transiently, VOUT jitters, and as VOUT decreases, I1 increases, reducing the charging current of the charging unit 310, thereby extending the upper tube conduction time. The maximum output current of I1 is limited to Ion / 2, so the maximum value of the upper tube conduction time is twice the upper tube conduction time during normal operation, so that in the case of an output short circuit, when the upper tube conduction time is infinitely extended, no excessive second current will be generated, thereby not causing the risk of burning of the current mirror module 200, improving the stability and safety of the circuit, and extending the service life.

[0034] For example, Figure 1 and 2 As shown in the figure, VREF represents the external output reference voltage, VOUT represents the external load output voltage, and Vus is the error voltage. The nonlinear upper tube conduction time control is realized by the cooperation of the transconductance amplifier and the diode. It can be seen that when the value of Vus exceeds 20mV, the upper tube conduction time will begin to extend, realizing that under steady-state conditions, VOUT will not affect the upper tube conduction time, and thus will not affect the stability of the system.

[0035] Understandably, referring to Figure 1As shown, the charging control unit 320 includes a comparator, a trigger, a first resistor and a first switch tube. The positive input end of the comparator is the first input end of the charging control unit 320, and the negative input end of the comparator is the second input end of the charging control unit 320; the negative input end of the comparator is connected to the external load output voltage, the positive input end of the comparator is connected to the input end of the charging unit 310, the reset end of the trigger is connected to the output end of the comparator, the set end of the trigger is connected to the external enable signal, the control end of the first switch tube is connected to the inverting output end of the trigger, the first end of the first resistor is connected to the positive input end of the comparator, the second end of the first resistor is connected to the input end of the first switch tube, and the The output ends of a switch tube are both connected to the ground end, the control end of the first switch tube is used to control the conduction state of the input end and the output end of the first switch tube according to the signal output from the inverting output end, the trigger is used to control the charging of the charging unit 310 or the conduction state of the input end and the output end of the first switch tube according to the external enable signal or the signal output by the comparator, the comparator is used to control the output signal of the inverting output end of the trigger according to the voltage across the charging unit 310 and the external load output voltage, thereby controlling the conduction state of the input end and the output end of the first switch tube, and the first resistor is used to prevent the voltage across the charging unit 310 from dropping to zero to compensate for the transmission delay of the comparator.

[0036] For example, Figure 1 As shown in the figure, CMP is a comparator, Q1 is a trigger, R4 is a first resistor, M4 is a first switch tube, VOUT is an external load output voltage, and EN is an external enable signal. Q1 is an RS trigger, and M4 is an NMOS tube. When the voltage across the charging unit 310 is lower than VOUT, EN will send a start pulse, so that the positive output terminal of Q1 outputs a high level and the negative output terminal outputs a low level, so that the charging unit 310 starts charging. When the voltage across the charging unit 310 is higher than VOUT, CMP will output a high level, triggering M4 to be in the on state. At this time, R4 will reduce the voltage across the charging unit 310 to a lower value that is not zero, thereby effectively compensating for the impact caused by the CMP transmission delay.

[0037] Understandably, referring to Figure 1 As shown, C1 represents a capacitor. The charging unit 310 includes a capacitor, a first end of the capacitor is connected to the output end of the current mirror module 200, and a second end of the capacitor is connected to the ground end. The upper tube conduction time is controlled by the charging time of the capacitor, and the upper tube conduction time is accurately controlled by the capacitor charging process. In some embodiments, the capacitor can be an electrolytic capacitor, a tantalum capacitor, a ceramic capacitor, or a film capacitor.

[0038] Understandably, referring to Figure 1As shown, the conversion module 100 includes an operational amplifier, a second resistor, a third resistor, a fourth resistor, and a second switch tube. The first end of the second resistor is connected to the input end of the current mirror module 200 and is used to access the external load input voltage. The first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the ground end. The positive input end of the operational amplifier is connected to the first end of the third resistor, the negative input end of the operational amplifier is connected to the output end of the second switch tube, the output end of the operational amplifier is connected to the control end of the second switch tube, the input end of the second switch tube is connected to the input end of the current mirror module 200, the first end of the third resistor is connected to the output end of the operational amplifier, and the second end of the third resistor is connected to the ground end. The precise conversion from the external input voltage to the first current is achieved through the cooperation of the operational amplifier, the second resistor, the third resistor, the fourth resistor, and the second switch tube.

[0039] For example, Figure 1 As shown in the figure, OPA is an operational amplifier, R1 is the second resistor, R2 is the third resistor, R3 is the fourth resistor, M1 is the second switch tube, and VIN is the external load input voltage. M1 is an NMOS tube. R1, R2, OPA and M1 form a buffer with a gain of 1, which can generate a voltage related to VIN at the source of M1, and the voltage is converted into a first current related to VIN through R3.

[0040] Understandably, referring to Figure 1 As shown, M2 is the third switch tube, and M3 is the fourth switch tube. The current mirror module 200 includes a third switch tube and a fourth switch tube, the input end of the third switch tube and the input end of the fourth switch tube are both connected to the first end of the second resistor, the control end of the third switch tube and the control end of the fourth switch tube are both connected to the input end of the second switch tube, the output end of the third switch tube is connected to the input end of the second switch tube, and the output end of the fourth switch tube is connected to the input end of the charging unit 310. By forming a current mirror with the third switch tube and the fourth switch tube, the first current can be accurately copied and the second current can be output, providing a stable mirror current for driving subsequent circuits, thereby achieving precise current control. In addition, the current mirror has a simple structure, occupies a small chip area, has low power consumption, and has good linear characteristics and temperature stability, which can effectively improve the stability and consistency of the system.

[0041] Understandably, referring to Figure 1 As shown, M4 represents the first switch tube, CMP represents the comparator, and C1 represents the capacitor. The first switch tube is an NMOS tube. The NMOS tube has strong driving capability, high efficiency, and low power consumption. M4 uses an NMOS tube to easily match the comparator output logic, thereby achieving fast and accurate capacitor discharge.

[0042] Understandably, referring to Figure 1As shown, M1 represents the second switch tube, M2 represents the third switch tube, and M3 represents the fourth switch tube. The second switch tube is an NMOS tube, and the third and fourth switch tubes are both PMOS tubes. NMOS tubes have the characteristics of low on-resistance, faster switching speed, stronger current driving capability, and low voltage operation, so M1 uses NMOS tubes to work more efficiently, quickly, and stably during signal transmission and buffering. M2 and M3 use PMOS tubes to better adapt to high voltage environments, provide more accurate current replication, and have lower leakage current, ensuring the performance and stability of the circuit.

[0043] Refer to the following Figures 1 to 3 The on-time control circuit of an embodiment of the present application is described as follows:

[0044] like Figure 1As shown, R1 represents the second resistor, R2 represents the third resistor, R3 represents the fourth resistor, R4 represents the first resistor, M1 represents the second switch tube, M2 represents the third switch tube, M3 represents the fourth switch tube, M4 represents the first switch tube, OPA represents an operational amplifier, CMP represents a comparator, Gm represents a transconductance amplifier, Q1 represents an RS trigger, S represents a set terminal, R represents a reset terminal, Q represents a positive output terminal, Q represents a negative output terminal, C1 represents a capacitor, VIN represents an external load input voltage, VOUT represents an external load output voltage, VREF represents an external output reference voltage, EN represents an external enable signal, C1 represents a capacitor, I1 represents an output current, I2 represents a first current, and Ion represents a second current. The buffer with a gain of 1 composed of R1 and R2, OPA and M1 can generate a voltage related to VIN at the source of M1. This voltage is converted into I2 related to VIN through R3. Then, I2 is mirrored and output Ion through the current mirror composed of M2 and M3 to charge C1. When the voltage on C1 is lower than VOUT, the EN signal will send an open pulse, making the Q output of the RS trigger high and the Q output low, so that the capacitor is charged. When the voltage on C1 is higher than VOUT, the comparator outputs a high level, triggering M4 to turn on. At this time, R4 reduces the voltage on C1 to a lower value instead of directly reducing it to 0, effectively compensating for the impact caused by the transmission delay of the comparator. When the output is loaded, D1 and Gm form a nonlinear TON control structure. When VOUT is higher than VREF-20mV, due to the existence of D1, the path where D1 is located is cut off, and I1 is 0; when VOUT is lower than VREF-20mV, I1 is (VREF-20mV-VOUT)*gm. As VOUT decreases, I1 increases, reducing the charging current of C1, thereby extending TON. The maximum output current capability of I1 is limited to Ion / 2, so the maximum value of TON is twice that of TON during normal operation, so as to avoid TON increasing infinitely when the output is short-circuited and generating excessive current, which makes M3 burn out.

[0045] like Figure 2 As shown in the figure, Vus represents the error voltage, VREF represents the output reference voltage, VOUT represents the load output voltage, and TON represents the upper tube conduction time. After adding nonlinear TON control, it can be seen that TON will only start to widen when the value of Vus exceeds 20mV. Under steady-state conditions, the VOUT voltage will not affect TON, and therefore will not affect the stability of the system.

[0046] like Figure 3As shown, the black curve represents the change of output current and load output voltage after nonlinear TON control processing; the green curve represents the change of output current and load output voltage before nonlinear TON control processing; the orange curve represents the change of load demand current. IL represents the output current, Iload represents the load demand current, and VOUT represents the load output voltage. The on-time control circuit of the embodiment of the present application enables the output current to reach the load demand value faster, and the undershoot voltage of the load output voltage is also smaller, thereby improving the stability of the power supply under high load conditions.

[0047] The circuit board of the second aspect embodiment of the present application includes the on-time control circuit of the first aspect embodiment of the present application, which can reduce the undershoot voltage of the output voltage during load transients and improve the stability of the power supply under high load conditions.

[0048] The electronic device of the third aspect embodiment of the present application includes the on-time control circuit of the first aspect embodiment of the present application, which can reduce the undershoot voltage of the output voltage during load transients and improve the stability of the power supply under high load conditions.

[0049] The embodiments of the present application have been described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the technical field without departing from the purpose of the present application.

Claims

1. A conduction time control circuit, characterized in that: include: A conversion module, the conversion module being used to output a first current related to the external load input voltage according to the external load input voltage; a current mirror module, wherein an input end of the current mirror module is connected to an output end of the conversion module, and the current mirror module is used to mirror the first current to generate a second current related to the first current; A generating module, the generating module comprising a charging unit and a charging control unit, the input end of the charging unit is connected to the output end of the current mirror module, the first input end of the charging control unit is connected to the input end of the charging unit, the second input end of the charging control unit is connected to the external load output voltage, the third input end of the charging control unit is connected to the external enable signal, the output end of the charging unit and the output end of the charging control unit are both connected to the ground end, and the charging control unit is used to control the charging unit to charge and control the voltage at both ends of the charging unit not to drop to zero according to the voltage at both ends of the charging unit, the external load output voltage and the external enable signal; A control module, wherein a first input terminal of the control module is connected to an external output reference voltage, a second input terminal of the control module is connected to an external load output voltage, an output terminal of the control module is connected to an input terminal of the charging unit, and the control module is used to control the charging time of the charging unit according to the external output reference voltage and the external load output voltage, thereby controlling the conduction time of the current mirror module.

2. The on-time control circuit according to claim 1, characterized in that: The control module includes a transconductance amplifier and a diode, the positive input end of the transconductance amplifier is the first input end of the control module, and the negative output end of the transconductance amplifier is the second input end of the control module; the positive input end of the transconductance amplifier is connected to an external reference voltage, and the negative input end of the transconductance amplifier is connected to an external load output voltage, the output end of the diode is connected to the output end of the transconductance amplifier, and the input end of the diode is connected to the input end of the charging unit, and the transconductance amplifier is used to control the charging time of the charging unit according to the external load output voltage and the external output reference voltage, thereby controlling the conduction time of the current mirror module.

3. The on-time control circuit according to claim 1, characterized in that: The charging control unit includes a comparator, a trigger, a first resistor and a first switch tube. The positive input end of the comparator is the first input end of the charging control unit, and the negative input end of the comparator is the second input end of the charging control unit; the negative input end of the comparator is connected to the external load output voltage, the positive input end of the comparator is connected to the input end of the charging unit, the reset end of the trigger is connected to the output end of the comparator, the set end of the trigger is connected to the external enable signal, the control end of the first switch tube is connected to the inverting output end of the trigger, the first end of the first resistor is connected to the positive input end of the comparator, and the second end of the first resistor is connected to the input end of the first switch tube. The output ends of the first switch tube are both connected to the ground end, the control end of the first switch tube is used to control the conduction state of the input end and the output end of the first switch tube according to the signal output from the inverting output end, the trigger is used to control the charging of the charging unit and the conduction state of the input end and the output end of the first switch tube according to the external enable signal and the signal output by the comparator, the comparator is used to control the output signal of the inverting output end of the trigger according to the voltage across the charging unit and the external load output voltage, thereby controlling the conduction state of the input end and the output end of the first switch tube, and the first resistor is used to prevent the voltage across the charging unit from dropping to zero to compensate for the transmission delay of the comparator.

4. The on-time control circuit according to claim 1, characterized in that: The charging unit comprises a capacitor, a first end of the capacitor is connected to the output end of the current mirror module, and a second end of the capacitor is connected to the ground end.

5. The on-time control circuit according to claim 1, characterized in that: The conversion module includes an operational amplifier, a second resistor, a third resistor, a fourth resistor and a second switch tube. The first end of the second resistor is connected to the input end of the current mirror module and is used to access an external load input voltage. The first end of the third resistor is connected to the second end of the second resistor, and the second end of the third resistor is connected to the ground end. The positive input end of the operational amplifier is connected to the first end of the third resistor, the negative input end of the operational amplifier is connected to the output end of the second switch tube, the output end of the operational amplifier is connected to the control end of the second switch tube, the input end of the second switch tube is connected to the input end of the current mirror module, the first end of the third resistor is connected to the output end of the operational amplifier, and the second end of the third resistor is connected to the ground end.

6. The conduction time control circuit according to claim 5, characterized in that: The current mirror module includes a third switch tube and a fourth switch tube, the input end of the third switch tube and the input end of the fourth switch tube are both connected to the first end of the second resistor, the control end of the third switch tube and the control end of the fourth switch tube are both connected to the input end of the second switch tube, the output end of the third switch tube is connected to the input end of the second switch tube, and the output end of the fourth switch tube is connected to the input end of the charging unit.

7. The conduction time control circuit according to claim 3, characterized in that: The first switch tube is an NMOS tube.

8. The on-time control circuit according to claim 6, characterized in that: The second switch tube is an NMOS tube, and the third switch tube and the fourth switch tube are both PMOS tubes.

9. A circuit board, characterized in that: It comprises a conduction time control circuit as described in any one of claims 1 to 8.

10. An electronic device, characterized in that: Comprising the circuit board as claimed in claim 9.

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