Power supply control circuit

Abstract

The invention discloses a power supply control circuit. The power supply control circuit comprises a switch unit and a control unit. The input end of the switch unit is connected with a power supply, the output end of the switch unit serves as the output end of the power supply control circuit, and the control end of the switch unit is connected with the output end of the control unit; the input end of the control unit is connected with the power supply, and the control unit is used for controlling the switch unit to connect the input end and the output end when the voltage of the power supply is larger than or equal to a first preset voltage and controlling the switch unit to disconnect the input end and the output end when the voltage of the power supply is smaller than or equal to a second preset voltage. The rising slope and the falling slope of the load voltage are effectively improved, and the probability that the load is abnormal is reduced.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more particularly to a power supply control circuit. Background Technology

[0002] In electrical equipment, the low-voltage power supply is the energy source for the control circuit. Typically, the low-voltage power supply is converted from a switching power supply, and the output of the power supply uses capacitors for filtering. The initial state of the capacitor voltage is 0, and the rise of the capacitor voltage from 0 to the voltage required by the control circuit can be approximated as linear. The low-voltage power supply will be connected to various loads, such as resistors, inductors, and integrated circuits. When the load is relatively large, considering the lifespan of the capacitors, they will be used in parallel. In this case, the equivalent capacitance value of the capacitors is usually relatively large. When the control circuit is powered on, the capacitor voltage starts charging from 0, and the time it takes for the capacitor voltage to rise to the required voltage is relatively long. When the control circuit is powered off, the large load is disconnected first, and the capacitor discharge leads to a long power-off time. When the control circuit is an integrated circuit, the integrated circuit will require that the slope of the power supply voltage during power-on and power-off must meet the specifications. When the slope of the power supply voltage during power-on and power-off does not meet the requirements, the integrated circuit may exhibit abnormal phenomena, further leading to power supply timing problems or even failure. Summary of the Invention

[0003] This invention provides a power control circuit to improve the slope of the power supply voltage during power-on and power-off, thereby improving the reliability of the power supply.

[0004] In a first aspect, embodiments of the present invention provide a power control circuit, including a switching unit and a control unit;

[0005] The input terminal of the switching unit is connected to the power supply, the output terminal of the switching unit serves as the output terminal of the power control circuit, and the control terminal of the switching unit is connected to the output terminal of the control unit. The input terminal of the control unit is connected to the power supply. The control unit is used to control the switching unit to connect its input terminal and output terminal when the voltage of the power supply is greater than or equal to a first preset voltage, and to control the switching unit to turn off its input terminal and output terminal when the voltage of the power supply is less than or equal to a second preset voltage. The second preset voltage is less than the first preset voltage.

[0006] Optionally, the control unit includes a first control circuit and a second control circuit;

[0007] The control terminal of the switching unit is connected to the output terminals of the first control circuit and the second control circuit. The input terminals of the first control circuit and the second control circuit are connected to the power supply. The first control circuit is used to output a first control signal with a delay based on the voltage of the power supply. The second control circuit is used to output a second control signal based on the voltage of the power supply. The first control signal is valid when the voltage of the power supply is greater than or equal to a first preset voltage, and invalid when it is less than the first preset voltage. The second control signal is valid when the voltage of the power supply is greater than the second preset voltage, and invalid when it is less than or equal to the second preset voltage. The second preset voltage is less than the first preset voltage. The switching unit is used to connect its input terminal and output terminal when the first control signal and the second control signal are valid, and to disconnect its input terminal and output terminal when the first control signal and / or the second control signal are invalid.

[0008] Optionally, the first control circuit includes a delay circuit, a first voltage adjustment circuit, and a first comparison circuit;

[0009] The first terminal of the delay circuit is connected to the power supply, the second terminal of the delay circuit is connected to the fixed potential terminal, the output terminal of the delay circuit is connected to the first input terminal of the first voltage adjustment circuit, the second input terminal and the output terminal of the first voltage adjustment circuit are connected to the first input terminal of the first comparator circuit, the second input terminal of the first comparator circuit is used to input a first reference voltage, and the output terminal of the first comparator circuit is connected to the control terminal of the switching unit; the delay circuit is used to divide the voltage of the power supply and output it with a delay, the first voltage adjustment circuit is used to transform the divided voltage to form a first voltage; the first comparator circuit is used to form the first control signal based on the first voltage and the first reference voltage.

[0010] Optionally, the delay circuit includes a first resistor, a second resistor, and a delay capacitor;

[0011] The first end of the first resistor is connected to the power supply, the second end of the first resistor is connected to the first end of the second resistor and the first terminal of the delay capacitor, and serves as the output terminal of the delay circuit, and the second end of the second resistor is connected to the fixed potential terminal.

[0012] Optionally, the first comparison circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a first comparator;

[0013] The first end of the third resistor is connected to the output terminal of the first voltage adjustment circuit. The second end of the third resistor is connected to the first end of the fourth resistor, the first end of the fifth resistor, and the positive input terminal of the first comparator. The second end of the fourth resistor is connected to the output terminal of the first comparator and the second end of the eighth resistor, and serves as the output terminal of the first control circuit. The second ends of the fifth resistor and the second ends of the sixth resistor are connected to the fixed potential terminal. The first end of the sixth resistor is connected to the negative input terminal of the first comparator and the second end of the seventh resistor. The first ends of the seventh resistor and the first ends of the eighth resistor are used to input the first reference voltage.

[0014] Optionally, the second control circuit includes a voltage divider circuit, a second voltage adjustment circuit, and a second comparison circuit;

[0015] The first terminal of the voltage divider circuit is connected to the power supply, the second terminal of the voltage divider circuit is connected to a fixed potential terminal, the output terminal of the voltage divider circuit is connected to the first input terminal of the second voltage adjustment circuit, the second input terminal and the output terminal of the second voltage adjustment circuit are connected to the first input terminal of the second comparator circuit, the second input terminal of the second comparator circuit is used to input a second reference voltage, and the output terminal of the second comparator circuit is connected to the control terminal of the switching unit; the voltage divider circuit is used to divide the voltage of the power supply, the second voltage adjustment circuit is used to transform the divided voltage to form a second voltage; the second comparator circuit is used to form a second control signal based on the second voltage and the second reference voltage.

[0016] Optionally, the voltage divider circuit includes a ninth resistor and a tenth resistor;

[0017] The first end of the ninth resistor is connected to the power supply, the second end of the ninth resistor is connected to the first end of the tenth resistor and serves as the output terminal of the voltage divider circuit, and the second end of the tenth resistor is connected to the fixed potential terminal.

[0018] Optionally, the second comparator circuit includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a second comparator;

[0019] The first end of the eleventh resistor is connected to the output terminal of the second voltage adjustment circuit. The second end of the eleventh resistor is connected to the first end of the twelfth resistor, the first end of the thirteenth resistor, and the positive input terminal of the second comparator. The second end of the twelfth resistor is connected to the output terminal of the second comparator and serves as the output terminal of the second control circuit. The second ends of the thirteenth resistor and the fourteenth resistor are connected to the fixed potential terminal. The first end of the fourteenth resistor is connected to the negative input terminal of the second comparator and the second end of the fifteenth resistor. The first end of the fifteenth resistor is used to input the second reference voltage.

[0020] Optionally, the switching unit includes a first power switch and a second power switch;

[0021] The control terminal of the first power switch is connected to the output terminal of the control unit, the first end of the first power switch is connected to the fixed potential terminal, the second end of the first power switch is connected to the control terminal of the second power switch, the first end of the second power switch is connected to the power supply, and the second end of the second power switch serves as the output terminal of the switching unit.

[0022] Optionally, when the voltage of the power supply is greater than or equal to a first preset voltage, the control unit delays controlling the switching unit to connect its input and output terminals for a delay time greater than or equal to 0.

[0023] The technical solution of this invention, during power-on, involves the control unit delaying the connection of its input and output terminals by controlling a switching unit when the power supply voltage is greater than or equal to a first preset voltage. This allows the voltage across the load to quickly rise to the power supply voltage (at which point the power supply voltage is greater than or equal to the first preset voltage), effectively increasing the voltage rise rate of the load and reducing the probability of load malfunctions. Furthermore, the control unit can delay the output to the load after the power supply voltage reaches the first preset voltage, making the power supply voltage output to the load more stable and improving the stability of the voltage provided by the power supply to the load. During power-off, the control unit controls the switching unit to turn off its input and output terminals when the power supply voltage is less than or equal to a second preset voltage. This quickly reduces the voltage across the load to 0, ensuring rapid power shut-off of the load, effectively increasing the voltage drop rate of the load, reducing the probability of load malfunctions, and improving the reliability of the power supply. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a power control circuit provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of another power control circuit provided in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the structure of a control unit provided in an embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of another power control circuit provided in an embodiment of the present invention;

[0028] Figure 5 A schematic diagram illustrating the simulation results of a power control circuit controlling the power-on and power-off states, provided as an embodiment of the present invention.

[0029] Figure 6 for Figure 5 A magnified view of the simulation results of the power supply control circuit controlling the power-on and power-off of the provided power supply is shown at the dashed box E.

[0030] Figure 7 for Figure 5 The simulation results of the provided power control circuit controlling the power-on and power-off are shown in a partially enlarged schematic diagram at the dashed box F. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0032] Figure 1 This is a schematic diagram of a power control circuit provided in an embodiment of the present invention. Figure 1 As shown, the power control circuit includes a switching unit 10 and a control unit 20; the input terminal of the switching unit 10 is connected to the power supply VIN, and the output terminal of the switching unit 10 serves as the output terminal OUT1 of the power control circuit; the input terminal of the control unit 20 is connected to the power supply VIN, and the control unit 20 is used to control the switching unit 10 to connect its input terminal and output terminal when the voltage of the power supply VIN is greater than or equal to a first preset voltage, and to control the switching unit 10 to turn off its input terminal and output terminal when the voltage of the power supply VIN is less than or equal to a second preset voltage; wherein, the second preset voltage is less than the first preset voltage.

[0033] Specifically, the power supply VIN can be a low-voltage power supply. For example... Figure 1As shown, a filter capacitor CIN is also provided between the power supply VIN and the switching unit 10. The filter capacitor CIN can filter the voltage output by the power supply VIN. At this time, the input terminal of the switching unit 10 can be connected to the positive terminal + of the power supply VIN and the first terminal of the filter capacitor CIN. The output terminal of the switching unit 10 is the positive output terminal OUT1 of the power control circuit. The control terminal of the switching unit 10 is connected to the output terminal DRV of the control unit 20. The other end of the switching unit 10, the negative terminal - of the power supply VIN, and the second terminal of the filter capacitor CIN are all connected to the fixed potential terminal V1 and serve as the negative output terminal OUT2 of the power control circuit. The initial state of the voltage of the filter capacitor CIN is 0. When the power supply VIN is powered on, the voltage of the filter capacitor CIN can rise linearly from 0 to the power supply voltage provided by the power supply VIN. The expression for the real-time power supply voltage of the power supply VIN at this time is:

[0034]

[0035] Where Vin(t) is the real-time power supply voltage of power supply VIN, Vin is the maximum power supply voltage of power supply VIN, t is the charging time of filter capacitor CIN, and Tx is the time required for filter capacitor CIN to finish charging.

[0036] The fixed potential terminal V1 is used to provide a fixed potential. For example, as shown... Figure 1As shown, the fixed potential terminal V1 can be the ground terminal GND. The first preset voltage can be set according to the rated voltage required by the load connected to the power supply VIN. For example, the maximum power supply voltage provided by the power supply VIN is the rated voltage required by the load, and the first preset voltage can be set to the maximum power supply voltage of the power supply VIN. The load can be a resistor, inductor, or integrated circuit, etc. During the power-on process of the load, when the voltage of the power supply VIN is less than the first preset voltage, the control unit 20 can control the switching unit 10 to turn off its input and output terminals, so that the voltage provided by the power supply VIN cannot be output to the output terminal OUT1 of the power control circuit through the switching unit 10, and the power supply VIN cannot supply power to the corresponding connected load. When the voltage of the power supply VIN is greater than or equal to the first preset voltage, the control unit 20 can delay the control of the switching unit 10 to connect its input and output terminals, so that the power supply voltage output by the power supply VIN can be delayed and output to the output terminal OUT1 of the power control circuit through the switching unit 10, which is the positive output terminal OUT1 of the power control circuit, supplying power to the corresponding connected load. The switching unit 10 has a switching function. When the input and output terminals of the switching unit 10 switch from an open state to an on state, the state switching rate of the switching unit 10 is very fast, allowing the voltage at the output terminal OUT1 of the power control circuit to quickly rise to the power supply voltage provided by the power supply VIN, and at this time the power supply voltage is greater than or equal to the first preset voltage. This allows the load voltage to rise quickly to the first preset voltage during power-on, effectively improving the voltage rise rate of the load and reducing the probability of abnormal load phenomena. Furthermore, the control unit 20 can delay the conduction of the input and output terminals of the switching unit 10 when the power supply VIN voltage is greater than or equal to the first preset voltage. During the delay phase, the power supply voltage provided by the power supply VIN becomes more stable, thereby improving the stability of the voltage provided by the power supply VIN to the load.

[0037] The second preset voltage can be set according to the normal operating voltage range of the load connected to the power supply VIN. For example, when the normal operating voltage range of the load is 12V-8V, the second preset voltage can be set to 8V. During the power-off process of the load, the power supply VIN stops supplying power, and the filter capacitor CIN begins to discharge, causing the voltage across the filter capacitor CIN to begin to drop, i.e., the voltage of the power supply VIN begins to drop. Before the voltage of the filter capacitor CIN drops to the second preset voltage, the switching unit 10 keeps its input and output terminals connected, and the filter capacitor CIN can continuously supply power to the corresponding connected load. When the voltage of the filter capacitor CIN drops to the second preset voltage, the control unit 20 immediately controls the switching unit 10 to disconnect its input and output terminals, so that the voltage provided by the filter capacitor CIN stops being output to the load. This allows the voltage across the load to drop rapidly to 0 when the voltage provided by the filter capacitor CIN is less than the normal operating voltage range of the load during the power-off process, ensuring that the power supply to the load is quickly turned off, effectively improving the voltage drop slope of the load and reducing the probability of abnormal phenomena in the load.

[0038] The technical solution of this embodiment, during power-on, involves the control unit delaying the connection of its input and output terminals by controlling the switching unit when the power supply voltage is greater than or equal to a first preset voltage. This allows the voltage across the load to quickly rise to the power supply voltage (at which point the power supply voltage is greater than or equal to the first preset voltage), effectively increasing the voltage rise rate of the load and reducing the probability of load malfunctions. Furthermore, the control unit can delay the output to the load after the power supply voltage reaches the first preset voltage, making the power supply voltage output to the load more stable and improving the stability of the voltage provided by the power supply to the load. During power-off, the control unit controls the switching unit to turn off its input and output terminals when the power supply voltage is less than or equal to a second preset voltage. This quickly reduces the voltage across the load to 0, ensuring rapid power shut-off of the load, effectively increasing the voltage drop rate of the load, reducing the probability of load malfunctions, and improving the reliability of the power supply.

[0039] Figure 2 This is a schematic diagram of another power control circuit provided in an embodiment of the present invention. Figure 2As shown, the control unit 20 includes a first control circuit 21 and a second control circuit 22; the control terminal of the switching unit 10 is connected to the output terminal of the first control circuit 21 and the output terminal of the second control circuit 22, and the input terminal of the first control circuit 21 and the input terminal of the second control circuit 22 are connected to the power supply VIN. The first control circuit 21 is used to output a first control signal with a delay according to the voltage of the power supply VIN, and the second control circuit 22 is used to output a second control signal according to the voltage of the power supply VIN. The first control signal is valid when the voltage of the power supply VIN is greater than or equal to a first preset voltage, and invalid when it is less than the first preset voltage. The second control signal is valid when it is greater than a second preset voltage, and invalid when it is less than or equal to the second preset voltage. The second preset voltage is less than the first preset voltage. The switching unit 10 is used to connect its input terminal and output terminal when the first control signal is valid and the second control signal is valid, and to turn off its input terminal and output terminal when the first control signal is invalid and / or the second control signal is invalid.

[0040] Specifically, the output terminals of the first control circuit 21 and the second control circuit 22 are connected and serve as the output terminal DRV of the control unit 20. The input terminals of the first control circuit 21 and the second control circuit 22 are connected to the positive terminal (+) of the power supply VIN to receive the voltage of the filter capacitor CIN. During power-on, when the voltage of the filter capacitor CIN is less than the second preset voltage, both the first and second control signals are at an invalid level. When both the first and second control signals are at an invalid level, the switching unit 10 shuts off its input and output terminals, and the power supply VIN cannot supply power to the load. When the voltage of the filter capacitor CIN is greater than the second preset voltage, the second control signal output by the second control circuit 22 changes from an invalid level to an active level. At this time, the first control signal is still at an invalid level, and the input and output terminals of the switching unit 10 remain open. When the voltage of the filter capacitor CIN is greater than or equal to the first preset voltage, the second control signal remains at an active level. The first control signal output by the first control circuit 21 changes from an invalid level to an active level after a delay. Then, the switching unit 10 connects its input and output terminals after a delay when the voltage of the filter capacitor CIN is greater than or equal to the first preset voltage. At this time, the power supply voltage output by the power supply VIN is quickly output to the load, causing the voltage of the load to rise rapidly to the first preset voltage, effectively improving the voltage rise slope of the load and reducing the probability of abnormal phenomena in the load. Moreover, the first control circuit 21 outputs a valid first control signal after a delay when the voltage of the filter capacitor CIN is greater than or equal to the first preset voltage, so that the power supply voltage output by the power supply VIN is more stable during the delay period before being output to the load, thereby improving the stability of the voltage provided by the power supply VIN to the load.

[0041] During power-down, when the voltage of the filter capacitor CIN is less than the first preset voltage but greater than or equal to the second preset voltage, the first control circuit 21 maintains the first control signal at an effective level during the delay phase, and the second control signal remains effective. The switching unit 10 can maintain its input and output terminals on, and the power supply VIN continuously supplies power to the load. When the voltage of the filter capacitor CIN is less than the second preset voltage, the second control signal changes from an effective level to an ineffective level. And / or, at the end of the delay phase of the first control circuit 21, the first control signal changes from an effective level to an ineffective level. The switching unit 10 turns off its input and output terminals, causing the voltage provided by the filter capacitor CIN to stop being output to the load. This allows the voltage across the load to drop rapidly to 0 when the voltage provided by the filter capacitor CIN is less than the normal operating voltage range of the load during power-down, ensuring a rapid power-off of the load and effectively improving the voltage drop slope of the load, thus reducing the probability of abnormal phenomena in the load.

[0042] Figure 3 This is a schematic diagram of a control unit provided in an embodiment of the present invention. Figure 3 As shown, the first control circuit 21 includes a delay circuit 211, a first voltage adjustment circuit 212, and a first comparator circuit 213. The first terminal of the delay circuit 211 is connected to the power supply VIN, the second terminal of the delay circuit 211 is connected to the fixed potential terminal V1, the output terminal of the delay circuit 211 is connected to the first input terminal A of the first voltage adjustment circuit 212, the second input terminal B and the output terminal of the first voltage adjustment circuit 212 are connected to the first input terminal of the first comparator circuit 213, the second input terminal of the first comparator circuit 213 is used to input the first reference voltage VREF1, and the output terminal of the first comparator circuit 213 is connected to the control terminal of the switching unit 10. The delay circuit 211 is used to divide the voltage of the power supply VIN and output it after a delay. The first voltage adjustment circuit 212 is used to transform the voltage after voltage division to form the first voltage. The first comparator circuit 213 is used to form a first control signal based on the first voltage and the first reference voltage VREF1.

[0043] Specifically, the fixed potential terminal V1 can be grounded. The first terminal of the delay circuit 211 is connected to the positive terminal + of the power supply VIN, so that the delay circuit 211 divides the potential between the positive terminal + of the power supply VIN and the fixed potential terminal V1, and then outputs the divided potential to the first input terminal A of the first voltage adjustment circuit 212 after delay. The first voltage adjustment circuit 212 modifies the divided voltage to form the first voltage. For example, the first voltage adjustment circuit 212 includes a first operational amplifier UA1, the positive input terminal A of the first operational amplifier UA1 is connected to the output terminal of the delay circuit 211, and the negative input terminal B of the first operational amplifier UA1 is connected to the output terminal of the first operational amplifier UA1, so that the first operational amplifier UA1 is a voltage follower circuit, and the first voltage is the divided voltage output by the delay circuit 211. The first comparator circuit 213 can compare the first voltage with the first reference voltage VREF1. When the power supply voltage VIN is less than the first preset voltage, the voltage divided by the delay circuit 211 is output to the first voltage adjustment circuit 212 after a delay. Since the first voltage output by the first voltage adjustment circuit 212 is smaller than the first preset voltage, the first control signal formed by the first comparison circuit 213 based on the first voltage and the first reference voltage VREF1 is invalid, and the switching unit 10 shuts off its input and output terminals. When the power supply voltage VIN is greater than or equal to the first preset voltage, the voltage divided by the delay circuit 211 is output to the first voltage adjustment circuit 212 after a delay. Since the first voltage output by the first voltage adjustment circuit 212 is greater than or equal to the first reference voltage VREF1, the first control signal formed by the first comparison circuit 213 based on the first voltage and the first reference voltage VREF1 is valid. The second control signal is also valid, and the switching unit 10 connects its input and output terminals. At this time, the power supply voltage VIN is quickly output to the load, causing the load voltage to rise rapidly to the first preset voltage, effectively increasing the voltage rise slope of the load and reducing the probability of abnormal phenomena in the load.

[0044] Continue to refer to Figure 3 The delay circuit 211 includes a first resistor R1, a second resistor R2, and a delay capacitor CC. The first end of the first resistor R1 is connected to the power supply VIN. The second end of the first resistor R1 is connected to the first end of the second resistor R2 and the first terminal of the delay capacitor CC, and serves as the output terminal of the delay circuit 211. The second end of the second resistor R2 is connected to the fixed potential terminal V1.

[0045] Specifically, the first resistor R1 and the second resistor R2 are connected in series between the positive terminal + of the power supply VIN and the fixed potential terminal V1, dividing the potential of the positive terminal of the power supply VIN and the potential of the fixed potential terminal V1, and outputting the voltage to the delay capacitor CC. The delay capacitor CC delays the voltage formed by the voltage division, and then outputs it to the first input terminal A of the first voltage adjustment circuit 212. According to Kirchhoff's Current Law (KCL) of the circuit, the expression for the voltage at the first input terminal A of the first voltage adjustment circuit 212 is as follows:

[0046]

[0047] Wherein, Vin is the maximum power supply voltage of power supply VIN, t is the charging time of filter capacitor CIN, Tx is the time required for filter capacitor CIN to finish charging, Uc is the voltage of delay capacitor CC, Cc is the capacitance value of delay capacitor CC, r1 is the resistance value of first resistor R1, and r2 is the resistance value of second resistor R2.

[0048] Performing a Laplace transform on the above expression, the time-domain function of the voltage at the first input terminal A of a voltage regulation circuit 212 is as follows:

[0049]

[0050] Where Uc0 is the voltage across the delay capacitor CC at time Tx, expressed as follows:

[0051]

[0052] The first voltage adjustment circuit 212 can be a voltage follower circuit to achieve the characteristics of high input impedance and low output impedance, preventing changes in the load of the subsequent stage from affecting the preceding stage. The potential of the second input terminal B of the first voltage adjustment circuit 212 is approximately equal to the potential of the first input terminal A of the first voltage adjustment circuit 212.

[0053] Continue to refer to Figure 3The first comparator circuit 213 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a first comparator UB1. The first end of the third resistor R3 is connected to the output of the first voltage adjustment circuit 212. The second end of the third resistor R3 is connected to the first end of the fourth resistor R4, the first end of the fifth resistor R5, and the positive input D of the first comparator UB1. The second end of the fourth resistor R4 is connected to the output of the first comparator UB1 and the second end of the eighth resistor R8, and serves as the output DRV of the first control circuit 21. The second ends of the fifth resistor R5 and the second ends of the sixth resistor R6 are connected to the fixed potential V1. The first end of the sixth resistor R6 is connected to the negative input C of the first comparator UB1 and the second end of the seventh resistor R7. The first ends of the seventh resistor R7 and the first ends of the eighth resistor R8 are used to input the first reference voltage VREF1.

[0054] Specifically, the first reference voltage VREF1 is a fixed potential voltage. When the first reference voltage VREF1 is transmitted to the negative input terminal C of the first comparator UB1 through the seventh resistor R7, the potential of the negative input terminal C of the first comparator UB1 is fixed and related to the first reference voltage VREF1. The positive input terminal D of the first comparator UB1 is connected between the third resistor R3 and the fourth resistor R4. The voltage at the positive input terminal D of the first comparator UB1 is related to the first voltage output by the first voltage adjustment circuit 212 and the voltage at the output terminal DRV of the first comparator UB1. At initial power-on, the voltage at the output terminal DRV of the first comparator UB1 is approximately equal to 0. At this time, the voltage at the positive input terminal D of the first comparator UB1 is related to the first voltage. The first comparator UB1 is a hysteresis comparator. The first voltage is proportional to the voltage division output by the delay circuit 211. For example, the first voltage is equal to the voltage division output by the delay circuit 211. When the voltage of the filter capacitor CIN is less than the first preset voltage, the voltage at the positive input terminal D of the first comparator UB1 is less than the voltage at the negative input terminal C of the first comparator UB1. At this time, the first comparator UB1 outputs an invalid level, meaning the first control signal is invalid. When the voltage of the filter capacitor CIN is greater than or equal to the first preset voltage, the voltage at the positive input terminal D of the first comparator UB1 is greater than or equal to the voltage at the negative input terminal C of the first comparator UB1. At this time, the first comparator UB1 outputs a valid level, meaning the first control signal is valid, thus achieving the level flipping of the first control signal. When the level of the first control signal flips, the voltage at the second input terminal B of the first voltage adjustment circuit 212 is:

[0055]

[0056] Where r3 is the resistance value of the third resistor R3, r4 is the resistance value of the fourth resistor R4, r5 is the resistance value of the fifth resistor R5, r6 is the resistance value of the sixth resistor R6, and r7 is the resistance value of the seventh resistor R7.

[0057] As can be seen from the above formula, by reasonably setting the resistance values ​​of the first resistor R1 to the eighth resistor R8, and the capacitance value of the delay capacitor CC, the voltage at the second input terminal B of the first voltage adjustment circuit 212 can reach the voltage required for the effective output level of the first comparator UB1 at the end of the delay stage. Thus, when the voltage of the filter capacitor CIN is greater than or equal to the first preset voltage, the first control signal output by the first control circuit 21 after the delay stage is at an effective level, controlling the switch unit 10 to conduct its input and output terminals.

[0058] Continue to refer to Figure 3 The second control circuit 22 includes a voltage divider circuit 221, a second voltage adjustment circuit 222, and a second comparator circuit 223. The first terminal of the voltage divider circuit 221 is connected to the power supply VIN, the second terminal of the voltage divider circuit 221 is connected to the fixed potential terminal V1, the output terminal of the voltage divider circuit 221 is connected to the first input terminal a of the second voltage adjustment circuit 222, the second input terminal b of the second voltage adjustment circuit 222 and the output terminal of the second voltage adjustment circuit 222 are connected to the first input terminal of the second comparator circuit 223, the second input terminal of the second comparator circuit 223 is used to input a second reference voltage VRFE2, and the output terminal of the second comparator circuit 223 is connected to the control terminal of the switching unit 10. The voltage divider circuit 221 is used to divide the voltage of the power supply VIN, the second voltage adjustment circuit 222 is used to transform the divided voltage to form a second voltage, and the second comparator circuit 223 is used to form a second control signal based on the second voltage and the second reference voltage VREF2.

[0059] Specifically, the second reference voltage VREF2 is a fixed potential voltage. The first reference voltage VREF1 can be reused as the second reference voltage VREF2. The first terminal of the voltage divider circuit 221 is connected to the positive terminal + of the power supply VIN, and the second terminal of the voltage divider circuit 221 is connected to the fixed potential terminal V1, so that the voltage divider circuit 221 divides the voltage between the positive terminal + of the power supply VIN and the fixed potential terminal V1, and outputs it to the second voltage adjustment circuit 222. The second voltage adjustment circuit 222 modifies the voltage of the positive terminal after voltage division to form the second voltage. For example, the second voltage adjustment circuit 222 includes a second operational amplifier UA2, the positive input terminal a of the second operational amplifier UA2 is connected to the output terminal of the voltage divider circuit 221, and the negative input terminal b of the second operational amplifier UA2 is connected to the output terminal of the second operational amplifier UA2, so that the second operational amplifier UA2 is a voltage follower circuit, and the second voltage is the divided voltage output by the voltage divider circuit 221. The second comparator circuit 223 compares the second voltage and the second reference voltage VREF2. When the power supply voltage VIN is less than the second preset voltage, the voltage divider circuit 221 divides the power supply voltage VIN and outputs the resulting voltage to the second voltage adjustment circuit 222. The second voltage adjustment circuit 222 outputs a second voltage that is smaller than the second voltage. The second comparator circuit 223, based on the second voltage and the second reference voltage VREF2, sets the second control signal to an invalid level, and the switching unit 10 shuts off its input and output terminals. When the power supply voltage VIN is greater than or equal to the second preset voltage, the voltage divider circuit 221 divides the power supply voltage VIN and outputs the resulting voltage to the second voltage adjustment circuit 222. The second voltage adjustment circuit 222 outputs a second voltage that is larger than the second voltage. The second comparator circuit 223, based on the second voltage and the second reference voltage VREF2, sets the second control signal to an active level, and the switching unit 10 determines whether it is in an on or off state based on the level of the first control signal. When the power supply voltage VIN is less than the second preset voltage, the voltage divider circuit 221 divides the power supply voltage VIN and outputs the resulting voltage to the second voltage adjustment circuit 222. The second voltage adjustment circuit 222 outputs a second voltage that is smaller than the second voltage. The second comparator circuit 223 then uses the second voltage and the second reference voltage VREF2 to form a second control signal that is invalid. At this time, the switching unit 10 shuts off its input and output terminals. This allows the voltage across the load to drop rapidly to 0 during power-down when the voltage provided by the filter capacitor CIN is less than the normal operating voltage range of the load, ensuring a rapid power-off of the load. This effectively increases the voltage drop slope of the load and reduces the probability of abnormal load phenomena.

[0060] Continue to refer to Figure 3The voltage divider circuit 221 includes a ninth resistor R9 and a tenth resistor R10; the first end of the ninth resistor R9 is connected to the power supply VIN, the second end of the ninth resistor R9 is connected to the first end of the tenth resistor R10 and serves as the output terminal of the voltage divider circuit 221, and the second end of the tenth resistor R10 is connected to the fixed potential terminal V1.

[0061] Specifically, the ninth resistor R9 and the tenth resistor R10 are connected in series between the positive terminal + of the power supply VIN and the fixed potential terminal V1, dividing the voltage between the positive terminal of the power supply VIN and the fixed potential terminal V1, and outputting the voltage to the first input terminal a of the second voltage adjustment circuit 222. According to Kirchhoff's Current Law (KCL), the expression for the voltage at the first input terminal a of the second voltage adjustment circuit 222 is as follows:

[0062]

[0063] Where r9 is the resistance value of the ninth resistor R9, and r10 is the resistance value of the tenth resistor R10.

[0064] The second voltage adjustment circuit 222 can be a voltage follower circuit to achieve a high input impedance and low output impedance, preventing changes in the load of the subsequent stage from affecting the preceding stage. The potential of the second input terminal b of the second voltage adjustment circuit 222 is approximately equal to the potential of the first input terminal a of the second voltage adjustment circuit 222.

[0065] Continue to refer to Figure 3 The second comparator circuit 223 includes an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a fifteenth resistor R15, and a second comparator UB2. The first end of the eleventh resistor R11 is connected to the output of the second voltage adjustment circuit 222. The second end of the eleventh resistor R11 is connected to the first end of the twelfth resistor R12, the first end of the thirteenth resistor R13, and the positive input terminal d of the second comparator UB2. The second end of the twelfth resistor R12 is connected to the output of the second comparator UB2 and serves as the output of the second control circuit 223. The second ends of the thirteenth resistor R13 and the fourteenth resistor R14 are connected to the fixed potential terminal V1. The first end of the fourteenth resistor R14 is connected to the negative input terminal c of the second comparator UB2 and the second end of the fifteenth resistor R15. The first end of the fifteenth resistor R15 is used to input the second reference voltage VREF2.

[0066] Specifically, when the second reference voltage VREF2 is transmitted to the negative input terminal c of the second comparator UB2 through the fifteenth resistor R15, the potential of the negative input terminal c of the second comparator UB2 is fixed and related to the second reference voltage VREF2. The positive input terminal d of the second comparator UB2 is connected between the eleventh resistor R11 and the twelfth resistor R12. The voltage at the positive input terminal d of the second comparator UB2 is related to the second voltage output by the second voltage adjustment circuit 222 and the voltage at the output terminal DRV of the second comparator UB2. During power-on, the first control circuit 21 controls the on or off state of the switching unit 10. During power-off, the second control circuit 22 controls the on or off state of the switching unit 10. The second comparator UB2 is a hysteresis comparator. The second voltage is proportional to the voltage divided by the voltage divider output by the voltage divider circuit 221. For example, the second voltage is equal to the voltage divided by the voltage divider output by the voltage divider circuit 221. When the voltage of the filter capacitor CIN is greater than or equal to the second preset voltage, the voltage at the positive input terminal d of the second comparator UB2 is greater than or equal to the voltage at the negative input terminal c of the second comparator UB2. At this time, the second comparator UB2 outputs a valid level, that is, the second control signal is valid. Based on the first control signal being valid, the switching unit 10 remains in the on state. When the voltage of the filter capacitor CIN is less than the second preset voltage, the voltage at the positive input terminal d of the second comparator UB2 is less than the voltage at the negative input terminal c of the second comparator UB2. At this time, the second comparator UB2 outputs an invalid level, that is, the second control signal is invalid, realizing the level flip of the second control signal. At this time, the switching unit 10 is in the off state according to the second control signal. The second reference voltage VREF2 and the first reference voltage VREF1 can be set to both be reference voltage VREF. When the level of the second control signal flips, the power supply voltage VIN is:

[0067]

[0068] Where r11 is the resistance value of the eleventh resistor R11, r12 is the resistance value of the twelfth resistor R12, r13 is the resistance value of the thirteenth resistor R13, r14 is the resistance value of the fourteenth resistor R14, r15 is the resistance value of the fifteenth resistor R15, and r8 is the resistance value of the eighth resistor R8.

[0069] As shown in the above formula, by reasonably setting the resistance values ​​of the ninth resistor R9 to the fifteenth resistor R15, the second control signal output by the second comparator UB2 can be flipped to an invalid level when the power supply voltage VIN drops to the second preset voltage. Therefore, when the voltage of the filter capacitor CIN is less than the second preset voltage, the second control signal becomes invalid, controlling the switching unit 10 to turn off its input and output terminals. This effectively increases the voltage drop slope of the load and reduces the probability of abnormal load phenomena.

[0070] Figure 4 This is a schematic diagram of another power control circuit provided in an embodiment of the present invention. Figure 4 As shown, the switching unit 10 includes a first power switch Q1 and a second power switch Q2; the control terminal of the first power switch Q1 is connected to the output terminal DRV of the control unit 20, the first terminal of the first power switch Q1 is connected to the fixed potential terminal V1, the second terminal of the first power switch Q1 is connected to the control terminal of the second power switch Q2, the first terminal of the second power switch Q2 is connected to the power supply VIN, and the second terminal of the second power switch Q2 serves as the output terminal of the switching unit 10.

[0071] Specifically, the first power switch Q1 can be an N-type power transistor, and the second power switch Q2 can be a P-type power transistor. In this case, the fixed potential terminal V1 provides a low-level potential, such as ground. (Continue to refer to...) Figure 4 The switching unit 10 may further include a sixteenth resistor R16 and a seventeenth resistor R17. The second terminal of the first power switch Q1 is connected to the control terminal of the second power switch Q2 through the sixteenth resistor R16. The seventeenth resistor R17 is connected between the first terminal and the control terminal of the second power switch Q2 for current limiting protection of the first power switch Q1 and the second power switch Q2. The control unit 20 outputs a high level when the voltage at the positive terminal of the power supply VIN is greater than or equal to the first preset voltage, controlling the first power switch Q1 to conduct. This allows the first power switch Q1 to transmit the potential of the fixed potential terminal V1 to the control terminal of the second power switch Q2 through the sixteenth resistor R16. The second power switch Q2 conducts according to the low level potential provided by the fixed potential terminal V1. The power supply voltage provided by the power supply VIN is transmitted to the load through the second power switch Q2, supplying power to the load. Since the turn-on time of the second power switch Q2 is V / μs, it meets the load load's requirement for voltage slope, thereby ensuring the voltage rise slope of the load load and reducing the probability of abnormal phenomena in the load load. When the positive terminal voltage of the power supply VIN is less than the second preset voltage, the control unit 20 immediately outputs a low level, controlling the first power switch Q1 to turn off. This causes the control terminal potential of the second power switch Q2 to be pulled up to a high level through the seventeenth resistor R17, thus turning off the second power switch Q2. This prevents the power supply voltage provided by VIN from being transmitted to the load through the second power switch Q2. Since the turn-off time of the second power switch Q2 is V / μs, it meets the load load's voltage slope requirement, thereby ensuring the voltage drop slope of the load load and reducing the probability of abnormal load load phenomena. For example, Figure 5 This is a schematic diagram illustrating the simulation results of a power control circuit controlling the power-on and power-off states in an embodiment of the present invention. Figure 6 for Figure 5The simulation results of the provided power control circuit controlling the power-on and power-off are shown in a partially enlarged schematic diagram at the dashed box E. Figure 7 for Figure 5 The simulation results of the provided power control circuit controlling the power-on and power-off are shown in a partially enlarged diagram at the dashed box F. The horizontal axis represents time, and the vertical axis represents voltage. Figures 5 to 7 As shown, channel 1 is the input voltage of the power supply VIN, and channel 2 is the output voltage of the power control circuit. With the input voltage configured as 12V and a rise rate of 20ms, the calculated turn-on delay time of the second power switch Q2 is 238.6ms, while the simulation result shows a delay time of 238.4ms. At this point, the power-on slope of the power control circuit's output voltage is 12V / μs. When the power supply VIN is de-energized, the second preset voltage can be set to 8.3V. The simulation result shows that the output voltage of the power control circuit begins to drop rapidly at 8.23V, at which point the power-off slope of the power control circuit's output voltage is 26V / µs.

[0072] It should be noted that in other embodiments, the second power switch Q2 can also be set as an N-type power transistor. In this case, the fixed potential provided by the fixed potential terminal V1 can be a high level, which is not limited here.

[0073] In some embodiments, when the voltage of the power supply VIN is greater than or equal to a first preset voltage, the delay time for the control unit 20 to connect the input and output terminals of the delay control unit 10 is greater than or equal to 0.

[0074] Specifically, the first preset voltage can be the stable voltage after the filter capacitor CIN has finished charging. When the delay time is equal to 0, the power supply VIN can provide a stable voltage to the load. When the delay time is greater than 0, the voltage across the filter capacitor CIN becomes more stable, allowing the power supply VIN to provide a more stable voltage to the load, thereby improving the stability of the power supply VIN to the load.

[0075] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A power supply control circuit, characterized in that, Includes switching units and control units; The input terminal of the switching unit is connected to the power supply, the output terminal of the switching unit serves as the output terminal of the power control circuit, and the control terminal of the switching unit is connected to the output terminal of the control unit. The input terminal of the control unit is connected to the power supply. The control unit is used to control the switching unit to connect its input terminal and output terminal when the voltage of the power supply is greater than or equal to a first preset voltage, and to control the switching unit to turn off its input terminal and output terminal when the voltage of the power supply is less than or equal to a second preset voltage. The second preset voltage is less than the first preset voltage.

2. The power control circuit according to claim 1, characterized in that, The control unit includes a first control circuit and a second control circuit; The control terminal of the switching unit is connected to the output terminal of the first control circuit and the output terminal of the second control circuit. The input terminals of the first control circuit and the second control circuit are connected to the power supply. The first control circuit is used to output a first control signal with a delay based on the voltage of the power supply. The second control circuit is used to output a second control signal based on the voltage of the power supply. The first control signal is valid when the voltage of the power supply is greater than or equal to a first preset voltage and invalid when it is less than the first preset voltage. The second control signal is valid when the voltage of the power supply is greater than the second preset voltage and invalid when it is less than or equal to the second preset voltage. The second preset voltage is less than the first preset voltage; the switching unit is used to connect its input terminal and output terminal when the level of the first control signal is valid and the level of the second control signal is valid, and to turn off its input terminal and output terminal when the level of the first control signal is invalid and / or the level of the second control signal is invalid.

3. The power control circuit according to claim 2, characterized in that, The first control circuit includes a delay circuit, a first voltage adjustment circuit, and a first comparison circuit; The first terminal of the delay circuit is connected to the power supply, the second terminal of the delay circuit is connected to the fixed potential terminal, the output terminal of the delay circuit is connected to the first input terminal of the first voltage adjustment circuit, the second input terminal and the output terminal of the first voltage adjustment circuit are connected to the first input terminal of the first comparison circuit, the second input terminal of the first comparison circuit is used to input a first reference voltage, and the output terminal of the first comparison circuit is connected to the control terminal of the switching unit; the delay circuit is used to divide the voltage of the power supply and output it with a delay, the first voltage adjustment circuit is used to transform the divided voltage to form a first voltage; the first comparison circuit is used to form the first control signal based on the first voltage and the first reference voltage.

4. The power control circuit according to claim 3, characterized in that, The delay circuit includes a first resistor, a second resistor, and a delay capacitor; The first end of the first resistor is connected to the power supply, the second end of the first resistor is connected to the first end of the second resistor and the first terminal of the delay capacitor, and serves as the output terminal of the delay circuit, and the second end of the second resistor is connected to the fixed potential terminal.

5. The power control circuit according to claim 3, characterized in that, The first comparator circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a first comparator; The first end of the third resistor is connected to the output terminal of the first voltage adjustment circuit. The second end of the third resistor is connected to the first end of the fourth resistor, the first end of the fifth resistor, and the positive input terminal of the first comparator. The second end of the fourth resistor is connected to the output terminal of the first comparator and the second end of the eighth resistor, and serves as the output terminal of the first control circuit. The second ends of the fifth resistor and the second ends of the sixth resistor are connected to the fixed potential terminal. The first end of the sixth resistor is connected to the negative input terminal of the first comparator and the second end of the seventh resistor. The first ends of the seventh resistor and the first ends of the eighth resistor are used to input the first reference voltage.

6. The power control circuit according to any one of claims 2-5, characterized in that, The second control circuit includes a voltage divider circuit, a second voltage adjustment circuit, and a second comparator circuit; The first terminal of the voltage divider circuit is connected to the power supply, the second terminal of the voltage divider circuit is connected to a fixed potential terminal, the output terminal of the voltage divider circuit is connected to the first input terminal of the second voltage adjustment circuit, the second input terminal and the output terminal of the second voltage adjustment circuit are connected to the first input terminal of the second comparator circuit, the second input terminal of the second comparator circuit is used to input a second reference voltage, and the output terminal of the second comparator circuit is connected to the control terminal of the switching unit; the voltage divider circuit is used to divide the voltage of the power supply, the second voltage adjustment circuit is used to transform the divided voltage to form a second voltage; the second comparator circuit is used to form a second control signal based on the second voltage and the second reference voltage.

7. The power control circuit according to claim 6, characterized in that, The voltage divider circuit includes a ninth resistor and a tenth resistor; The first end of the ninth resistor is connected to the power supply, the second end of the ninth resistor is connected to the first end of the tenth resistor and serves as the output terminal of the voltage divider circuit, and the second end of the tenth resistor is connected to the fixed potential terminal.

8. The power control circuit according to claim 6, characterized in that, The second comparator circuit includes an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, and a second comparator; The first end of the eleventh resistor is connected to the output terminal of the second voltage adjustment circuit. The second end of the eleventh resistor is connected to the first end of the twelfth resistor, the first end of the thirteenth resistor, and the positive input terminal of the second comparator. The second end of the twelfth resistor is connected to the output terminal of the second comparator and serves as the output terminal of the second control circuit. The second ends of the thirteenth resistor and the fourteenth resistor are connected to the fixed potential terminal. The first end of the fourteenth resistor is connected to the negative input terminal of the second comparator and the second end of the fifteenth resistor. The first end of the fifteenth resistor is used to input the second reference voltage.

9. The power control circuit according to claim 1, characterized in that, The switching unit includes a first power switch and a second power switch; The control terminal of the first power switch is connected to the output terminal of the control unit, the first end of the first power switch is connected to the fixed potential terminal, the second end of the first power switch is connected to the control terminal of the second power switch, the first end of the second power switch is connected to the power supply, and the second end of the second power switch serves as the output terminal of the switching unit.

10. The power control circuit according to claim 1, characterized in that, When the voltage of the power supply is greater than or equal to a first preset voltage, the control unit controls the switching unit to connect its input and output terminals with a delay time greater than or equal to 0.

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