Power supply protection circuit

Abstract

The utility model discloses a power supply protection circuit, which comprises a linear voltage stabilization unit, a short circuit detection unit and an output control unit, and is characterized in that the linear voltage stabilization unit is connected to a load power supply and a load input end; the short circuit detection unit is connected to the load input end and the linear voltage stabilization unit; the output control unit is connected to the load power supply, the short circuit detection unit and the linear voltage stabilization unit. According to the power supply protection circuit provided by the invention, the linear voltage stabilization unit is used for providing the voltage in a linear relation with the load power supply to the load input end, and the short circuit detection unit is used for detecting the voltage state of the load input end and outputting a feedback signal to the output control unit when short circuit is detected, so that the output control unit drives the linear voltage stabilization unit to stop outputting; power supply protection of a load loop is realized, the safety of a power supply circuit is guaranteed, the problem that a system circuit is complex due to the fact that an integrated operational amplifier is used in a traditional mode is solved, the circuit structure is simpler, and the reliability is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, in particular to a power supply protection circuit. Background Art

[0002] With more and more modular circuits on boards, the power supply requirements are becoming more and more stringent. In order to ensure that the circuit can work in a reasonable voltage range, most of them need to use linear voltage regulator circuits to protect the load circuit. In the current technology, when powering the load circuit, most of them will use integrated operational amplifiers to sample and process the signal of the load circuit, and control the input state of the load circuit when the load circuit has problems, so as to improve the input stability of the system. Although this method has high sensitivity, it requires the introduction of additional auxiliary power supply to power the integrated operational amplifier, and the auxiliary power supply must also work stably to ensure that the line does not have problems. This makes the system line complicated, the risk of line failure increases, and the reliability is insufficient. Utility Model Content

[0003] The embodiment of the utility model provides a power supply protection circuit, which solves the problem that the integrated operational amplifier used in the prior art leads to complex system circuits.

[0004] The present invention provides a power supply protection circuit, which includes:

[0005] A linear voltage stabilizing unit, connected to a load power supply and a load input terminal, the linear voltage stabilizing unit being used to output a voltage having a linear relationship with the load power supply to the load input terminal;

[0006] a short-circuit detection unit connected to the load input terminal and the linear voltage stabilization unit, the short-circuit detection unit being used to detect a voltage state of the load input terminal and output a feedback signal when the load input terminal is short-circuited;

[0007] An output control unit is connected to the load power supply, the short circuit detection unit and the linear voltage stabilizing unit, and the output control unit is used to receive the feedback signal to drive the linear voltage stabilizing unit to stop outputting voltage.

[0008] In the power supply protection circuit provided in an embodiment of the utility model, the output control unit includes a delay unit and a drive unit, the delay unit is connected to the load power supply and the short-circuit detection unit, and the drive unit is connected to the delay unit and the linear voltage stabilization unit; wherein the delay unit is used to receive the feedback signal to output a shutdown signal to the drive unit to control it to cut off the output of the linear voltage stabilization unit.

[0009] In the power supply protection circuit provided by an embodiment of the utility model, the delay unit includes a MOS tube, a first capacitor and a discharge unit, the gate of the MOS tube and one end of the first capacitor are both connected to the discharge unit, the source of the MOS tube and the other end of the first capacitor are both connected to the load power supply, and the drain of the MOS tube is connected to the drive unit and the short-circuit detection unit; wherein the discharge unit is used to discharge the parasitic capacitance of the first capacitor and the MOS tube.

[0010] In the power supply protection circuit provided in an embodiment of the utility model, the discharge unit includes a first resistor and a second resistor, one end of the second resistor is connected to the gate of the MOS tube and one end of the first capacitor, one end of the first resistor is connected to the load power supply, the source of the MOS tube and the other end of the first capacitor, and the other ends of the first resistor and the second resistor are grounded.

[0011] In the power supply protection circuit provided in an embodiment of the utility model, the driving unit includes a first transistor and a third resistor, one end of the third resistor is connected to the drain of the MOS tube, and the other end is connected to the base of the first transistor, the collector of the first transistor is connected to the linear voltage stabilization unit, and the emitter is grounded.

[0012] In the power supply protection circuit provided in an embodiment of the utility model, the short circuit detection unit includes a second transistor and a fourth resistor, one end of the fourth resistor is connected to the load input end, and the other end is connected to the base of the second transistor, the collector of the second transistor is connected to the drain of the MOS tube and one end of the third resistor, and the emitter is grounded.

[0013] In the power supply protection circuit provided in an embodiment of the utility model, the linear voltage stabilizing unit includes a third transistor, a fifth resistor and a clamping unit, the base of the third transistor is connected to the clamping unit and one end of the fifth resistor, the collector is connected to the load power supply and the other end of the fifth resistor, and the emitter is connected to the load input end.

[0014] In the power supply protection circuit provided by the embodiment of the utility model, the clamping unit includes a voltage regulator diode, the anode of the voltage regulator diode is grounded, and the cathode is connected to the base of the third transistor and one end of the fifth resistor.

[0015] In the power supply protection circuit provided by the embodiment of the utility model, the resistance value of the first resistor is 10KΩ, the resistance value of the second resistor is 100KΩ, and the capacitance value of the first capacitor is 1uF.

[0016] In the power supply protection circuit provided by the embodiment of the utility model, the MOS tube is a depletion type PMOS tube.

[0017] The embodiment of the utility model provides a power supply protection circuit, which includes a linear voltage stabilizing unit, a short circuit detection unit and an output control unit, wherein the linear voltage stabilizing unit is connected to a load power supply and a load input terminal; the short circuit detection unit is connected to the load input terminal and the linear voltage stabilizing unit; the output control unit is connected to the load power supply, the short circuit detection unit and the linear voltage stabilizing unit. The power supply protection circuit provided by the present application provides a voltage that is linearly related to the load power supply to the load input terminal through a linear voltage stabilizing unit, and uses a short circuit detection unit to detect the voltage state of the load input terminal and outputs a feedback signal to the output control unit when a short circuit is detected so that it drives the linear voltage stabilizing unit to stop outputting, thereby realizing power supply protection for the load circuit, ensuring the safety of the power supply line, overcoming the problem of complex system lines caused by the use of integrated operational amplifiers in the traditional way, and making the circuit structure more concise and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A structural block diagram of a power supply protection circuit provided in an embodiment of the utility model;

[0020] Figure 2 Another structural block diagram of the power supply protection circuit provided by an embodiment of the utility model;

[0021] Figure 3 A circuit diagram of a power supply protection circuit provided in an embodiment of the utility model;

[0022] The reference numerals in the figures are:

[0023] 10. Linear voltage stabilization unit; 101. Clamping unit; 20. Short circuit detection unit; 30. Output control unit; 31. Delay unit; 310. Discharge unit; 32. Drive unit. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] Reference Figures 1 to 3 , please refer to Figure 1 , which shows an embodiment of the power supply protection circuit provided by the utility model. The structure and working principle of the power supply protection circuit are described in detail below in conjunction with the drawings of the specification. The power supply protection circuit includes a linear voltage stabilizing unit 10, a short circuit detection unit 20, and an output control unit 30; the linear voltage stabilizing unit 10 is connected to the load power supply and the load input terminal, and the linear voltage stabilizing unit 10 is used to output a voltage that is linearly related to the load power supply to the load input terminal; the short circuit detection unit 20 is connected to the load input terminal and the linear voltage stabilizing unit 10, and the short circuit detection unit 20 is used to detect the voltage state of the load input terminal and output a feedback signal when the load input terminal is short-circuited; the output control unit 30 is connected to the load power supply, the short circuit detection unit 20 and the linear voltage stabilizing unit 10, and the output control unit 30 is used to receive the feedback signal to drive the linear voltage stabilizing unit 10 to stop outputting voltage.

[0026] In this embodiment, the linear voltage stabilizing unit 10 is connected to the load power supply V1, and can output a stable voltage V0 to the load input terminal according to the load power supply V1. The load input terminal is the power supply terminal of the load, such as the positive power supply signal terminal, etc. The linear voltage stabilizing unit 10 can process the voltage V1 of the load power supply to form a stable voltage V0 for output. The output voltage V0 is linearly related to the voltage V1 of the load power supply, that is, the larger the voltage V1 of the load power supply, the larger the voltage V0 output by the linear voltage stabilizing unit 10. The short circuit detection unit 20 is connected to the load input terminal, and can detect the load input terminal in real time. When the load is short-circuited, the voltage state of the load input terminal will change. The short-circuit detection unit 20 can detect the change in the voltage state and output a feedback signal to the signal output unit. The feedback signal can specifically be a high or low level signal. The signal output unit is used to drive and control the output state of the linear voltage stabilizing unit 10. The driving state is controlled by the feedback signal output by the short-circuit detection unit 20. When the feedback signal is received, the linear voltage stabilizing unit 10 will be directly driven to stop output, so that there is no signal input at the load input terminal, the load circuit is disconnected, and power supply protection is formed for the load.

[0027] This embodiment adopts a linear voltage stabilization unit to provide a stable input for the load, adopts a short-circuit detection unit to detect the voltage state of the load input terminal and drives the signal output unit to control the output state of the linear voltage stabilization unit according to the detection result, thereby realizing power supply protection for the load. Overall, the system circuit is simpler, the reliability is improved, and the practicality is stronger.

[0028] In one embodiment, referring to Figure 2The output control unit 30 includes a delay unit 31 and a drive unit 32. The delay unit 31 is connected to the load power supply and the short-circuit detection unit 20, and the drive unit 32 is connected to the delay unit 31 and the linear voltage regulator unit 10; wherein the delay unit 31 is used to receive the feedback signal to output a shutdown signal to the drive unit 32 to control it to cut off the output of the linear voltage regulator unit 10. Specifically, the delay unit 31 can output a signal that can control the driving state of the drive unit 32, that is, output a shutdown signal. The shutdown signal can be a high or low level signal, or other types of driving signals. The output of the shutdown signal is controlled by the feedback signal output by the short-circuit detection unit 20, that is, when the short-circuit detection unit 20 does not output a feedback signal, the delay unit 31 will not output a shutdown signal. Only when the load is short-circuited and the short-circuit detection unit outputs a feedback signal, the delay unit 31 will output a shutdown signal to the drive unit 32. The output end of the drive unit 32 is connected to the linear voltage regulator unit 10. The drive unit 32 is equivalent to a driving switch that controls the linear voltage regulator. The on / off state of the output of the unit 10 can directly control the output or stop output of the linear voltage stabilizing unit 10, which is specifically controlled by the shutdown signal. That is, under normal circumstances, when the driving unit 32 does not receive the shutdown signal, it drives the linear voltage stabilizing unit 10 to normally output the voltage V0, and when the driving unit 32 receives the shutdown signal, it directly drives the linear voltage stabilizing unit 10 to stop output. Overall, the short-circuit detection unit 20 detects the voltage state of the load input terminal and outputs a feedback signal to control the output of the shutdown signal of the delay unit 31, thereby driving the driving unit 32 to cut off the voltage output of the linear voltage stabilizing unit 10, thereby effectively realizing the power supply protection of the load.

[0029] In one embodiment, referring to Figure 3The delay unit 31 includes a MOS tube Q1, a first capacitor C1 and a discharge unit 310, the gate of the MOS tube Q1 and one end of the first capacitor C1 are both connected to the discharge unit 310, the source of the MOS tube Q1 and the other end of the first capacitor C1 are both connected to the load power supply, and the drain of the MOS tube Q1 is connected to the driving unit 32 and the short circuit detection unit 20; wherein the discharge unit 310 is used to discharge the first capacitor C1 and the parasitic capacitance of the MOS tube Q1. The discharge unit 310 includes a first resistor R1 and a second resistor R2, one end of the second resistor R2 is connected to the gate of the MOS tube Q1 and one end of the first capacitor C1, one end of the first resistor R1 is connected to the load power supply, the source of the MOS tube Q1 and the other end of the first capacitor C1, and the other ends of the first resistor R1 and the second resistor R2 are grounded. The driving unit 32 includes a first transistor Q3 and a third resistor R5, one end of the third resistor R5 is connected to the drain of the MOS transistor Q1, and the other end is connected to the base of the first transistor Q3, the collector of the first transistor Q3 is connected to the linear voltage stabilizing unit 10, and the emitter is grounded. The short circuit detection unit 20 includes a second transistor Q2 and a fourth resistor R4, one end of the fourth resistor R4 is connected to the load input end, and the other end is connected to the base of the second transistor Q2, the collector of the second transistor Q2 is connected to the drain of the MOS transistor Q1 and one end of the third resistor R5, and the emitter is grounded.

[0030] In this embodiment, the MOS tube Q1 is a depletion type PMOS tube. The resistance of the first resistor R1 is 10KΩ, the resistance of the second resistor R2 is 100KΩ, and the capacitance of the first capacitor C1 is 1uF. After calculation, when the circuit is actually working, the first resistor R1 adopts a resistance of 10KΩ, the second resistor R2 adopts a resistance of 100KΩ, and the first capacitor C1 adopts a capacitance of 1uF, which can make the voltage VA output by the drain of the MOS tube Q1 delayed by about 15ms than the voltage V0 output by the linear voltage regulator unit 10, which can well meet the normal startup requirements of the circuit.

[0031] In one embodiment, referring to Figure 3 The linear voltage stabilizing unit 10 includes a third triode Q4, a fifth resistor R6 and a clamping unit 101. The base of the third triode Q4 is connected to the clamping unit 101 and one end of the fifth resistor R6, the collector is connected to the load power supply and the other end of the fifth resistor R6, and the emitter is connected to the load input end. The clamping unit 101 includes a voltage stabilizing diode ZD1. The anode of the voltage stabilizing diode ZD1 is grounded, and the cathode is connected to the base of the third triode Q4 and one end of the fifth resistor R6.

[0032] In this embodiment, the load power supply voltage V1 passes through the third transistor Q4 and then outputs the voltage V0. The fifth resistor R6 is a current limiting resistor connected to the base of the third transistor Q4. The voltage stabilizing diode ZD1 is connected between the base of the third transistor Q4 and the ground, and can clamp the base voltage of the third transistor Q4 at a stable value. The values ​​of the fifth resistor R6 and the voltage stabilizing diode ZD1 must be reasonable. Under normal circumstances, the third transistor Q4 must work in the linear amplification region to ensure the stability of V0. For a fixed output, the output current I0 of V0 is related to the amplification factor β of the third transistor Q4, that is, I0 = (1 + β) * [(V1-VZD1) / R6] - IZD1, VZD1 is the clamping voltage of the Zener diode ZD1, and IZD1 is the clamping current of the Zener diode ZD1. Since the clamping voltage VZD1 of the Zener diode ZD1 is fixed, the variation range of the output current I0 is related to the variation range of the clamping current IZD1 of the Zener diode ZD1. When the clamping current IZD1 of the Zener diode ZD1 reaches the minimum, the output current I0 is the maximum, so the specifications of the third transistor Q4 need to be determined according to the output current I0 of the output end and the actual requirements of the input voltage V1 and the output voltage V0, and the selection is made according to the input and output requirements.

[0033] In one embodiment, in order to clearly describe the signal control process, this embodiment provides an example for illustration. Figure 3 In the load power-on stage, the load power supply starts to input. After the load power supply voltage V1 is established, the fifth resistor R6 first provides current input to the base of the third transistor Q4, which is amplified by the third transistor Q4 and output to the load input terminal. The output voltage is V0, which is the voltage at the load input terminal. After that, the load has the following states:

[0034] (1) The load is in normal state

[0035] After the output voltage V0 is normally established, the second transistor Q2 is turned on and operates in the saturation region. The voltage VA of the collector of the second transistor Q2 is the saturation voltage drop VCES2 of the second transistor Q2. At this time, the voltage VA pulls down the base potential of the first transistor Q3. At this time, the first transistor Q3 is in the cut-off state. The voltage VB on the base of the third transistor Q4 is maintained at a high level. The voltage VB on the base of the third transistor Q4 is the clamping voltage of the Zener diode ZD1. The third transistor Q4 is in the operating amplification region. The delay unit 31 composed of the first resistor R1, the second resistor R2, the first capacitor C1, the MOS tube Q1 and the resistor R3 is started after a period of time after the voltage VA is established. The MOS tube Q1 adopts a depletion field effect tube PMOS. The delay time is mainly affected by the first capacitor C1 and the second resistor R2. The second resistor R2 is mainly used to discharge the parasitic capacitance CGS of the MOS tube Q1 to accelerate its triggering and conducting speed. After the first capacitor C1 is fully charged, it is necessary to discharge the energy. A discharge path is formed between the first resistor R1, the second resistor R2 and the ground. When the MOS tube Q1 is turned off, the second resistor R2 quickly releases the charge stored in the first capacitor C1 and the parasitic capacitance CGS of the MOS tube Q1, waiting for the arrival of the next switching cycle. After the MOS tube Q1 is turned on, its drain outputs a voltage that differs from the load power supply V1 by a tube voltage drop of the MOS tube Q1, which is applied to The collector of the second transistor Q2, and the voltage is always maintained at a high level. In practice, the voltage will be established for a period of time later than the voltage V0 input at the load input end. The specific delay time is determined by the specific values ​​of the first resistor R1, the second resistor R2 and the first capacitor C1. Since the voltage V0 at the load input end is established first, the second transistor Q2 is in a conducting state when the voltage V0 at the load input end is normal, and the voltage VA at the collector of the second transistor Q2 is forcibly pulled down. Even if the source of the MOS tube Q1 continues to output a high level, the voltage VA at the collector of the second transistor Q2 is still in a pulled-down state, and the voltage of the base of the first transistor Q3 is at a low level. Therefore, when the voltage V0 at the load input end is just established, the first transistor Q3 is in a cut-off state, so that the third transistor Q4 can be kept in an amplified state, meeting the normal startup power supply conditions of the load.

[0036] (2) The load is in a short-circuit state

[0037] When a short circuit fault occurs in the load, after the voltage V0 at the load input terminal drops to the cut-off voltage drop of the second transistor Q2, the second transistor Q2 stops being in the cut-off state. Since the drain of the MOS tube Q1 provides a high-level output, the voltage VA at the collector of the second transistor Q2 is pulled up, and the first transistor Q3 is in a deep saturation working state, which pulls down the potential VB of the base of the third transistor Q4. At this time, the voltage VB at the base of the third transistor Q4 is the saturation voltage drop VCES3 of the third transistor Q4, and the voltage regulator diode ZD1 is equivalent to being short-circuited. The base potential of the third transistor Q4 in the linear voltage stabilizing unit 10 is pulled down, the third transistor Q4 is in the cut-off state, and the input of the load input terminal is cut off, thereby forming power supply short-circuit protection for the load.

[0038] By implementing this embodiment, the power supply short-circuit protection of the load circuit is effectively achieved without introducing additional auxiliary power supplies and sampling circuits such as integrated operational amplifiers, making the overall system circuit simpler and more reliable.

[0039] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A power supply protection circuit, characterized in that: include: A linear voltage stabilizing unit, connected to a load power supply and a load input terminal, the linear voltage stabilizing unit being used to output a voltage having a linear relationship with the load power supply to the load input terminal; a short-circuit detection unit connected to the load input terminal and the linear voltage stabilization unit, the short-circuit detection unit being used to detect a voltage state of the load input terminal and output a feedback signal when the load input terminal is short-circuited; An output control unit is connected to the load power supply, the short circuit detection unit and the linear voltage stabilizing unit, and the output control unit is used to receive the feedback signal to drive the linear voltage stabilizing unit to stop outputting voltage.

2. The power supply protection circuit according to claim 1, characterized in that: The output control unit includes a delay unit and a drive unit, the delay unit is connected to the load power supply and the short circuit detection unit, and the drive unit is connected to the delay unit and the linear voltage stabilization unit; The delay unit is used to receive the feedback signal to output a shutdown signal to the driving unit to control it to cut off the output of the linear voltage stabilizing unit.

3. The power supply protection circuit according to claim 2, characterized in that: The delay unit includes a MOS tube, a first capacitor and a discharge unit, the gate of the MOS tube and one end of the first capacitor are connected to the discharge unit, the source of the MOS tube and the other end of the first capacitor are connected to the load power supply, and the drain of the MOS tube is connected to the driving unit and the short-circuit detection unit; The discharge unit is used to discharge the first capacitor and the parasitic capacitance of the MOS tube.

4. The power supply protection circuit according to claim 3, characterized in that: The discharge unit includes a first resistor and a second resistor, one end of the second resistor is connected to the gate of the MOS tube and one end of the first capacitor, one end of the first resistor is connected to the load power supply, the source of the MOS tube and the other end of the first capacitor, and the other ends of the first resistor and the second resistor are grounded.

5. The power supply protection circuit according to claim 3, characterized in that: The driving unit includes a first transistor and a third resistor, one end of the third resistor is connected to the drain of the MOS tube, and the other end is connected to the base of the first transistor, the collector of the first transistor is connected to the linear voltage stabilizing unit, and the emitter is grounded.

6. The power supply protection circuit according to claim 5, characterized in that: The short circuit detection unit includes a second transistor and a fourth resistor, one end of the fourth resistor is connected to the load input end, and the other end is connected to the base of the second transistor, the collector of the second transistor is connected to the drain of the MOS tube and one end of the third resistor, and the emitter is grounded.

7. The power supply protection circuit according to claim 1, characterized in that: The linear voltage stabilizing unit includes a third transistor, a fifth resistor and a clamping unit, wherein the base of the third transistor is connected to the clamping unit and one end of the fifth resistor, the collector is connected to the load power supply and the other end of the fifth resistor, and the emitter is connected to the load input end.

8. The power supply protection circuit according to claim 7, characterized in that: The clamping unit includes a voltage-stabilizing diode, an anode of the voltage-stabilizing diode is grounded, and a cathode of the voltage-stabilizing diode is connected to a base of the third transistor and one end of the fifth resistor.

9. The power supply protection circuit according to claim 4, characterized in that: The resistance value of the first resistor is 10KΩ, the resistance value of the second resistor is 100KΩ, and the capacitance value of the first capacitor is 1uF.

10. The power supply protection circuit according to claim 3, characterized in that: The MOS tube is a depletion-type PMOS tube.

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