A power supply failure detection and power supply protection circuit

Abstract

The present invention discloses a power failure detection and power supply protection circuit, comprising: a sampling module, a comparison module, a switch module and a control module. The sampling module samples the input end of the circuit and outputs a sampled voltage; the comparison module compares the sampled voltage with a reference voltage, and outputs a switch control signal from a first output end and a result feedback signal from a second output end according to the comparison result; the switch module controls the connection relationship between the first output end and the input end according to the switch control signal, and outputs a latch control signal through the second output end; the comparison module is also used to determine whether to enter a latched state according to the latch control signal; the control module is used to output a reset signal once at a preset interval when the result feedback signal indicates that the power supply fails; the reset signal is used to release the latched state of the comparison module. The present invention can restore power supply in time on the basis of ensuring power supply safety, and realize reliable power supply of the power supply.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of power supply protection, and in particular to a power supply fault detection and power supply protection circuit. Background Art

[0002] As a power supply device for electronic products, in addition to the basic electrical performance that must meet the requirements of electrical equipment, the power supply itself also has very important fault detection and protection measures, such as overvoltage, overcurrent, and short circuit protection. Conventional power supply fault protection circuits are usually set to self-recovery or self-locking types. Among them, the self-recovery protection circuit will automatically restore the output after detecting that the fault disappears. If the circuit encounters an irreversible fault, but the fault is determined to be resolved due to reasons such as the suspension of the power device or signal fluctuations, and the output is restored, it will cause secondary damage to the power supply itself or the electrical equipment. The self-locking circuit will cut off the power output after detecting the fault signal and lock it in the power-off state. No matter what kind of fault occurs, it needs to be manually checked comprehensively. After the fault is eliminated, the power supply can be restarted only after the power is turned on again. The detection process is cumbersome and time-consuming. Therefore, there is a contradiction between the existing power supply fault detection and power supply protection circuits in terms of power supply safety and the timeliness of power supply restoration. Summary of the invention

[0003] The embodiment of the present invention provides a power supply failure detection and power supply protection circuit, so as to restore power supply in time and realize reliable power supply while ensuring power supply safety.

[0004] The embodiment of the present invention provides a power failure detection and power supply protection circuit, including: a sampling module, a comparison module, a switch module and a control module;

[0005] The sampling module is connected between the input end of the power supply fault detection and power supply protection circuit and the input end of the switch module, and the first output end of the switch module serves as the output end of the power supply fault detection and power supply protection circuit; the sampling module is used to sample the input end of the power supply fault detection and power supply protection circuit and output the sampled voltage;

[0006] The first input terminal of the comparison module is electrically connected to the output terminal of the sampling module, the second input terminal of the comparison module is connected to the reference voltage, and the first output terminal of the comparison module is electrically connected to the control terminal of the switch module; the comparison module is used to compare the sampling voltage with the reference voltage, and output a switch control signal from the first output terminal according to the comparison result, and output a result feedback signal from the second output terminal;

[0007] The second output terminal of the switch module is electrically connected to the third input terminal of the comparison module; the switch module is used to control the conduction or disconnection between the first output terminal and the input terminal according to the switch control signal; and output a latch control signal through the second output terminal according to the switch control signal; the comparison module is also used to determine whether to enter a latch state according to the latch control signal;

[0008] The input end of the control module is electrically connected to the second output end of the comparison module, and the output end of the control module is electrically connected to the third input end of the comparison module; the control module is used to output a reset signal once at a preset time interval when the result feedback signal indicates that the power supply has failed; wherein the reset signal is used to release the latched state of the comparison module.

[0009] Optionally, the control module comprises: an alarm unit; the alarm unit is used to issue a fault alarm when the control module outputs the reset signal for a number of times exceeding a set number of times.

[0010] Optionally, the sampling module includes: a first resistor, a second resistor, a third resistor, a first transistor and a second transistor;

[0011] The first end of the first resistor is electrically connected to the input end of the power supply fault detection and power supply protection circuit and the first electrode of the second transistor respectively; the first electrode of the second transistor is electrically connected to the input end of the switch module; the first electrode of the first transistor is electrically connected to the second end of the first resistor, and the control electrode of the first transistor is electrically connected to the control electrode of the second transistor, the second electrode of the second transistor and the first end of the third resistor respectively; the first end of the second resistor is electrically connected to the second electrode of the first transistor and serves as the second output end of the sampling module; the second end of the second resistor and the second end of the third resistor are both grounded.

[0012] Optionally, the sampling module further includes: a fourth resistor;

[0013] A first end of the fourth resistor is electrically connected to a first end of the second resistor, and a second end of the fourth resistor is electrically connected to a first electrode of the second transistor.

[0014] Optionally, the comparison module includes: a first comparator, a second comparator and a fifth resistor;

[0015] The first input terminal of the first comparator serves as the first input terminal of the comparison module, the second input terminal of the first comparator is electrically connected to the first terminal of the fifth resistor and the output terminal of the second comparator respectively, and the output terminal of the first comparator serves as the first output terminal of the comparison module; the first input terminal of the second comparator serves as the third input terminal of the comparison module, the second input terminal of the second comparator is electrically connected to the second terminal of the fifth resistor and serves as the second input terminal of the comparison module, and the output terminal of the second comparator serves as the second output terminal of the comparison module.

[0016] Optionally, the switch module includes: a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third transistor and a fourth transistor;

[0017] The first end of the sixth resistor is electrically connected to the first electrode of the third transistor and the first electrode of the fourth transistor, respectively, and serves as the input end of the switch module; the first end of the seventh resistor is electrically connected to the second end of the sixth resistor and the control electrode of the third transistor, respectively, and the second end of the seventh resistor serves as the control end of the switch module; the first end of the eighth resistor is electrically connected to the second electrode of the third transistor, the first end of the ninth resistor and the control electrode of the fourth transistor, respectively, and the second end of the eighth resistor serves as the second output end of the switch module; the second end of the ninth resistor is grounded; and the second electrode of the fourth transistor serves as the first output end of the switch module.

[0018] Optionally, the control module includes: a tenth resistor, a fifth transistor, a sixth transistor and a control unit;

[0019] The input end of the control unit is electrically connected to the second end of the tenth resistor and the first electrode of the sixth transistor respectively, and the output end of the control unit is electrically connected to the control electrode of the fifth transistor; the first electrode of the fifth transistor serves as the output end of the control module, and the second electrode of the fifth transistor is grounded; the first end of the tenth resistor is connected to the first level signal; the control electrode of the sixth transistor serves as the input end of the control module, and the second electrode of the sixth transistor is grounded.

[0020] Optionally, the power supply fault detection and power supply protection circuit further includes: a status indication module;

[0021] The input end of the state indication module is electrically connected to the first output end of the switch module; the state indication module is used to indicate the power state according to the output signal of the first output end of the switch module.

[0022] Optionally, the state indication module comprises: an eleventh resistor and an indication unit;

[0023] The first end of the eleventh resistor is used as the input end of the state indicating module, the second end of the eleventh resistor is electrically connected to the first end of the indicating unit, and the second end of the indicating unit is grounded;

[0024] The indicating unit includes: an indicator light or an alarm.

[0025] Optionally, the power failure detection and power supply protection circuit further includes: a reference voltage generation module; the reference voltage generation module includes: a voltage stabilizing chip, a twelfth resistor, a thirteenth resistor and a fourteenth resistor;

[0026] The first end of the twelfth resistor is connected to the first level signal; the second end of the twelfth resistor is electrically connected to the first end of the voltage stabilizing chip, the first end of the thirteenth resistor and the second input end of the comparison module respectively; the third end of the voltage stabilizing chip is electrically connected to the second end of the thirteenth resistor and the first end of the fourteenth resistor respectively; the second end of the voltage stabilizing chip and the second end of the fourteenth resistor are both grounded.

[0027] In the power supply fault detection and power supply protection circuit provided in the embodiment of the present invention, a sampling module, a comparison module, a switch module and a control module are provided; the following working process can be realized: when the power supply is normal, the comparison result indicates that the power supply is normal; the switch module is turned on under the control of the switch control signal, and the power supply input signal is output normally after passing through the sampling module and the switch module; under the control of the latch control signal, the comparison module operates normally and does not enter the latch state; the result feedback signal received by the control module always indicates that the power supply is normal, and the control module does not output a reset signal. When a power failure occurs, the comparison result indicates a power failure, and the input end and the first output end of the switch module are turned off under the control of the switch control signal, cutting off the transmission path of the power signal; under the control of the latch control signal, the comparison module enters a latched state; in the latched state, regardless of whether the fault has been eliminated, the output state of the circuit will not be changed; the result feedback signal received by the control module indicates that a power failure has occurred; at this time, the control module outputs a reset signal once at a preset interval; during the output of the reset signal, the latched state of the comparison module is released, and if the power failure has been eliminated (for example, a transient fault has disappeared by itself), the power supply can be restored; after the power supply is restored, the result feedback signal output by the comparison module to the control module also resumes indicating that the power supply is normal.

[0028] In summary, the circuit can collect the electrical signal at the input end of the circuit in real time, so as to monitor the power supply fault status in real time. When the power supply fails, the switch module cuts off the power supply path, and the comparison module enters the latching state to prevent the impact of the power supply or power consumption system caused by the erroneous restoration of power supply; and after the failure occurs, the control module sends a reset signal at a fixed time, and releases the latching state of the comparison module at a fixed time to ensure that the power supply can be restored in time after the failure is eliminated. Therefore, compared with the prior art, the embodiment of the present invention can restore the power supply in time on the basis of ensuring the safety of power supply, so as to realize the reliable power supply of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a power supply fault detection and power supply protection circuit provided by an embodiment of the present invention;

[0030] Figure 2 It is a structural schematic diagram of another power supply fault detection and power supply protection circuit provided by an embodiment of the present invention;

[0031] Figure 3 It is a structural schematic diagram of another power supply fault detection and power supply protection circuit provided by an embodiment of the present invention;

[0032] Figure 4 It is a structural schematic diagram of another power supply fault detection and power supply protection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0034] An embodiment of the present invention provides a power failure detection and power supply protection circuit. Figure 1 Schematic diagram of a power supply fault detection and power supply protection circuit provided by an embodiment of the present invention. Figure 1 The power supply fault detection and power supply protection circuit includes: a sampling module 110, a comparison module 120, a switch module 130 and a control module 140.

[0035] The sampling module 110 is connected between the input terminal IN of the power supply fault detection and power supply protection circuit and the input terminal of the switch module 130 (the input terminal of the sampling module 110 is electrically connected to the input terminal IN of the circuit, and the power supply input signal is connected, and the power supply output terminal of the sampling module 110 is electrically connected to the input terminal of the switch module 130); the first output terminal of the switch module 130 is used as the output terminal OUT of the power supply fault detection and power supply protection circuit; the sampling module 110 is used to sample the input terminal IN of the power supply fault detection and power supply protection circuit, and output the sampled voltage. The first input terminal of the comparison module 120 is electrically connected to the output terminal of the sampling module 110, the second input terminal of the comparison module 120 is connected to the reference voltage VREF, and the first output terminal of the comparison module 120 is electrically connected to the control terminal of the switch module 130; the comparison module 120 is used to compare the sampled voltage with the reference voltage VREF, and output the switch control signal from the first output terminal according to the comparison result, and output the result feedback signal from the second output terminal. The second output terminal of the switch module 130 is electrically connected to the third input terminal of the comparison module 120; the switch module 130 is used to control the conduction or disconnection between the first output terminal and the input terminal according to the switch control signal; and output the latch control signal through the second output terminal according to the switch control signal; the comparison module 120 is also used to determine whether to enter the latch state according to the latch control signal. The input terminal of the control module 140 is electrically connected to the second output terminal of the comparison module 120, and the output terminal of the control module 140 is electrically connected to the third input terminal of the comparison module 120; the control module 140 is used to output a reset signal once every preset time interval when the result feedback signal indicates that the power supply fails; wherein the reset signal is used to release the latch state of the comparison module 120.

[0036] Exemplarily, the working process of the power supply fault detection and power supply protection circuit includes:

[0037] The input terminal IN of the circuit is connected to the power input signal; the sampling module 110 collects the electrical signal (such as voltage or current) of the circuit input terminal IN and converts it into a sampled voltage output; the comparison module 120 obtains a comparison result based on the sampled voltage and the reference voltage VREF, and generates a switch control signal and a result feedback signal based on the comparison result. The output signals of the two output terminals of the comparison module 120 control the output states of the switch module 130 and the control module 140 respectively; and the output signal (latch control signal) of the second output terminal of the switch module 130 and the output signal (reset signal) of the comparison module 140 determine the latching state of the comparison module 120; wherein, the reset signal can forcibly release the latching state of the comparison module 120.

[0038] Specifically, when the power supply system is operating normally, the provided power input signal is within a normal range; the comparison result obtained by the comparison module 120 comparing the sampled voltage and the reference voltage VREF indicates that the power supply is normal; the switch module 130 is turned on under the control of the switch control signal, and the power input signal is output normally after passing through the sampling module 110 and the switch module 130; when the input terminal and the first output terminal of the switch module 130 are turned on, the latch control signal indicates that the comparison module 120 is operating normally and is not latched; the result feedback signal indicates that the power supply is normal, and the control module 140 does not output a reset signal.

[0039] When a power supply system fails, such as an overcurrent, overvoltage or short circuit, the power supply input signal provided by the power supply system will have overvoltage or overcurrent. Therefore, compared with normal conditions, the electrical signal collected by the sampling module 110 will increase; at this time, the comparison result obtained by the comparison module 120 comparing the sampled voltage and the reference voltage VREF indicates that the power supply has failed; the input end and the first output end of the switch module 130 are turned off under the control of the switch control signal, cutting off the transmission path of the power supply signal, so that the output end OUT of the circuit cannot output the power supply output signal, preventing the subsequent circuit from being damaged; at this time, under the control of the latch control signal, the comparison module 120 enters the latch state; in the latch state, regardless of whether the fault in the power supply system has been eliminated, the input of the comparison module 120 The output signal will not change, and the output state of the circuit will not be changed; the result feedback signal received by the control module 140 indicates that the power supply has failed; the control module 140 outputs a reset signal once at a preset interval; during the output of the reset signal, the latched state of the comparison module 120 is released under the control of the reset signal. At this time, if the power supply failure has been eliminated (for example, the instantaneous failure has disappeared by itself), the output terminal OUT of the circuit can output the power supply output signal again, and the power supply of the subsequent circuit is restored; after the power supply is restored, the result feedback signal output by the comparison module 120 to the control module 140 also resumes to indicate that the power supply is normal.

[0040] In summary, the circuit can collect the electrical signal of the circuit input terminal IN in real time, so as to monitor the power supply fault status in real time. When the power supply fails, the switch module 130 cuts off the power supply path, and the comparison module 120 enters the latching state to prevent the impact of the power supply erroneously restored on the front-stage power supply system or the rear-stage power consumption system; and, after the failure occurs, the control module 140 sends a reset signal regularly, and releases the latching state of the comparison module 120 regularly to ensure that the power supply can be restored in time after the failure is eliminated. Therefore, the embodiment of the present invention can restore the power supply in time on the basis of ensuring the safety of the power supply, and it is not easy to lose control when the power supply fails, thereby realizing the reliable power supply of the power supply.

[0041] The above embodiments exemplarily provide the basic working process of the power failure detection and power supply protection circuit. The specific structure that each module in the circuit may have is described below, but it is not intended to limit the present invention.

[0042] Figure 2 FIG. 1 is a schematic diagram of another power supply fault detection and power supply protection circuit provided by an embodiment of the present invention. Figure 2 In one embodiment, the sampling module 120 may be optionally composed of a proportional current source circuit. Compared with a common sampling circuit in the form of a resistor divider, the use of a proportional current source circuit to construct an overvoltage and overcurrent acquisition module can make the sampling module 110 have higher sampling accuracy, better stability and reliability.

[0043] Specifically, the sampling module 110 includes: a first resistor R1, a second resistor R2, a third resistor R3, a first transistor V1 and a second transistor V2; the first end of the first resistor R1 is electrically connected to the input end of the power failure detection and power supply protection circuit, connected to the power input signal POW_IN, and electrically connected to the first electrode of the second transistor V2; the first electrode of the second transistor V2 serves as the power output end of the sampling module 110 and is electrically connected to the input end of the switch module 130; the first electrode of the first transistor V1 is electrically connected to the second end of the first resistor R1, and the control electrode of the first transistor V1 is electrically connected to the control electrode of the second transistor V2, the second electrode of the second transistor V2 and the first end of the third resistor R3 respectively; the first end of the second resistor R2 is electrically connected to the second electrode of the first transistor V1 and serves as the second output end of the sampling module 110; the second end of the second resistor R2 and the second end of the third resistor R3 are both grounded.

[0044] Exemplarily, in the sampling module 110, the first transistor V1 and the second transistor V2 can be the same triode, such as a completely identical PNP triode. The current flowing through the first resistor R1 is recorded as I1, and the current flowing through the first pole of the second transistor V2 is recorded as I2; according to the characteristics of the proportional current source circuit, it can be obtained that: I2 = R2*I1 / R3; therefore, by adjusting the resistance values ​​of the second resistor R2 and the third resistor R3, the output signal of the power output end of the sampling module 110 can be changed. Taking the voltage at the first end of the second resistor R2 as the sampling voltage (recorded as Vx), if it is approximately assumed that the current flowing through the first pole and the second pole of the first transistor V1 is the same (both are I1), it can be obtained that: Vx = I1*R2. At this time, the sampling voltage Vx can represent the overcurrent detection value of the circuit. Since the overcurrent may be caused by the overvoltage of the power supply system, the sampling voltage Vx can also represent the overvoltage detection value.

[0045] Continue to see Figure 2On the basis of the above embodiments, optionally, the sampling module 110 further includes: a fourth resistor R4; a first end of the fourth resistor R4 is electrically connected to the first end of the second resistor R2, and a second end of the fourth resistor R4 is electrically connected to the first electrode of the second transistor V2.

[0046] Exemplarily, the fourth resistor R4 can use a resistor with a smaller resistance value (such as 0.1Ω) as a fuse to achieve short-circuit protection. Since the current flowing through the fourth resistor R4 (denoted as I3) is: I3=I2-I1; the voltage obtained on the fourth resistor R4 (denoted as V) is: V=I3*R4. The voltage V can represent the overcurrent detection value of the circuit. Once a short circuit fault occurs in the front-stage power supply system, the current I3 will increase instantaneously, causing the fourth resistor R4 to be directly blown to prevent the power input signal POW_IN from continuing to be transmitted, and prevent the subsequent power circuit from being damaged by the impact.

[0047] Continue to see Figure 2 Based on the above embodiments, optionally, the comparison module 120 can be composed of a plurality of comparators.

[0048] Specifically, the comparison module 120 includes: a first comparator CMP1, a second comparator CMP2 and a fifth resistor R5; the first input terminal of the first comparator CMP1 serves as the first input terminal of the comparison module 120, the second input terminal of the first comparator CMP1 is electrically connected to the first end of the fifth resistor R5 and the output terminal of the second comparator CMP2 respectively, and the output terminal of the first comparator CMP1 serves as the first output terminal of the comparison module 120; the first input terminal of the second comparator CMP2 serves as the third input terminal of the comparison module 120, the second input terminal of the second comparator CMP2 is electrically connected to the second end of the fifth resistor R5 and serves as the second input terminal of the comparison module 120, and the output terminal of the second comparator CMP2 serves as the second output terminal of the comparison module 120.

[0049] The reference voltage VREF can be set to a critical value between a sampling voltage indicating a normal power supply and a sampling voltage indicating a power supply failure. Since the sampling voltage Vx is equal to the product of the current I1 and the resistance value of the second resistor R2, the reference voltage VERF can be set to the product of the critical value of the current I1 and the resistance value of the second resistor R2. In other words, the value of the reference voltage VERF can be set according to the overcurrent critical value of the current I1 and the resistance value of the second resistor R2.

[0050] Continue to see Figure 2 On the basis of the above embodiments, optionally, the switch module 130 mainly realizes on-off control inside the module through transistors.

[0051] Specifically, the switch module 130 includes: a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a third transistor V3 and a fourth transistor V4. The first end of the sixth resistor R6 is electrically connected to the first electrode of the third transistor V3 and the first electrode of the fourth transistor V4, respectively, and serves as the input end of the switch module 130; the first end of the seventh resistor R7 is electrically connected to the second end of the sixth resistor R6 and the control electrode of the third transistor V3, respectively, and the second end of the seventh resistor R7 serves as the control end of the switch module 130; the first end of the eighth resistor R8 is electrically connected to the second electrode of the third transistor V3, the first end of the ninth resistor R9 and the control electrode of the fourth transistor V4, respectively, and the second end of the eighth resistor R8 serves as the second output end of the switch module 130; the second end of the ninth resistor R9 is grounded; and the second electrode of the fourth transistor V4 serves as the first output end of the switch module 130.

[0052] The third transistor V3 may be a PNP transistor; the fourth transistor V4 may be a PMOS transistor. The ninth resistor R9 may be a pull-down resistor connected to the control electrode of the fourth transistor V4. The eighth resistor R8 may be a current limiting resistor between the switch module 130 and the comparison module 120.

[0053] Continue to see Figure 2 On the basis of the above embodiments, optionally, the control module 140 includes: a tenth resistor R10, a fifth transistor V5, a sixth transistor V6 and a control unit 141. The input end of the control unit 141 is electrically connected to the second end of the tenth resistor R10 and the first electrode of the sixth transistor V6 respectively, and the output end of the control unit 141 is electrically connected to the control electrode of the fifth transistor V5; the first electrode of the fifth transistor V5 serves as the output end of the control module 140, and the second electrode of the fifth transistor V5 is grounded; the first end of the tenth resistor R10 is connected to the first level signal VCC; the control electrode of the sixth transistor V6 serves as the input end of the control module 140, and the second electrode of the sixth transistor V6 is grounded.

[0054] The fifth transistor V5 may be an NPN transistor, and the sixth transistor V6 may be an NMOS transistor. The first level signal VCC may be a high level. The control logic of the control module 140 may be completely built into the control unit 141; or the control signal sent by the control unit 141 may be manually intervened.

[0055] For example, Figure 2 The working process of the power failure detection and power supply protection circuit shown includes:

[0056] 1) When the power supply system is working normally, the sampling voltage output by the sampling module 110 is less than the reference voltage VREF. The first input terminal (negative input terminal) of the first comparator CMP1 is connected to the sampling voltage, and the second input terminal (positive input terminal) of the first comparator CMP1 is connected to the reference voltage VREF through the pull-up resistor (fifth resistor R5). Since the sampling voltage is less than the reference voltage VREF, the first comparator CMP1 outputs a high level, that is, the switch control signal is a high level. The control electrode of the third transistor V3 is connected to a high level through the seventh resistor R7, causing the third transistor V3 to be in a cut-off state. The control electrode of the fourth transistor V4 is connected to the ground signal through the ninth resistor R9, thereby turning on the fourth transistor V4. Therefore, the power signal transmission path between the input terminal and the output terminal of the circuit is turned on, and the power output signal POW_OUT is output normally.

[0057] Since the third transistor V3 is turned off, the ground signal is output to the first input terminal (negative input terminal) of the second comparator CMP2 through the ninth resistor R9 and the eighth resistor R8, that is, the latch control signal is low level. Since the second input terminal (positive input terminal) of the second comparator CMP2 is connected to the reference voltage VREF (high level), the output terminal of the second comparator CMP2 outputs a high level, that is, the result feedback signal is a high level. At this time, the output signal of the second comparator CMP2 and the reference voltage VREF are both high levels, so the output signal does not affect the output of the first comparator CMP1, and the comparison module 120 operates normally.

[0058] The sixth transistor V6 is turned on under the control of the high level (result feedback signal), and the ground signal is transmitted to the input end of the control unit 141 through the sixth transistor V6, that is, the fault output signal input to the control unit 141 is a low level. The control unit 141 determines that there is no fault in the front-stage power supply system according to the low level, and controls the fifth transistor V5 to turn off, and the control module 140 does not output a reset signal.

[0059] 2) When a fault occurs in the power supply system (such as overvoltage, overcurrent, short circuit, etc.), the sampling voltage output by the sampling module 110 is greater than the reference voltage VREF, and the first comparator CMP1 outputs a low level, that is, the switch control signal is a low level. The control electrode of the third transistor V3 is connected to the low level through the seventh resistor R7, causing the third transistor V3 to be turned on. The control electrode of the fourth transistor V4 is connected to the power signal (high level) through the third transistor V3, causing the fourth transistor V4 to be turned off. Therefore, the power signal transmission path between the input end and the output end of the circuit is cut off, and the power output signal POW_OUT cannot be output.

[0060] Since the third transistor V3 is turned on, the power signal (usually the power input signal POW_IN is a high level whose voltage value is greater than the reference voltage VREF, so the power signal transmitted to the third transistor V3 is still a high level greater than the reference voltage VREF) is output to the first input terminal of the second comparator CMP2 through the third transistor V3 and the eighth resistor R8, that is, the latch control signal is a high level. At this time, since the second input terminal (positive input terminal) of the second comparator CMP2 is connected to the reference voltage VREF, the output terminal of the second comparator CMP2 outputs a low level, that is, the result feedback signal is a low level.

[0061] At this time, the low level output by the second comparator CMP2 is transmitted to the second input terminal of the first comparator CMP1, so that the input signal of the second input terminal (positive input terminal) of the first comparator CMP1 is kept at a low level, so that the comparison module 120 enters a latched state. That is, in this case, the signal compared with the sampled voltage is no longer the reference voltage VREF, but the low level signal (result feedback signal) output by the second comparator CMP2; therefore, regardless of whether the sampled voltage falls below the reference voltage VREF, its value is always greater than the result feedback signal, and the output signal (switch control signal) of the first comparator CMP1 is locked at a low level.

[0062] The sixth transistor V6 is cut off under the control of the low level (result feedback signal), and the first level signal VCC (high level) is transmitted to the input end of the control unit 141 through the pull-up resistor (the tenth resistor R10), that is, the fault output signal input to the control unit 141 is a high level. The control unit 141 determines that the front-stage power supply system has a fault according to the high level. At this time, the control unit sends a reset control signal to control the conduction of the fifth transistor V5 once at a preset time interval, so that the control module 140 outputs a reset signal once every preset time. Among them, the preset time can be set according to the circuit requirements, such as 10 minutes.

[0063] Specifically, the process of sending the reset signal is as follows: the output terminal of the control unit 141 outputs a high-level signal, controls the fifth transistor V5 to be turned on, and the ground signal is output to the first input terminal of the second comparator CMP2 after passing through the fifth transistor V5, that is, the reset signal is output. The reset signal forcibly pulls the input signal of the first input terminal of the second comparator CMP2 to a low level, so that the second comparator CMP2 outputs a high level, thereby restoring the input signal of the second input terminal of the first comparator CMP1 to a high level. Therefore, the latch state of the comparison module 120 is released. Among them, the size of the high level output by the second comparator CMP2 can be set to be the same as the size of the reference voltage VREF.

[0064] At this time, if the power supply fault has been eliminated, the first comparator CMP1 resumes outputting a high level, and the fault output signal transmitted to the control unit 141 resumes a low level, indicating that the fault has been eliminated. At this time, the working state of the circuit is the same as when the power supply system is working normally, and no further description is given. If the power supply fault still exists, the first comparator CMP1 still outputs a low level, and the comparison module 120 enters the latched state again until the next reset signal is output.

[0065] Figure 3 1 is a schematic diagram of the structure of another power failure detection and power supply protection circuit provided by an embodiment of the present invention. Figure 3 On the basis of the above embodiments, the circuit may further include: a state indicating module 150. The input end of the state indicating module 150 is electrically connected to the first output end of the switch module 130; the state indicating module 150 is used to indicate the power state according to the output signal of the first output end of the switch module 130. In this way, the operation state of the power supply system can be reflected in real time in the form of hardware, making the feedback mode of the power supply fault state more diverse and more intuitive.

[0066] Continue to see Figure 3 On the basis of the above embodiments, the circuit may further include: a reference voltage generating module 160; the output end of the reference voltage generating module is electrically connected to the second input end of the comparison module 120, and is used to generate a reference voltage. In this embodiment, a separate reference voltage generating module 160 is provided, which can provide a more stable reference voltage, making the fault judgment of the entire circuit more accurate.

[0067] Figure 4 This is a schematic diagram of the structure of another power failure detection and power supply protection circuit provided by an embodiment of the present invention. Figure 4 , the structure of the power supply fault detection and power supply protection circuit is described through a specific embodiment, but it is not intended to limit the present invention.

[0068] See also Figure 4 In one implementation, the circuit may further include a first capacitor C1. The first capacitor C1 is connected between the input terminal of the circuit and the ground, and serves as a filter capacitor, so that the power input signal POW_IN is filtered before being input into the sampling module 110.

[0069] Optionally, the sampling module 110 also includes a second capacitor C2; the second capacitor C2 is connected in parallel at both ends of the second resistor R2 as a filter capacitor; illustratively, the capacitance of the second capacitor C2 can be set to 3.3nF. Exemplarily, the first transistor and the second transistor can be implemented using a bipolar transistor chip U1 to ensure the consistency of the two; for example, a chip with model BC857BS is selected. Specifically, pin 1 of chip U1 represents the first pole of the first transistor, pin 2 represents the first pole of the second transistor, pin 3 represents the second pole of the first transistor, pin 4 represents the control pole of the first transistor, pin 5 represents the control pole of the second transistor, and pin 6 represents the second pole of the second transistor. Exemplarily, the first resistor R1 can use a 22Ω resistor, the second resistor R2 can use a 3.9kΩ resistor, and the third resistor R3 can use a 15kΩ resistor.

[0070] Optionally, each comparator in the comparison module 120 can be implemented by an integrated comparator chip U2; for example, a chip of model LM2901 is used. Specifically, pins 7 and 8 of the chip U2 are both power pins of the chip U2, which are respectively connected to the first level signal VCC and the ground signal to provide the working power of the chip U2; pin 9 represents the first input terminal of the first comparator, pin 10 represents the second input terminal of the first comparator, and pin 11 represents the output terminal of the first comparator; pin 12 represents the first input terminal of the second comparator, pin 13 represents the second input terminal of the second comparator, and pin 14 represents the output terminal of the second comparator.

[0071] Optionally, the control module 140 further includes a third capacitor C3; the third capacitor C3 is connected between the first electrode of the fifth transistor V5 and the ground, and has the functions of buffer protection and filtering. Optionally, the control module 140 further includes: an alarm unit 1421; the alarm unit 1421 is used to issue a fault alarm when the number of times the control module 140 outputs a reset signal exceeds a set number. For example, Figure 4 As shown, the control unit 141 can be composed of an MCU (Micro Control Unit), and the logical relationship conversion between the fault output signal and the reset signal is mainly realized by the MCU. The circuit fault information can be read and controlled by the software, so that the circuit state can be monitored in real time. The control module 140 can include a host computer 142, which is connected to the MCU; the alarm unit 1421 can be set in the host computer or exist separately. The MCU can transmit the received fault output signal and its own output state to the host computer in real time. If the fault is not eliminated after the MCU issues the reset command for many times, it means that the fault cannot be eliminated by itself and needs manual processing; at this time, the host computer 142 controls the alarm unit 1421 to send an alarm message for timely maintenance. Among them, the range of the set number of times can be 5-10 times.

[0072] Continue to see Figure 4 On the basis of the above embodiments, optionally, the state indicating module 150 includes: an eleventh resistor R11 and an indicating unit 151; the first end of the eleventh resistor R11 serves as the input end of the state indicating module 150, the second end of the eleventh resistor R11 is electrically connected to the first end of the indicating unit 151, and the second end of the indicating unit 151 is grounded. Among them, the indicating unit 151 can be an indicator light, such as a light emitting diode D1; or it can be an alarm device such as an alarm bell. Taking the indicating unit 151 as a light emitting diode D1 as an example, when the light emitting diode is on, it indicates that the power output is normal and there is no fault; when the light emitting diode D1 is off, it indicates that there is a fault in the power output.

[0073] Optionally, the state indication module may further include a fourth capacitor C4 and a voltage stabilizing diode TVS; the fourth capacitor is connected between the output end of the circuit and the ground, and has a filtering effect; the voltage stabilizing diode TVS is connected between the output end of the circuit and the ground, and has a voltage stabilizing effect. With the combined effect of the two, it can effectively ensure that the ripple of the power output signal POW_OUT is small, and the reliability and stability are high.

[0074] Continue to see Figure 4 On the basis of the above embodiments, optionally, the reference voltage generating module 160 includes: a voltage stabilizing chip U3, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14; the first end of the twelfth resistor R12 is connected to the first level signal VCC; the second end of the twelfth resistor R12 is electrically connected to the first end (pin 15) of the voltage stabilizing chip U3, the first end of the thirteenth resistor R13 and the second input end of the comparison module 120 respectively; the third end (pin 17) of the voltage stabilizing chip U3 is electrically connected to the second end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14 respectively; the second end (pin 16) of the voltage stabilizing chip U3 and the second end of the fourteenth resistor R14 are both grounded.

[0075] In the reference voltage generating module 160, the voltage stabilizing chip U3 can be a chip of model LM431. The voltage stabilizing chip U3 outputs a reference voltage VREF through matching resistors (the thirteenth resistor R13 and the fourteenth resistor R14). The reference voltage VREF can be expressed as: VREF = V0*(1+R13 / R14), where V0 is the voltage stably output by the voltage stabilizing chip U3. The reference voltage VREF output by the module can be changed by changing the resistance value of the matching resistor.

[0076] For example, assuming V0 = 2.5 V, R13 = R14 = 33 kΩ, the reference voltage VREF is 5 V. Referring to the values ​​of the resistors in the sampling module 110 in the above embodiments, it can be obtained that in this case, the critical value of the current I1 in the circuit is: I1 = VREF / R2 = 5 / 3.9k = 1.28 mA.

[0077] In summary, the power supply fault detection and power supply protection circuit provided in the embodiment of the present invention can realize real-time monitoring, protection and function recovery of the power supply operation status. When the power supply system has faults such as overcurrent, overvoltage, short circuit, etc., the power supply can be cut off immediately to prevent damage to the load equipment, and it has both hardware and software fault indication functions. When the control module 140 outputs a reset signal and the fault has been eliminated, the power supply can resume normal power supply again. The overall circuit design is simple and the response is fast. It can be made into a standard circuit module, which is easy to embed in a large circuit design to realize the monitoring of the power supply system.

[0078] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A power supply fault detection and power supply protection circuit, characterized in that: include: Sampling module, comparison module, switch module and control module; The sampling module is connected between the input end of the power supply fault detection and power supply protection circuit and the input end of the switch module, and the first output end of the switch module serves as the output end of the power supply fault detection and power supply protection circuit; the sampling module is used to sample the input end of the power supply fault detection and power supply protection circuit and output the sampled voltage; The first input terminal of the comparison module is electrically connected to the output terminal of the sampling module, the second input terminal of the comparison module is connected to the reference voltage, and the first output terminal of the comparison module is electrically connected to the control terminal of the switch module; the comparison module is used to compare the sampling voltage with the reference voltage, and output a switch control signal from the first output terminal according to the comparison result, and output a result feedback signal from the second output terminal; The second output terminal of the switch module is electrically connected to the third input terminal of the comparison module; the switch module is used to control the conduction or disconnection between the first output terminal and the input terminal according to the switch control signal; and output a latch control signal through the second output terminal according to the switch control signal; the comparison module is also used to determine whether to enter a latch state according to the latch control signal; The input end of the control module is electrically connected to the second output end of the comparison module, and the output end of the control module is electrically connected to the third input end of the comparison module; the control module is used to output a reset signal once at a preset time interval when the result feedback signal indicates that the power supply fails; wherein the reset signal is used to release the latch state of the comparison module; The comparison module includes: a first comparator, a second comparator and a fifth resistor; The first input end of the first comparator serves as the first input end of the comparison module, the second input end of the first comparator is electrically connected to the first end of the fifth resistor and the output end of the second comparator respectively, and the output end of the first comparator serves as the first output end of the comparison module; the first input end of the second comparator serves as the third input end of the comparison module, the second input end of the second comparator is electrically connected to the second end of the fifth resistor and serves as the second input end of the comparison module, and the output end of the second comparator serves as the second output end of the comparison module; The switch module includes: a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third transistor and a fourth transistor; The first end of the sixth resistor is electrically connected to the first electrode of the third transistor and the first electrode of the fourth transistor respectively, and serves as the input end of the switch module; the first end of the seventh resistor is electrically connected to the second end of the sixth resistor and the control electrode of the third transistor respectively, and the second end of the seventh resistor serves as the control end of the switch module; the first end of the eighth resistor is electrically connected to the second electrode of the third transistor, the first end of the ninth resistor and the control electrode of the fourth transistor respectively, and the second end of the eighth resistor serves as the second output end of the switch module; the second end of the ninth resistor is grounded; the second electrode of the fourth transistor serves as the first output end of the switch module; The control module includes: a tenth resistor, a fifth transistor, a sixth transistor and a control unit; The input end of the control unit is electrically connected to the second end of the tenth resistor and the first electrode of the sixth transistor respectively, and the output end of the control unit is electrically connected to the control electrode of the fifth transistor; the first electrode of the fifth transistor serves as the output end of the control module, and the second electrode of the fifth transistor is grounded; the first end of the tenth resistor is connected to the first level signal; the control electrode of the sixth transistor serves as the input end of the control module, and the second electrode of the sixth transistor is grounded.

2. The power failure detection and power supply protection circuit according to claim 1, characterized in that: The control module comprises: an alarm unit; the alarm unit is used to issue a fault alarm when the number of times the control module outputs the reset signal exceeds a set number.

3. The power failure detection and power supply protection circuit according to claim 1, characterized in that: The sampling module includes: a first resistor, a second resistor, a third resistor, a first transistor and a second transistor; The first end of the first resistor is electrically connected to the input end of the power supply fault detection and power supply protection circuit and the first electrode of the second transistor respectively; the first electrode of the second transistor is electrically connected to the input end of the switch module; the first electrode of the first transistor is electrically connected to the second end of the first resistor, and the control electrode of the first transistor is electrically connected to the control electrode of the second transistor, the second electrode of the second transistor and the first end of the third resistor respectively; the first end of the second resistor is electrically connected to the second electrode of the first transistor and serves as the second output end of the sampling module; the second end of the second resistor and the second end of the third resistor are both grounded.

4. The power failure detection and power supply protection circuit according to claim 3, characterized in that: The sampling module further includes: a fourth resistor; A first end of the fourth resistor is electrically connected to a first end of the second resistor, and a second end of the fourth resistor is electrically connected to a first electrode of the second transistor.

5. The power failure detection and power supply protection circuit according to claim 1, characterized in that: Also includes: Status indication module; The input end of the state indication module is electrically connected to the first output end of the switch module; The state indicating module is used for indicating the power state according to the output signal of the first output terminal of the switch module.

6. The power failure detection and power supply protection circuit according to claim 5, characterized in that: The state indication module comprises: an eleventh resistor and an indication unit; The first end of the eleventh resistor is used as the input end of the state indicating module, the second end of the eleventh resistor is electrically connected to the first end of the indicating unit, and the second end of the indicating unit is grounded; The indicating unit includes: an indicator light or an alarm.

7. The power failure detection and power supply protection circuit according to claim 1, characterized in that: Also includes: Reference voltage generating module; The reference voltage generating module comprises: a voltage stabilizing chip, a twelfth resistor, a thirteenth resistor and a fourteenth resistor; The first end of the twelfth resistor is connected to the first level signal; the second end of the twelfth resistor is electrically connected to the first end of the voltage stabilizing chip, the first end of the thirteenth resistor and the second input end of the comparison module respectively; the third end of the voltage stabilizing chip is electrically connected to the second end of the thirteenth resistor and the first end of the fourteenth resistor respectively; the second end of the voltage stabilizing chip and the second end of the fourteenth resistor are both grounded.

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