CN113113894A

CN113113894A - Power failure detection and power supply protection circuit

Info

Publication number: CN113113894A
Application number: CN202110517183.4A
Authority: CN
Inventors: 许杰; 高纪凡
Original assignee: Trina Solar Co Ltd
Current assignee: Trina Energy Storage Solutions Jiangsu Co Ltd
Priority date: 2021-05-12
Filing date: 2021-05-12
Publication date: 2021-07-13

Abstract

The invention discloses a power failure detection and power supply protection circuit, which comprises: the device comprises 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 sampling voltage; the comparison module compares the sampling voltage with the reference voltage, outputs a switch control signal from a first output end according to a comparison result, and outputs a result feedback signal from a second output end; the switch module controls the connection relation 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 for determining whether to enter a latch state according to the latch control signal; the control module is used for outputting a reset signal at preset time intervals when the result feedback signal indicates that the power supply has a fault; the reset signal is used for releasing the latch state of the comparison module. The invention can timely recover power supply on the basis of ensuring the power supply safety, thereby realizing reliable power supply of the power supply.

Description

Power failure detection and power supply protection circuit

Technical Field

The embodiment of the invention relates to the technical field of power supply protection, in particular to a power failure detection and power supply protection circuit.

Background

The power supply is used as a power supply device of an electronic product, and besides the basic electrical performance of the power supply needs to meet the requirements of electric equipment, fault detection and protection measures of the power supply are very important, such as overvoltage, overcurrent and short-circuit protection. Conventional power fail-safe circuits are typically configured to be self-healing or self-locking. The self-recovery protection circuit can automatically recover output after detecting that a fault disappears, if the circuit encounters an irreversible fault, the fault is determined to be removed due to reasons such as power device work suspension or signal fluctuation, the output is recovered again, and secondary damage can be caused to a power supply or electric equipment. The self-locking circuit can cut off power output after detecting a fault signal and is latched in a power-off state, no matter what kind of faults occur, manual comprehensive inspection is needed, power is supplied again after the faults are eliminated, and power supply can be restarted. Therefore, the existing power failure detection and power supply protection circuit has a contradiction relationship between the power supply safety and the timeliness of power supply restoration.

Disclosure of Invention

The embodiment of the invention provides a power failure detection and power supply protection circuit, which is used for recovering power supply in time on the basis of ensuring the power supply safety and realizing reliable power supply of a power supply.

The embodiment of the invention provides a power failure detection and power supply protection circuit, which comprises: the device comprises a sampling module, a comparison module, a switch module and a control module;

the sampling module is connected between the input end of the power failure detection and power supply protection circuit and the input end of the switch module, and a first output end of the switch module is used as the output end of the power failure detection and power supply protection circuit; the sampling module is used for sampling the input end of the power failure detection and power supply protection circuit and outputting sampling voltage;

the first input end of the comparison module is electrically connected with the output end of the sampling module, the second input end of the comparison module is connected with a reference voltage, and the first output end of the comparison module is electrically connected with the control end of the switch module; the comparison module is used for comparing the sampling voltage with the reference voltage, outputting a switch control signal from a first output end according to a comparison result, and outputting a result feedback signal from a second output end;

the second output end of the switch module is electrically connected with the third input end of the comparison module; the switch module is used for controlling the connection or disconnection between the first output end and the input end according to the switch control signal; outputting a latch control signal through a second output end according to the switch control signal; the comparison module is also used for determining whether to enter a latch state according to the latch control signal;

the input end of the control module is electrically connected with the second output end of the comparison module, and the output end of the control module is electrically connected with the third input end of the comparison module; the control module is used for outputting a reset signal every preset time when the result feedback signal indicates that the power supply has a fault; the reset signal is used for releasing the latch state of the comparison module.

Optionally, the control module comprises: an alarm unit; the alarm unit is used for giving a fault alarm when the number of times of the reset signal output by the control module exceeds a set number of times.

Optionally, the sampling module comprises: the circuit comprises 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 with the input end of the power failure detection and power supply protection circuit and the first pole of the second transistor respectively; the first pole of the second transistor is electrically connected with the input end of the switch module; a first electrode of the first transistor is electrically connected with a second end of the first resistor, and a control electrode of the first transistor is electrically connected with a control electrode of the second transistor, a second electrode of the second transistor and a first end of the third resistor respectively; the first end of the second resistor is electrically connected with the second pole of the first transistor and is used 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.

Optionally, the sampling module further comprises: a fourth resistor;

a first end of the fourth resistor is electrically connected to the first end of the second resistor, and a second end of the fourth resistor is electrically connected to the first pole of the second transistor.

Optionally, the comparison module comprises: the first comparator, the second comparator and the fifth resistor;

a first input end of the first comparator is used as a first input end of the comparison module, a second input end of the first comparator is respectively and electrically connected with a first end of the fifth resistor and an output end of the second comparator, and an output end of the first comparator is used as a first output end of the comparison module; the first input end of the second comparator is used as the third input end of the comparison module, the second input end of the second comparator is electrically connected with the second end of the fifth resistor and is used as the second input end of the comparison module, and the output end of the second comparator is used as the second output end of the comparison module.

Optionally, the switch module comprises: a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third transistor, and a fourth transistor;

a first end of the sixth resistor is respectively connected with a first pole of the third transistor and a first pole of the fourth transistor and serves as an input end of the switch module; a first end of the seventh resistor is electrically connected to a second end of the sixth resistor and a control electrode of the third transistor, respectively, and a second end of the seventh resistor is used as a control end of the switch module; a first end of the eighth resistor is electrically connected to the second pole of the third transistor, the first end of the ninth resistor and the control electrode of the fourth transistor, respectively, and a second end of the eighth resistor is used as a second output end of the switch module; a second end of the ninth resistor is grounded; the second pole of the fourth transistor is used as the first output end of the switch module.

Optionally, the control module comprises: a tenth resistor, a fifth transistor, a sixth transistor, and a control unit;

an input end of the control unit is electrically connected with a second end of the tenth resistor and a first electrode of the sixth transistor respectively, and an output end of the control unit is electrically connected with a control electrode of the fifth transistor; a first pole of the fifth transistor is used as an output end of the control module, and a second pole of the fifth transistor is grounded; a first end of the tenth resistor is connected to a first level signal; and the control electrode of the sixth transistor is used as the input end of the control module, and the second electrode of the sixth transistor is grounded.

Optionally, the power failure detection and power supply protection circuit further includes: a status indication module;

the input end of the state indicating module is electrically connected with the first output end of the switch module; the state indicating module is used for indicating the power supply state according to the output signal of the first output end of the switch module.

Optionally, the status indication module includes: an eleventh resistor and indicator unit;

a first end of the eleventh resistor is used as an input end of the state indicating module, a second end of the eleventh resistor is electrically connected with a first end of the indicating unit, and a second end of the indicating unit is grounded;

the indication unit includes: an indicator light or an alarm bell.

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

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

The power failure detection and power supply protection circuit provided by the embodiment of the invention is provided with a sampling module, a comparison module, a switch module and a control module; 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 conducted under the control of the switch control signal, and the power input signal is normally output after passing through the sampling module and the switch module; under the control of the latch control signal, the comparison module normally operates and does not enter a 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 the power supply fails, the comparison result indicates the power supply failure, the input end and the first output end of the switch module are switched off under the control of the switch control signal, and the transmission path of the power supply signal is cut off; under the control of the latch control signal, the comparison module enters a latch state; in the latch state, the output state of the circuit is not changed no matter whether the fault is eliminated or not; the result feedback signal received by the control module indicates that the power supply has a fault; at the moment, the control module outputs a reset signal every preset time interval; during the output period of the reset signal, the latch state of the comparison module is released, and at the moment, if the power supply fault is eliminated (for example, the transient fault disappears automatically), the power supply can recover power supply; after the power supply is restored to supply power, the result feedback signal output to the control module by the comparison module also restores to indicate that the power supply is normal.

In conclusion, the circuit can collect the electric signals at the input end of the circuit in real time, so that the power failure state can be monitored in real time. When the power supply fails, the switch module cuts off a power supply path, and the comparison module enters a latching state to prevent the impact of power supply error recovery on a power supply or power utilization system; and after the fault occurs, the control module sends out a reset signal at regular time, and the latch state of the comparison module is released at regular time so as to ensure that the power supply can be recovered in time after the fault is eliminated. Therefore, compared with the prior art, the embodiment of the invention can timely recover power supply on the basis of ensuring the power supply safety, thereby realizing reliable power supply of the power supply.

Drawings

Fig. 1 is a schematic structural diagram of a power failure detection and power supply protection circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of another power failure detection and protection circuit according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a power failure detection and protection circuit according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of another power failure detection and power supply protection circuit according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The embodiment of the invention provides a power failure detection and power supply protection circuit. Fig. 1 is a schematic structural diagram of a power failure detection and power supply protection circuit according to an embodiment of the present invention. Referring to fig. 1, the power failure detection and supply protection circuit includes: a sampling module 110, a comparison module 120, a switching module 130, and a control module 140.

The sampling module 110 is connected between the input terminal IN of the power failure 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 with the input terminal IN of the circuit, a power input signal is accessed, and the power output terminal of the sampling module 110 is electrically connected with the input terminal of the switch module 130); a first output end of the switching module 130 is used as an output end OUT of the power failure detection and power supply protection circuit; the sampling module 110 is configured to sample an input terminal IN of the power failure detection and power supply protection circuit, and output a sampling voltage. A first input end of the comparison module 120 is electrically connected with an output end of the sampling module 110, a second input end of the comparison module 120 is connected to a reference voltage VREF, and a first output end of the comparison module 120 is electrically connected with a control end of the switch module 130; the comparison module 120 is configured to compare the sampling voltage with the reference voltage VREF, and output a switch control signal from a first output terminal and a result feedback signal from a second output terminal according to a comparison result. A second output end of the switch module 130 is electrically connected with a third input end of the comparison module 120; the switch module 130 is configured to control the connection or disconnection between the first output terminal and the input terminal according to the switch control signal; and outputting a latch control signal through a second output end according to the switch control signal; the comparing module 120 is further configured to determine whether to enter a latch state according to the latch control signal. The input end of the control module 140 is electrically connected to the second output end of the comparison module 120, and the output end of the control module 140 is electrically connected to the third input end of the comparison module 120; the control module 140 is configured to output a reset signal every preset time when the result feedback signal indicates that the power supply fails; the reset signal is used to release the latch state of the comparing module 120.

Illustratively, the working process of the power failure detection and power supply protection circuit comprises the following steps:

the input end IN of the circuit is connected with a power supply input signal; the sampling module 110 collects an electrical signal (such as voltage or current) at an input terminal IN of the circuit and converts the electrical signal into a sampling voltage for output; the comparison module 120 obtains a comparison result according to the sampling voltage and the reference voltage VREF, and generates a switch control signal and a result feedback signal according to the comparison result. The output signals of the two output ends of the comparison module 120 control the output states of the switch module 130 and the control module 140, respectively; 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 latch condition of the comparison module 120; wherein the reset signal can force the latch state of the comparing module 120 to be released.

Specifically, when the power supply system works normally, the provided power supply input signal is in a normal range; the comparison module 120 compares the sampling voltage with the reference voltage VREF to obtain a comparison result indicating 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 normally output 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 normally operates without latching; as a result, the feedback signal indicates that the power supply is normal, and the control module 140 does not output the reset signal.

When a power supply system has a fault, such as an overcurrent, overvoltage or short-circuit fault, the power supply input signal provided by the power supply system has an overvoltage or overcurrent condition. Therefore, compared to the normal case, the electrical signal collected by the sampling module 110 may increase; at this time, the comparison result obtained by comparing the sampling voltage with the reference voltage VREF by the comparison module 120 indicates that the power supply has a fault; the input end and the first output end of the switch module 130 are turned off under the control of the switch control signal, and the transmission path of the power supply signal is cut off, so that the output end OUT of the circuit cannot output the power supply output signal, and the rear-stage circuit is prevented from being damaged; at this time, under the control of the latch control signal, the comparing module 120 enters a latch state; in the latched state, the output signal of the comparison module 120 is not changed and the output state of the circuit is not changed no matter whether the fault in the power supply system is eliminated; 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 every preset time; during the output period of the reset signal, the latch state of the comparing module 120 is released under the control of the reset signal, and at this time, if the power failure is eliminated (for example, the transient failure has disappeared by itself), the output end OUT of the circuit can output the power output signal again, and the power supply of the later stage circuit is recovered; after the power supply is recovered, the result feedback signal output to the control module 140 by the comparing module 120 also indicates that the power supply is normal.

IN conclusion, the circuit can collect the electric signal of the input end IN of the circuit IN real time, thereby monitoring the power failure state IN real time. When the power supply fails, the switch module 130 cuts off the power supply path, and the comparison module 120 enters a latch state to prevent the impact of power supply error recovery on a preceding power supply system or a subsequent power utilization system; and, after the fault occurs, the control module 140 sends out a reset signal at regular time, and the latch state of the comparison module 120 is released at regular time, so as to ensure that the power supply can be recovered in time after the fault is eliminated. Therefore, the embodiment of the invention can timely recover power supply on the basis of ensuring the power supply safety, is not easy to lose control when the power supply fails, and realizes reliable power supply of the power supply.

The above embodiments exemplarily give the basic operation process of the power failure detection and power supply protection circuit, and the following description is about a specific structure that each module in the circuit may have, but is not intended to limit the present invention.

Fig. 2 is a schematic structural diagram of another power failure detection and power protection circuit according to an embodiment of the present invention. Referring to fig. 2, in one embodiment, the sampling module 120 may alternatively be formed of a proportional current source circuit. Compared with a common sampling circuit in the forms of resistance voltage division and the like, the overvoltage and overcurrent acquisition module is constructed by using the proportional current source circuit, so that the sampling precision of the sampling module 110 is higher, and the stability and the reliability are better.

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; a first end of the first resistor R1 is electrically connected with an input end of the power failure detection and power supply protection circuit, is connected with a power input signal POW _ IN, and is electrically connected with a first pole of the second transistor V2; a first pole of the second transistor V2 is used as a power output end of the sampling module 110 and is electrically connected with an input end of the switch module 130; a first pole of the first transistor V1 is electrically connected to the second end of the first resistor R1, and a control pole of the first transistor V1 is electrically connected to a control pole of the second transistor V2, a second pole of the second transistor V2 and a first end of the third resistor R3, respectively; a first end of the second resistor R2 is electrically connected to the second pole of the first transistor V1 and serves as a second output end of the sampling module 110; the second terminal of the second resistor R2 and the second terminal of the third resistor R3 are both grounded.

For example, in the sampling module 110, the first transistor V1 and the second transistor V2 may be the same transistor, such as an identical PNP transistor. The current flowing through the first resistor R1 is denoted as I1, and the current flowing through the first pole of the second transistor V2 is denoted as I2; according to the characteristics of the proportional current source circuit, it can be obtained that: i2 ═ R2I 1/R3; therefore, by adjusting the resistance values of the second resistor R2 and the third resistor R3, the output signal of the power output terminal of the sampling module 110 can be changed. Taking the voltage at the first end of the second resistor R2 as a sampling voltage (denoted as Vx), if the currents flowing through the first pole and the second pole of the first transistor V1 are considered to be approximately the same (I1), we can obtain: vx I1R 2. At this time, the sampled voltage Vx may represent an overcurrent detection value of the circuit. Since the overcurrent may be caused by the overvoltage of the power supply system, the sampled voltage Vx may also represent an overvoltage detection value.

With continued reference to fig. 2, based on the foregoing embodiments, optionally, the sampling module 110 further includes: a fourth resistor R4; a first end of the fourth resistor R4 is electrically connected to a first end of the second resistor R2, and a second end of the fourth resistor R4 is electrically connected to the first pole of the second transistor V2.

For example, the fourth resistor R4 may use a resistor with a smaller resistance (e.g. 0.1 Ω) 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 (denoted V) obtained across the fourth resistor R4 is: v ═ I3 × R4. The voltage V may represent an over-current detection value of the circuit. Once the front stage power system has a short-circuit fault, the current I3 will increase instantaneously, resulting IN direct blowing at the fourth resistor R4 to prevent the power input signal POW _ IN from continuing to transmit, and prevent the rear stage power circuit from being damaged by impact.

With continued reference to fig. 2, on the basis of the above embodiments, the comparing module 120 may be optionally composed of a plurality of comparators.

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

Wherein the reference voltage VREF may be set to a critical value between a sampled voltage indicating that the power supply is normal and a sampled voltage indicating that the power supply is failed. Since the sampled voltage Vx is equal to the product of the current I1 and the resistance of the second resistor R2, the reference voltage VERF can be set to the product of the threshold value of the current I1 and the resistance of the second resistor R2. That is, the value of the reference voltage VERF may be set according to the overcurrent critical value of the current I1 and the resistance value of the second resistor R2.

With continued reference to fig. 2, based on the above embodiments, the switch module 130 optionally implements on-off control inside the module mainly through a transistor.

Specifically, the switching 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. A first end of the sixth resistor R6 is electrically connected to a first pole of the third transistor V3 and a first pole of the fourth transistor V4, respectively, and serves as an input terminal of the switching module 130; a first end of the seventh resistor R7 is electrically connected to a second end of the sixth resistor R6 and the control electrode of the third transistor V3, respectively, and a second end of the seventh resistor R7 serves as a control end of the switch module 130; a first end of the eighth resistor R8 is electrically connected to the second pole of the third transistor V3, a first end of the ninth resistor R9 and the control electrode of the fourth transistor V4, respectively, and a second end of the eighth resistor R8 is used as a second output end of the switch module 130; a second end of the ninth resistor R9 is grounded; the second pole of the fourth transistor V4 serves as the first output terminal of the switching module 130.

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 gate of the fourth transistor V4. The eighth resistor R8 may serve as a current limiting resistor between the switch module 130 and the comparison module 120.

With continued reference to fig. 2, based on the above embodiments, the control module 140 optionally includes: a tenth resistor R10, a fifth transistor V5, a sixth transistor V6, and a control unit 141. An input terminal of the control unit 141 is electrically connected to the second terminal of the tenth resistor R10 and the first terminal of the sixth transistor V6, respectively, and an output terminal of the control unit 141 is electrically connected to the control electrode of the fifth transistor V5; a first pole of the fifth transistor V5 is used as the output terminal of the control module 140, and a second pole of the fifth transistor V5 is grounded; a 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 terminal of the control module 140, and the second electrode of the sixth transistor V6 is grounded.

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; the control signal sent by the control unit 141 may also be manually intervened.

Illustratively, the operation of the power failure detection and supply protection circuit shown in fig. 2 includes:

1) when the power system is working normally, the sampling voltage output by the sampling module 110 is less than the reference voltage VREF. A first input terminal (negative input terminal) of the first comparator CMP1 is connected to the sampling voltage, and a second input terminal (positive input terminal) of the first comparator CMP1 is connected to the reference voltage VREF via a 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, i.e., the switch control signal is a high level. The gate of the third transistor V3 is turned high through the seventh resistor R7, causing the third transistor V3 to be in the off state. The control electrode of the fourth transistor V4 is connected to the ground signal via the ninth resistor R9, thereby turning on the fourth transistor V4. Therefore, the power signal transmission path from the input end to the output end of the circuit is conducted, and the power output signal POW _ OUT is normally output.

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, i.e., the latch control signal is low. 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 high level, that is, the resultant feedback signal is high level. At this time, the output signal of the second comparator CMP2 and the reference voltage VREF are both high level, so the output signal does not affect the output of the first comparator CMP1, and the comparison module 120 operates normally.

The sixth transistor V6 is turned on under the control of a high level (resulting feedback signal), and the ground signal is transmitted to the input terminal of the control unit 141 through the sixth transistor V6, i.e., the fault output signal input to the control unit 141 is at a low level. The control unit 141 determines that no malfunction occurs in the front stage power supply system based on the low level, and controls the fifth transistor V5 to be turned off, and the control block 140 does not output the reset signal.

2) When the power system fails (e.g., over-voltage, over-current, 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, i.e., the switch control signal is at a low level. The control electrode of the third transistor V3 is turned on low through the seventh resistor R7, which causes the third transistor V3 to be turned on. The control electrode of the fourth transistor V4 switches on the power supply signal (high level) via the third transistor V3, causing the fourth transistor V4 to turn off. Therefore, the power supply signal transmission path from the input terminal to the output terminal of the circuit is cut off, and the power supply output signal POW _ OUT cannot be output.

Since the third transistor V3 is turned on, the power signal (normally, the power input signal POW _ IN is high level with a voltage value greater than the reference voltage VREF, so the power signal transmitted to the third transistor V3 is still high level with the voltage value 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, i.e., the latch control signal is 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, i.e., the resultant feedback signal is at a low level.

At this time, the low level output from 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 maintained in a low-level state, thereby bringing the comparison module 120 into a latch state. That is, in this case, the signal to be compared with the sampling voltage is not the reference voltage VREF but a low-level signal (result feedback signal) output from the second comparator CMP 2; therefore, the output signal (switch control signal) of the first comparator CMP1 is latched at a low level regardless of whether the sampled voltage falls below the reference voltage VREF at a value that is always greater than the resultant feedback signal.

The sixth transistor V6 is turned off under the control of the low level (resulting feedback signal), and the first level signal VCC (high level) is transmitted to the input terminal of the control unit 141 through the pull-up resistor (tenth resistor R10), i.e., the fault output signal inputted to the control unit 141 is at the high level. The control unit 141 determines that the preceding stage power supply system is malfunctioning based on the high level. At this time, the control unit sends out a reset control signal for controlling the fifth transistor V5 to be turned on every preset time interval, so that the control module 140 outputs a reset signal every preset time interval. The preset time can be set according to the circuit requirement, for example, 10 minutes.

Specifically, the process of sending out the reset signal is as follows: the output terminal of the control unit 141 outputs a high level signal to control the fifth transistor V5 to be turned on, and the ground signal passes through the fifth transistor V5 and is output to the first input terminal of the second comparator CMP2, i.e., the reset signal is output. The reset signal forcibly pulls the input signal at the first input terminal of the second comparator CMP2 to a low level, causing the second comparator CMP2 to output a high level, thereby restoring the input signal at the second input terminal of the first comparator CMP1 to a high level. Therefore, the latch state of the comparison block 120 is released. Wherein, the magnitude of the high level output from the second comparator CMP2 may be set to be the same as the magnitude of the reference voltage VREF.

At this time, if the power failure is eliminated, the first comparator CMP1 resumes outputting the high level, and the failure output signal transmitted to the control unit 141 resumes the low level, indicating that the failure is eliminated, and at this time, the operating state of the circuit is the same as that of the power system during normal operation, and will not be described again. If the power failure still exists, the first comparator CMP1 still outputs a low level, and the comparison module 120 enters the latch state again until the next reset signal is output.

Fig. 3 is a schematic structural diagram of another power failure detection and power supply protection circuit according to an embodiment of the present invention. Referring to fig. 3, on the basis of the foregoing embodiments, optionally, the circuit further includes: status indication module 150. The input end of the status indication module 150 is electrically connected with the first output end of the switch module 130; the status indication module 150 is configured to indicate a power status according to an output signal of the first output terminal of the switch module 130. By the arrangement, the running state of the power supply system can be embodied in real time in a hardware form, so that the feedback mode of the power supply fault state is more diversified and more visual.

With continuing reference to fig. 3, based on the foregoing embodiments, optionally, the circuit further includes: a reference voltage generation module 160; the output terminal of the reference voltage generating module is electrically connected to the second input terminal of the comparing module 120 for generating the reference voltage. In this embodiment, the single reference voltage generation module 160 is provided, so that a more stable reference voltage can be provided, and the fault judgment of the whole circuit is more accurate.

Fig. 4 is a schematic structural diagram of another power failure detection and power supply protection circuit according to an embodiment of the present invention. The following describes the structure of the power failure detection and power supply protection circuit with an embodiment, but the invention is not limited thereto, with reference to fig. 4.

Referring to fig. 4, in one embodiment, the circuit optionally further includes a first capacitor C1. The first capacitor C1 is connected between the input terminal of the circuit and ground, and serves as a filter capacitor, so that the power input signal POW _ IN is filtered and then input to the sampling module 110.

Optionally, the sampling module 110 further includes a second capacitor C2; the second capacitor C2 is connected in parallel with two ends of the second resistor R2 and is used as a filter capacitor; illustratively, the capacitance value of the second capacitor C2 may be set to 3.3 nF. Illustratively, the first transistor and the second transistor may be implemented using a bipolar transistor chip U1 to ensure consistency therebetween; for example, a chip model BC857BS is selected. Specifically, pin 1 of the chip U1 represents a first pole of a first transistor, pin 2 represents a first pole of a second transistor, pin 3 represents a second pole of the first transistor, pin 4 represents a control pole of the first transistor, pin 5 represents a control pole of the second transistor, and pin 6 represents a second pole of the second transistor. Illustratively, the first resistor R1 may be a 22 Ω resistor, the second resistor R2 may be a 3.9k Ω resistor, and the third resistor R3 may be a 15k Ω resistor.

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

Optionally, the control module 140 further comprises a third capacitance C3; the third capacitor C3 is connected between the first pole of the fifth transistor V5 and ground, and has the functions of buffer protection and filtering. Optionally, the control module 140 further comprises: an alarm unit 1421; the alarm unit 1421 is configured to perform a malfunction alarm when the number of times the control module 140 outputs the reset signal exceeds a set number of times. Illustratively, as shown in fig. 4, the Control Unit 141 may be formed by an MCU (Micro Control Unit), the logic relationship between the fault output signal and the reset signal is mainly switched by the MCU, and the circuit fault information can be read and controlled by software, so that the circuit status is monitored in real time. The control module 140 may include an upper computer 142, and the upper computer 142 is connected with the MCU; the alarm unit 1421 may be provided in the upper computer or exist separately. The MCU can transmit the received fault output signal and the output state of the fault output signal to the upper computer in real time. If the MCU issues the reset command for multiple times, the fault is still not eliminated, namely the fault cannot be eliminated by itself and needs manual processing; at this time, the upper computer 142 controls the alarm unit 1421 to send out alarm information, so as to perform timely maintenance. Wherein the set number of times may range from 5 to 10 times.

With continued reference to fig. 4, based on the above embodiments, the status indication module 150 optionally includes: an eleventh resistor R11 and an indicating unit 151; the first terminal of the eleventh resistor R11 is used as the input terminal of the status indication module 150, the second terminal of the eleventh resistor R11 is electrically connected to the first terminal of the indication unit 151, and the second terminal of the indication unit 151 is grounded. The indication unit 151 may be an indicator light, such as a light emitting diode D1; or alarm devices such as alarm bells and the like. Taking the indicating unit 151 as the light emitting diode D1 as an example, when the light emitting diode is turned on, it indicates that the power output is normal and there is no fault; when the light emitting diode D1 goes out, it indicates that there is a failure in the power output.

Optionally, the state indicating module may further include a fourth capacitor C4 and a zener diode TVS; the fourth capacitor is connected between the output end of the circuit and the ground and has a filtering function; the voltage stabilizing diode TVS is connected between the output end of the circuit and the ground and has a voltage stabilizing effect. Under the combined action of the power supply and the power supply, the ripple of the power supply output signal POW _ OUT can be effectively ensured to be small, and the reliability and the stability are high.

With continued reference to fig. 4, on the basis of the above embodiments, the reference voltage generating module 160 optionally includes: a voltage stabilizing chip U3, a twelfth resistor R12, a thirteenth resistor R13 and a fourteenth resistor R14; a first end of the twelfth resistor R12 is connected to the first level signal VCC; a second end of the twelfth resistor R12 is electrically connected to the first end (pin 15) of the regulator 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 with the second end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14 respectively; the second terminal (pin 16) of the regulator chip U3 and the second terminal of the fourteenth resistor R14 are both grounded.

In the reference voltage generating module 160, the voltage regulator chip U3 may be a chip with a model LM 431. The voltage regulation chip U3 outputs a reference voltage VREF through matching resistors (a thirteenth resistor R13 and a fourteenth resistor R14), and the reference voltage VREF can be expressed as: VREF is V0 (1+ R13/R14), where V0 is the voltage that the regulator chip U3 outputs stably. The reference voltage VREF output by the module can be changed by changing the resistance value of the matching resistor.

For example, if V0 ═ 2.5V and R13 ═ R14 ═ 33k Ω, then the resulting reference voltage VREF is 5V. Referring to the values of the resistors in the sampling module 110 in the above embodiments, the critical value of the current I1 in the circuit under this condition can be obtained as follows: i1 VREF/R2 5/3.9k 1.28 mA.

In summary, the power failure detection and power supply protection circuit provided by the embodiment of the invention can realize real-time monitoring, protection and function recovery of the power supply running state. When the power supply system has faults of overcurrent, overvoltage, short circuit and the like, the power supply can be immediately cut off, the load equipment is prevented from being damaged, and the power supply system has a hardware and software fault indication function. When the control module 140 outputs the reset signal and the fault has cleared, the power supply may again resume normal power. The whole circuit is simple in design and quick in response, can be manufactured into a standard circuit module, is convenient to embed into a large-scale circuit design, and realizes monitoring of a power supply system.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments illustrated herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A power failure detection and supply protection circuit, comprising: the device comprises a sampling module, a comparison module, a switch module and a control module;

2. The power failure detection and supply protection circuit of claim 1, wherein the control module comprises: an alarm unit; the alarm unit is used for giving a fault alarm when the number of times of the reset signal output by the control module exceeds a set number of times.

3. The power failure detection and supply protection circuit of claim 1, wherein the sampling module comprises: the circuit comprises a first resistor, a second resistor, a third resistor, a first transistor and a second transistor;

4. The power failure detection and supply protection circuit of claim 3, wherein the sampling module further comprises: a fourth resistor;

5. The power failure detection and supply protection circuit of claim 1, wherein the comparison module comprises: the first comparator, the second comparator and the fifth resistor;

6. The power failure detection and supply protection circuit of claim 1, wherein the switch module comprises: a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a third transistor, and a fourth transistor;

7. The power failure detection and supply protection circuit of claim 1, wherein the control module comprises: a tenth resistor, a fifth transistor, a sixth transistor, and a control unit;

8. The power failure detection and supply protection circuit of claim 1, further comprising: a status indication module;

9. The power failure detection and supply protection circuit of claim 8, wherein the status indication module comprises: an eleventh resistor and indicator unit;

the indication unit includes: an indicator light or an alarm bell.

10. The power failure detection and supply protection circuit of claim 1, further comprising: a reference voltage generation module; the reference voltage generation module includes: the voltage stabilizing chip, the twelfth resistor, the thirteenth resistor and the fourteenth resistor;