CN214850457U - Input overvoltage protection circuit, circuit board assembly and electronic equipment - Google Patents

Abstract

The embodiment of the utility model provides an input overvoltage crowbar, circuit board subassembly and electronic equipment are disclosed in the field of circuit technology. The utility model discloses in, by the voltage between live wire and the zero line among the electronic equipment that the sampling unit was gathered, to comparing unit output voltage, when the voltage between live wire and the zero line is big more, voltage to comparing unit output is big more, comparing unit judges when the voltage between live wire and the zero line is higher than the preset threshold value according to the voltage of sampling unit output, to the control unit output enable signal, by the disconnection of the control unit control switch, promptly, control electronic equipment's power supply circuit disconnection, can not damage because supply voltage is too big with protection electronic equipment.

Description

Input overvoltage protection circuit, circuit board assembly and electronic equipment

Technical Field

The embodiment of the utility model provides a relate to circuit technical field, in particular to input overvoltage crowbar, circuit board subassembly and electronic equipment.

Background

In an industrial or civil power supply incoming line switch cabinet, for example, in an incoming line switch cabinet of an elevator power supply, a power transmission line generally adopts a three-phase four-wire system or a three-phase five-wire system, the three-phase four-wire system transmits power through three-phase power lines and a neutral line, the three-phase five-wire system transmits power through three-phase power lines, a neutral line and a ground line, and the power transmission line is connected to a product to supply power to the product. At present, electronic equipment needing power supply is mostly three-phase power supply equipment and single-phase power supply equipment, wherein, single-phase power supply equipment's live wire joint and zero line joint need link to each other with arbitrary power cord and neutral conductor in three-phase power cords respectively to arbitrary power cord in three-phase power cords is as the live wire of single-phase power supply product, and the neutral conductor is as single-phase power supply equipment's zero line, and supply voltage generally is 220V.

The inlet wire in the inlet wire switch board is often more, and the relation of connection is complicated, can appear connecting the condition that the live wire that connects and zero line joint with single-phase power supply equipment respectively with arbitrary two in three-phase power supply lines, and the voltage between arbitrary two in three-phase power supply lines is 380V generally, if use this voltage to supply power for single-phase power supply equipment, then can lead to single-phase power supply equipment to take place irreversible damage because of excessive pressure.

SUMMERY OF THE UTILITY MODEL

An object of the embodiment of the utility model is to provide an input overvoltage crowbar, circuit board subassembly and electronic equipment, when judging electronic equipment's supply voltage too big, control electronic equipment's supply circuit disconnection to guarantee that electronic equipment can not take place to damage because supply voltage is too big.

In order to solve the above technical problem, a first aspect of the present invention provides an input overvoltage protection circuit, which is disposed in an electronic device, the input overvoltage protection circuit includes: the sampling unit is used for collecting voltage between a live wire and a zero line in the electronic equipment, a first input end of the sampling unit is connected with the live wire, and a second input end of the sampling unit is connected with the zero line; the first input end and the second input end of the comparison unit are respectively connected to the first output end and the second output end of the sampling unit, and the comparison unit is configured to output an enable signal when the voltage between the live wire and the zero wire is higher than a preset threshold value; the first input end of the control unit is connected with the output end of the comparison unit; the output end of the control unit is connected to the control end of the switch, the switch is connected to the live wire and/or the zero wire and is controlled to be opened or closed by the control unit, the control unit is configured to control the switch to be opened when receiving an enabling signal, and a line where the switch in the open state is located is in the open state.

In a second aspect, the present invention further provides a circuit board assembly, which includes the input overvoltage protection circuit in the above embodiments.

In a third aspect, the present invention further provides an electronic device, including the circuit board assembly in the above embodiments.

The embodiment of the utility model provides a for correlation technique, by the voltage between live wire and the zero line among the electronic equipment that the sampling unit was gathered, to comparing element output voltage, when the voltage between live wire and the zero line is big more, voltage to comparing element output is big more, comparing element judges when the voltage between live wire and the zero line is higher than the preset threshold value according to the voltage of sampling element output, to the control unit output enable signal, by the disconnection of the control unit control switch, namely, control electronic equipment's power supply circuit disconnection, can not damage because supply voltage is too big with protection electronic equipment.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

FIG. 1 is a block schematic diagram of an input overvoltage protection circuit in one embodiment;

FIG. 2 is a detailed circuit diagram of a sampling unit in the input overvoltage protection circuit in one embodiment;

FIG. 3 is a detailed circuit diagram of a sampling unit in the input overvoltage protection circuit in one embodiment;

FIG. 4 is a detailed circuit diagram of a comparison unit in the input overvoltage protection circuit in one embodiment;

FIG. 5 is a detailed circuit diagram of a comparison unit in the input overvoltage protection circuit in one embodiment;

FIG. 6 is a detailed circuit diagram of a control unit in the input overvoltage protection circuit in one embodiment;

FIG. 7 is a detailed circuit diagram of a control unit in the input overvoltage protection circuit in one embodiment;

FIG. 8 is a detailed circuit diagram of a control unit in the input overvoltage protection circuit in one embodiment;

FIG. 9 is a block schematic diagram of an input overvoltage protection circuit in one embodiment;

FIG. 10 is a detailed circuit diagram of a control unit in the input overvoltage protection circuit in one embodiment;

FIG. 11 is a detailed circuit diagram of a control unit in the input overvoltage protection circuit in one embodiment;

FIG. 12 is a circuit diagram of the connection of the comparison unit to the control unit in the input overvoltage protection circuit in one embodiment;

fig. 13 is a detailed circuit diagram of an input overvoltage protection circuit in one embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that in the embodiments of the present invention, numerous technical details are set forth in order to provide a better understanding of the present application. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments. The following embodiments are divided for convenience of description, and should not constitute any limitation to the specific embodiments of the present invention, and the embodiments may be mutually incorporated and referred to without contradiction.

The utility model discloses an embodiment relates to an input overvoltage crowbar, and input overvoltage crowbar sets up in electronic equipment, specifically sets up on live wire and/or zero line in electronic equipment for when electronic equipment's supply voltage is too big, the power supply loop of disconnection electronic equipment, in order to protect electronic equipment not because of supply voltage is too big and damage.

Referring to fig. 1, the input overvoltage protection circuit includes: the sampling unit 1 is used for collecting voltage between a live wire L and a zero line N in electronic equipment, a first input end 101 of the sampling unit 1 is connected with the live wire L, and a second input end 102 of the sampling unit is connected with the zero line N; a comparison unit 2, a first input end 201 and a second input end 202 of the comparison unit 2 are respectively connected to the first output end 103 and the second output end 104 of the sampling unit 1, and the comparison unit 2 is configured to output an enable signal when a voltage between the live line L and the zero line N is higher than a preset threshold; a control unit 3, wherein a first input end 301 of the control unit 3 is connected to an output end 203 of the comparison unit 2; and a switch 4, wherein an output terminal of the control unit 3 is connected to a control terminal of the switch 4, and the control unit 3 includes a first output terminal 304 and a second output terminal 305, and a first input terminal 401 and a second input terminal 402 of the switch 4 are shown as the control terminal of the switch 4 in fig. 1 as an example. At this time, the first output end 304 and the second output end 305 of the control unit 3 are respectively connected to the first input end 401 and the second input end 402 of the switch 4, the switch 4 is connected in the live wire L and/or the neutral wire N and is controlled by the control unit 3 to be opened or closed, and the line (live wire and/or neutral wire) where the switch 4 in the open state is located is in the open state.

In this embodiment, the sampling unit outputs voltage to the comparison unit according to the voltage between the live wire and the zero line in the collected electronic device, when the voltage between the live wire and the zero line is higher, the voltage output to the comparison unit is higher, when it is determined that the voltage between the live wire and the zero line is higher than the preset threshold value according to the voltage output by the sampling unit, the enable signal is output to the control unit, and the control unit controls the switch to be turned off, that is, the power supply loop of the electronic device is controlled to be turned off, so that the electronic device is protected from being damaged due to the fact that the power supply voltage is too high.

The electronic device may be a single-phase power supply device, and the input overvoltage protection circuit needs to be disposed on the circuit board, and specifically, a circuit board with an input overvoltage protection circuit may be additionally disposed in the electronic device, or the input overvoltage protection circuit may be directly disposed on an existing circuit board in the electronic device.

In an embodiment, on the basis of the embodiment shown in fig. 1, the present application provides a specific implementation circuit of the sampling unit 1, please refer to fig. 2, which takes the numbers of the bidirectional regulator tubes and the current limiting resistors as an example for explanation, the sampling unit 1 includes a sampling branch 100, the sampling branch 100 includes a bidirectional regulator tube TZ1 and a current limiting resistor R0 connected in series, two ends of the sampling branch 100 are a first input end 101 and a second input end 102 of the sampling unit 1, respectively, and two ends of the bidirectional regulator tube TZ1 are a first output end 103 and a second output end 104 of the sampling unit 1, respectively.

In this embodiment, the voltages at the two ends of the voltage regulator tube can be stabilized at different voltage values along with the difference of the current flowing through the voltage regulator tube, so that the situation that the voltage of the sampling unit is lost in a half period due to the fact that the voltage between the live wire and the zero line collected by the sampling unit is alternating current voltage due to the fact that the peak value of the voltage input into the comparison unit is too large and the devices in the comparison unit are damaged is avoided.

In this application, a plurality of bidirectional regulator tubes may be connected in series, please refer to fig. 3, which takes the example of two bidirectional regulator tubes TZ1 and TZ2 connected in series, where one end of TZ1 is used as the first output terminal 103 of the sampling unit 1, the other end of TZ1 is connected to one end of TZ2, the other end of TZ2 is used as the second output terminal 104 of the sampling unit 1, and the voltage between the first output terminal 103 and the second output terminal 104 of the sampling unit 1 is equal to the sum of the voltage at two ends of TZ1 and the voltage at two ends of TZ 2.

From the above analysis, it can be known that the voltage (the voltage between the first output terminal 103 and the second output terminal 104) required to be output by the sampling unit 1 can be satisfied by selecting an appropriate number of bidirectional voltage regulators to be connected in series.

In an embodiment, on the basis of the embodiment shown in fig. 1, the present application provides a specific implementation circuit of the comparison unit 2, please refer to fig. 4, where the comparison unit 2 includes a first rectifier bridge 21, a first unidirectional regulator 22, a comparator 23, a first voltage-dividing resistor R1, a second voltage-dividing resistor R2, a third voltage-dividing resistor R3, a fourth voltage-dividing resistor R4, and a fifth voltage-dividing resistor R5.

Specifically, the first rectifier bridge 21 includes a first diode, a second diode, a third diode and a fourth diode, an anode of the first diode is connected to a cathode of the second diode, an anode of the second diode is connected to an anode of the third diode, a cathode of the third diode is connected to an anode of the fourth diode, a cathode of the fourth diode is connected to a cathode of the first diode, one input end 211 of the first rectifier bridge 21 is connected between the first diode and the second diode, the other input end 212 of the first rectifier bridge 21 is connected between the third diode and the fourth diode, an anode output end 213 of the first rectifier bridge 21 is connected between the first diode and the fourth diode, and a cathode output end 214 of the first rectifier bridge 21 is connected between the second diode and the third diode.

Two input ends 211 and 212 of the first rectifier bridge 21 are a first input end 201 and a second input end 202 of the comparison unit 2, a positive output end 213 of the first rectifier bridge 21 is respectively connected to one end of a first voltage-dividing resistor R1 and one end of a second voltage-dividing resistor R2, the other end of the first voltage-dividing resistor R1 is respectively connected to a negative electrode of the first unidirectional regulator tube 22 and one end of a third voltage-dividing resistor R3, a positive electrode of the first unidirectional regulator tube 22 is connected to a negative output end 214 of the first rectifier bridge 21, the other end of the second voltage-dividing resistor R2 is connected to one end of a fourth voltage-dividing resistor R4, the other end of the fourth voltage-dividing resistor R4 is connected to the negative output end 214 of the first rectifier bridge 21, the other end of the third voltage-dividing resistor R3 is connected to one end of a fifth voltage-dividing resistor R5, the other end of the fifth voltage-dividing resistor R5 is connected to the negative output end 214 of the first rectifier bridge 21, a non-phase input end 231 of the comparator 23 is connected between the third voltage-dividing resistor R3 and the fifth voltage-dividing resistor R5, the inverting input 232 of the comparator 23 is connected between the second voltage-dividing resistor R2 and the fourth voltage-dividing resistor R4, and the output 233 of the comparator 23 is the output 203 of the comparing unit 2. Optionally, a capacitor C1 may be connected between the positive output terminal 213 and the negative output terminal 214 of the first rectifier bridge 21, so as to stabilize the dc voltage rectified and output by the rectifier bridge, thereby performing a filtering function.

Two input ends 211 and 212 of the first rectifier bridge 21 are a first input end 201 and a second input end 202 of the comparison unit 2, and are respectively connected to the first output end 103 and the second output end 104 of the sampling unit 1, so as to rectify the voltage output by the sampling unit 1 to obtain a rectified voltage U1.

One working example of the comparison unit 2 is as follows.

It should be noted that the specific value of the clamp voltage U2 of the first single-phase regulator 22 is an inherent characteristic of the first single-phase regulator 22, and is related to the specific type of the first single-phase regulator 22.

When the voltage across the first single-phase regulator tube 22 is not yet equal to the clamping voltage U2, the voltage across the first single-phase regulator tube 22 increases with the increase of the rectified voltage, at this time, the voltage U + at the non-inverting input of the comparator is obtained by dividing the rectified voltage U1 by the first voltage dividing resistor R1, the third voltage dividing resistor R3 and the fifth voltage dividing resistor R5, specifically, U + ═ U1R 5/(R1+ R3+ R5), and the voltage U-at the inverting input of the comparator is obtained by dividing the rectified voltage U1 by the second voltage dividing resistor R2 and the fourth voltage dividing resistor R4, specifically, U- ═ U1R 4/(R2+ R4). When the voltage dividing resistors are arranged, attention needs to be paid that when the voltage at the two ends of the first single-phase voltage-stabilizing tube 22 is not yet clamped, the voltage U + at the non-inverting input end of the comparator is larger than the voltage U-at the inverting input end of the comparator, and at the moment, the comparator 23 outputs high level.

When the voltage at the two ends of the first single-phase voltage-stabilizing tube 22 is increased to the clamp voltage U2, the rectified voltage U1 is increased, and the voltage at the two ends of the first single-phase voltage-stabilizing tube 22 is maintained at the clamp voltage U2 and is not increased any more, at this time, the reverse-phase input voltage U-of the comparator is obtained by dividing the rectified voltage U1 by the second voltage-dividing resistor R2 and the fourth voltage-dividing resistor R4, that is, U- ═ U1R 4/(R2+ R4), but the same-phase input voltage U + of the comparator is obtained by dividing the clamp voltage U2 by the first voltage-dividing resistor R1, the third voltage-dividing resistor R3 and the fifth voltage-dividing resistor R5, specifically, U + ═ U2R 5/(R3+ R5), then the rectified voltage U1 is increased, the reverse-phase input voltage U-of the comparator is increased, and the same-phase input voltage U + of the comparator is maintained unchanged, when the reverse-phase input voltage U-phase input voltage of the comparator is greater than the same-phase input voltage U + U, the comparator 23 outputs a low level. After receiving the low level, the control unit 3 controls the switch 4 to disconnect the power supply loop of the electronic device, so as to ensure the safety of the electronic device.

Specifically, referring to fig. 4, the comparator 23 further includes two power supply terminals 234 and 235, one power supply terminal 234 of the comparator 23 is connected to the positive output terminal 213 of the first rectifier bridge 21, and the other power supply terminal 235 of the comparator 23 is connected to the negative output terminal 214 (not shown in the figure) of the first rectifier bridge 21.

In this embodiment, a specific implementation circuit of the comparison unit is provided, and whether the voltage between the live line and the zero line collected by the sampling voltage is too large is determined by using a characteristic that the first single-phase voltage regulator tube has a clamping voltage, and then when the voltage between the live line and the zero line of the comparator is too large, the enable signal is output to the control circuit, and the control unit controls the switch to be turned off, that is, the power supply loop of the electronic device is turned off, so as to protect the electronic device from being damaged due to too large power supply voltage.

In an embodiment, a specific implementation circuit of the comparing unit 2 is provided, please refer to fig. 5, and based on the embodiment shown in fig. 4, the comparing unit 2 further includes a second unidirectional regulator 24.

The first one-way voltage regulator tube 22 is connected with the negative electrode output end 214 of the first rectifier bridge 21 through the second one-way voltage regulator tube 24, the positive electrode of the first one-way voltage regulator tube 22 is connected with the negative electrode of the second one-way voltage regulator tube 24, the positive electrode of the second one-way voltage regulator tube 24 is connected with the negative electrode output end 214 of the first rectifier bridge 21, and the output end 233 of the comparator 23 is connected between the first one-way voltage regulator tube 22 and the second one-way voltage regulator tube 24.

Taking as an example that the clamping voltages of the first single-phase regulator tube 22 and the second single-phase regulator tube 24 are equal and equal to U2, another working example of the comparison unit 2 is as follows.

When the voltage across the first single-phase voltage-regulator tube 22 or the second single-phase voltage-regulator tube 24 is not yet equal to the clamping voltage U2, the comparator non-inverting input terminal voltage U + is obtained by dividing the sum of the voltages across the first single-phase voltage-regulator tube 22 and the second single-phase voltage-regulator tube 24 through a first voltage-dividing resistor R1, a third voltage-dividing resistor R3 and a fifth voltage-dividing resistor R5, specifically, U + ═ U1R 5/(R1+ R3+ R5), and the comparator inverting input terminal voltage U-is obtained by dividing the rectified voltage through a second voltage-dividing resistor R2 and a fourth voltage-dividing resistor R4, specifically, U-U1R 4/(R2+ R4). When the voltage dividing resistors are arranged, attention needs to be paid that when the voltage at the two ends of the first single-phase voltage-stabilizing tube 22 is not yet clamped, the voltage U + at the non-inverting input end of the comparator is larger than the voltage U-at the inverting input end of the comparator, and at the moment, the comparator 23 outputs high level.

When the voltages at the two ends of the first single-phase voltage-stabilizing tube 22 and the second single-phase voltage-stabilizing tube 24 are both increased to the clamping voltage U2, the sum of the voltages at the two ends of the first single-phase voltage-stabilizing tube 22 and the second single-phase voltage-stabilizing tube 24 is not increased with the increase of the rectified voltage and is maintained to be 2 × U2, at this time, the voltage U + at the inverting input end of the comparator is obtained by dividing the rectified voltage U1 through the second voltage-dividing resistor R2 and the fourth voltage-dividing resistor R4, but the voltage U + at the non-inverting input end of the comparator is obtained by dividing the sum of the clamping voltages at the two ends of the first single-phase voltage-stabilizing tube 22 and the second single-phase voltage-stabilizing tube 24 through the first voltage-dividing resistor R1, the third voltage-dividing resistor R3 and the fifth voltage-dividing resistor R5, specifically, U + (2U 2 × R5/(R3+ R5), the rectified voltage U1 is increased, the voltage U-at the input end of the comparator is increased, and the voltage U + at the inverting input end of the non-inverting input end of the comparator is maintained to be unchanged, when the voltage U-of the inverting input end of the comparator is greater than the voltage U + of the non-inverting input end of the comparator, the comparator 23 outputs a low level, both ends of the second unidirectional voltage-regulator tube 24 are low level, the second unidirectional voltage-regulator tube 24 is short-circuited, the voltage U + of the non-inverting input end of the comparator is obtained by only dividing the clamping voltage of the first single-phase voltage-regulator tube 22 through the first voltage-dividing resistor R1, the third voltage-dividing resistor R3 and the fifth voltage-dividing resistor R5, specifically, the voltage U + ═ U2R 5/(R3+ R5), then the rectified voltage is increased, the voltage of the non-inverting input end of the comparator is kept unchanged, the voltage U2R 5R 3+ R5 is kept lower than that of the voltage U + R2R 5/(R3+ R5) before the second unidirectional voltage-regulator tube 24 is short-circuited, and the voltage U + 3652, the rectified voltage U + 1 is reduced, when the voltage U-at the inverting input terminal of the comparator is lower than U + U2R 5/(R3+ R5), the comparator 23 outputs high level, and the second single-phase voltage regulator tube 24 is not short-circuited any more.

In this embodiment, a hysteresis voltage difference is formed by setting the second unidirectional regulator tube and using whether the second regulator tube is short-circuited, and when the rectified voltage is reduced to a certain voltage range, the voltage at the inverting input end of the comparator is smaller than the voltage at the non-inverting input end of the comparator, that is, when U- < U + ═ U2R 5/(R3+ R5), the comparator is switched from outputting a low level to outputting a high level, and then the control unit controls the switch to be closed again, so that the switch is prevented from being repeatedly opened and closed near a certain critical voltage value, and the reliability of the system is enhanced.

When the comparator is arranged, the output end of one comparator integrated on a chip can be connected between the first one-way voltage-regulator tube and the second one-way voltage-regulator tube while being connected to the control unit, the output end of one comparator integrated on the chip can be connected to the control unit, and the output end of the other comparator integrated on the chip is connected between the first one-way voltage-regulator tube and the second one-way voltage-regulator tube.

In an embodiment, on the basis of the embodiment shown in fig. 1, a specific implementation circuit of the control unit 3 is provided, referring to fig. 6, the control unit 3 includes an enabling unit 31, a first transistor 32 and a freewheeling diode 33, the switch 4 includes a relay 41, and the first transistor 32 is an NPN-type transistor.

A first input end 311 of the enabling unit 31 serves as a second input end 302 of the control unit 3, a second input end 312 of the enabling unit 31 serves as a first input end 301 of the control unit 3, an output end 313 of the enabling unit 31 is connected to a base 321 of the first triode 32, a negative electrode of the freewheeling diode 33 is connected to the second input end 302 of the control unit 3, a positive electrode of the freewheeling diode 33 is connected to a collector 322 of the first triode 32, an emitter 323 of the first triode 32 is connected to a third input end 303 of the control unit 3, two ends of the freewheeling diode 33 are respectively a first output end 304 and a second output end 305 of the control unit 3, and two ends of a control coil 411 of the relay 41 serve as a first input end 401 and a second input end 402 of the switch 4; wherein the enabling unit 31 is configured to output a high level through the output terminal 313 of the enabling unit 31 when the first input terminal 311 of the enabling unit 31 is at a high level and the second input terminal 312 of the enabling unit 31 is at a low level.

An example of the operation of the control unit 3 is as follows.

The external power supply or the sampling unit 1 outputs a high level to the first input terminal 311 of the enabling unit 31, when the comparing unit 2 outputs a low level to the second input terminal 312 of the enabling unit 31, the output terminal 313 of the enabling unit 31 outputs a high level, the first triode 32 is turned on at this time, the collector 322 of the first triode 32 is at a low level, the voltage across the control coil 411 of the relay 41 is greater than the working threshold of the relay 41 at this time, and the control coil 411 of the relay 41 controls the switch 4 to be turned off to disconnect the power supply loop of the electronic device, thereby ensuring the safety of the electronic device.

In this embodiment, a specific implementation circuit of the control unit is provided, when the first triode is turned off, the residual energy on the control coil of the relay is consumed through a loop formed by the freewheeling diode and the control coil of the relay, so that the first triode is protected from being damaged.

In an embodiment, based on the embodiment shown in fig. 6, a specific implementation circuit of the control unit 3 is provided, and referring to fig. 7, the enabling unit 31 is specifically a second transistor, and the second transistor is a PNP transistor.

The emitter of the second transistor serves as the first input 311 of the enabling unit 31, the base of the second transistor serves as the second input 312 of the enabling unit 31, and the collector of the second transistor serves as the output 313 of the enabling unit 31.

An example of the operation of the control unit 3 is as follows.

The base of the second triode is directly used as the first input end 301 of the control unit 3, when the comparison unit 2 outputs a low level, the second triode is conducted, a high level is output to the base 321 of the first triode 32, the first triode 32 is conducted, the collector 322 of the first triode 32 is at a low level, at this time, the voltage at two ends of the control coil 411 of the relay 41 is greater than the working threshold of the relay 41, the control coil 411 of the relay 41 controls the switch 4 to be disconnected, namely the live wire L is controlled to be disconnected, and specifically, the live wire L is controlled to be connected with the ground wire GND.

In this embodiment, a specific implementation circuit of the control unit is provided, and an enabling unit in the control unit may specifically be a second triode (PNP type triode).

In an embodiment, on the basis of the embodiment shown in fig. 6, a specific implementation circuit of the control unit 3 is provided, please refer to fig. 8, and the enabling unit 31 is specifically a photo coupling unit.

The positive electrode of the light emitting diode of the photoelectric coupling unit is connected to the collector of the phototriode of the photoelectric coupling unit, the positive electrode of the light emitting diode of the photoelectric coupling unit serves as the first input end 311 of the enabling unit 31, the negative electrode of the light emitting diode of the photoelectric coupling unit serves as the second input end 312 of the enabling unit 31, and the emitter of the phototriode of the photoelectric coupling unit serves as the output end 313 of the enabling unit 31.

An example of the operation of the control unit 3 is as follows.

When the comparing unit 3 outputs a low level, the voltage at two ends of the light emitting diode of the photoelectric coupling unit is greater than the light emitting voltage of the light emitting diode, the light emitting diode emits light, the phototriode of the photoelectric coupling unit is conducted after receiving the light emitted by the light emitting diode, a high level is output to the base 321 of the first triode 32 by the emitter of the phototriode, at this time, the first triode 32 is conducted, the collector 322 of the first triode 32 is at a low level, the voltage at two ends of the control coil 411 of the relay 41 is greater than the working threshold of the relay 41, the switch 4 is controlled to be disconnected by the control coil 411 of the relay 41, namely, the live wire L is controlled to be disconnected, and specifically, the live wire L is controlled to be connected with the ground wire GND.

In this embodiment, a concrete realization circuit of the control unit is provided, the enabling unit in the control unit can be specifically a photoelectric coupling unit, and the photoelectric coupling unit can realize the electricity-light-electricity conversion, because photoelectric coupling unit has the characteristics such as the mutual isolation between input and output, signal transmission unidirectionality, adopts photoelectric coupling unit can improve the electric insulating ability and the interference killing feature between comparing unit and the control unit in comparing in adopting the second triode.

The utility model discloses an embodiment relates to an input overvoltage crowbar, on the basis of the embodiment that fig. 1 shows, please refer to fig. 9, first output 103 and the second output 104 of sampling unit 1 are connected respectively in the second input 302 and the third input 303 of the control unit 3, and voltage is the power supply of control unit 3 between live wire and the zero line that gather through sampling unit 1, and wherein, the second input 302 and the third input 303 of the control unit 3 are two feeder ear of the control unit 3.

In this embodiment, because the main purpose of input overvoltage crowbar is that protection electronic equipment can not damage because supply voltage is too big, namely, input overvoltage crowbar just makes sense when electronic equipment is supplied power, so only when externally supplying power to electronic equipment, gather the voltage between live wire and the zero line by the sampling unit and supply power for the control unit, make the control unit begin to work, compare in additionally setting up external power supply, no matter whether electronic equipment is supplied power and continue to supply power for the control unit, this embodiment can avoid power resource waste to a certain extent.

The utility model discloses an embodiment relates to an input overvoltage crowbar, on the basis of the embodiment that any shown in fig. 6, 7 and 8, provides a concrete realization circuit of control unit 3 to enable unit 31 explains for example for the optoelectronic coupling unit, please specifically refer to fig. 10, and control unit 3 still includes second rectifier bridge 35 and decoupling capacitor C2, and the concrete structure of second rectifier bridge 35 can be the same with the concrete structure of first rectifier bridge 32.

The first output terminal 103 and the second output terminal 104 of the sampling unit 1 are connected to the second input terminal 302 and the third input terminal 303 of the control unit 3, respectively. Two input ends 351 and 352 of the second rectifier bridge 35 are respectively used as the second input end 302 and the third input end 303 of the control unit 3, a positive output end 353 of the second rectifier bridge 35 is respectively connected to the first input end 311 of the enabling unit 31 and the negative electrode of the freewheeling diode 33, a negative output end 354 of the second rectifier bridge 35 is connected to the emitter 323 of the first triode 32, and two ends of a decoupling capacitor C2 are respectively connected to the positive output end 353 and the negative output end 354 of the second rectifier bridge 35.

The positive output terminal 353 of the second rectifier bridge 35 is connected to the positive terminal of the light emitting diode of the photoelectric coupling unit, the negative terminal of the light emitting diode of the photoelectric coupling unit is used as the first input terminal 301 of the control unit 3, the collector of the phototransistor of the photoelectric coupling unit is connected to the positive output terminal 353 of the second rectifier bridge 35, the emitter of the phototransistor of the photoelectric coupling unit is connected to the base 321 of the first triode 32, the negative terminal of the freewheel diode 33 is connected to the positive output terminal 353 of the second rectifier bridge 35, the positive terminal of the freewheel diode 33 is connected to the collector 322 of the first triode 32, the emitter 323 of the first triode 32 is connected to the negative output terminal 354 of the second rectifier bridge 35, the two terminals of the decoupling capacitor C2 are respectively connected to the positive output terminal 353 and the negative output terminal 354 of the second rectifier bridge 35, the two terminals of the freewheel diode 33 are respectively used as the first output terminal 304 and the second output terminal 305 of the control unit 3, the two ends of the control coil 411 of the relay 41 are respectively used as the first input end 401 and the second input end 402 of the switch 4.

In this embodiment, when being supplied power for the control unit by the sampling unit, need set up the second rectifier bridge and carry out the rectification to the alternating current that the sampling unit gathered earlier, in addition, set up decoupling capacitor between two output of second rectifier bridge, can let the direct current voltage through rectifier bridge rectification output more stable, played the effect of filtering, improved the stability of input overvoltage protection circuit work.

An embodiment of the present invention relates to an input overvoltage protection circuit, and on the basis of any one of the embodiments shown in fig. 6, fig. 7 and fig. 8, a specific implementation circuit of the control unit 3 is provided, so that the enabling unit 31 is a photoelectric coupling unit for example, and specifically please refer to fig. 11, the control unit 3 further includes a filter resistor R6 and a filter capacitor C3.

The first output end 103 and the second output end 104 of the sampling unit 1 are respectively connected to the second input end 302 and the third input end 303 of the control unit 3, one end of a filter resistor R6 is used as the second input end 302 of the control unit 3, the other end of a filter resistor R6 is respectively connected to the first input end 311 of the enabling unit 31 and the negative electrode of the freewheeling diode 33, the emitter 323 of the first triode 32 is used as the third input end 303 of the control unit 3, and the filter capacitor C3 is connected between the second input end 302 and the third input end 303 of the control unit 3.

In this embodiment, when the requirement on the stability of voltage waveform is not high, only the RC filter circuit can be adopted to filter the alternating current output by the sampling unit, and compared with the rectification of the alternating current output by the sampling unit by adopting the second rectifier bridge, only the RC filter circuit can be adopted to simplify the circuit structure to a certain extent, and the circuit cost is reduced.

An embodiment of the present invention relates to an input overvoltage protection circuit, and please refer to fig. 12 on the basis of the embodiment shown in fig. 4. A second input 302 of the control unit 3 is connected to the positive output 213 of the first rectifier bridge 21, and a third input 303 of the control unit 3 is connected to the negative output 214 of the first rectifier bridge 21.

In this embodiment, the voltage obtained by rectification of the first rectifier bridge in the comparison unit can be used to supply power to the control unit, and a second rectifier bridge, a filter resistor and a filter capacitor are not required to be additionally arranged, so that the circuit is simplified, and the circuit cost is effectively saved.

An embodiment of the present invention relates to an input overvoltage protection circuit, please refer to fig. 13, a specific structure of the sampling unit 1 refers to the embodiment shown in fig. 2, a specific structure of the comparing unit 2 refers to the embodiment shown in fig. 5, and a specific structure of the switch 4 refers to the embodiment shown in fig. 8, which is not described herein again.

The specific structure of the control unit 3 differs from the embodiment shown in fig. 8 in that the anode of the light emitting diode of the photocoupler is not connected to the collector of the phototransistor of the photocoupler, but is connected to the anode output terminal 213 of the first rectifier bridge 21 in the comparison unit 2.

In this embodiment, a specific circuit of the input overvoltage protection circuit is provided, and as can be seen from the above analysis, the positive electrode of the light emitting diode of the photoelectric coupling unit is connected to the positive electrode output terminal of the first rectifier bridge in the comparison unit, and the negative electrode of the light emitting diode of the photoelectric coupling unit is connected to the comparator output terminal of the comparison unit.

An embodiment of the present invention relates to a circuit board assembly, including the input overvoltage protection circuit in the above-mentioned embodiment.

An embodiment of the present invention relates to an electronic device, including the input overvoltage protection circuit in the above-mentioned embodiment.

Claims (10)

1. An input overvoltage protection circuit, provided in an electronic device, comprising:

the sampling unit is used for collecting voltage between a live wire and a zero line in the electronic equipment, a first input end of the sampling unit is connected to the live wire, and a second input end of the sampling unit is connected to the zero line;

the first input end and the second input end of the comparison unit are respectively connected to the first output end and the second output end of the sampling unit, and the comparison unit is configured to output an enable signal when the voltage between the live wire and the zero wire is higher than a preset threshold value;

the first input end of the control unit is connected with the output end of the comparison unit;

the output end of the control unit is connected to the control end of the switch, the switch is connected to the live wire and/or the zero wire and is controlled to be opened or closed by the control unit, the control unit is configured to control the switch to be opened when receiving the enabling signal, and a line where the switch is in an open state.

2. The input overvoltage protection circuit according to claim 1, wherein the first output terminal and the second output terminal of the sampling unit are connected to the second input terminal and the third input terminal of the control unit, respectively;

the second input end and the third input end of the control unit are two power supply ends of the control unit.

3. The input overvoltage protection circuit according to claim 1 or 2, wherein the sampling unit comprises a sampling branch, the sampling branch comprises a bidirectional voltage regulator tube and a current limiting resistor which are connected in series, two ends of the sampling branch are respectively a first input end and a second input end of the sampling unit, and two ends of the bidirectional voltage regulator tube are respectively a first output end and a second output end of the sampling unit.

4. The input overvoltage protection circuit according to claim 1, wherein the comparison unit comprises a first rectifier bridge, a first unidirectional voltage regulator tube, a comparator, a first voltage dividing resistor, a second voltage dividing resistor, a third voltage dividing resistor, a fourth voltage dividing resistor and a fifth voltage dividing resistor;

the two input ends of the first rectifier bridge are a first input end and a second input end of the comparison unit, the positive output end of the first rectifier bridge is respectively connected to one end of the first voltage-dividing resistor and one end of the second voltage-dividing resistor, the other end of the first voltage-dividing resistor is respectively connected to the negative electrode of the first unidirectional voltage-stabilizing tube and one end of the third voltage-dividing resistor, the positive electrode of the first unidirectional voltage-stabilizing tube is connected to the negative output end of the first rectifier bridge, the other end of the second voltage-dividing resistor is connected to one end of the fourth voltage-dividing resistor, the other end of the fourth voltage-dividing resistor is connected to the negative output end of the first rectifier bridge, the other end of the third voltage-dividing resistor is connected to one end of the fifth voltage-dividing resistor, and the other end of the fifth voltage-dividing resistor is connected to the negative output end of the first rectifier bridge, the non-inverting input end of the comparator is connected between the third voltage-dividing resistor and the fifth voltage-dividing resistor, the inverting input end of the comparator is connected between the second voltage-dividing resistor and the fourth voltage-dividing resistor, and the output end of the comparator is the output end of the comparison unit.

5. The input overvoltage protection circuit of claim 4, wherein the comparison unit further comprises a second unidirectional regulator tube;

the first one-way voltage-stabilizing tube is connected to the negative electrode output end of the first rectifier bridge through the second one-way voltage-stabilizing tube, the positive electrode of the first one-way voltage-stabilizing tube is connected to the negative electrode of the second one-way voltage-stabilizing tube, and the positive electrode of the second one-way voltage-stabilizing tube is connected to the negative electrode output end of the first rectifier bridge; the output end of the comparator is also connected between the first one-way voltage-regulator tube and the second one-way voltage-regulator tube.

6. The input overvoltage protection circuit according to claim 1, wherein the control unit comprises an enabling unit, a first triode and a freewheeling diode, the switch comprises a relay, and the first triode is an NPN-type triode;

a first input end of the enabling unit is used as a second input end of the control unit, a second input end of the enabling unit is used as a first input end of the control unit, an output end of the enabling unit is connected to a base electrode of the first triode, a negative electrode of the freewheeling diode is connected to a second input end of the control unit, an anode of the freewheeling diode is connected to a collector electrode of the first triode, an emitter electrode of the first triode is used as a third input end of the control unit, two ends of the freewheeling diode are respectively a first output end and a second output end of the control unit, and two ends of a control coil of the relay are respectively used as a first input end and a second input end of the switch;

wherein the enable unit is configured to output a high level through an output terminal of the enable unit when a first input terminal of the enable unit is at a high level and a second input terminal of the enable unit is at a low level.

7. The input overvoltage protection circuit according to claim 6, wherein the enabling unit is a photocoupling unit or a second triode, wherein the second triode is a PNP type triode;

when the enabling unit is the photoelectric coupling unit, the anode of the light emitting diode of the photoelectric coupling unit is connected to the collector of the phototriode of the photoelectric coupling unit, the anode of the light emitting diode of the photoelectric coupling unit is used as the first input end of the enabling unit, the cathode of the light emitting diode of the photoelectric coupling unit is used as the second input end of the enabling unit, and the emitter of the phototriode of the photoelectric coupling unit is used as the output end of the enabling unit;

when the enabling unit is the second triode, an emitting electrode of the second triode is used as a first input end of the enabling unit, a base electrode of the second triode is used as a second input end of the enabling unit, and a collector electrode of the second triode is used as an output end of the enabling unit.

8. The input overvoltage protection circuit according to claim 6 or 7, wherein the control unit further comprises a second rectifier bridge and a decoupling capacitor;

the first output end and the second output end of the sampling unit are respectively connected with the second input end and the third input end of the control unit; two input ends of the second rectifier bridge are respectively used as a second input end and a third input end of the control unit, an anode output end of the second rectifier bridge is respectively connected to the first input end of the enabling unit and the cathode of the freewheeling diode, a cathode output end of the second rectifier bridge is connected to an emitter of the first triode, and two ends of the decoupling capacitor are respectively connected to the anode output end and the cathode output end of the second rectifier bridge;

the second input end and the third input end of the control unit are two power supply ends of the control unit.

9. A circuit board assembly comprising an input overvoltage protection circuit according to any one of claims 1 to 8.

10. An electronic device comprising the circuit board assembly of claim 9.

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