CN217486154U - Overvoltage protection circuit, device and system - Google Patents
Overvoltage protection circuit, device and system Download PDFInfo
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- CN217486154U CN217486154U CN202123447500.4U CN202123447500U CN217486154U CN 217486154 U CN217486154 U CN 217486154U CN 202123447500 U CN202123447500 U CN 202123447500U CN 217486154 U CN217486154 U CN 217486154U
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Abstract
The utility model provides an overvoltage protection circuit, device and system, this overvoltage protection circuit includes: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit; the overvoltage control circuit is respectively connected with the power supply and the protection execution circuit, and the protection execution circuit is connected with the load; when the power supply voltage output by the power supply is greater than the preset voltage, the overvoltage control circuit outputs an overvoltage protection signal to the protection execution circuit; when receiving the overvoltage protection signal, the protection execution circuit disconnects a loop between the power supply and the load and stops supplying power to the load. The utility model discloses when mains voltage is greater than preset voltage, the return circuit between output overvoltage protection signal disconnection power and the load is protected the load.
Description
Technical Field
The utility model relates to the field of electronic technology, especially, relate to an overvoltage protection circuit, device and system.
Background
Most industrial control products such as PLC, industrial personal computer and the like adopt direct current power supply to supply power. When designing such a port circuit, it is generally necessary to consider: based on the poor electromagnetic environment of industrial control product operation, in order to improve the EMC performance of the product, design engineers usually add anti-interference protection measures, such as transient interference suppressors of TVS tubes, piezoresistors, air discharge tubes, and the like, to the power supply port of the product; the maximum value limiting requirements are set for voltage value parameters of input port filter capacitors, power ICs and other devices, and over-design is avoided based on cost and PCB space consideration. Aiming at the two design considerations, the maximum clamping voltage of the transient interference suppressor is selected to be smaller than the voltage values of other devices of the input port; however, the difference between the breakdown voltage of the glitch suppressor and the maximum clamping voltage is large, which results in the normally selected device being only a few volts larger than the normal input voltage range; the client often has the problem that the port device is burnt out due to overvoltage and the product works abnormally because a wiring person does not pay attention to the silk screen printing of the product shell or the wrong wiring of a user manual. Therefore, there is a need for accurate overvoltage protection for devices selected for the input port, including transient suppressors, capacitors, ICs, etc.
In the prior art, an overvoltage protection circuit controlled by an integrated chip has the defects of complex circuit structure and high cost due to the adoption of the chip for control; the partial protection circuit adopts an overvoltage protection circuit consisting of a thermal fuse, a voltage stabilizing diode and an MOS (metal oxide semiconductor) tube, and the scheme mechanism is that the MOS tube is short-circuited to the ground during overvoltage, and the thermal fuse is changed into a high-resistance state due to heating to achieve the purpose of protection. When a large current exists in the scheme, the system response is poor and the precision is very low due to the slow response of the fuse; and the rated current parameters of the thermal fuse and the Mos tube need to be larger, resulting in high design cost.
The above is only for the purpose of assisting understanding of the technical solutions of the present invention, and does not represent an admission that the above is the prior art.
SUMMERY OF THE UTILITY MODEL
A primary object of the present invention is to provide an overvoltage protection circuit, an overvoltage protection device and an overvoltage protection system, which are capable of solving the technical problem of low overvoltage protection precision in the prior art.
In order to achieve the above object, the utility model provides an overvoltage protection circuit, overvoltage protection circuit includes: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit;
the overvoltage control circuit is respectively connected with a power supply and the protection execution circuit, and the protection execution circuit is connected with a load;
the overvoltage control circuit is used for outputting an overvoltage protection signal to the protection execution circuit when the power supply voltage output by the power supply is greater than a preset voltage;
and the protection execution circuit is used for disconnecting a loop between the power supply and the load and stopping supplying power to the load when the overvoltage protection signal is received.
Optionally, the overvoltage protection circuit further comprises: a voltage detection circuit;
the voltage detection circuit is connected with the power supply and the overvoltage control circuit;
the voltage detection circuit is used for detecting the power supply voltage output by the power supply and outputting a voltage abnormal signal to the overvoltage control circuit when the power supply voltage is greater than the preset voltage;
and the overvoltage control circuit is used for outputting an overvoltage protection signal to the protection execution circuit when receiving the voltage abnormal signal.
Optionally, the voltage detection circuit is further configured to output an operation signal to the overvoltage control circuit when the power supply voltage is less than the preset voltage;
the overvoltage control circuit is used for outputting a power supply signal to the protection execution circuit when receiving the operation signal;
and the protection execution circuit is used for conducting a loop between the power supply and the load to supply power to the load when receiving the power supply signal.
Optionally, the voltage detection circuit includes: the circuit comprises a first resistor, a second resistor and a first capacitor;
the first end of the first resistor is connected with the power supply, the second end of the first resistor is respectively connected with the first end of the second resistor, the first end of the first capacitor and the overvoltage control circuit, and the second end of the second resistor and the second end of the first capacitor are grounded.
Optionally, the overvoltage control circuit comprises: the circuit comprises a third resistor, a fourth resistor, a fifth resistor, a control chip and a second capacitor;
the first end of the third resistor is connected with the power supply, the second end of the third resistor is connected with the first end of the control chip and the first end of the fourth resistor, the second end of the control chip is connected with the second end of the first resistor, the first end of the second resistor and the first end of the first capacitor, the second end of the fourth resistor is connected with the first end of the fifth resistor, the first end of the second capacitor and the protection execution circuit, and the third end of the control chip, the second end of the fifth resistor and the second end of the second capacitor are grounded.
Optionally, the protection performing circuit includes: the power supply comprises a sixth resistor, a seventh resistor, a first power tube, a second power tube and a third capacitor;
the first end of the sixth resistor is connected with the power supply, the first end of the third capacitor and the input end of the second power tube respectively, the second end of the sixth resistor is connected with the second end of the third capacitor, the first end of the seventh resistor and the control end of the second power tube respectively, the second end of the seventh resistor is connected with the input end of the first power tube, the control end of the first power tube is connected with the second end of the fourth resistor, the first end of the fifth resistor and the first end of the second capacitor, the output end of the second power tube is connected with the load, and the output end of the first power tube is grounded.
Optionally, the control chip includes: the first comparator, the first triode and the first diode;
the first input end of the first comparator is connected with the second end of the first resistor, the first end of the second resistor and the first end of the first capacitor respectively, the second input end of the first comparator is connected with a threshold power supply, the output end of the first comparator is connected with the base electrode of the first triode, the collector electrode of the first triode is connected with the second end of the third resistor, the first end of the fourth resistor and the cathode of the first diode respectively, and the emitter electrode of the first triode is grounded with the anode of the first diode.
Optionally, the overvoltage protection circuit further comprises: a voltage stabilizing circuit;
the voltage stabilizing circuit is connected with the power supply through the protection execution circuit;
the voltage stabilizing circuit is used for stabilizing the power supply voltage output by the power supply and providing stable power supply voltage for the load.
In order to achieve the above object, the present invention further provides an overvoltage protection device, which comprises the overvoltage protection circuit.
In order to achieve the above object, the utility model discloses still provide an overvoltage protection system, overvoltage protection system includes overvoltage protection device.
The utility model provides an overvoltage protection circuit, device and system, this overvoltage protection circuit includes: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit; the overvoltage control circuit is respectively connected with a power supply and the protection execution circuit, and the protection execution circuit is connected with a load; when the power supply voltage output by the power supply is greater than a preset voltage, the overvoltage control circuit outputs an overvoltage protection signal to the protection execution circuit; and when receiving the overvoltage protection signal, the protection execution circuit disconnects a loop between the power supply and the load and stops supplying power to the load. The utility model discloses when mains voltage is greater than preset voltage, the return circuit between output overvoltage protection signal disconnection power and the load is protected the load.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a first embodiment of an overvoltage protection circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a second embodiment of the overvoltage protection circuit according to the embodiment of the present invention;
fig. 3 is a circuit diagram of a second embodiment of an overvoltage protection circuit in accordance with the novel embodiment;
fig. 4 is a circuit diagram of a control chip in a second embodiment of the overvoltage protection circuit according to the novel embodiment.
The reference numbers indicate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| 10 | Overvoltage control circuit | R1～R7 | First to |
| 20 | Protection execution circuit | C1～C4 | First to |
| 30 | Voltage detection circuit | D1 | |
| 40 | Voltage stabilizing circuit | T1～T2 | First to second power transistors |
| U1 | Control chip | VCC | Power supply |
| A1 | First comparator | Vout | Voltage of input load |
| Q1 | A first triode | D1 | First diode |
| Vref | Threshold voltage | GND | Ground connection |
The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
Furthermore, the descriptions in the present application related to "first", "second", etc. are for descriptive purposes only and are not to be construed as indicating or implying relative importance or to imply that the number of technical features indicated are implicitly being indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, it should be considered that the combination of the technical solutions does not exist, and is not within the protection scope of the present invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a first embodiment of an overvoltage protection circuit according to an embodiment of the present invention. Based on fig. 1, the utility model discloses a first embodiment of overvoltage protection circuit is proposed.
In this embodiment, the overvoltage protection circuit includes: an overvoltage control circuit 10 and a protection execution circuit 20;
the overvoltage control circuit 10 is connected to a power source VCC and the protection execution circuit 20, and the protection execution circuit 20 is connected to a load.
It should be appreciated that when the power supply VCC is supplying a load, the power supply voltage output by the power supply VCC should match the driving voltage required by the load. When the power supply voltage is greater than the driving voltage of the load, the excessive voltage may affect the operation of the load or even directly damage the load. When the power supply voltage is lower than the driving voltage of the load, the load may not operate normally due to the insufficient voltage provided by the power supply VCC.
The overvoltage control circuit 10 is a circuit for controlling a load when the load is in an overvoltage state. The overvoltage control circuit 10 may determine the load condition by collecting the power voltage output by the power source VCC and then comparing the power voltage with a predetermined voltage. The overvoltage control circuit 10 may include a comparator and other related components. The overvoltage control circuit 10 may compare the power voltage with a preset voltage through an internal comparator, and determine the magnitude between the power voltage and the preset voltage, i.e., whether the load is in an overvoltage state according to an output result of the comparator. The protection execution circuit 20 is a circuit for directly protecting a load. The protection execution circuit 20 may bypass the voltage supplied by the power source VCC or directly disconnect the power source VCC from the load to protect the load.
In a specific implementation, the power voltage provided by the power source VCC may be compared with a preset voltage, and when the power voltage is greater than the preset voltage, the overvoltage control circuit 10 may output an overvoltage protection signal to the protection execution circuit 20; the protection execution circuit 20 may disconnect a loop between the power supply and the load and stop supplying power to the load when receiving the overvoltage protection signal.
Wherein the preset voltage is a preset voltage for determining whether the power supply is in an overvoltage state. The overvoltage protection signal is a signal for starting overvoltage protection.
In this embodiment, an overvoltage protection circuit is provided, which includes: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit; the overvoltage control circuit is respectively connected with a power supply and the protection execution circuit, and the protection execution circuit is connected with a load; when the power supply voltage output by the power supply is greater than a preset voltage, the overvoltage control circuit outputs an overvoltage protection signal to the protection execution circuit; and when receiving the overvoltage protection signal, the protection execution circuit disconnects a loop between the power supply and the load and stops supplying power to the load. In this embodiment, when the power voltage is greater than the preset voltage, the overvoltage protection signal is output to disconnect a loop between the power supply and the load to protect the load.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a first embodiment of an overvoltage protection circuit according to an embodiment of the present invention. The utility model discloses overvoltage protection circuit's second embodiment is proposed based on above-mentioned overvoltage protection circuit first embodiment.
In this embodiment, the overvoltage protection circuit further includes: a voltage detection circuit 30;
the voltage detection circuit 30 is connected to the power source VCC and the overvoltage control circuit 10.
The voltage detection circuit 30 is a circuit for collecting and detecting a power supply voltage. The voltage detection circuit 30 may be directly connected to the power VCC to collect the power voltage, or may collect the power voltage after voltage reduction by the voltage dividing resistor. When the power supply voltage after the voltage reduction of the divider resistor is collected, the threshold voltage can be set, and when the power supply voltage after the voltage reduction is greater than the threshold voltage, the power supply voltage is greater than the preset voltage.
In a specific implementation, the voltage detection circuit 30 may detect a power voltage output by the power supply, and then compare the power voltage with a preset voltage through a comparator. When the power supply voltage is greater than the preset voltage, outputting a voltage abnormal signal to the overvoltage control circuit 10; when receiving the voltage abnormal signal, the overvoltage control circuit 10 outputs an overvoltage protection signal to the protection execution circuit 20 to protect the load.
Of course, when the power voltage is less than or equal to the preset voltage, the power VCC may directly supply power to the load without damaging the load. In this embodiment, the voltage detection circuit 30 may further output an operation signal to the overvoltage control circuit 10 when the power supply voltage is less than the preset voltage; the overvoltage control circuit 10 may output a power supply signal to the protection execution circuit 20 when receiving the operation signal; the protection execution circuit 20 may, upon receiving the power supply signal, turn on a loop between the power supply and the load to supply power to the load.
The voltage abnormal signal is a signal for indicating that the power supply voltage is greater than a preset voltage, and the running signal is a signal for indicating that the power supply voltage is not greater than the preset voltage. The voltage abnormal signal and the operation signal are signals with different voltage values. The voltage value of the voltage abnormal signal is greater than the threshold voltage, and the voltage value of the running signal is less than or equal to the threshold voltage.
Referring to fig. 3, in the present embodiment, the voltage detection circuit 30 includes: a first resistor R1, a second resistor R2 and a first capacitor C1;
wherein, first resistance R1's first end with the power VCC connects, first resistance R1's second end respectively with second resistance R2's first end, first electric capacity C1's first end and overvoltage control circuit 10 connects, second resistance R2's second end and first electric capacity C1's second end ground connection.
It should be understood that the first resistor R1 and the second resistor R2 step down the power voltage supplied by the power source VCC to obtain a stepped-down power voltage Vth, VCC R2/(R1+ R2) (1). Meanwhile, the first capacitor C1 and the first resistor R1 can form a filter circuit, and the filter circuit can filter the stepped-down power supply voltage Vth to reduce interference in the circuit, so that accurate stepped-down power supply voltage is obtained.
In specific implementation, the power voltage output by the power VCC is divided by the first resistor R1 and the second resistor R2 to reduce the voltage of the power voltage to obtain a reduced power voltage Vth, and then the reduced power voltage Vth is filtered by the filter circuit formed by the first capacitor C1 and the first resistor R1 to obtain an accurate reduced power voltage, and the accurate reduced power voltage is output to the overvoltage control circuit 10.
In this embodiment, the overvoltage control circuit includes: a third resistor R3, a fourth resistor R4, a fifth resistor R5, a control chip U1 and a second capacitor C2;
the first end of the third resistor R3 is connected to the power VCC, the second end of the third resistor R3 is connected to the first end of the control chip U1 and the first end of the fourth resistor R4, the second end of the control chip U1 is connected to the second end of the first resistor R1, the first end of the second resistor R2 and the first end of the first capacitor C1, the second end of the fourth resistor R4 is connected to the first end of the fifth resistor R5, the first end of the second capacitor C2 and the protection execution circuit 20, and the third end of the control chip U1, the second end of the fifth resistor R5 and the second end of the second capacitor C2 are grounded GND.
The control chip U1 is a chip for comparing the stepped-down power supply voltage Vth with the threshold voltage Vref. The control chip U1 may be composed of a comparator, a switch tube and other related components. The path of the control chip U1 is connected in parallel with the branch of the fifth resistor R5 and the fourth resistor R4. When the stepped-down power voltage Vth is greater than the threshold voltage Vref, the control chip U1 directly connects the power voltage to the ground through the third resistor R3, and then outputs a low-level signal to the protection execution circuit 20 at the second end of the fourth resistor R4, and the protection execution circuit 20 disconnects the power VCC from the load when receiving the low-level signal.
It should be understood that, here, the second capacitor C2, the third resistor R3 and the fourth resistor R4 form a filter circuit for filtering noise in the branch circuit, so as to output an overvoltage protection signal with a standard voltage value to the overvoltage protection execution circuit 20 at the second end of the fourth resistor R4.
In the present embodiment, the protection execution circuit 20 includes: a sixth resistor R6, a seventh resistor R7, a first power tube T1, a second power tube T2 and a third capacitor C3;
a first end of the sixth resistor R6 is connected to the power VCC, a first end of the third capacitor C3, and an input end of the second power transistor T2, a second end of the sixth resistor R6 is connected to a second end of the third capacitor C3, a first end of the seventh resistor R7, and a control end of the second power transistor T2, a second end of the seventh resistor R7 is connected to an input end of the first power transistor T1, a control end of the first power transistor T1 is connected to a second end of the fourth resistor, a first end of the fifth resistor R5, and a first end of the second capacitor C2, an output end of the second power transistor T2 is connected to the load, and an output end of the first power transistor T1 is connected to the ground GND.
It should be understood that in the present embodiment, the first power transistor T1 and the second power transistor T2 are both NMOS transistors. When the voltage between the grid electrode and the source electrode of the NMOS tube is larger than the breakover voltage of the NMOS tube, the NMOS tube is conducted. The third capacitor C3 is a filter capacitor.
When the stepped-down power supply voltage Vth is smaller than the threshold voltage Vref, the control chip U1 outputs an on/off state, and at this time, a high-level power supply signal is output to the gate of the first power transistor T1 at the second end of the fourth resistor R4, and the voltage between the gate and the source of the first power transistor T1 is Vgs VCC R5/(R3+ R4+ R5) (2). When the voltage Vgs between the gate and the source of the first power transistor T1 is smaller than the turn-on voltage of the first power transistor T1, the first power transistor T1 is turned off and directly causes the second power transistor T2 to be turned off, the output value of the voltage Vout input to the load is 0, and the load does not operate. When the voltage Vgs between the gate and the source of the first power transistor T1 is greater than the turn-on voltage of the first power transistor T1, the first power transistor T1 and the second power transistor T2 are turned on, the value of the voltage Vout input to the load is approximately equal to the power supply voltage VCC, and the load enters a normal operating state.
Therefore, in a normal operation state (no undervoltage or overvoltage state), the resistances of the fourth resistor R4 and the fifth resistor R5 should be properly adjusted, and the voltage value of the power supply signal output by the second terminal of the fourth resistor R4 should be greater than the turn-on voltage of the first power transistor T1. In addition, when the power voltage Vth after the voltage reduction of the first resistor R1 and the second resistor R2 is smaller than the threshold voltage Vref, the power tube T1 can be set to be in the blocking state by adjusting the resistance values of the fourth resistor R4 and the fifth resistor R5, so as to set the power voltage under-voltage range
When the stepped-down power voltage Vth is greater than the threshold voltage Vref, the power VCC is directly grounded in the control chip U1 through the third resistor R3, and at this time, the second end of the fourth resistor R4 outputs a low-level overvoltage protection signal to the gate of the first power transistor T1, and due to the voltage division effect of the control chip U1, the voltage Vka at the two ends of the fourth resistor R4 and the fifth resistor R5 is a voltage with a very small voltage value. The voltage input to the gate of the first power transistor T1 at this time is Vgs-V KA R5/(R5+ R4) (3). At this time, the voltage Vgs input to the gate of the first power transistor T1 is set to be smaller than the driving voltage of the first power transistor T1, the first power transistor T1 and the second power transistor T2 are turned off, the voltage Vout output to the load is 0, the load does not operate, and the overvoltage protection mode is entered.
When the stepped-down power voltage Vth is approximately equal to the threshold voltage Vref, the first resistor R1 and the second resistor R2 integrated inside the control chip U1 determine the voltage value accuracy and the hysteresis threshold of the overvoltage protection. In this embodiment, the model selection of the control chip U1 can be performed by selecting SGM431B as an example, the threshold voltage Vref is 2.5V, and the accuracy of the threshold voltage Vref is 0.5%. Assuming that the accuracy of the resistance values of the first resistor R1 and the second resistor R2 is ± X%, the preset voltage of the overvoltage protection is Vop, which can be defined as V ref X (R1+ R2)/R2(4) to calculate an ideal value. After the precision errors of the control chip U1, the first resistor R1 and the second resistor R2 are combined, the range of the preset voltage of the overvoltage protection is Vop (Min-Max) Vop (Min-Max) ＝V ref *(1±0.5％)×(R1+R2)*(1±X％)/[R2×(1±X％)](5) Simplified Vop (Min-Max) ＝V ref ×(1±0.5％)×(1+R1*(1±2X％)/R2)，
Since (1+ R1 (1 ± 2X%)/R2) < (R1+ R2) (1 ± 2X%)/(R2) ((1 ± 2X%)), that is, the compound was obtained
Vop (Min-Max) ＜V ref ×(1+R1/R2)×(1±0.5％)×(1±2X％) (6)。
The Vop is obtained by substituting the above formula (4) into the above formula (6) (Min-Max) < Vop X (1. + -. 0.5%) × (1. + -. 2X%) (7). When the accuracy of the resistance values of the first resistor R1 and the second resistor R2 is +/-5%, the preset overvoltage protection is obtained by the formula (7)The voltage range is Vop +/-10.55%; when the accuracy of the resistance values of the first resistor R1 and the second resistor R2 is +/-1%, the preset voltage range of the overvoltage protection is Vop +/-2.51% obtained by the formula (7); when the accuracy of the selected resistances of the first resistor R1 and the second resistor R2 is +/-0.1%, the preset voltage range of the overvoltage protection is Vop +/-0.701% according to the formula (7). The precision of the designed overvoltage protection value Vop is mainly determined by a control chip U1, a first resistor R1 and a second resistor R2, and the high-precision overvoltage protection design can be realized through type selection.
Referring to fig. 4, in this embodiment, the control chip U1 includes: a first comparator a1, a first transistor Q1, and a first diode D1;
a first input end of the first comparator a1 is connected to the second end of the first resistor R1, the first end of the second resistor R2, and the first end of the first capacitor C1, a second input end of the first comparator a1 is connected to a threshold power source Vref, an output end of the first comparator a1 is connected to a base of the first triode Q1, a collector of the first triode Q1 is connected to the second end of the third resistor R3, the first end of the fourth resistor R4, and a cathode of the first diode D1, and an emitter of the first triode Q1 is grounded to the anode of the first diode D1.
In a specific implementation, the stepped-down power voltage Vth output by the second end of the first resistor R1 is input to the positive input end of the first comparator a1, the threshold voltage Vref is input to the negative input end of the first comparator a1, when the stepped-down power voltage Vth is greater than the threshold voltage Vref, the output end of the first comparator a1 outputs a high-level signal, the first triode Q1 is turned on, and the power voltage VCC is grounded through the third resistor R3 and the first triode Q1; when the stepped-down power voltage Vth is smaller than the threshold voltage Vref, the output terminal of the first comparator a1 outputs a low level signal, at this time, the first triode Q1 is turned off, the power voltage VCC is grounded through the third resistor R3, the fourth resistor R4, and the fifth resistor R5, a high level power supply signal is input to the second terminal of the fourth resistor R4, the first power tube T1 and the second power tube T2 are turned on, and the power supply VCC can output the power voltage to a load through the second power tube T2.
In this embodiment, the overvoltage protection circuit further includes: a voltage stabilizing circuit 40;
the voltage stabilizing circuit 40 is connected to the power source VCC through the protection execution circuit 20.
Referring to fig. 3, in the present embodiment, the voltage stabilizing circuit 40 includes a fourth capacitor C4, a first terminal of the fourth capacitor C4 is connected to the source of the second power transistor T2, and a second terminal of the fourth capacitor C4 is grounded.
In a specific implementation, the voltage stabilizing circuit 40 may stabilize the power voltage output by the power VCC through the charge-discharge characteristics of the fourth capacitor C4. In addition, the C3 can be adjusted according to the capacitance value parameter of the C4 to realize the slow start function, so as to prevent the abnormal circuit operation caused by the overlarge capacitive load of the rear stage of the Vout during the power-on transient state and provide stable power voltage for the load
In this embodiment, an overvoltage protection circuit is provided, which includes: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit; the overvoltage control circuit is respectively connected with a power supply and the protection execution circuit, and the protection execution circuit is connected with a load; when the power supply voltage output by the power supply is greater than a preset voltage, the overvoltage control circuit outputs an overvoltage protection signal to the protection execution circuit; and when receiving the overvoltage protection signal, the protection execution circuit disconnects a loop between the power supply and the load and stops supplying power to the load. In this embodiment, when the power supply voltage is greater than the preset voltage, the overvoltage protection signal is output to control the cut-off of the first power tube and the second power tube, and a loop between the power supply and the load is disconnected to protect the load.
In order to achieve the above object, the present invention also provides an overvoltage protection device, which includes an overvoltage protection circuit as described above. The specific structure of the overvoltage protection circuit refers to the above embodiments, and since the overvoltage protection device adopts all technical solutions of all the above embodiments, all beneficial effects brought by the technical solutions of the above embodiments are at least achieved, and are not repeated herein.
In order to achieve the above object, the present invention also provides an overvoltage protection system, which comprises the overvoltage protection device as described above. The specific structure of the overvoltage protection device refers to the above embodiments, and since the overvoltage protection system adopts all technical solutions of all the above embodiments, all beneficial effects brought by the technical solutions of the above embodiments are at least achieved, and are not described in detail herein.
The above is only the preferred embodiment of the present invention, and not the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings or the direct or indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (7)
1. An overvoltage protection circuit, characterized in that the overvoltage protection circuit comprises: the overvoltage protection circuit comprises an overvoltage control circuit and a protection execution circuit;
the overvoltage control circuit is respectively connected with a power supply and the protection execution circuit, and the protection execution circuit is connected with a load;
the overvoltage protection circuit further comprises: a voltage detection circuit;
the voltage detection circuit is used for detecting the power supply voltage output by the power supply and outputting a voltage abnormal signal to the overvoltage control circuit when the power supply voltage is greater than a preset voltage;
the overvoltage control circuit is used for outputting an overvoltage protection signal to the protection execution circuit when receiving the voltage abnormal signal;
the protection execution circuit is used for disconnecting a loop between the power supply and the load and stopping supplying power to the load when receiving the overvoltage protection signal;
the voltage detection circuit includes: the circuit comprises a first resistor, a second resistor and a first capacitor;
the first end of the first resistor is connected with the power supply, the second end of the first resistor is respectively connected with the first end of the second resistor, the first end of the first capacitor and the overvoltage control circuit, and the second end of the second resistor and the second end of the first capacitor are grounded;
the overvoltage control circuit includes: the circuit comprises a third resistor, a fourth resistor, a fifth resistor, a control chip and a second capacitor;
the first end of the third resistor is connected with the power supply, the second end of the third resistor is connected with the first end of the control chip and the first end of the fourth resistor, the second end of the control chip is connected with the second end of the first resistor, the first end of the second resistor and the first end of the first capacitor, the second end of the fourth resistor is connected with the first end of the fifth resistor, the first end of the second capacitor and the protection execution circuit, and the third end of the control chip, the second end of the fifth resistor and the second end of the second capacitor are grounded.
2. The overvoltage protection circuit of claim 1, wherein the voltage detection circuit is further configured to output an operation signal to the overvoltage control circuit when the power supply voltage is less than the predetermined voltage;
the overvoltage control circuit is used for outputting a power supply signal to the protection execution circuit when receiving the operation signal;
and the protection execution circuit is used for conducting a loop between the power supply and the load to supply power to the load when receiving the power supply signal.
3. The overvoltage protection circuit of claim 2, wherein the protection enforcement circuit comprises: the power supply comprises a sixth resistor, a seventh resistor, a first power tube, a second power tube and a third capacitor;
the first end of the sixth resistor is connected with the power supply, the first end of the third capacitor and the input end of the second power tube, the second end of the sixth resistor is connected with the second end of the third capacitor, the first end of the seventh resistor and the control end of the second power tube, the second end of the seventh resistor is connected with the input end of the first power tube, the control end of the first power tube is connected with the second end of the fourth resistor, the first end of the fifth resistor and the first end of the second capacitor, the output end of the second power tube is connected with the load, and the output end of the first power tube is grounded.
4. The overvoltage protection circuit of claim 3, wherein the control chip comprises: the first comparator, the first triode and the first diode;
the first input end of the first comparator is connected with the second end of the first resistor, the first end of the second resistor and the first end of the first capacitor respectively, the second input end of the first comparator is connected with a threshold power supply, the output end of the first comparator is connected with the base electrode of the first triode, the collector electrode of the first triode is connected with the second end of the third resistor, the first end of the fourth resistor and the cathode of the first diode respectively, and the emitter electrode of the first triode is grounded with the anode of the first diode.
5. The overvoltage protection circuit of claim 4, wherein the overvoltage protection circuit further comprises: a voltage stabilizing circuit;
the voltage stabilizing circuit is connected with the power supply through the protection execution circuit;
the voltage stabilizing circuit is used for stabilizing the power supply voltage output by the power supply and providing stable power supply voltage for the load.
6. An overvoltage protection device, characterized in that the overvoltage protection device comprises an overvoltage protection circuit according to any one of claims 1-5.
7. An overvoltage protection system, characterized in that the overvoltage protection system comprises an overvoltage protection device according to claim 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123447500.4U CN217486154U (en) | 2021-12-31 | 2021-12-31 | Overvoltage protection circuit, device and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202123447500.4U CN217486154U (en) | 2021-12-31 | 2021-12-31 | Overvoltage protection circuit, device and system |
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| Publication Number | Publication Date |
|---|---|
| CN217486154U true CN217486154U (en) | 2022-09-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202123447500.4U Active CN217486154U (en) | 2021-12-31 | 2021-12-31 | Overvoltage protection circuit, device and system |
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| Country | Link |
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| CN (1) | CN217486154U (en) |
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