CN112952741A - Self-locking protection circuit with unlocking switch for overvoltage protection - Google Patents
Self-locking protection circuit with unlocking switch for overvoltage protection Download PDFInfo
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- CN112952741A CN112952741A CN202110215122.2A CN202110215122A CN112952741A CN 112952741 A CN112952741 A CN 112952741A CN 202110215122 A CN202110215122 A CN 202110215122A CN 112952741 A CN112952741 A CN 112952741A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/02—Details
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
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Abstract
A self-locking protection circuit with an unlocking switch for overvoltage protection comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a switch S1, a diode D1 and a comparator U1; the Vcc pin is respectively connected with one end of a first resistor R1, a third resistor R3 and a sixth resistor R6, the other end of the first resistor R1 is connected with a switch S1 and a second resistor R2 in parallel, the other end of the switch S1 and the other end of the second resistor R2 are connected with a GND pin in parallel, the other end of the third resistor R3 is connected with the negative input end of a comparator U1 and is also connected with the GND pin through a fourth resistor R4, Vo is connected with the cathode of a diode D1 through a fifth resistor R5 and is connected with the positive + input end of a comparator U1, and the other end of the sixth resistor R6 is connected with the anode of the diode D1 and the output end Protect pin of the comparator U1.
Description
Technical Field
The invention relates to the technical field of electronic product protection circuits, in particular to a self-locking protection circuit with an unlocking switch for overvoltage protection.
Background
Transient voltage overvoltages can severely damage integrated circuits, some small CMOS structure devices can handle very low voltages, transient or sustained overvoltage conditions can permanently damage devices, and therefore electronic products almost always design protection circuits. When some protection circuits output overvoltage, the circuits are protected, and when the output voltage is normal when the next switching period comes, the protection circuits are not protected; however, when the output voltage repeatedly jumps between the overvoltage and the normal state, the protection circuit also repeatedly acts, and in this case, components in the circuit are damaged.
Disclosure of Invention
The technical problem solved by the invention is as follows: aiming at the defects existing in the prior art, the self-locking protection circuit with the unlocking switch for overvoltage protection is provided, and the problem that the protection circuit cannot be self-locked due to repeated work caused by abnormal output overvoltage is solved.
The invention is realized by the following technical scheme: a self-locking protection circuit with an unlocking switch for overvoltage protection comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a switch S1, a diode D1 and a comparator U1;
a Vcc pin is respectively connected with one end of a first resistor R1, a third resistor R3 and a sixth resistor R6, the other end of the first resistor R1 is connected with a switch S1 and a second resistor R2 in parallel, the other end of the switch S1 and the other end of the second resistor R2 are connected with a GND pin in parallel, the other end of the third resistor R3 is connected with a negative input end of a comparator U1 and is also connected with the GND pin through a fourth resistor R4, Vo is connected with a cathode of a diode D1 through a fifth resistor R5 and is connected with a positive + input end of a comparator U1, and the other end of the sixth resistor R6 is connected with an anode of the diode D1 and a Protect pin of an output end of the comparator U1;
the Vcc pin is connected with a power supply end of the electronic product control circuit;
the Protect pin is connected with a protection trigger end of the electronic product control circuit;
and the GND pin is connected with the negative electrode of the direct current input of the electronic product or the public end of the alternating current input after rectification.
The first resistor (R1), the second resistor (R2), the third resistor (R3), the fourth resistor (R4) and the fifth resistor (R5) have the following relations: when the circuit works normally, R4/(R3+ R4) > R2/(R1+ R2); vo × (R1 × R2)/(R1+ R2)/[ R5+ (R1 × R2)/(R1+ R2) ] + Vcc × (R5 × R2)/(R5+ R2)/[ R1+ (R5 × R2)/(R5+ R2) ] > Vcc × R4/(R3+ R4) at the time of output overvoltage.
The invention has the beneficial effects that:
when the existing circuit is used, the circuit is in a repeated switching state of working and protection due to repeated oscillation at the critical value of overvoltage, so that the circuit and devices are easily damaged; the invention provides a self-locking protection circuit with an unlocking switch for overvoltage protection, which can protect and lock a circuit when the circuit has a first fault, maintain a protection state before the fault is eliminated, and manually unlock the circuit through the switch after the fault is eliminated.
Drawings
FIG. 1 is a schematic diagram of a typical implementation of an over-voltage protection circuit;
FIG. 2 is a self-locking protection circuit with an unlocking switch for overvoltage protection provided by the invention;
fig. 3 is an example of a self-locking protection circuit with an unlocking switch for overvoltage protection implemented by the present invention.
Detailed Description
The method for implementing the multi-spacecraft series state detection circuit of the invention will be further explained with reference to fig. 1 to 3. 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 invention relates to a self-locking protection circuit with an unlocking switch for overvoltage protection, which comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a switch S1, a diode D1 and a comparator U1;
a Vcc pin is respectively connected with one end of a first resistor R1, a third resistor R3 and a sixth resistor R6, the other end of the first resistor R1 is connected with a switch S1 and a second resistor R2 in parallel, the other end of the switch S1 and the other end of the second resistor R2 are connected with a GND pin in parallel, the other end of the third resistor R3 is connected with a negative input end of a comparator U1 and is also connected with the GND pin through a fourth resistor R4, Vo is connected with a cathode of a diode D1 through a fifth resistor R5 and is connected with a positive + input end of a comparator U1, and the other end of the sixth resistor R6 is connected with an anode of the diode D1 and a Protect pin of an output end of the comparator U1;
the Vcc pin is connected with a power supply end of the electronic product control circuit;
the Protect pin is connected with a protection trigger end of the electronic product control circuit;
and the GND pin is connected with the negative electrode of the direct current input of the electronic product or the public end of the alternating current input after rectification.
When the circuit works normally (the Vo pin is in a high-impedance state), the voltages of the positive and negative input ends of the comparator U1 are respectively U + ═ Vcc xR 2/(R1+ R2) and U- ═ Vcc xR 4/(R3+ R4), the U + < U-in a default state is realized by setting resistor voltage division, and at the moment, the comparator U1 outputs a Protect signal as a low level, so that the circuit does not need self-locking protection; when the output voltage of the circuit is over-voltage, U + - [ Vox (R1 xR 2)/(R1+ R2)/[ R5+ (R1 xR 2)/(R1+ R2) ] + Vcc x (R5 xR 2)/(R5+ R2)/[ R1+ (R5 xR 2)/(R5+ R2) ], the output of the comparator is in a high-resistance state, Vcc pulls up U + through D1 to enable U + > U-to be kept, the output signal of the comparator keeps a high level, and the circuit realizes protection self-locking; when the fault is removed through the checking circuit, the switch S1 can be closed to forcibly pull the U + to zero, at the moment, the U + < U-, and the comparator outputs a Protect signal to recover to a low level, so that the circuit is unlocked and recovers to normal work.
In conclusion, when the U + is less than the U-, the circuit works normally; when U + is over U-, the circuit is over-voltage self-locking protection. Therefore, the resistances of the resistors R1, R2, R3, R4, R5 and R6 are reasonably selected, so that R4/(R3+ R4) > R2/(R1+ R2) is ensured during normal operation; when overvoltage is output, Vo x (R1 xR 2)/(R1+ R2)/[ R5+ (R1 xR 2)/(R1+ R2) ] + Vcc x (R5 xR 2)/(R5+ R2)/[ R1+ (R5 xR 2)/(R5+ R2) ] > Vcc xR 4/(R3+ R4), and the overvoltage self-locking protection function can be realized. The self-locking protection circuit with the unlocking switch for overvoltage protection can be realized by the following steps:
step 1: the magnitude of the power supply voltage Vcc is determined.
Step 2: the resistances of the resistors R1, R2, R3, R4, R5 and R6 are selected to be appropriate such that R4/(R3+ R4) > R2/(R1+ R2) and Vo × (R1 × R2)/(R1+ R2)/[ R5+ (R1 × R2)/(R1+ R2) ] + Vcc × (R5 × R2)/(R5+ R2)/[ R1+ (R5 × R2)/(R5+ R2) ] > Vcc × R4/(R3+ R4).
As shown in fig. 1, in the prior art, when the circuit normally operates, the output feedback end Vo is in a high impedance state, the positive and negative input ends of the comparator are obtained by dividing the voltage of the power supply Vcc by R1, R2, R3, and R4, at this time, U + < U —, that is, the protection signal output by the comparator U1 is in a low level, and the circuit is not protected.
When the output feedback end Vo of the circuit is over-voltage, at the moment, U < + > U < - >, the comparator U1 outputs a Protect signal as high level, the circuit is protected, and the circuit stops working. When the output feedback end Vo fluctuates greatly and oscillates repeatedly at the critical value of overvoltage, the circuit is in a repeated switching state of working and protection, and the circuit and devices are easily damaged.
As shown in fig. 2, when the circuit is in normal operation (the Vo pin is in a high impedance state), voltages of positive and negative input terminals of the comparator U1 are U + ═ Vcc × R2/(R1+ R2), and U- ═ Vcc × R4/(R3+ R4), respectively, and the comparator U1 outputs a Protect signal at a low level at this time in a default state by setting a resistance voltage division, so that the circuit does not need self-locking protection.
When the output voltage of the circuit is overvoltage, U + - [ Vox (R1 × R2)/(R1+ R2)/[ R5+ (R1 × R2)/(R1+ R2) ] + Vcc × (R5 × R2)/(R5+ R2)/[ R1+ (R5 × R2)/(R5+ R2) ], at the moment, the output of the comparator is in a high-impedance state, Vcc pulls up U + through D1 to enable U + > U-to be kept, the output signal of the comparator keeps a high level, and the circuit achieves protection self-locking; when the fault is removed through the checking circuit, the switch S1 can be closed to forcibly pull the U + to zero, at the moment, the U + < U-, and the comparator outputs a Protect signal to recover to a low level, so that the circuit is unlocked and recovers to normal work.
In conclusion, when the U + is less than the U-, the circuit works normally; when U + is over U-, the circuit is over-voltage self-locking protection. Therefore, the resistances of the resistors R1, R2, R3, R4, R5 and R6 are reasonably selected, so that R4/(R3+ R4) > R2/(R1+ R2) is ensured during normal operation; when overvoltage is output, Vo x (R1 xR 2)/(R1+ R2)/[ R5+ (R1 xR 2)/(R1+ R2) ] + Vcc x (R5 xR 2)/(R5+ R2)/[ R1+ (R5 xR 2)/(R5+ R2) ] > Vcc xR 4/(R3+ R4), and the overvoltage self-locking protection function can be realized. It is obvious that the functions implemented in fig. 2 include the functions implemented in fig. 1, and therefore, the present invention has a wider application field.
EXAMPLE III
As shown in fig. 3, the Vcc supplied by the power supply is 15V, the values of the resistors R1, R3, R4 and R5 are 100k Ω, the value of the resistor R2 is 51k Ω, the value of the resistor R6 is 5.1k Ω, and the model of the comparator U1 is LM 193.
When the circuit normally works, U < + > approximately equals 5.07V and U < - > approximately equals 7.5V are obtained according to the voltage division, so that U < + > U < - >, the output signal Protect of the comparator approximately equals 150mV, and the protection circuit does not work.
When the circuit output voltage is over-voltage, if the feedback signal Vo is 16V, U + ≈ 7.827, U-7.5V, therefore U + > U-, and the comparator output signal Protect is 15V, and the protection circuit works. Meanwhile, the D1 is conducted in the forward direction, the U + is forcibly pulled high to maintain, the protection circuit is self-locked, the circuit maintains a protection state and is not influenced by the output feedback signal Vo, and the circuit and the device can be prevented from being damaged when being repeatedly turned on and turned off.
After the fault is eliminated, the switch S1 can be manually closed, at the moment, the U + grounding is forced to be zero, therefore, the output signal Protect of the comparator is approximately equal to 150mV, the protection circuit is unlocked, and the protection circuit can normally work after being electrified again.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. While the present disclosure has been described in detail with reference to the preferred embodiments thereof, it will be understood that the foregoing description is not to be construed as limiting the present disclosure, but is intended to cover various changes and modifications within the spirit and scope of the present disclosure. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (2)
1. A self-locking protection circuit with an unlocking switch for overvoltage protection is characterized by comprising a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a switch S1, a diode D1 and a comparator U1;
a Vcc pin is respectively connected with one end of a first resistor R1, a third resistor R3 and a sixth resistor R6, the other end of the first resistor R1 is connected with a switch S1 and a second resistor R2 in parallel, the other end of the switch S1 and the other end of the second resistor R2 are connected with a GND pin in parallel, the other end of the third resistor R3 is connected with a negative input end of a comparator U1 and is also connected with the GND pin through a fourth resistor R4, Vo is connected with a cathode of a diode D1 through a fifth resistor R5 and is connected with a positive + input end of a comparator U1, and the other end of the sixth resistor R6 is connected with an anode of the diode D1 and a Protect pin of an output end of the comparator U1;
the Vcc pin is connected with a power supply end of the electronic product control circuit;
the Protect pin is connected with a protection trigger end of the electronic product control circuit;
and the GND pin is connected with the negative electrode of the direct current input of the electronic product or the public end of the alternating current input after rectification.
2. The self-locking protection circuit with an unlocking switch for overvoltage protection as claimed in claim 1, wherein said first resistor (R1), second resistor (R2), third resistor (R3), fourth resistor (R4) and fifth resistor (R5) have the following relations: when the circuit works normally, R4/(R3+ R4) > R2/(R1+ R2); vo × (R1 × R2)/(R1+ R2)/[ R5+ (R1 × R2)/(R1+ R2) ] + Vcc × (R5 × R2)/(R5+ R2)/[ R1+ (R5 × R2)/(R5+ R2) ] > Vcc × R4/(R3+ R4) at the time of output overvoltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110215122.2A CN112952741A (en) | 2021-02-25 | 2021-02-25 | Self-locking protection circuit with unlocking switch for overvoltage protection |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110215122.2A CN112952741A (en) | 2021-02-25 | 2021-02-25 | Self-locking protection circuit with unlocking switch for overvoltage protection |
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| Publication Number | Publication Date |
|---|---|
| CN112952741A true CN112952741A (en) | 2021-06-11 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110215122.2A Pending CN112952741A (en) | 2021-02-25 | 2021-02-25 | Self-locking protection circuit with unlocking switch for overvoltage protection |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202550472U (en) * | 2011-12-20 | 2012-11-21 | 北京汇能精电科技有限公司 | Pulse-by-pulse detection short circuit protective circuit |
| CN205960624U (en) * | 2016-08-18 | 2017-02-15 | 河北国耀新能源科技有限公司 | Switch power -supply overvoltage protecting circuit |
| CN206180563U (en) * | 2016-11-22 | 2017-05-17 | 亿嘉和科技股份有限公司 | Load current foldback circuit |
| CN209390030U (en) * | 2019-01-18 | 2019-09-13 | 洛阳隆盛科技有限责任公司 | A kind of comparator circuit locking output state |
-
2021
- 2021-02-25 CN CN202110215122.2A patent/CN112952741A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202550472U (en) * | 2011-12-20 | 2012-11-21 | 北京汇能精电科技有限公司 | Pulse-by-pulse detection short circuit protective circuit |
| CN205960624U (en) * | 2016-08-18 | 2017-02-15 | 河北国耀新能源科技有限公司 | Switch power -supply overvoltage protecting circuit |
| CN206180563U (en) * | 2016-11-22 | 2017-05-17 | 亿嘉和科技股份有限公司 | Load current foldback circuit |
| CN209390030U (en) * | 2019-01-18 | 2019-09-13 | 洛阳隆盛科技有限责任公司 | A kind of comparator circuit locking output state |
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Application publication date: 20210611 |