Overvoltage protection circuit
By using a protection circuit composed of fuses, resistors, voltage regulators, transistors and thyristors in low-voltage electronic circuits, the thermal failure problem of voltage regulators under long-term overvoltage pulses is solved, and the reliable protection and safety of the circuit are improved.
Patent Information
- Application Number
- CN202421511449.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-28
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-06-28
AI Technical Summary
In existing low-voltage electronic circuits, the voltage regulator tube is prone to overheating, burning or explosion when facing long-term overvoltage pulses, and cannot reliably protect the sudden overvoltage event for a long time.
The protection circuit consisting of fuses, resistors, voltage regulators, transistors and thyristors is used. After the voltage regulator is turned on, the transistors and thyristors are short-circuited, and the fuses are fused to protect the circuit from heat damage.
It realizes a reliable protection circuit during overvoltage, avoids thermal failure of the voltage regulator tube, adapts to wide pulse width overvoltage, and improves the reliability and safety of the circuit.
Smart Images
Figure CN223181795U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of circuit protection, in particular to an overvoltage protection circuit. Background Art
[0002] In the field of electronic circuit design, short-term overvoltage generated by electromagnetic interference has always been a design difficulty, and often there are pulse overvoltages of unknown origin that cause circuit damage.
[0003] For short-term pulse overvoltages (such as those caused by electromagnetic interference) in low-voltage electronic circuits with ≤ 36V, at present, zener diodes are mostly selected for treatment, but the disadvantage of zener diodes is that the conduction time cannot be too long. Existing zener diode protection schemes have a "thermal failure bottleneck" because they need to continuously conduct to absorb energy:
[0004] (1) When the duration of the overvoltage pulse > the transient thermal tolerance time of the zener diode (usually < 1ms), it will inevitably overheat and burn out or explode;
[0005] (2) The thermal capacity of low-voltage zener diodes is extremely small, further amplifying this risk;
[0006] (3) It cannot reliably protect sudden overvoltage events with a long duration (> 1ms).
[0007] Therefore, there is an urgent need for an overvoltage protection circuit that can avoid the thermal failure of zener diodes, adapt to low-voltage scenarios, and can cover overvoltages with a wide pulse width. Summary of the Invention
[0008] The technical problem to be solved by the utility model is: in view of the above problems, to provide an overvoltage protection circuit.
[0009] The technical solution adopted by the utility model is: an overvoltage protection circuit, characterized by comprising: a fuse F1, a resistor R1, a resistor R2, a zener diode Q1, a triode Q2, and a thyristor Q3. The positive pole and the negative pole of the power supply are sequentially connected in series with the fuse F1, the resistor R1, and the resistor R2. The connection end between the resistor R2 and the resistor R1 is connected to the cathode of the zener diode Q1, and the connection end between the resistor R2 and the negative pole of the power supply is connected to the anode of the zener diode Q1;
[0010] The emitter of the triode Q2 is connected to the connection end between the fuse F1 and the resistor R1, the base of the triode Q2 is connected to the cathode of the zener diode Q1, and the collector of the triode Q2 is connected to the anode of the zener diode Q1;
[0011] The anode of the thyristor Q3 is connected to the emitter of the triode Q2, and the gate and the cathode of the thyristor Q3 are both connected to the collector of the triode Q2;
[0012] The anode of thyristor Q3 can be connected to the positive terminal of the external circuit, and the cathode of thyristor Q3 can be connected to the negative terminal of the external circuit.
[0013] In some embodiments, a resistor R3 is connected in series between the cathode of the voltage regulator diode Q1 and the base of the triode Q2.
[0014] In some embodiments, a capacitor C1 is connected between the base and the emitter of the triode Q2.
[0015] In some embodiments, the collector of the triode Q2 is connected to the negative pole of the power supply through a resistor R4. The connection terminal between the resistor R4 and the triode Q2 is connected to the gate of the thyristor Q3, and the connection terminal between the resistor R4 and the negative pole of the power supply is connected to the cathode of the thyristor Q3.
[0016] In some embodiments, when an overvoltage Vccm appears in the circuit, the potential difference between the cathode and the anode of the voltage regulator diode Q1 is Uq1 = R2 * Vccm / (R1 + R2).
[0017] Another technical solution adopted by the present utility model is: an overvoltage protection circuit, which is characterized by comprising: a fuse F1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a voltage regulator diode Q1, a triode Q2 and a thyristor Q3. A fuse F1, a resistor R1 and a resistor R2 are connected in series between the positive and negative poles of the power supply. The connection terminal between the resistor R2 and the resistor R1 is the first end of the resistor R2, and the connection terminal between the resistor R2 and the negative pole of the power supply is the second end of the resistor R2;
[0018] A voltage regulator diode Q1 is connected in parallel across the two ends of the resistor R2. The cathode of the voltage regulator diode Q1 is connected to the first end of the resistor R2, and the anode of the voltage regulator diode Q1 is connected to the second end of the resistor R2;
[0019] The base of the triode Q2 is connected to the first end of the resistor R2 through a resistor R3. The emitter of the triode Q2 is connected to the connection terminal between the fuse F1 and the resistor R1. The collector of the triode Q2 is connected to the second end of the resistor R2 through a resistor R4. A capacitor C1 is connected between the base and the emitter of the triode Q2;
[0020] The anode of the thyristor Q3 is connected to the emitter of the triode Q2. The cathode of the thyristor Q3 is connected to the second end of the resistor R2. The gate of the thyristor Q3 is connected to the collector of the triode Q2. The anode of the thyristor Q3 is connected to the anode of the output terminal of the external circuit, and the cathode of the thyristor Q3 is connected to the negative pole of the output terminal of the external circuit.
[0021] In some embodiments, when an overvoltage Vccm appears in the circuit, the potential difference between the cathode and the anode of the voltage regulator diode Q1 is Uq1 = R2 * Vccm / (R1 + R2).
[0022] The beneficial effects of the present utility model are as follows:
[0023] 1. When the overvoltage Vccm in the circuit exceeds the conduction voltage of the voltage stabilizing diode Q1, the voltage stabilizing diode Q1 conducts, the voltage at the base of the triode Q2 decreases, and the triode Q2 then conducts, causing the gate voltage of the thyristor Q3 to rise to make the thyristor Q3 conduct. After conduction, the thyristor shorts the power supply side, and the fuse F1 then fuses, thereby protecting the circuit connected to the output end.
[0024] 2. The voltage stabilizing diode Q1 only conducts in the initial stage, without absorbing the heat during the voltage absorption process, and there is no threat of overheating and explosion. Description of the Drawings
[0025] Figure 1 is the circuit structure diagram of the present application.
[0026] Figure 2 is the circuit schematic diagram of the present application.
[0027] This specification includes references to "one embodiment" or "embodiments". The appearance of the phrase "in one embodiment" or "in embodiments" does not necessarily refer to the same embodiment. Specific features, structures, or characteristics may be combined in any suitable manner consistent with the present disclosure.
[0028] "Comprising", this term is open-ended. As used in the appended claims, this term does not exclude additional structures or steps.
[0029] "First", "second", etc. As used herein, these terms serve as labels for the nouns preceding them and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.). Detailed Embodiments
[0030] In order to enable those skilled in the art to better understand the solution of the present utility model, the technical solution of the present utility model will be further described below in conjunction with specific embodiments.
[0031] Embodiment 1:
[0032] Combined with Figure 1 and Figure 2 As shown, this embodiment is an overvoltage protection circuit, including: fuse F1, resistor R1, resistor R2, voltage stabilizing diode Q1, triode Q2, and thyristor Q3. A fuse F1, a resistor R1, and a resistor R2 are sequentially connected in series between the positive pole and the negative pole of the power supply. The connection end between the resistor R2 and the resistor R1 is connected to the cathode of the voltage stabilizing diode Q1, and the connection end between the resistor R2 and the negative pole of the power supply is connected to the anode of the voltage stabilizing diode Q1;
[0033] The emitter of the transistor Q2 is connected to the connection terminal between the fuse F1 and the resistor R1, the base of the transistor Q2 is connected to the cathode of the voltage regulator Q1, and the collector of the transistor Q2 is connected to the anode of the voltage regulator Q1;
[0034] The anode of the thyristor Q3 is connected to the emitter of the transistor Q2, and the gate and cathode of the thyristor Q3 are both connected to the collector of the transistor Q2;
[0035] The anode of the thyristor Q3 can be connected to the positive terminal of the external circuit, and the cathode of the thyristor Q3 can be connected to the negative terminal of the external circuit.
[0036] In some embodiments, a resistor R3 is connected in series between the cathode of the voltage regulator Q1 and the base of the transistor Q2.
[0037] In some embodiments, a capacitor C1 is connected between the base and emitter of the transistor Q2 .
[0038] In some embodiments, the collector of transistor Q2 is connected to the negative power supply via resistor R4, the connection between resistor R4 and transistor Q2 is connected to the gate of thyristor Q3, and the connection between resistor R4 and the negative power supply is connected to the cathode of thyristor Q3.
[0039] In some embodiments, if an overvoltage Vccm appears in the circuit, the potential difference between the cathode and anode of the voltage regulator Q1 is Uq1=R2*Vccm / (R1+R2).
[0040] Example 2:
[0041] This embodiment is an overvoltage protection circuit, comprising: a fuse F1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a capacitor C1, a voltage regulator Q1, a transistor Q2, and a thyristor Q3. The fuse F1, the resistor R1, and the resistor R2 are connected in series between the positive and negative electrodes of a power supply. The connection end between the resistor R2 and the resistor R1 serves as a first end of the resistor R2, and the connection end between the resistor R2 and the negative electrode of the power supply serves as a second end of the resistor R2.
[0042] A voltage regulator Q1 is connected in parallel to both ends of the resistor R2, the cathode of the voltage regulator Q1 is connected to the first end of the resistor R2, and the anode of the voltage regulator Q1 is connected to the second end of the resistor R2;
[0043] The base of the transistor Q2 is connected to the first end of the resistor R2 via the resistor R3, the emitter of the transistor Q2 is connected to the connection end between the fuse F1 and the resistor R1, the collector of the transistor Q2 is connected to the second end of the resistor R2 via the resistor R4, and a capacitor C1 is connected between the base and emitter of the transistor Q2;
[0044] The anode of thyristor Q3 is connected to the emitter of triode Q2, the cathode of thyristor Q3 is connected to the second end of resistor R2, the gate of thyristor Q3 is connected to the collector of triode Q2, the anode of thyristor Q3 is connected to the anode of the external circuit output terminal, and the cathode of thyristor Q3 is connected to the negative pole of the external circuit output terminal.
[0045] In some embodiments, when an overvoltage Vccm appears in the circuit, the potential difference between the cathode and anode of zener diode Q1 is Uq1 = R2 * Vccm / (R1 + R2).
[0046] Embodiment The implementation principle of an overvoltage protection circuit is as follows:
[0047] When an overvoltage Vccm appears in the circuit, the potential difference between the cathode and anode of zener diode Q1 is Uq1 = R2 * Vccm / (R1 + R2). When Uq1 exceeds the conduction voltage of zener diode Q1, zener diode Q1 conducts, the base voltage of triode Q2 drops to zero, and then triode Q2 conducts, raising the gate voltage of thyristor Q3 to Vccm. As a result, thyristor Q3 conducts and shorts the power supply side, and fuse F1 immediately blows, further protecting the circuit connected to the output terminal.
[0048] By shorting the power supply terminal when an overvoltage appears in the circuit, the circuit at the output terminal can be reliably protected. Moreover, zener diode Q1 only conducts in the initial stage, without the need to absorb heat during the overvoltage process, and there is no threat of heat generation and explosion. All devices in the device are analog devices, and the reliability is relatively high.
[0049] The above are all the preferred embodiments of the present invention, and the protection scope of the present invention is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.
Claims
1. An overvoltage protection circuit, characterized in that, Comprising: Fuse F1, resistor R1, resistor R2, zener diode Q1, triode Q2 and thyristor Q3. Between the positive pole and the negative pole of the power supply, fuse F1, resistor R1 and resistor R2 are connected in series in sequence. The connection terminal between resistor R2 and resistor R1 is connected to the cathode of zener diode Q1, and the connection terminal between resistor R2 and the negative pole of the power supply is connected to the anode of zener diode Q1; The emitter of triode Q2 is connected to the connection terminal between fuse F1 and resistor R1, the base of triode Q2 is connected to the cathode of zener diode Q1, and the collector of triode Q2 is connected to the anode of zener diode Q1; The anode of thyristor Q3 is connected to the emitter of triode Q2, and the gate and cathode of thyristor Q3 are both connected to the collector of triode Q2; The anode of thyristor Q3 can be connected to the positive extreme of the external circuit, and the cathode of thyristor Q3 can be connected to the negative extreme of the external circuit.
2. The overvoltage protection circuit according to claim 1, wherein: A resistor R3 is connected in series between the cathode of the zener diode Q1 and the base of the triode Q2.
3. The overvoltage protection circuit according to claim 2, characterized in that: A capacitor C1 is connected between the base and the emitter of the triode Q2.
4. An overvoltage protection circuit according to claim 1, characterized in that: The collector of the triode Q2 is connected to the negative pole of the power supply through a resistor R4. The connection terminal between resistor R4 and the triode Q2 is connected to the gate of the thyristor Q3, and the connection terminal between resistor R4 and the negative pole of the power supply is connected to the cathode of the thyristor Q3.
5. An overvoltage protection circuit according to any one of claims 1 to 4, characterized in that: If an overvoltage Vccm appears in the circuit, the potential difference between the cathode and the anode of the zener diode Q1 is Uq1 = R2 * Vccm / (R1 + R2).
6. An overvoltage protection circuit, characterized in that, Comprising: Fuse F1, resistor R1, resistor R2, resistor R3, resistor R4, capacitor C1, zener diode Q1, triode Q2 and thyristor Q3. Between the positive and negative poles of the power supply, fuse F1, resistor R1 and resistor R2 are connected in series in sequence. The connection terminal between resistor R2 and resistor R1 is the first end of resistor R2, and the connection terminal between resistor R2 and the negative pole of the power supply is the second end of resistor R2; A zener diode Q1 is connected in parallel across the two ends of resistor R2. The cathode of zener diode Q1 is connected to the first end of resistor R2, and the anode of zener diode Q1 is connected to the second end of resistor R2; The base of triode Q2 is connected to the first end of resistor R2 through a resistor R3. The emitter of triode Q2 is connected to the connection terminal between fuse F1 and resistor R1. The collector of triode Q2 is connected to the second end of resistor R2 through a resistor R4. A capacitor C1 is connected between the base and the emitter of triode Q2; The anode of thyristor Q3 is connected to the emitter of triode Q2, the cathode of thyristor Q3 is connected to the second end of resistor R2, the gate of thyristor Q3 is connected to the collector of triode Q2, the anode of thyristor Q3 is connected to the anode of the output terminal of the external circuit, and the cathode of thyristor Q3 is connected to the negative pole of the output terminal of the external circuit.
7. An overvoltage protection circuit according to claim 6, characterized in that: If an overvoltage Vccm appears in the circuit, the potential difference between the cathode and the anode of the zener diode Q1 is Uq1 = R2 * Vccm / (R1 + R2).