A high-voltage protection control circuit

Abstract

This utility model discloses a high-voltage protection control circuit, including a first connector CN1 and a second connector CN2. Between the first connector CN1 and the second connector CN2, there are also: a second Zener diode D2, a first Zener diode D1, a second transistor Q2, a first transistor Q1, a switching transistor Q3, a voltage divider resistor R8, and a step-down chip U1. This utility model utilizes the second Zener diode D2 and the first Zener diode D1 to implement the avalanche effect, directly driving the second transistor Q2 and the first transistor Q1, and delaying overvoltage response, resulting in a significant improvement in response speed. Furthermore, the combination of the second Zener diode D2, the first Zener diode D1, the second transistor Q2, the first transistor Q1, and the switching transistor Q3 implements a complete protection function, reducing the overall circuit area and achieving high circuit integration. Moreover, it eliminates the need for a dedicated IC chip for control, reducing production costs.

Description

Technical Field

[0001] This utility model relates to the field of power supply circuit technology, and in particular to a high voltage protection control circuit. Background Technology

[0002] With the rapid development of automation control technology, switching power supply circuits are widely used in controllers across various PCBA industries. Switching power supplies are becoming increasingly important in many fields, such as agricultural irrigation, industrial production, and smart home applications. Switching power supply output circuits also vary, and people have increasingly higher demands for quality of life and the user experience of electrical appliances. Overvoltage protection input voltage control is constantly being innovated, while also protecting and controlling the downstream MCU. This utility model proposes a high-voltage protection control circuit that outputs 24VDC from the switching power supply and controls the 24VDC output voltage to prevent overvoltage. The aim is to provide a new approach to solving this problem and promote the intelligent and efficient development of power supply technology. Summary of the Invention

[0003] This utility model aims to solve at least one of the technical problems existing in the prior art. Therefore, one objective of this utility model is to provide a high-voltage protection control circuit that provides immediate protection for the back-end MCU and load when abnormal high voltage input occurs; addresses the shortcomings of traditional overvoltage protection circuits, such as large size and slow response speed; and reduces the design complexity and production cost of the protection circuit.

[0004] This utility model also provides a high-voltage protection control circuit, including a first connector CN1 and a second connector CN2. Between the first connector CN1 and the second connector CN2, there are also: a second Zener diode D2, a first Zener diode D1, a second transistor Q2, a first transistor Q1, a switching transistor Q3, a voltage divider resistor R8, and a step-down chip U1.

[0005] The first connector CN1 and the second connector CN2 are respectively connected to the step-down chip U1.

[0006] The cathode of the second Zener diode D2 is connected to the second connector CN2, and the anode of the second Zener diode D2 is grounded through the voltage divider resistor R8; the base of the second transistor Q2 is connected to the junction of the anode of the second Zener diode D2 and the voltage divider resistor R8.

[0007] The anode of the first Zener diode D1 is connected to pin 2 of the first connector CN1, and the first Zener diode D1 is connected to the collector and emitter of the second transistor Q2.

[0008] The collector of the second transistor Q2 is connected to the base of the first transistor Q1; the emitter of the second transistor Q2 and the collector of the first transistor Q1 are both connected to the gate of the switching transistor Q3, and the emitter of the first transistor Q1 is connected to the source of the switching transistor Q3.

[0009] The switching transistor Q3 is connected to pin 1 of the first connector CN1, and the connection point between pins 1 and 2 of the second connector CN2 is connected to the +24V_org terminal. The negative terminal of the second Zener diode D2 is led out to the +5V_org terminal.

[0010] Specifically, the first connector CN1 has a first capacitor C1, a second capacitor C2, and a transient diode RV1 connected in parallel to pins 1 and 2, respectively. The first connector CN1 also has a fuse FU1 connected to pin 1, and the fuse FU1 has a +24V_in terminal connected to its end.

[0011] Specifically, the cathode of the first Zener diode D1 is connected to a fourth resistor R2, the fourth resistor R2 is connected to a second resistor R2 and a seventh resistor R7, the seventh resistor R7 is connected to a third resistor R3, and the seventh resistor R7 is also connected to the base of the first transistor Q1.

[0012] Furthermore, the emitter and collector of the first transistor Q1 are also connected to a fifth resistor R5.

[0013] Specifically, the source (S) terminal of the switching transistor Q3 is connected to a sixth resistor R6.

[0014] Furthermore, the input terminal of the step-down chip U1 is also connected in parallel with a first electrolytic capacitor EC1 and a third capacitor C3.

[0015] Furthermore, the output terminal of the step-down chip U1 is also connected to a third Zener diode D3, and the third Zener diode D3 is also connected to an inductor L1.

[0016] Specifically, a second electrolytic capacitor EC2, a fourth capacitor C4, and a fifth capacitor C5 are connected in parallel between one end of the inductor L1 and the anode of the fourth capacitor C4.

[0017] This utility model achieves significant improvements through the above technical means, and the specific beneficial effects are as follows.

[0018] I. By utilizing the second Zener diode D2 and the first Zener diode D1 to implement the avalanche effect, the second transistor Q2 and the first transistor Q1 are directly driven, and the overvoltage decoding delay is significantly improved, resulting in a significant improvement in response speed.

[0019] Second, by using the combination of the second Zener diode D2, the first Zener diode D1, the second transistor Q2, the first transistor Q1, and the switching transistor Q3 to implement a complete protection function, the overall circuit area is reduced, achieving a high degree of circuit integration.

[0020] Third, the elimination of dedicated IC control chip reduces production costs; in addition, this circuit adds fuse FU1 and transient diode RV1 to resist surge current.

[0021] Fourth, the voltage divider resistor R8 enables precise threshold adjustment. In addition, it is compatible with 24V input / 5V output, providing strong compatibility. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings.

[0023] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0024] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0025] The following is for reference. Figure 1A high-voltage protection control circuit according to an embodiment of the present invention includes a first connector CN1 and a second connector CN2. Between the first connector CN1 and the second connector CN2, there are further components: a second Zener diode D2, a first Zener diode D1, a second transistor Q2, a first transistor Q1, a switching transistor Q3, a voltage divider resistor R8, and a step-down chip U1. The first connector CN1 and the second connector CN2 are respectively connected to the step-down chip U1. The cathode of the second Zener diode D2 is connected to the second connector CN2, and the anode of the second Zener diode D2 is grounded through the voltage divider resistor R8. The base of the second transistor Q2 is connected to the anode of the second Zener diode D2 and the voltage divider resistor R8. Connection point 8; the anode of the first Zener diode D1 is connected to pin 2 of the first connector CN1, and the first Zener diode D1 is connected to the collector and emitter of the second transistor Q2; the collector of the second transistor Q2 is connected to the base of the first transistor Q1; the emitter of the second transistor Q2 and the collector of the first transistor Q1 are connected to the gate of the switching transistor Q3, and the emitter of the first transistor Q1 is connected to the source of the switching transistor Q3; the switching transistor Q3 is connected to pin 1 of the first connector CN1, the connection point of pins 1 and 2 of the second connector CN2 is connected to the +24V_org terminal, and the negative terminal of the second Zener diode D2 leads out to the +5V_org terminal.

[0026] First embodiment: During normal operation: the power supply output voltage at the +5V_org terminal is 5V, the first Zener diode D2 and the second Zener diode D4 are both cut off, the base of the second transistor Q2 is low and turned off, the base of the first transistor Q1 is high and turned off, and the switching transistor Q3 is turned on. More specifically, when the input voltage +24V_in is within the normal range: the buck converter U1 outputs a stable DC voltage with an output voltage range of 5.0V ± 2%; the cathode voltage of the second Zener diode D2 is ≤ 5.6V, at which point the second Zener diode D2 is in the off state; since the second Zener diode D2 is off, the base voltage of the second transistor Q2 is ≈ 0V, causing the second transistor Q2 to turn off; the base of the first transistor Q1 is pulled up to a high level of +24V_in through the seventh resistor R7, causing the first transistor Q1 to turn off; the gate of the switching transistor Q3 is pulled up to a high level of +24V_in through the fourth resistor R4, causing the switching transistor Q3 to conduct; after the switching transistor Q3 is turned on, the downstream load circuit obtains the operating voltage, and the system is powered normally.

[0027] Second embodiment: Overvoltage protection: When the power supply output voltage abnormally rises to exceed the breakdown voltage of the first Zener diode D2, the first Zener diode D2 conducts and generates a voltage drop across the voltage divider resistor R8, triggering the second transistor Q2 to conduct, thereby bypassing the first Zener diode D1 and causing it to fail; at this time, the base of the first transistor Q1 becomes low and conducts, pulling the control terminal of the switching transistor Q3 low to ground potential, forcing the switching transistor Q3 to turn off to cut off the power supply to the downstream circuit. More specifically: When the voltage at the +5V_org terminal abnormally rises to 6.3V, the second Zener diode D2 undergoes avalanche breakdown, forming a current path: flowing from the 5V_org terminal through the cathode of the second Zener diode D2, passing through the second Zener diode D2, flowing out from its anode, entering the voltage divider resistor R8, and finally flowing to the ground terminal GND.

[0028] The voltage drop across the voltage divider resistor R8 is calculated as follows.

[0029] VR8 = (Vout − VZ) × R8 / R8 + rd ≈ (6.3V − 5.6V) × 0.99 = 0.693V, (where rd is the dynamic resistance of the second diode D2, approximately 10Ω).

[0030] When the voltage across the voltage divider resistor R8 exceeds 0.6V: The second transistor Q2 conducts: The voltage drop across the voltage divider resistor R8 > 0.6V provides a forward bias voltage to the base and emitter of the second transistor Q2, causing Q2 to conduct; The first Zener diode D1 is cut off: After the second transistor Q2 conducts, its collector potential is pulled down to approximately ground potential (≈0.3V), causing the anode potential of the first Zener diode D1 to drop to ≈0.3V. The first Zener diode D1 is cut off due to insufficient cathode-anode voltage difference; The first transistor Q1 conducts: The base of the first transistor Q1 is pulled down to ground potential through the conducting second transistor Q2, causing the emitter of the base of the first transistor Q1 to be forward biased, and the first transistor Q1 conducts.

[0031] When the first transistor Q1 is turned on: the switch Q3 is turned off: the collector-emitter junction of the first transistor Q1 forms a low-resistance path, which shorts the gate and source of the switch Q3, resulting in the gate-source voltage VGS≈0V of the switch Q3, and the switch Q3 is turned off.

[0032] When the power supply path is cut off: After the switching transistor Q3 is turned off, the power supply path from +24V_in to the downstream circuit is disconnected. When the voltage at the +5V_org terminal drops to 0V, the downstream load is completely de-energized, completing the overvoltage protection.

[0033] Protection threshold formula: Vprotect=VZ(D2)+VBE(Q2), where VBE(Q2)=0.6V~0.7V. The protection point can be adjusted by changing the type of the second diode D2 (e.g., when a 6.2V Zener diode is selected, Vprotect=6.8V~6.9V).

[0034] Specifically, pins 1 and 2 of the first connector CN1 are connected in parallel to a first capacitor C1, a second capacitor C2, and a transient diode RV1, respectively. Pin 1 of the first connector CN1 is also connected to a fuse FU1, with the end of the fuse FU1 connected to a +24V_in terminal. The cathode of the first Zener diode D1 is connected to a fourth resistor R2. The fourth resistor R2 is connected to a second resistor R2 and a seventh resistor R7, respectively. The seventh resistor R7 is connected to a third resistor R3, and the seventh resistor R7 is also connected to the base of the first transistor Q1. The emitter and collector of the first transistor Q1 are also connected to a fifth resistor R5. The source terminal of the switching transistor Q3 is connected to a sixth resistor R6. The input terminal of the buck converter U1 is also connected in parallel to a first electrolytic capacitor EC1 and a third capacitor C3. The output terminal of the buck converter U1 is also connected to a third Zener diode D3, which is also connected to an inductor L1. A second electrolytic capacitor EC2, a fourth capacitor C4, and a fifth capacitor C5 are connected in parallel between one end of the inductor L1 and the anode of the fourth capacitor C4.

[0035] The following is the third embodiment.

[0036] I. Surge protection: Transient diode RV1 absorbs input-side surges (operates when >36V); fuse FU1 blows during continuous overcurrent; the parameters of fuse FU1 are 2A / 60s.

[0037] 2. False triggering suppression: Add capacitor C6 between the base and ground of Q2 to filter out voltage spikes <1μs. The capacitance of capacitor C6 is 10nF.

[0038] III. Overcurrent Protection Interlock: When the voltage drop across the sixth resistor R6 exceeds 0.6V (i.e., current exceeds 60A), the external overcurrent protection is triggered. Additionally, the input protection is as follows: Transient diode RV1: connected in parallel to pin 1 / 2 of the first connector CN1, absorbing surges exceeding 36V; Fuse FU1: connected in series in the +24V_in path. Fuse FU1's overcurrent protection triggers at 2A / 60s.

[0039] Anti-interference design: Capacitor C6: A 10nF capacitor is added between the base and ground of the second transistor Q2 to filter out spikes <1μs; Overcurrent protection linkage: Sixth resistor R6: When the source current of the switching transistor Q3 is >60A (VR6>0.6V), the external overcurrent protection is triggered.

[0040] An electrolytic capacitor EC1 and a third capacitor C3 are connected in parallel at the input terminal of the step-down chip U1 to serve as power supply filtering.

[0041] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A high-voltage protection control circuit, comprising a first connector CN1 and a second connector CN2, characterized in that, Between the first connector CN1 and the second connector CN2, there are also: a second Zener diode D2, a first Zener diode D1, a second transistor Q2, a first transistor Q1, a switching transistor Q3, a voltage divider resistor R8, and a step-down chip U1; The first connector CN1 and the second connector CN2 are respectively connected to the step-down chip U1; The cathode of the second Zener diode D2 is connected to the second connector CN2, and the anode of the second Zener diode D2 is grounded through the voltage divider resistor R8; the base of the second transistor Q2 is connected to the junction of the anode of the second Zener diode D2 and the voltage divider resistor R8. The anode of the first Zener diode D1 is connected to pin 2 of the first connector CN1, and the first Zener diode D1 is connected to the collector and emitter of the second transistor Q2; The collector of the second transistor Q2 is connected to the base of the first transistor Q1; the emitter of the second transistor Q2 and the collector of the first transistor Q1 are both connected to the gate of the switching transistor Q3, and the emitter of the first transistor Q1 is connected to the source of the switching transistor Q3. The switching transistor Q3 is connected to pin 1 of the first connector CN1, and the connection point between pins 1 and 2 of the second connector CN2 is connected to the +24V_org terminal. The negative terminal of the second Zener diode D2 is led out to the +5V_org terminal.

2. The high-voltage protection control circuit according to claim 1, characterized in that: The first connector CN1 has a first capacitor C1, a second capacitor C2, and a transient diode RV1 connected in parallel to pins 1 and 2, respectively. A fuse FU1 is also connected to pin 1 of the first connector CN1, and the end of the fuse FU1 is connected to a +24V_in terminal.

3. The high-voltage protection control circuit according to claim 1, characterized in that: The cathode of the first Zener diode D1 is connected to a fourth resistor R2. The fourth resistor R2 is connected to a second resistor R2 and a seventh resistor R7. The seventh resistor R7 is connected to a third resistor R3. The seventh resistor R7 is also connected to the base of the first transistor Q1.

4. The high-voltage protection control circuit according to claim 1, characterized in that: The emitter and collector of the first transistor Q1 are also connected to a fifth resistor R5.

5. The high-voltage protection control circuit according to claim 1, characterized in that: The source (S) terminal of the switching transistor Q3 is connected to a sixth resistor R6.

6. The high-voltage protection control circuit according to claim 1, characterized in that: The input terminal of the step-down chip U1 is also connected in parallel with a first electrolytic capacitor EC1 and a third capacitor C3.

7. The high-voltage protection control circuit according to claim 1, characterized in that: The output terminal of the step-down chip U1 is also connected to a third Zener diode D3, which is also connected to an inductor L1.

8. The high-voltage protection control circuit according to claim 7, characterized in that: A second electrolytic capacitor EC2, a fourth capacitor C4, and a fifth capacitor C5 are connected in parallel between one end of the inductor L1 and the anode of the fourth capacitor C4.

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