A surge protection switching control circuit

Abstract

This invention discloses a surge protection switching control circuit. The control circuit includes an operational amplifier, a switching transistor, an optocoupler switch, and several resistors. The non-inverting input of the operational amplifier U2 is connected to the working voltage reference Vref terminal, the inverting input is connected to one end of resistor R2 and one end of resistor R7, and the output terminal is connected to one end of resistor R1, one end of resistor R8, and the anode of optocoupler switch U4. The source of the switching transistor Q1 is connected to one end of resistor R12 and the working voltage output Out terminal, and the gate is connected to the emitter of optocoupler switch U4. The collector of optocoupler switch U4 is connected to one end of resistor R4. The other ends of resistor R2 and resistor R4 are connected to the power supply input DC terminal and connected to the other end of resistor R12 through the Port1 line. The other end of resistor R1 is connected to the power supply. The drain of switching transistor Q1, the cathode of optocoupler switch U4, the other end of resistor R7, and the other end of resistor R8 are grounded.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, and in particular to a surge protection switching control circuit. Background Technology

[0002] Traditional surge protection mainly utilizes the breakdown characteristics of the PN junction in a Zener diode (TVS) to achieve current discharge, such as... Figure 2 , Figure 3 As shown, the parameter selection of the TVS in the existing surge protection circuit needs to follow the maximum reverse working voltage V. WM The condition of being greater than or equal to the upper limit of the downstream circuit's operating voltage is to meet power supply requirements and also to avoid the power supply being below V. WM Interval V BR When the TVS is turned on, it generates a significant leakage current. The working principle of the TVS is that when a surge transient event occurs, the TVS will release leakage current when it reaches V. BR It then begins to conduct, and through the dynamic resistor R DYN Limit the voltage to the clamping voltage V. C Above, in this process, from V BR Rise to V C The response time depends on R DYN The value characteristics of TVS, ideally V should make V C As close to V as possible BR However, due to the physical properties of silicon, junction area limitations, and temperature effects, the R of TVS diodes is limited. DYN There is an inherent lower limit, which leads to TVS often having a relatively high V. C It will be in V WM Upgrade to V C The impact on downstream devices before clamping, especially V BR To V C The impact of avalanche zones is more pronounced. Existing solutions include either increasing the voltage withstand capability of downstream circuits, which leads to increased power consumption and increased area, or using the lowest possible supply voltage to allow the power supply range of devices to serve as a reserve for impact, but this reduces the circuit's anti-interference capability and narrows the selection range of downstream components. Summary of the Invention

[0003] To address the aforementioned technical problems, the purpose of this invention is to provide a surge protection switching control circuit. The control circuit includes an operational amplifier, a switching transistor, an optocoupler switch, and several resistors. The non-inverting input of the operational amplifier U2 is connected to the operating voltage reference Vref terminal, the inverting input is connected to one end of resistor R2 and one end of resistor R7, and the output terminal is connected to one end of resistor R1, one end of resistor R8, and the anode of optocoupler switch U4. The source of the switching transistor Q1 is connected to one end of resistor R12 and the operating voltage output Out terminal, and its gate is connected to the emitter of optocoupler switch U4. The collector of optocoupler switch U4 is connected to one end of resistor R4. The other ends of resistors R2 and R4 are connected to the power supply input DC terminal and connected to the other end of resistor R12 via Port1. The other end of resistor R1 is connected to the power supply. The drain of the switching transistor Q1, the cathode of optocoupler switch U4, the other ends of resistors R7 and R8 are grounded.

[0004] Furthermore, the control circuit also includes several operational amplifiers, several diodes, several resistors, and a solid-state relay. In the control circuit, the inverting input of operational amplifier U1 is connected to one end of resistor R20 and one end of resistor R21, and its output is connected to the other end of resistor R20 and the anode of diode D3. The non-inverting input of operational amplifier U3 is connected to one end of resistor R2, the inverting input is connected to one end of resistor R15, and its output is connected to one end of resistor R9 and the other end of resistor R15. The non-inverting input of operational amplifier U5 is connected to the other end of resistor R9 and one end of resistor R11, the inverting input is connected to one end of resistor R10 and one end of resistor R14, and its output is connected to the other end of resistor R10 and the other end of resistor R21. The non-inverting input of operational amplifier U6 is connected to operational amplifier U8. The inverting input is connected to one end of resistor R16 and one end of resistor R18. The inverting input is connected to one end of resistor R13, and the output input is connected to the other end of resistor R13 and the other end of resistor R14. The non-inverting input of op-amp U7 is connected to the cathode of diode D3, and the output input is connected to the anode of diode D2. The output input of op-amp U8 is connected to the anode of diode D1. One end of solid-state relay K1 is connected to Port1, and the other end is connected to Port2. One end of the coil is connected to the cathodes of diode D1 and D2, and the MR terminal. The other end of the coil is connected to one end of resistor R5. The other end of resistor R18 is connected to the Out terminal. The non-inverting input of op-amp U1, the other end of resistor R5, the other end of resistor R11, and the other end of resistor R16 are grounded.

[0005] Furthermore, the control circuit also includes a resistor, namely resistor R6, one end of which is connected to the non-inverting input of operational amplifier U7, and the other end is grounded.

[0006] Furthermore, the control circuit also includes several resistors. One end of resistor R22 in the control circuit is connected to the power supply, and the other end is connected to one end of resistor R23 and the non-inverting input of operational amplifier U8; the other end of resistor R23 is grounded.

[0007] Furthermore, the control circuit also includes several resistors. One end of resistor R3 in the control circuit is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U7 and one end of resistor R19; the other end of resistor R19 is grounded.

[0008] Furthermore, the control circuit also includes capacitors and resistors. One end of capacitor C1 in the control circuit is connected to the source of switching transistor Q1; one end of resistor R17 is connected to the gate of switching transistor Q1; and the other ends of capacitor C1 and resistor R17 are grounded.

[0009] Furthermore, resistors R22 and R23 in the control circuit are adjustable resistors.

[0010] The advantages of this invention compared to the prior art are:

[0011] Compared to solutions using Zener diodes, this invention avoids impacting downstream circuits, reduces unnecessary power consumption, increases surge margin, provides wider power supply protection, and allows for multiplexing of different operating voltage levels. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic diagram of the control circuit structure.

[0014] Figure 2 and Figure 3 This is a schematic diagram of the TVS structure curve. Detailed Implementation

[0015] To make the objectives and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection specifically claimed by the present invention.

[0016] This invention discloses a surge protection switching control circuit. In the control circuit, the non-inverting input of operational amplifier U2 is connected to the working reference voltage Vref, the inverting input is connected to one end of resistor R2 and one end of resistor R7, and the output is connected to one end of resistor R1, one end of resistor R8, and the anode of optocoupler switch U4. The source of switching transistor Q1 is connected to one end of resistor R12 and the working voltage output Out terminal, and the gate is connected to the emitter of optocoupler switch U4. The collector of optocoupler switch U4 is connected to one end of resistor R4. The other ends of resistor R2 and resistor R4 are connected to the power supply input DC terminal and connected to the other end of resistor R12 through Port1 line. The other end of resistor R1 is connected to the power supply. The drain of switching transistor Q1, the cathode of optocoupler switch U4, the other end of resistor R7, and the other end of resistor R8 are grounded.

[0017] Specifically, in the control circuit, the inverting input of operational amplifier U1 is connected to one end of resistor R20 and one end of resistor R21, and the output terminal is connected to the other end of resistor R20 and the anode of diode D3; the non-inverting input of operational amplifier U3 is connected to one end of resistor R2, the inverting input is connected to one end of resistor R15, and the output terminal is connected to one end of resistor R9 and the other end of resistor R15; the non-inverting input of operational amplifier U5 is connected to the other end of resistor R9 and one end of resistor R11, the inverting input is connected to one end of resistor R10 and one end of resistor R14, and the output terminal is connected to the other end of resistor R10 and the other end of resistor R21; the non-inverting input of operational amplifier U6 is connected to the inverting input of operational amplifier U8, one end of resistor R16, and resistor R1... One end of the op-amp U7 is connected to one end of resistor R13, and the output end is connected to the other end of resistor R13 and the other end of resistor R14. The non-inverting end of op-amp U7 is connected to the cathode of diode D3, and the output end is connected to the anode of diode D2. The output end of op-amp U8 is connected to the anode of diode D1. One end of solid-state relay K1 is connected to Port1, and the other end is connected to Port2. One end of the coil is connected to the cathodes of diode D1 and D2, and the MR terminal. The other end of the coil is connected to one end of resistor R5. The other end of resistor R18 is connected to the Out terminal. The non-inverting end of op-amp U1, the other end of resistor R5, the other end of resistor R11, and the other end of resistor R16 are grounded.

[0018] Specifically, in the control circuit, one end of resistor R6 is connected to the non-inverting input of operational amplifier U7, and the other end is grounded.

[0019] Specifically, in the control circuit, one end of resistor R22 is connected to the power supply, and the other end is connected to one end of resistor R23 and the non-inverting input of operational amplifier U8; the other end of resistor R23 is grounded.

[0020] Specifically, in the control circuit, one end of resistor R3 is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U7 and one end of resistor R19; the other end of resistor R19 is grounded.

[0021] Specifically, in the control circuit, one end of capacitor C1 is connected to the source of switching transistor Q1; one end of resistor R17 is connected to the gate of switching transistor Q1; and the other ends of capacitor C1 and resistor R17 are grounded.

[0022] Specifically, resistors R22 and R23 in the control circuit are adjustable resistors.

[0023] In one embodiment, a control circuit for a protection scheme is provided. This circuit uses closed-loop isolation to avoid impacts on downstream circuits as in traditional protection schemes. It eliminates the parameter limitations of Zener diodes, provides a wider power supply protection range, and can reuse different operating voltage levels. In this scheme, Vref is the required operating voltage reference input used to adjust the protection range of the Out power supply. DC is the power supply input, and Out is the operating voltage output. Since the actual voltage after Out adjustment may exceed the VCC voltage, resulting in sampling voltage overflow, the sampling of operational amplifier U2 uses a voltage divider network of resistors R2 and R7 to proportionally convert the input voltage. To prevent sampling overflow, the DC power supply voltage is input normally to the downstream via Port1 line through resistor R12 for current limiting, and via resistor R4 for current limiting, the collector of optocoupler U4, and the emitter of optocoupler U4 to the gate of switch Q1. The required operating voltage reference input Vref at the non-inverting input of op-amp U2 has an amplitude greater than and close to the sampling voltage of resistor R7 / (resistance R2 + resistor R7), allowing op-amp U2 to maintain the output state under normal operating conditions. Resistor R8 is used to divide the voltage with resistor R1 to set the conduction threshold bias voltage of optocoupler U4. The bias voltage is used to increase the output of op-amp U2 again. When the optocoupler U4 responds, the output of operational amplifier U2 will turn on the optocoupler U4 after passing through its anode, cathode, and ground. The internal photodiode of optocoupler U4 will couple to the optotransistor, allowing the DC feedback to be input to the gate of switching transistor Q1 after current limiting by resistor R4. The gate and source of switching transistor Q1 are in a state where the voltage is positive when Out is connected or below the negative voltage threshold when Out is unconnected, meaning switching transistor Q1 is off. This allows the DC voltage and optocoupler U4 to form a closed-loop isolation control of the gate state of switching transistor Q1. When a surge current occurs, the voltage at the connection point of the DC voltage divider network connected by resistors R2 and R7 changes... The operation will cut off the output of operational amplifier U2 and stop the coupling of optocoupler switch U4. At this time, the gate and source of switch Q1 form a negative voltage. The DC voltage forms a ground loop through resistor R12 and the source and drain of switch Q1 to complete the closed-loop control of surge protection for the downstream circuit of Out. Compared with the traditional solution, it can avoid the impact of VBR to VC on the downstream circuit when using TVS. In addition, since the drive of switch Q1 is closed-loop by DC and the optocoupler switch U4 is isolated, the output range of Out is not limited by the gate drive range under the source voltage of switch Q1. Therefore, the protection adjustment range of Out power supply is wider and can be reused for different power supply levels.

[0024] In one embodiment, a control circuit for another protection scheme is provided based on the above scheme. Compared with the above embodiment, a self-test switching function for the surge circuit is added. This function can perform a self-test to switch the power supply state when the protection device switch Q1 fails. The self-test protection in this scheme has the function of generating corresponding circuit-breaking protection signals for different adjusted Out power supplies and distinguishing normal surge current discharge in short-circuit faults. Specifically, the connection between Port1 line and resistor R12 is removed, and Port2 line and resistor R12 are connected in parallel and series with solid-state relay K1. Solid-state relay K1 adopts a normally closed contact type. The attached figure shows the open state after a fault. In the case of a circuit-breaking fault, the Out power supply voltage is first input to the circuit through a voltage divider network of resistors R18 and R16. The non-inverting input of op-amp U6 and the inverting input of op-amp U8 are connected. Op-amp U6, following resistor R13, is input to the inverting input of op-amp U5 via resistor R14 to obtain the current Out voltage. Simultaneously, the voltage at the voltage divider point of resistors R2 and R7 is input to op-amp U3, followed by resistor R15, and then input to the non-inverting input of op-amp U5 via resistor R9 to obtain the current DC supply voltage. The voltage at the non-inverting input of op-amp U5 is then fed back through a negative feedback loop via the output of op-amp U5, resistor R10, and the inverting input of op-amp U5. This feedback loop differentially divides the current DC and Out signals to obtain the circuit breaker protection signal corresponding to the Out supply voltage. This signal is then input to the inverting input of op-amp U1 via resistor R21. After passing through resistor R20, op-amp U1 is inverted and input to op-amp U7 via diode D3, triggering the circuit breaker. The protection signal is only input to operational amplifier U7 when switching transistor Q1 fails. The inverting input of operational amplifier U7 uses resistors R3 and R19 to divide the voltage, setting a reference voltage signal for the Q1 open-circuit fault. At this time, after inversion by operational amplifier U1, the output is a negative voltage signal, which is intercepted by diode D3. When in an open-circuit state, the voltage difference between Out and DC, after inversion by operational amplifier U1, becomes a positive voltage input to operational amplifier U7. The output of operational amplifier U7 is fed back to the coil of solid-state relay K1 via diode D2, controlling the normally closed contact to disconnect the power supply for protection. Subsequently, the voltage potential at the Out terminal is pulled down again after the corresponding open-circuit protection signal process and maintained in the state shown in the attached diagram of solid-state relay K1. Resistor R6 at the non-inverting input of operational amplifier U7 is a pull-up resistor. When adding surge protection testing... Except for resistor R6, which is tested by enabling the pull-down resistor via the upper-level chip, and vice versa, when there is no voltage difference between the reference voltage at the non-inverting input of op-amp U8 and ground, the short-circuit function is disabled. In a short-circuit fault, the non-inverting input of op-amp U8 sets the short-circuit fault reference voltage signal for switching transistor Q1 through a voltage divider between resistors R22 and R23. Under normal conditions or during surge protection, the Out voltage will drop to the connected impedance point or the conduction impedance point of switching transistor Q1. When in a short-circuit fault, the voltage at the inverting input of op-amp U8 is lower than the voltage at the non-inverting input. Op-amp U8 then controls the auxiliary contact of solid-state relay K1 to open via diode D1. During reset, the pull-down resistor of MR is enabled or a series switch is connected to disconnect the coil circuit of solid-state relay K1, and the auxiliary contact of solid-state relay K1 closes again.Resistor R17 discharges the parasitic capacitance inside the gate of switching transistor Q1 and capacitor C1 decouples the circuit for fault tolerance when frequent switching is required in downstream circuits. The reference voltage signals for operational amplifiers U7 and U8 can be adjusted via adjustable resistors or input by the host chip based on the supply voltage.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A surge protection switching control circuit, characterized in that, The control circuit includes an operational amplifier U2 whose non-inverting input is connected to the operating voltage reference Vref, its inverting input is connected to one end of resistor R2 and one end of resistor R7, and its output is connected to one end of resistor R1, one end of resistor R8, and the anode of optocoupler U4. The source of switching transistor Q1 is connected to one end of resistor R12 and the operating voltage output Out terminal, and its gate is connected to the emitter of optocoupler U4. The collector of optocoupler U4 is connected to one end of resistor R4. The other ends of resistors R2 and R4 are connected to the power supply input DC terminal and then connected to the other end of resistor R12 via Port1. The other end of resistor R1 is connected to the power supply. The drain of switching transistor Q1, the cathode of optocoupler U4, the other end of resistor R7, and the other end of resistor R8 are grounded. The inverting input of operational amplifier U1 is connected to one end of resistor R20 and one end of resistor R21, and its output is connected to the other end of resistor R20 and the anode of diode D3. The non-inverting input of operational amplifier U3 is connected to one end of resistor R2, its inverting input is connected to one end of resistor R15, and its output is connected to... One end of R9 and the other end of resistor R15; the non-inverting input of op-amp U5 is connected to the other end of resistor R9 and one end of resistor R11, the inverting input is connected to one end of resistor R10 and one end of resistor R14, and the output is connected to the other end of resistor R10 and the other end of resistor R21; the non-inverting input of op-amp U6 is connected to the inverting input of op-amp U8, one end of resistor R16 and one end of resistor R18, the inverting input is connected to one end of resistor R13, and the output is connected to the other end of resistor R13 and the other end of resistor R14; the non-inverting input of op-amp U7 is connected to the cathode of diode D3, and the output is connected to the anode of diode D2; the output is connected to the anode of diode D1; one end of solid-state relay K1 is connected to Port1 and the other end is connected to Port2, one end of the coil is connected to the cathodes of diode D1 and D2, and the MR terminal, and the other end of the coil is connected to one end of resistor R5; the other end of resistor R18 is connected to the Out terminal; the non-inverting input of op-amp U1, the other end of resistor R5, the other end of resistor R11, and the other end of resistor R16 are grounded.

2. The surge protection switching control circuit according to claim 1, characterized in that, In the control circuit, one end of resistor R6 is connected to the non-inverting input of operational amplifier U7, and the other end is grounded.

3. The surge protection switching control circuit according to claim 1, characterized in that, In the control circuit, one end of resistor R22 is connected to the power supply, and the other end is connected to one end of resistor R23 and the non-inverting input of operational amplifier U8; the other end of resistor R23 is grounded.

4. The surge protection switching control circuit according to claim 1, characterized in that, In the control circuit, one end of resistor R3 is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U7 and one end of resistor R19; the other end of resistor R19 is grounded.

5. The surge protection switching control circuit according to claim 1, characterized in that, In the control circuit, one end of capacitor C1 is connected to the source of switching transistor Q1; one end of resistor R17 is connected to the gate of switching transistor Q1; and the other ends of capacitor C1 and resistor R17 are grounded.

6. The surge protection switching control circuit according to claim 3, characterized in that, Resistors R22 and R23 in the control circuit are adjustable resistors.

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