A high-voltage operational amplifier circuit with scalable constant current protection

Abstract

The utility model discloses a kind of high voltage operational amplifier circuit of expandable constant current protection, by high-voltage power main loop and low-voltage signal control loop cooperation constitutes, the high-voltage power main road is provided with energy by high-voltage input end HV_VCC, the high-voltage power main road is two-way structure symmetrical power control branch composition;The low-voltage signal control loop is powered by +12V auxiliary power supply, and the regulation and control of high-voltage power main loop is passed through operational amplifier and switching device;The circuit is through the "signal generation-buffering-attenuation-regulation" link of low-voltage side and the "constant current branch-pressure sensitive link" structure of high-voltage side, realizes the efficient cooperation of "low-voltage precision control" and "high-voltage power execution".Both guarantee the constant current precision and voltage programmability of high-voltage output, and also provide reliable hardware foundation for the diversification application (such as large current drive, high-voltage power supply etc.) of high-voltage domain through the flexible expansion mode of "parallel expansion flow, series expansion pressure".

Description

Technical Field

[0001] This utility model relates to the field of constant current protection circuit technology, specifically a high-voltage operational amplifier circuit with expandable constant current protection. Background Technology

[0002] In the current operational amplifier (op-amp) chip market, there is an increasing demand for high-performance, high-precision, and high-voltage op-amps. However, most common op-amps can only output a limited number of high voltages and currents. In modern analog design, amplifier circuits that require high voltage and high current outputs typically use op-amps for current and voltage amplification to meet output requirements. However, op-amp current and voltage amplification circuits, whether using complementary symmetry circuits or Class A op-amp transformer coupling, present numerous challenges. These circuits have many components, requiring repeated debugging and matching to ensure proper operation. While integrated chips offer convenience, their internal device performance is limited. Key components like MOSFETs and transistors either have insufficient voltage withstand capability or unstable current amplification; high-voltage MOSFETs are also prone to overheating. New semiconductor materials, while promising, are expensive and the technology is not yet mature. This results in commonly used current and voltage amplification circuit solutions struggling to meet the requirements of high-voltage, high-current applications and severely limiting their scalability. Utility Model Content

[0003] The purpose of this invention is to provide a high-voltage operational amplifier circuit with expandable constant current protection to solve the problems mentioned in the background art.

[0004] This utility model provides the following technical solution: a high-voltage operational amplifier circuit with expandable constant current protection, which is composed of a high-voltage power main circuit and a low-voltage signal control circuit. The high-voltage power main circuit is powered by the high-voltage input terminal HV_VCC and consists of two symmetrical power regulation branches. The low-voltage signal control circuit is powered by a +12V auxiliary power supply and regulates the high-voltage power main circuit through operational amplifiers and switching devices. Preferably, the +12V auxiliary power supply powers operational amplifier U1.1 via current-limiting resistor R12. The non-inverting input (pin 3) of operational amplifier U1.1 is connected to the node of reference voltage REF_VCC, which serves as a reference signal. The inverting input (pin 2) of operational amplifier U1.1 is directly connected to common ground HV_GND, forming a preliminary amplification path for the reference signal. The signal output from the output (pin 1) of operational amplifier U1.1 is smoothed by an RC coupling filter circuit composed of resistor R13 and capacitor C1 before being connected to the non-inverting input of operational amplifier U1.2. Input terminal (pin 6); The inverting input terminal (pin 5) of the operational amplifier U1.2 is connected to one end of the high-voltage feedback voltage divider resistors R14 and R15 respectively. The other end of the high-voltage feedback voltage divider resistor R14 is connected to the HV_OUT node, and the other end of the high-voltage feedback voltage divider resistor R15 is connected to the HV_GND node, forming a feedback adjustment network to ensure stable output signal; The output terminal (pin 7) of the operational amplifier U1.2 is connected to the gate of the MOSFET Q6 to control the on and off states of Q6; The source of the MOSFET Q6 is connected to the HV_GND node.

[0005] Preferably, in the first path, the drain of the MOSFET Q1 is directly connected to the HV_VCC node to obtain high-voltage power. The source of the MOSFET Q1 is connected to the base of the transistor Q3 through a driving resistor R5, forming a drive signal transmission path from the MOSFET Q1 to the transistor Q3. Simultaneously, the drain of the MOSFET Q1 is also connected to the collector of the transistor Q3 through series voltage divider resistors R1 and R3, providing a stable collector bias voltage for the transistor Q3. The emitter of the transistor Q3 is connected to the cathode of the Zener diode ZD1.

[0006] Preferably, the anode of the Zener diode ZD1 forms two branches; one branch is connected back to the HV_VCC node via the current-limiting protection resistor R7 to provide the basic operating current for the Zener diode ZD1 and limit overcurrent; the other branch is connected to the anode of the second Zener diode ZD2 via the interconnecting resistor R8, so that the regulated reference voltages of the two branches are linked to ensure symmetry. The second branch corresponds completely to the structure of the first branch: the drain of the MOSFET Q2 is connected to the HV_VCC node, the source of the MOSFET Q2 is connected to the base of the transistor Q4 via the driving resistor R6; the drain of the MOSFET Q2 is connected to the collector of the transistor Q4 via the series voltage divider resistors R2 and R4 to provide collector bias for the transistor Q4; the emitter of the transistor Q4 is connected to the cathode of the Zener diode ZD2, forming a voltage-regulating drive structure consistent with the first branch.

[0007] Preferably, the varistor R9 is connected across the anode of Zener diode ZD1 and the corresponding node, and the varistor R10 is connected to the associated path of the anode of Zener diode ZD2. Both provide overvoltage protection for the two voltage regulator components. The high-voltage output terminal HV_OUT is led out from the connection node between the source of MOSFET Q2 and the base of transistor Q4, and directly outputs the regulated high-voltage signal.

[0008] Preferably, the drain of the MOSFET Q6 is connected to the base of the transistor Q5 via resistors R11 and R10 in series, and the collector of the transistor Q5 is directly connected to the interconnection node between the anode of ZD2 and R8 in the second path, thus forming a complete control link of "low voltage reference signal → U1.1 amplification → RC coupling filtering → U1.2 adjustment → Q6 switching → Q5 current attenuation drive → high voltage main circuit", realizing real-time control of the high voltage power circuit by the low voltage signal.

[0009] Compared with the prior art, the beneficial effects of this utility model are: The circuit adopts a hierarchical architecture of "low-voltage control signal generation + high-voltage constant current branch execution + varistor cross-domain connection", which can not only achieve precise constant current and voltage regulation of high-voltage output, but also has significant high-voltage domain expansion capability.

[0010] The significant advantage of this circuit lies in its flexible expansion capability in the high-voltage domain, specifically in two dimensions: current amplification and voltage amplification. Regarding current amplification, since the high-voltage side exhibits constant current output characteristics, and the constant current control signal is independently provided by the low-voltage side attenuation circuit, it is not limited by a single module. Therefore, the total output current can be increased by connecting multiple high-voltage constant current circuits in parallel. When multiple branches operate in parallel, the total current is the sum of the currents of each branch, easily meeting the needs of high-current scenarios. Regarding voltage amplification, relying on the bridging signal transmission characteristics of the varistor R9, the total output voltage can be superimposed by connecting multiple constant current modules in series. The output voltage of the previous stage module, after being connected via the varistor, provides the control and power supply basis for the next stage module. After multiple modules are connected in series, the total voltage is the sum of the voltages of each module, effectively expanding the high-voltage output range.

[0011] Overall, this circuit achieves efficient coordination between "low-voltage precision control" and "high-voltage power execution" through the "signal generation-buffering-attenuation-regulation" link on the low-voltage side and the "constant current branch-varistor connection" structure on the high-voltage side. It ensures both the constant current accuracy and voltage programmability of the high-voltage output, and provides a reliable hardware foundation for diverse applications in the high-voltage domain (such as high-current drive and high-voltage power supply) through flexible expansion methods such as "parallel current amplification and series voltage amplification." Attached Figure Description

[0012] Figure 1 This is the topology diagram of the dual-module high-voltage operational amplifier circuit for constant current protection in this practical application. Detailed Implementation

[0013] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0014] Please see Figure 1 This utility model provides a technical solution: a high-voltage operational amplifier circuit with expandable constant current protection, which is composed of a high-voltage power main circuit and a low-voltage signal control circuit. The high-voltage power main circuit is powered by the high-voltage input terminal HV_VCC and consists of two symmetrical power regulation branches. The low-voltage signal control circuit is powered by a +12V auxiliary power supply and regulates the high-voltage power main circuit through operational amplifiers and switching devices.

[0015] Please see Figure 1 The +12V auxiliary power supply powers operational amplifier U1.1 via current-limiting resistor R12. The non-inverting input (pin 3) of operational amplifier U1.1 is connected to the reference voltage REF_VCC node, serving as the reference signal. The inverting input (pin 2) of operational amplifier U1.1 is directly connected to the common ground HV_GND, forming the initial amplification path for the reference signal. The signal output from the output (pin 1) of operational amplifier U1.1 is smoothed by an RC-coupled filter circuit composed of resistor R13 and capacitor C1 before being connected to the non-inverting input of operational amplifier U1.2. Input terminal (pin 6); The inverting input terminal (pin 5) of operational amplifier U1.2 is connected to one end of high-voltage feedback voltage divider resistors R14 and R15 respectively. The other end of high-voltage feedback voltage divider resistor R14 is connected to the HV_OUT node, and the other end of high-voltage feedback voltage divider resistor R15 is connected to the HV_GND node, forming a feedback adjustment network to ensure stable output signal; The output terminal (pin 7) of operational amplifier U1.2 is connected to the gate of MOSFET Q6 to control the on and off states of Q6; The source of MOSFET Q6 is connected to the HV_GND node.

[0016] Please see Figure 1 In the first path, the drain of MOSFET Q1 is directly connected to the HV_VCC node to obtain high-voltage power. The source of MOSFET Q1 is connected to the base of transistor Q3 through driving resistor R5, forming the drive signal transmission path from MOSFET Q1 to transistor Q3. Simultaneously, the drain of MOSFET Q1 is also connected to the collector of transistor Q3 through series voltage divider resistors R1 and R3, providing a stable collector bias voltage for transistor Q3. The emitter of transistor Q3 is connected to the cathode of Zener diode ZD1.

[0017] Please see Figure 1 The anode of Zener diode ZD1 forms two branches: one branch is connected back to the HV_VCC node via current-limiting protection resistor R7, providing the basic operating current for Zener diode ZD1 and limiting overcurrent; the other branch is connected to the anode of Zener diode ZD2 via interconnect resistor R8, so that the reference voltages of the two branches are linked to ensure symmetry. The second branch corresponds completely to the structure of the first branch: the drain of MOSFET Q2 is connected to the HV_VCC node, and the source of MOSFET Q2 is connected to the base of transistor Q4 via drive resistor R6; the drain of MOSFET Q2 is connected to the collector of transistor Q4 via series voltage divider resistors R2 and R4, providing collector bias for transistor Q4; the emitter of transistor Q4 is connected to the cathode of Zener diode ZD2, forming a voltage-regulating drive structure consistent with the first branch.

[0018] Please see Figure 1 Varistor R9 is connected across the anode of Zener diode ZD1 and the corresponding node, and varistor R10 is connected to the associated path of the anode of Zener diode ZD2. Both provide overvoltage protection for the two voltage regulator components. The high-voltage output terminal HV_OUT is led out from the connection node between the source of MOSFET Q2 and the base of transistor Q4, and directly outputs the regulated high-voltage signal.

[0019] Please see Figure 1 The drain of MOSFET Q6 is connected to the base of transistor Q5 via series resistors R11 and R10. The collector of transistor Q5 is directly connected to the interconnection node between the anode of ZD2 and R8 in the second path, thus forming a complete control link of "low voltage reference signal → U1.1 amplification → RC coupling filtering → U1.2 adjustment → Q6 switching → Q5 current decay drive → high voltage main circuit", realizing real-time control of the high voltage power circuit by the low voltage signal.

[0020] Working principle: This circuit adopts a layered architecture of "low-voltage control signal generation + high-voltage constant current branch execution + varistor cross-domain connection", which not only realizes precise constant current and voltage regulation of high-voltage output, but also has significant high-voltage domain expansion capability. Its working principle can be divided into the following core parts: The low-voltage control side is the "signal hub" of the entire system, responsible for generating and finely adjusting the control signal. Operational amplifier U1.1, acting as a non-inverting amplifier, receives the reference voltage REF_VCC, amplifies it, and outputs the initial control signal. To avoid interference from the load of the preceding circuit, this signal is buffered and isolated by U1.2, which is configured as a voltage follower, and then sent to the high-voltage feedback voltage divider sampling network composed of R14 and R15 for further conditioning. Transistor Q5, current-limiting resistor R10, and sampling resistor R11 constitute the key "high-voltage constant current threshold control current signal attenuation circuit"—by using the conduction state of Q5 in conjunction with the current-limiting effect of R10 and the current sampling of the control signal by R11, the control signal output by the op-amp is precisely attenuated, and the final output signal directly acts on the gate of the high-voltage MOSFET Q6. Q6, acting as a "voltage-controlled variable resistor," has its on-resistance dynamically changing with the gate signal. Since the threshold signal of the high-voltage constant current remains constant, this resistance adjustment directly translates into precise control of the high-voltage side output voltage, providing a stable reference for subsequent high-voltage execution.

[0021] The high-voltage main circuit is the core of power execution, consisting of two symmetrical constant current branches (Q1 / Q3 branch and Q2 / Q4 branch), both powered by the high-voltage power supply HV_VCC. Varistor R9 plays a dual role as a "signal bridge across voltage domains" and a "state switching switch": when the drain-source voltage drop across Q2 (i.e., the voltage across Q2) has not yet reached the clamping voltage of R9, R9 is in a high-resistance state, maintaining electrical isolation between the low-voltage and high-voltage sides, and the high-voltage branch operates independently based solely on its own bias; however, when the Q2 voltage drop rises to the clamping voltage of R9, R9 quickly switches from a high-resistance state to a low-resistance state, utilizing its characteristic of "resistance dropping sharply after voltage reaches a threshold" to "bridging and transmitting" the attenuated control signal from the Q5 branch to the first constant current branch (the loop composed of Q1 and Q3), achieving coordinated control of multiple constant current modules and ensuring stable and consistent current across all branches.

[0022] The significant advantage of this circuit lies in its flexible expansion capability in the high-voltage domain, specifically in two dimensions: current amplification and voltage amplification. Regarding current amplification, since the high-voltage side exhibits constant current output characteristics, and the constant current control signal is independently provided by the low-voltage side attenuation circuit, it is not limited by a single module. Therefore, the total output current can be increased by connecting multiple high-voltage constant current circuits in parallel—when multiple branches operate in parallel, the total current is the sum of the currents of each branch, easily meeting the needs of high-current scenarios. Regarding voltage amplification, relying on the bridging signal transmission characteristics of the varistor R9, the total output voltage can be superimposed by connecting multiple constant current modules in series—the output voltage of the previous stage module, after being connected via the varistor, provides the control and power supply basis for the next stage module. After multiple modules are connected in series, the total voltage is the sum of the voltages of each module, effectively expanding the high-voltage output range.

[0023] Overall, this circuit achieves efficient coordination between "low-voltage precision control" and "high-voltage power execution" through the "signal generation-buffering-attenuation-regulation" link on the low-voltage side and the "constant current branch-varistor connection" structure on the high-voltage side. It ensures both the constant current accuracy and voltage programmability of the high-voltage output, and provides a reliable hardware foundation for diverse applications in the high-voltage domain (such as high-current drive and high-voltage power supply) through flexible expansion methods such as "parallel current amplification and series voltage amplification."

[0024] The technical features of this application are as follows: 1. Precise constant current protection: Utilizing constant current protection, each channel can automatically output constant current and provide protection when the test current exceeds the hardware preset value. 2. High-efficiency voltage adaptation: The high-voltage source provides adjustable and stable high-voltage DC, and the constant current circuit and precision operational amplifier control enable precise output of the specified voltage waveform while maintaining automatic constant current protection. 3. Strong expandability: During testing, multiple constant current module circuits can be stacked to meet high voltage and high current testing requirements.

Claims

1. A high-voltage operational amplifier circuit with expandable constant current protection, comprising a high-voltage power main circuit and a low-voltage signal control circuit, characterized in that: The high-voltage power main circuit is powered by the high-voltage input terminal HV_VCC, and the high-voltage power main circuit consists of two symmetrically structured power regulation branches; the low-voltage signal control circuit uses a +12V auxiliary power supply as its power source and regulates the high-voltage power main circuit through operational amplifiers and switching devices; The +12V auxiliary power supply powers operational amplifier U1.1 via current-limiting resistor R12. The non-inverting input (pin 3) of operational amplifier U1.1 is connected to the reference voltage REF_VCC node. The inverting input (pin 2) of operational amplifier U1.1 is directly connected to the common ground HV_GND. The signal output from the output (pin 1) of operational amplifier U1.1 is smoothed by an RC coupling filter circuit composed of resistor R13 and capacitor C1, and then connected to the non-inverting input (pin 6) of operational amplifier U1.

2. The inverting input (pin 5) of operational amplifier U1.2 is connected to one end of high-voltage feedback voltage divider resistors R14 and R15, respectively. The other end of high-voltage feedback voltage divider resistor R14 is connected to the HV_OUT node, and the other end of high-voltage feedback voltage divider resistor R15 is connected to the HV_GND node. The output (pin 7) of operational amplifier U1.2 is connected to the gate of MOSFET Q6, and the source of MOSFET Q6 is connected to the HV_GND node.

2. The high-voltage operational amplifier circuit with expandable constant current protection according to claim 1, characterized in that: In the first path, the drain of the MOS transistor Q1 is directly connected to the node of HV_VCC. The source of the MOS transistor Q1 is connected to the base of the transistor Q3 through the driving resistor R5. The drain of the MOS transistor Q1 is also connected to the collector of the transistor Q3 through the series voltage divider resistors R1 and R3. The emitter of the transistor Q3 is connected to the cathode of the Zener diode ZD1.

3. The high-voltage operational amplifier circuit with expandable constant current protection according to claim 2, characterized in that: The anode of the Zener diode ZD1 forms two branches: one branch is connected back to the HV_VCC node via the current-limiting protection resistor R7, and the other branch is connected to the anode of the second Zener diode ZD2 via the interconnection resistor R8. The second branch corresponds completely to the structure of the first branch: the drain of the MOSFET Q2 is connected to the HV_VCC node, the source of the MOSFET Q2 is connected to the base of the transistor Q4 via the drive resistor R6, the drain of the MOSFET Q2 is connected to the collector of the transistor Q4 via the series voltage divider resistors R2 and R4, and the emitter of the transistor Q4 is connected to the cathode of the Zener diode ZD2, forming a voltage-regulating drive structure consistent with the first branch.

4. The high-voltage operational amplifier circuit with expandable constant current protection according to claim 3, characterized in that: A varistor R9 is connected across the anode of Zener diode ZD1 and the corresponding node. A varistor R10 is connected to the associated path of the anode of Zener diode ZD2. The high-voltage output terminal HV_OUT is led out from the connection node between the source of MOSFET Q2 and the base of transistor Q4.

5. The high-voltage operational amplifier circuit with expandable constant current protection according to claim 4, characterized in that: The drain of the MOS transistor Q6 is connected to the base of the transistor Q5 via resistors R11 and R10 in series, and the collector of the transistor Q5 is directly connected to the interconnection node between the anode of ZD2 and R8 in the second path.

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