A power supply output voltage tracking circuit based on operational amplifier

Abstract

The utility model relates to voltage follower circuit technical field, concretely is a kind of power output voltage tracking circuit based on operational amplifier, its circuit structure is simple, and the ability of anti-interference is strong, use occasion is wide, the positive phase input end of operational amplifier U1A is connected resistance R11 one end and resistance R14 one end, the inverting input end of operational amplifier U1A is connected resistance R10 one end and capacitor C3 one end, resistance R10 other end is connected resistance R9 one end, capacitor C4 one end and is external voltage Track input end, the output end of operational amplifier U1A is connected diode D2's anode, resistance R14 other end and capacitor C3 other end, diode D2's cathode is connected resistance R7 one end, resistance R7 other end is connected resistance R3 one end, resistance R4 one end, resistance R6 one end, resistance R12 one end, resistance R13 one end, the positive phase input end of operational amplifier U1B, the inverting input end of operational amplifier U1B is connected and connects resistance R8 one end, resistance R8 other end is connected power supply chip circuit's feedback end FB, capacitor C1 one end is power supply chip circuit's output end VOUT.

Description

Technical Field

[0001] This utility model relates to the field of voltage follower circuit technology, specifically a power output voltage tracking circuit based on an operational amplifier. Background Technology

[0002] Voltage follower circuits are important circuits that accurately track the output voltage from the input voltage, amplifying the signal and maintaining stability. With the rapid development of modern power electronics technology, high-precision sensing is required in many fields such as industrial control, power transmission, and new energy, where voltage follower circuits play a crucial role.

[0003] Currently, some voltage tracking circuits are implemented using logic chips, which require the construction of external circuits, are susceptible to signal interference, and have limited application scenarios. Summary of the Invention

[0004] To solve the above-mentioned technical problems, this utility model provides a power output voltage tracking circuit based on an operational amplifier, which has a simple circuit structure, strong anti-interference ability, and wide application range.

[0005] The technical solution is as follows: A power output voltage tracking circuit based on an operational amplifier, characterized in that it includes operational amplifier U1A and operational amplifier U1B. The non-inverting input terminal of operational amplifier U1A is connected to one end of resistor R11 and one end of resistor R14. The inverting input terminal of operational amplifier U1A is connected to one end of resistor R10 and one end of capacitor C3. The other end of resistor R10 is connected to one end of resistor R9 and one end of capacitor C4 and serves as the external voltage track input terminal. The output terminal of operational amplifier U1A is connected to the anode of diode D2, the other end of resistor R14, and the other end of capacitor C3. The cathode of 2 is connected to one end of resistor R7. The other end of resistor R7 is connected to one end of resistor R3, one end of resistor R4, one end of resistor R6, one end of resistor R12, one end of resistor R13, and the non-inverting input terminal of operational amplifier U1B. The inverting input terminal and output terminal of operational amplifier U1B are connected and connected to one end of resistor R8. The other end of resistor R8 is connected to the feedback terminal FB of the power chip circuit. The other end of resistor R6 is connected to one end of capacitor C1. The other ends of capacitor C1, resistor R3, and resistor R4 are all connected to the other end of resistor R11 and the output terminal VOUT of the power chip circuit.

[0006] A further feature is that the operational amplifier U1A and the operational amplifier U1B constitute an operational amplifier U1 of model LM2904XM-G; The operational amplifier U1 is connected to a power supply circuit, which includes a transistor Q1. The base of the transistor Q1 is connected to one end of resistor R1, one end of resistor R2, and the cathode of diode D1. The collector of the transistor Q1 is connected to the other end of resistor R1 and the other end of resistor R2 and serves as the power supply input terminal VIN+. The anode of diode D1 is grounded. The emitter of the transistor Q1 is connected to one end of resistor R5. The other end of resistor R5 is connected to pin 8 of the operational amplifier U1. The power chip circuit includes a power chip U2. Pin 1 of the power chip U2 is the power input terminal VIN+ and is connected to one end of capacitor C7, one end of capacitor C8, and one end of resistor R16. Pin 2 of the power chip U2 is connected to one end of resistor R17, the other end of capacitor C7, the other end of capacitor C8, and grounded. Pin 3 of the power chip U2 is connected to VCC through resistor R20. Pin 4 of the power chip U2 is connected to the other end of resistor R17. Pin 6 of the power chip U2 is connected to VCC through resistor R22. Pin 12 of the power chip U2 is connected to one end of resistor R18, one end of resistor R19, and the other end of resistor R16. The other ends of resistors R18 and R19 are both grounded. Pin 11 of chip U2 is the feedback terminal FB. Pin 10 of power chip U2 is connected to one end of capacitor C12 and ground. Pin 9 of power chip U2 is connected to the other end of capacitor C12. Pin 8 of power chip U2 is connected to one end of resistor R21. The other end of resistor R21 is connected to one end of capacitor C13. The other end of capacitor C13 is connected to pin 7 of power chip U2 and inductor L1. The other end of inductor L1 is connected to one end of capacitor C9, one end of capacitor C10, one end of capacitor C11, and one end of resistor R22, which is the output terminal VOUT of the power chip circuit. The other end of resistor R22 is connected to pin 5 of power chip U2. The other ends of capacitors C9, C10, and C11 are all grounded.

[0007] With this invention, the voltage tracker has the characteristic that the difference (offset voltage) between the input voltage at the track terminal and the output voltage can be very small because the output voltage follows the input voltage at the track terminal. Furthermore, it is implemented using a fully analog circuit, which has strong anti-interference ability, a wide operating temperature range, low input current at the track terminal, and low power consumption. Attached Figure Description

[0008] Figure 1 This is the circuit schematic diagram of this utility model; Figure 2 This is the circuit schematic of the power chip. Detailed Implementation

[0009] See Figure 1As shown, a power supply output voltage tracking circuit based on an operational amplifier includes operational amplifiers U1A and U1B, which together constitute operational amplifier U1 (model LM2904XM-G). The non-inverting input of operational amplifier U1A is connected to one end of resistor R11 and one end of resistor R14, while the inverting input is connected to one end of resistor R10 and one end of capacitor C3. The other end of resistor R10 is connected to one end of resistor R9 and one end of capacitor C4, serving as the external voltage track input. The output of operational amplifier U1A is connected to the anode of diode D2 and the other end of resistor R14. The other end of capacitor C3, the cathode of diode D2 is connected to one end of resistor R7, the other end of resistor R7 is connected to one end of resistor R3, one end of resistor R4, one end of resistor R6, one end of resistor R12, one end of resistor R13, the non-inverting input of op-amp U1B, the inverting input and output of op-amp U1B are connected and connected to one end of resistor R8, the other end of resistor R8 is the feedback terminal FB of the power chip circuit, the other end of resistor R6 is connected to one end of capacitor C1, the other end of capacitor C1, the other end of resistor R3, the other end of resistor R4 (i.e. the VOUT terminal of the power chip circuit) are all connected to the other end of resistor R11.

[0010] Operational amplifier U1 is connected to a power supply circuit, which includes transistor Q1. The base of transistor Q1 is connected to one end of resistor R1, one end of resistor R2, and the cathode of diode D1. The collector of transistor Q1 is connected to the other end of resistor R1 and the other end of resistor R2 and serves as the power input terminal VIN+. The anode of diode D1 is grounded. The emitter of transistor Q1 is connected to one end of resistor R5. The other end of resistor R5 is connected to pin 8 of operational amplifier U1 and one end of capacitor C2. The other end of capacitor C2 is grounded.

[0011] See Figure 2As shown, the power chip circuit includes power chip U2. Pin 1 of power chip U2 is the power input terminal VIN+ and is connected to one end of capacitor C7, one end of capacitor C8, and one end of resistor R16. Pin 2 of power chip U2 is connected to one end of resistor R17, the other end of capacitor C7, the other end of capacitor C8, and grounded. Pin 3 of power chip U2 is connected to VCC through resistor R20. Pin 4 of power chip U2 is connected to the other end of resistor R17. Pin 6 of power chip U2 is connected to VCC through resistor R22. Pin 12 of power chip U2 is connected to one end of resistor R18, one end of resistor R19, and the other end of resistor R16. The other ends of resistors R18 and R19 are both grounded. Pin 11 of the source chip U2 is the feedback terminal FB. Pin 10 of the power chip U2 is connected to one end of capacitor C12 and ground. Pin 9 of the power chip U2 is connected to the other end of capacitor C12. Pin 8 of the power chip U2 is connected to one end of resistor R21. The other end of resistor R21 is connected to one end of capacitor C13. The other end of capacitor C13 is connected to pin 7 of the power chip U2 and inductor L1. The other end of inductor L1 is connected to one end of capacitor C9, one end of capacitor C10, one end of capacitor C11, and one end of resistor R22, which is the output terminal VOUT of the power chip circuit. The other end of resistor R22 is connected to pin 5 of the power chip U2. The other ends of capacitors C9, C10, and C11 are all grounded.

[0012] The working principle is as follows: The power input passes through transistor Q1 and current-limiting resistor R5 into the operational amplifier. Zener diode D1 stabilizes the VCC voltage within a suitable range, and capacitor C2 filters and stores energy for VCC. Pins 1 and 2 of the LM2904XM-G operational amplifier (i.e., the inverting input and output of op-amp U1B) are connected to the feedback terminal FB of the power supply chip circuit. The power supply output voltage VOUT is divided by resistors R3, R4, R12, and R13 and then connected to pin 3 of the LM2904XM-G operational amplifier (i.e., the non-inverting input of op-amp U1B). By comparing the voltages at pins 2 and 3, the voltage at pin FB of the power supply chip is affected, thereby adjusting the power supply output voltage VOUT. The voltage divider resistors R3, R4 and R12, R13 are connected in parallel to improve the accuracy of the power supply output voltage VOUT. Capacitor C1 and resistor R6 are used to adjust the high and low temperature drift of the power supply output voltage VOUT.

[0013] The output voltage tracking function is implemented by connecting the Track terminal to pin 6 of the operational amplifier LM2904XM-G (i.e., the inverting input of op-amp U1A), and connecting the power supply output voltage VOUT to pin 5 of the LM2904XM-G (i.e., the non-inverting input of op-amp U1A). When a voltage lower than VOUT is applied to the Track terminal, the output voltage at pin 7 of the LM2904XM-G (i.e., the output of op-amp U1A) adjusts the feedback voltage of VOUT through resistor R7, affecting the voltage at the feedback terminal FB of the power supply chip circuit. The power supply chip U2 is used to adjust the voltage of VOUT to achieve the output voltage tracking function. The power supply output voltage VOUT is the same as the input voltage at the Track terminal. However, when the input voltage at the Track terminal exceeds the power supply output voltage VOUT, the voltage of VOUT will not change; the Track terminal can only adjust the voltage of VOUT downwards, not upwards. The diode D2 is used to prevent the VOUT feedback circuit from affecting the voltage tracking circuit function. Resistor R9 is the pull-up resistor at the Track terminal. Capacitor C4 filters and stores energy for it. Resistors R15 and R17 limit current. Resistors R9, R19, and capacitor C8 form a feedback circuit.

[0014] The circuit of this application has a backflow current prevention function, which can prevent current from flowing from the voltage tracking track terminal into the downstream load during a power supply short circuit fault.

Claims

1. An operational amplifier-based power supply output voltage tracking circuit, characterized by, It includes operational amplifiers U1A and U1B. The non-inverting input of operational amplifier U1A is connected to one end of resistor R11 and one end of resistor R14. The inverting input of operational amplifier U1A is connected to one end of resistor R10 and one end of capacitor C3. The other end of resistor R10 is connected to one end of resistor R9 and one end of capacitor C4, and serves as the external voltage track input. The output of operational amplifier U1A is connected to the anode of diode D2, the other end of resistor R14, and the other end of capacitor C3. The cathode of diode D2 is connected to one end of resistor R7.

7. The other end is connected to one end of resistor R3, one end of resistor R4, one end of resistor R6, one end of resistor R12, one end of resistor R13, and the non-inverting input terminal of the operational amplifier U1B. The inverting input terminal and output terminal of the operational amplifier U1B are connected and connected to one end of resistor R8. The other end of resistor R8 is connected to the feedback terminal FB of the power chip circuit. The other end of resistor R6 is connected to one end of capacitor C1. The other end of capacitor C1, the other end of resistor R3, and the other end of resistor R4 are all connected to the other end of resistor R11 and the output terminal VOUT of the power chip circuit.

2. The power supply output voltage tracking circuit based on an operational amplifier according to claim 1, characterized in that, The operational amplifiers U1A and U1B constitute operational amplifier U1 with model number LM2904XM-G.

3. The power supply output voltage tracking circuit based on an operational amplifier according to claim 2, characterized in that, The operational amplifier U1 is connected to a power supply circuit, which includes a transistor Q1. The base of the transistor Q1 is connected to one end of resistor R1, one end of resistor R2, and the cathode of diode D1. The collector of the transistor Q1 is connected to the other end of resistor R1 and the other end of resistor R2 and serves as the power supply input terminal VIN+. The anode of diode D1 is grounded. The emitter of the transistor Q1 is connected to one end of resistor R5. The other end of resistor R5 is connected to pin 8 of the operational amplifier U1.

4. The power supply output voltage tracking circuit based on an operational amplifier according to claim 3, characterized in that, The power chip circuit includes a power chip U2. Pin 1 of the power chip U2 is the power input terminal VIN+ and is connected to one end of capacitor C7, one end of capacitor C8, and one end of resistor R16. Pin 2 of the power chip U2 is connected to one end of resistor R17, the other end of capacitor C7, the other end of capacitor C8, and grounded. Pin 3 of the power chip U2 is connected to VCC through resistor R20. Pin 4 of the power chip U2 is connected to the other end of resistor R17. Pin 6 of the power chip U2 is connected to VCC through resistor R22. Pin 12 of the power chip U2 is connected to one end of resistor R18, one end of resistor R19, and the other end of resistor R16. The other ends of resistors R18 and R19 are both grounded. Pin 11 of chip U2 is the feedback terminal FB. Pin 10 of power chip U2 is connected to one end of capacitor C12 and ground. Pin 9 of power chip U2 is connected to the other end of capacitor C12. Pin 8 of power chip U2 is connected to one end of resistor R21. The other end of resistor R21 is connected to one end of capacitor C13. The other end of capacitor C13 is connected to pin 7 of power chip U2 and inductor L1. The other end of inductor L1 is connected to one end of capacitor C9, one end of capacitor C10, one end of capacitor C11, and one end of resistor R22, which is the output terminal VOUT of the power chip circuit. The other end of resistor R22 is connected to pin 5 of power chip U2. The other ends of capacitors C9, C10, and C11 are all grounded.

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