CN-121995095-A - Voltage sampling circuit and electronic equipment

Abstract

The voltage sampling circuit is characterized in that an impedance compensation circuit is arranged, the equivalent impedance of an inverting input end of an operational amplification circuit is configured to be infinite, the input impedance of the inverting input end under different sampling voltages is fixed, the influence on the resistance coefficient of the input front end is greatly reduced, the sampling precision of the voltage sampling circuit is greatly improved, and the sampling amplification gain consistency is good in a full input voltage range.

Inventors

• LIU JIANZHI
• Lai Risong
• ZHONG BO

Assignees

• 宁德时代未来能源(上海)研究院有限公司
• 宁德时代新能源科技股份有限公司

Dates

Publication Date

20260508

Application Date

20241104

Claims (14)

1. 1. The voltage sampling circuit is characterized by comprising an operational amplification circuit, a voltage division circuit, a negative feedback circuit and an impedance compensation circuit, wherein the voltage division circuit is connected with a signal source, a non-inverting input end and an inverting input end of the operational amplification circuit, the voltage division circuit is used for dividing output voltage components of output of the signal source and outputting the voltage components to the non-inverting input end and the inverting input end of the operational amplification circuit, the negative feedback circuit is connected between the inverting input end and the output end of the operational amplification circuit, the impedance compensation circuit is at least coupled with the inverting input end of the operational amplification circuit, and the impedance compensation circuit is used for configuring equivalent impedance of the inverting input end of the operational amplification circuit to be infinity.
2. 2. The voltage sampling circuit of claim 1, further comprising a bias current compensation circuit coupled to at least one of the non-inverting input and the inverting input of the operational amplifier circuit, the bias current compensation circuit configured to configure an external equivalent resistance of the non-inverting input of the operational amplifier circuit to be equal to an external equivalent resistance of the inverting input of the operational amplifier circuit.
3. 3. The voltage sampling circuit of claim 2, wherein the bias current compensation circuit comprises a first compensation resistor coupled to a non-inverting input of the operational amplifier circuit.
4. 4. A voltage sampling circuit according to claim 2 or 3, wherein the bias current compensation circuit comprises a second compensation resistor coupled to an inverting input of the operational amplifier circuit.
5. 5. The voltage sampling circuit of claim 1, wherein the voltage divider circuit comprises a first voltage divider network having an input for connection to the signal source, an output of the first voltage divider network comprising an output of the voltage divider circuit.
6. 6. The voltage sampling circuit of claim 1, wherein the voltage divider circuit comprises a first voltage divider network and a second voltage divider network, an input of the first voltage divider network is used for connecting the signal source, an output of the first voltage divider network forms a first output of the voltage divider circuit and is connected to an inverting input of the operational amplifier circuit, an input of the second voltage divider network is used for connecting the signal source, an output of the second voltage divider network forms a second output of the voltage divider circuit and is connected to a non-inverting input of the operational amplifier circuit.
7. 7. The voltage sampling circuit of claim 5 or 6, wherein the first voltage divider network comprises a first voltage divider and a second voltage divider, a first end of the first voltage divider forming an input of the first voltage divider network, a second end of the first voltage divider being connected to a first end of the second voltage divider forming an output of the first voltage divider network, a second end of the second voltage divider being grounded.
8. 8. The voltage sampling circuit of claim 6 wherein the second voltage divider network comprises a third voltage divider and a fourth voltage divider, a first end of the third voltage divider forming an input of the second voltage divider network, a second end of the third voltage divider being connected to a first end of the fourth voltage divider forming an output of the second voltage divider network, a second end of the fourth voltage divider being grounded.
9. 9. The voltage sampling circuit of claim 6, further comprising a fifth voltage divider having a first end for connection to a power supply positive electrode, a second end connected to the input of the first voltage divider network and the input of the second voltage divider network, the signal source comprising the power supply positive electrode.
10. 10. The voltage sampling circuit of any one of claims 1 to 9, wherein the impedance compensation circuit comprises an input impedance circuit, a first end of the input impedance circuit being connected to the output of the voltage divider circuit, a second end of the input impedance circuit being connected to the inverting input of the operational amplifier circuit and the negative feedback circuit, the input impedance circuit having the same impedance as the negative feedback circuit.
11. 11. The voltage sampling circuit of any one of claims 1 to 9, wherein the impedance compensation circuit comprises a current suppressing component and an input impedance circuit, a first terminal of the current suppressing component being connected to the output terminal of the voltage dividing circuit, a second terminal of the current suppressing component being connected to the inverting input terminal of the operational amplifier circuit and the negative feedback circuit through the input impedance circuit, the current suppressing component being configured to suppress current flow through the input impedance circuit.
12. 12. The voltage sampling circuit of claim 11, wherein the current suppressing component comprises two diodes that are co-anode and in anti-phase series on a first end of the input impedance circuit.
13. 13. The voltage sampling circuit according to any one of claims 1 to 9, wherein the impedance compensation circuit includes the voltage dividing circuit and an input impedance circuit, an output terminal of the voltage dividing circuit is connected to an inverting input terminal of the operational amplifier and the negative feedback circuit through the input impedance circuit, an output terminal of the voltage dividing circuit is further connected to a non-inverting input terminal of the operational amplifier circuit, and the voltage dividing circuit is configured to output the voltage component having the same voltage value to the non-inverting input terminal of the operational amplifier circuit and the input impedance circuit.
14. 14. An electronic device comprising at least one voltage sampling circuit according to any one of claims 1 to 13.

Description

Voltage sampling circuit and electronic equipment Technical Field The present application relates to electronic circuits, and particularly to a voltage sampling circuit and an electronic device. Background In the technical field of voltage detection, for direct-current voltage sampling, a non-isolated differential amplifying circuit is generally adopted, and two input resistors are configured on the input side of the differential amplifying circuit, so that the resistance values of the two input resistors are equal, and the feedback resistor is equal to the voltage dividing resistor, so that the output voltage and the input voltage are in a linear relation. Therefore, in the conventional voltage sampling circuit, the voltage dividing circuit is connected in series to the input of the differential amplifying circuit, but the voltage dividing precision of the voltage dividing circuit is affected by the input impedance, especially in a small voltage range, the influence is obvious, and finally the sampling precision is reduced. Disclosure of Invention In view of the above problems, the present application provides a voltage sampling circuit and an electronic device, which aim to solve the problem of low sampling precision of the conventional voltage sampling circuit. In a first aspect, an embodiment of the present application provides a voltage sampling circuit, including an operational amplifying circuit, a voltage dividing circuit, a negative feedback circuit and an impedance compensation circuit, where the voltage dividing circuit is connected with a signal source, an in-phase input end and an anti-phase input end of the operational amplifying circuit, the voltage dividing circuit is configured to divide an output of the signal source to output a voltage component to the in-phase input end and the anti-phase input end of the operational amplifying circuit, the negative feedback circuit is connected between the anti-phase input end and the output end of the operational amplifying circuit, the impedance compensation circuit is coupled with at least the anti-phase input end of the operational amplifying circuit, and the impedance compensation circuit is configured to configure an equivalent impedance of the anti-phase input end of the operational amplifying circuit to be infinity. According to the technical scheme provided by the embodiment of the application, the voltage sampling circuit is provided with the impedance compensation circuit, so that the equivalent impedance of the inverting input end of the operational amplification circuit is configured to be infinite, the input impedance of the inverting input end under different sampling voltages is fixed, the influence on the resistance coefficient of the input front end is greatly reduced, the sampling precision of the voltage sampling circuit is greatly improved, and the sampling amplification gain consistency is better in the whole input voltage range. In some embodiments, the voltage sampling circuit further comprises a bias current compensation circuit coupled to at least one of the non-inverting input and the inverting input of the operational amplifier circuit, the bias current compensation circuit configured to configure an external equivalent resistance of the non-inverting input of the operational amplifier circuit to be equal to an external equivalent resistance of the inverting input of the operational amplifier circuit. According to the technical scheme provided by the embodiment of the application, the bias current compensation circuit equalizes the external equivalent resistance connected with the non-inverting input end of the operational amplifier circuit with the external equivalent resistance connected with the inverting input end of the operational amplifier circuit, so that the influence of bias current and offset voltage of the operational amplifier circuit is reduced, and the sampling precision is improved. In some embodiments, the bias current compensation circuit includes a first compensation resistor coupled to the non-inverting input of the operational amplifier circuit. In the technical scheme of the embodiment of the application, when the external equivalent resistance connected with the non-inverting input end of the operational amplifier circuit is unequal to the external equivalent resistance connected with the inverting input end of the operational amplifier circuit, the external equivalent resistance connected with the non-inverting input end of the operational amplifier circuit is equal to the external equivalent resistance connected with the inverting input end of the operational amplifier circuit through the compensation of the first compensation resistor coupled with the non-inverting input end of the operational amplifier circuit. In some embodiments, the bias current compensation circuit further comprises a second compensation resistor coupled to the inverting input of the operational amplifier circuit. In the technic