Precision voltage sampling circuit and sampling method

Abstract

The invention discloses a precision voltage sampling circuit and a sampling method. The circuit comprises a voltage input end, a voltage division circuit, an isolation operational amplification circuit, a differential amplification circuit and a voltage output end. The voltage input end is electrically connected with the input end of the voltage division circuit, the negative electrode of the voltage division circuit is electrically connected with the analog ground, the isolation operational amplifier circuit comprises an isolation amplifier, an input end power supply and an output end power supply, and the input end of the isolation amplifier is connected with the voltage division circuit; the isolation amplifier is introduced, so that the sampling circuit has a good input and output ohmic isolation characteristic, the anti-interference capability is enhanced, and signals can be transmitted with high impedance and high common-mode rejection capability in a noise environment; by adopting the differential amplification circuit, the amplification capability of a differential mode signal and the inhibition capability of a common mode signal are improved, the common mode rejection ratio is effectively improved, the temperature drift can be better inhibited, and different voltage division modes are adopted according to the range of the voltage to realize the segmented sampling of the input voltage.

Description

technical field [0001] The invention relates to the technical field of voltage detection, in particular to a precision voltage sampling circuit and a precision voltage sampling method. Background technique [0002] In a high-voltage DC-DC converter, a non-isolated differential amplifier circuit is usually used for feedback sampling of the DC output voltage. For details, see image 3 , is a simple differential amplifier circuit commonly used in the prior art, specifically: the negative pole (VIN-) of the input terminal is connected to the reverse input terminal of the integrated operational amplifier, a resistor 1 is connected in series between the two, and the positive pole of the input interface ( One end of VIN+) is connected to the non-inverting input terminal of the integrated operational amplifier, and resistor two is connected in series between the two, and the two ends of resistor three are respectively connected to the inverting input terminal and output terminal of t...

AI Technical Summary

Problems solved by technology

[0004] However, when the input of the above-mentioned differential amplifier circuit is a strong electric signal and the output is a weak electric signal, the insulation resistance between the strong and weak electric currents is connected in parallel with the resistor 1 and the resistor 2 in the circuit, so the values ​​of the resistor 1 and the resistor 2 must be In addition, when a small voltage signal is input, the existence of the bias current of the integrated operational amplifier will make the voltage sampling accuracy of the circuit At the same time, limited by the resolution of the A / D converter, the voltage sampling accuracy of the circuit will further decrease, and there is no input voltage limiting component, it is easy to make the input voltage too large, making the integrated operational amplifier work at Non-linear region, causing the output voltage to be constant and affecting the measurement results

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