Constant resistance control loop

Abstract

The invention provides a constant resistance control loop. The constant resistance control loop comprises an input voltage differential sampling unit used for attenuating a voltage signal of an external constant voltage input power source, and outputting the attenuated voltage signal to a reference input pin of a first DAC; the first DAC used for outputting a constant current control voltage signal to a constant current control loop according to the attenuated voltage signal and an input code value of the first DAC; the constant current control loop used for controlling the constant current which changes with an input voltage signal of the external constant voltage input power according to the constant current control voltage signal when the constant resistance is output; the output end ofthe constant resistance control loop outputs a constant resistance value according to the ratio of a full-scale code value of the first DAC to the input code value, attenuation coefficients of the input voltage differential sampling unit and the relationship between output coefficients of the constant current control loop. According to the constant resistance control loop, the speed and accuracyof constant resistance output control are improved.

Description

technical field [0001] The invention relates to the technical field of constant resistance control, in particular to a constant resistance control loop. Background technique [0002] In the prior art, the general CR (Constant Resistance, constant resistance) control mode is implemented by software, that is, the ADC reads back the input voltage value of the input power supply, and the processor divides the voltage value by the resistance value set by the user to obtain the required pull-out value. The current value of the load is converted into the output voltage of the DAC, and the CC (constant current) control loop is controlled to obtain a constant resistance value. The circuit structure is shown in the following figure. figure 1 shown. [0003] The software implementation method makes the response speed of the entire CR control subject to the sampling speed of the ADC, and the control accuracy of the CR is also subject to the sampling resolution of the ADC. It is well k...

AI Technical Summary

Problems solved by technology

As we all know, high-resolution ADCs are difficult to achieve high-speed sampling, and high-speed sampling ADCs are difficult to achieve high-resolution

Therefore, if the ADC uses a high-precision and high-resolution ADC, the response of the CR will seriously lag behind the change of the external input voltage; and if a low-resolution high-speed sampling ADC is used, it will be difficult for the CR to achieve high-precision control

[0004] To sum up, in the existing constant resistance control loop, the speed and precision of constant resistance output control are low

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