How to use an op amp to control the FB feedback pin of an adjustable power supply?

尘埃海

How to use an op amp to control the FB feedback pin of an adjustable power supply? [Copy link]

In the figure: ADC and TX pins are two functional interfaces connected to the single chip, but we don’t know how to use them specifically. OUT+ is the positive output of the adjustable power supply, and FB is the FB pin of the adjustable power supply. What should the output formula be like?

maychang

The op amp works in a DC open loop, and the ADC and TX points are only connected to the two pins of the microcontroller. No one knows what the op amp output should be.

尘埃海

ADC outputs voltage analog quantity. If tx only outputs high and low levels, can it control the on and off of the adjustable power supply? The adjustable power supply chip is xl4015

尘埃海

maychang posted on 2020-10-10 13:42 The op amp works in DC open loop, and the ADC and TX points are only connected to the two pins of the microcontroller. No one knows what the op amp output should be.

ADC outputs voltage analog quantity. If tx only outputs high and low levels, can it control the on and off of the adjustable power supply? The adjustable power supply chip is xl4015

maychang

Chenhai published on 2020-10-10 15:29 ADC outputs voltage analog quantity. If tx only outputs high and low levels, can it control the on and off of the adjustable power supply? The adjustable power supply chip is...

This op amp works in a DC open loop, with a capacitor C7 connected between the output and the inverting input, and the capacity of C7 is relatively large.

This is an integration circuit that integrates the voltage output by the ADC. However, there are three capacitors C3, C4, and C5 from the ADC to the inverting input of the op amp, forming a third-order low-pass filter.

If the TX output is high or low level, then the TX high or low level will definitely cause the op amp to enter forward saturation after a period of time.

So, I don't understand this circuit.

yangjeff

Chenhai published on 2020-10-10 15:28 ADC outputs voltage analog quantity. If tx only outputs high and low levels, can it control the on and off of the adjustable power supply? The adjustable power supply chip is xl4015

Thanks for sharing, it's really great