Current control by an OpAmp with unipolar power supply

121

00:57:43

The Zener diodes allow one to detach the reference voltage level from zero and use an opamp which cannot work rail-to-rail with a unipolar supply.

published 2 years ago

592azy2circuitdude

2 years ago

Interesting. I'm having trouble finding the voltage reference and where the current control is. Could you elaborate on that, or recommend a simplified example I could look at?

stanislav_maslovski

2 years ago

Hi, what you see, is a part of the control circuit, which includes an opamp-based aplifier the purpose of which is to pick up a small voltage from a shunt resistor (1 Ohm resistor in the right half of the schematic and amplify it to a level of about 1.2 V.

stanislav_maslovski

2 years ago

The ref voltage is taken from the voltage divider with the potentiometer. The 18 V is assumed to come from a regulated power supply, but 38 V is, for example, obtained from that by a DC-DC upconverter, unregulated.

stanislav_maslovski

2 years ago

Basically, you should insert all this circuit into the feed-back loop of the DC-DC converter.

stanislav_maslovski

2 years ago

The converter can be XL6009, for instance

stanislav_maslovski

2 years ago

Check also the other two variants: With one Zener and with one MOSFET

592azy2circuitdude

2 years ago

Wow, thank you for all the in-depth information. I'll start going through it...

592azy2circuitdude

2 years ago

Ok. I understand a little better what is happening. Some of it is kinda beyond my current electronics knowledge, but I learned more. Thanks for the extra circuits and explanations.

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