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fridrikfreyr / DPS201-Hardware

DPS201: Ultrasmall lab power supply with digital control
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Schematic PDF feedback error #1

Open mihnen opened 8 years ago

mihnen commented 8 years ago

In the PDF schematic you have the voltage/current control outputs going to the comp/SD pin and the feedback pin grounded. This can't be right.

fridrikfreyr commented 8 years ago

Hi Matt, Look at page 9 in the LM3477 datasheet. The idea is to completely bypass the internal error amplifier (and voltage reference) by grounding the fb pin. We use external opamps (U6) to control the feedback together with the voltage reference set by the DAC. I found this in some application note from TI although I dont remember exactly which one. This kind of feedback does work although the circuit shown is not exactly stable at any load/voltage output.