I am developing the automated test system depicted in the following picture.
Everything works fine.
To simplify the system I replaced the power supply 2 with a isolated DC-DC converter (DPAN02A-05) connected to power supply 1.
After that the current measurements (differential voltage across R1) are completely screwed up. Measured current is definitely lower than the correct value and it is negative instead of positive.
Conversely, voltage measured across DUT is correct (even if a little bit lower than the expected value. Maybe because the supply voltage is noisy since the DC-DC converter).
I measured +5V and +3.3V and they are correct.
I have been bumping my head on the wall for days trying to figure out what’s wrong.
Please, give me some help!
Because you should use a filter and then a LDO and then yet another filter, ferrite bead. This DPAN02A-05 actually has a dual output +/-5v which you dont use it correctly. You should indeed find some low ripple, low noise 3.3V & 5V converter.
Answered by Marko Buršič on December 22, 2020
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