Buck converted shuts down if any wire is touched by probes or some other wire.

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1

Strange thing happening,

I tried to use https://www.mouser.com/ds/2/631/ACT4088 … 345917.pdf

Followed the example guide for step down 12V to 5V. Than, connected LM1117 on the 5V out to get 3.3 and now i have an issue. When i power up the circuit with 12V, everything works until i touch it with probe or some other wire.

The input is 12V 2.5A PSU

What could i do wrong?

p.s. here is the video how it happens

https://goo.gl/byqtNK

p.s.

Ah, i noticed something very strange,

if i hold with my fingers the main 12V input (directly on the contacts), and touch some pads with wire in another hand, it doesn’t happen :smiley:

Must me some mess with potentials, grounding … etc…

Any thoughts?

2

what schema did you apply ? Did you connect the enable to high or left it open ? Is it only the 3.3V or also the 5V that drops off ?

regards,

Paul

3

paulvha:
what schema did you apply ? Did you connect the enable to high or left it open ? Is it only the 3.3V or also the 5V that drops off ?

regards,

Paul

The schematics in case it can help: http://www.hepek.ba/buck.png

4

And what is that orange wire supposed to be in that schematic? Asside from the fact that part of the top board is out of view. How are we to figure out this jumble of wires in this 3 second video.

5

Thank you for your concerns… The issue was the displaced potentiometer on another board.

The resistors have very close ties to chips internal regulations and in this case extracting those wires made confusion in chip so it was shutting down(not being able to boot again) as a protection.

I changed the layout on the PCB so it’s great now.

Thnx anyway…