Fried sensor board with external AC/DC adapter

[mardah]

[sundberg84]

A read somewhere here that cheap clones use cheap/fake voltage converter and supplying 12v to RAW is living on the edge even if 12v is within limits.

Maybe you have a bad batch of voltage regulators?
Did you try with another AC/DC converter? It can limit your search.

[mardah]

The MCP1703 does provide 3.3V until it fries. But yes, it could be a non genuine voltage regulator.

[sundberg84]

How about the HLK-PM01 or use a AC to 5v DC converter (Iphone plug)?
Then you dont need regulate your voltage twise.

[Yveaux]

@mardah what's the maximum input voltage for the MCP1703?
I've fried some AM1117's supplying '12V' from an unregulated adapter.

[mardah]

The MCP1703 should handle up to 20V input. Maybe the input cap is 10V , I guess it would handle 12V most of the time?

[Yveaux]

@mardah said:

he MCP1703 should handle up to 20V input.

Datasheet states 18V as absolute maximum (http://ww1.microchip.com/downloads/en/DeviceDoc/22049e.pdf).
Also check the maximum on the cap, as you already suggested.

[m26872]

I've fried a lot of Arduino boards by powering on my breadboard AC/DC supply while still having the FTDI port supply from Laptop connected or vs. (Laptop is on its own AC/DC.)
Change Atmega has always saved the boards then, but I don't use the v-reg very often.

[Yveaux]

@m26872 ground-loops... Terrible :rage:

[mardah]

I soldered just the two caps and an MCP1703 on a new board and have not manage to fry it. So maybe there is another cause. I'm suspecting the WS2812, it's new on my latest batch of sensor boards. But I don't understand how it could destroy the voltage regulator or ATMega.

Maybe something is wrong with the PCB layout causing some unwanted currents?