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Topic: Board powering via Analog pins? (Read 119 times) previous topic - next topic


Hi All,

Just a quick question: Should the board power-up if a power source is applied across A0 and GND?

I've been working on a datalogging project that monitors the voltage values of a few Lithium Polymer cells over their life span. I noticed that my board gets powered when i connect my battery sense leads to the analog inputs.

It does make sense & obviously the solution is to place a large resistance in series with the AI's but its strange that ive not seen this mentioned at all anywhere :smiley-surprise:


Power can leak thru the clamp to VCC and clamp to Gnd pin protection diodes make the chip appear to be partially powered. If current going in that way exceeds 1A, the diode and other pin parts can be damaged.
That's why the spec says Vin High not to exceed VCC + 0.5V, and Vin Low not to go below Gnd - 0.5V.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.


1A? That doesn't sound right...
ATtiny core for 841+1634+828 and x313/x4/x5/x61/x7/x8 series Board Manager:
ATtiny breakouts (some assembled), mosfets and awesome prototyping board in my store http://tindie.com/stores/DrAzzy

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