I have 1000W adjustable 4.8-24V output SMPS and smaller 5W 12V output SMPS.
In my design I need regulated 5V for Atmel AVR (VCC and reference voltage for AD-conversion). 12V out from small SMPS and 7805 regulator and there we have 5V. Atmel and 7805 is grounded to the smaller SMPS.
There's two resistors in series connected to 1000W SMPS output and AD-conversion voltage is took between those two resistors.
Now I'm thinking that does this work? There are two grounds. 1000W SMPS ground and 5W SMPS ground.
In this situation I have reference voltage and its ground from smaller SMPS and voltage which should be measured is from bigger SMPS. I'm not really sure does AD-converison work now.
If (or because) somebody didn't understand what I mean here's a pic:
**broken link removed**
5V_maa = ground from smaller 5W, 12V SMPS
1000W_GROUND = ground from 1000W, 4.8-24V SMPS
J4_4.8-24V TBLOCK is connector where is 1000W SMPS's out and ground connected.
Does this system blow or does it burn my atmel?