Hey,
I am using an LCD (MIDAS LCD MC42004A6W-FPTLW or PC1602 LCD ) on a powered down ATmega2560. I noticed that during this power down mode, the LCD uses 1.2 mA (display off). When I detach +5V and ground, the use is still 1mA. The only way to reduce the power use is by disconnecting D7.
Has anybody seen this before?
Any hints at how to solve this or what to look for?
Michel
Has anybody seen this before?
Yes it is called parasitic powering. It is a bad thing it can damage your chips.
how to solve this
Never connect an active output to an unpowered chip. If you are going to power down sections of your circuit under program control then make all the outputs connected to it into inputs before you do.
michelv:
Has anybody seen this before?
Only every few weeks. 