I am trying to design a datalogger that runs off battery power and am trying to maximise runtime.
The logger is infrequently (every 5 minutes) logging 0-30V analog and digital signals.
One of the key current draws at this stage is the voltage dividers required to reduce the signals to the 3.3V or 5V tolerated by the microcontroller. As even loads as high as 1Mohm begin to add up (16 inputs total = approx 0.48 mA).
This seems like a pretty common problem but I haven't been able to turn up an accepted solution.
I have contemplated options such as
- Reed Relays - Semi impractical due to the required quantity, possibly more beneficial at even lower sample rates.
- Some kind of buffer IC - Haven't been able to turn up any parts that accept a voltage so far out of the supply range