Hi, I'm currently developing a control system based on arduino mega. I need to use 15 analog sensor that needs 3v @10mA each one of power. The sensor has 4 pins, you need to feed it with 3v@10ma for 20ms before read the analog value, keep the power during read and then switch off. You can't power the sensor continously because the sensor may be killed, ;).
I'm figuring out how can i make it and i've 3 choices, but every one with problems:
a) Feed each sensor with an DigitalOutput through a voltage divisor. Each I/O pin should be able to give 50mA, so the current is not a problem, but adjusting the voltaje divisor with resistors exactly at 3v I think isn't a easy thing, because the Output High threshold of TTL output.
b) Use a LM317 to feed all the sensor, but I don't know how to add an enable pin to a LM317 to power the sensor only when needed.
c) Use a commercial voltage regulator with EN line, like: http://www.lineagepower.com/oem/pdf/minilynx_sip_12v_ds.pdf or http://www.murata-ps.com/data/power/okr-t3-w12.pdf
The problem with this last option is mainly the price (10$) near to a 3.3 power source.
I'll be thankfull for any kind of ideas of how to manage the problem.
P.D: I've a 12V power Source that will be used to feed the arduino, but available too to feed the sensor if needed.