I am using the GS405 GPS in a hand held project but I need to be able to put it to sleep or some low power mode. That GPS does not have a mode like that so I need a way to power it down. I was thinking of using a transistor or MOSFET to turn it on and off. Is there any better ways of doing this?
Thanks,
Justin
Given you want to keep the thing powered, so as not to lose the almanac and whatnot, you’ll not want to do it by switching ground (eg n-channel mosfet or the like).
P-channel mosfet would work OK, but watch the on-resistance of the part you choose.
If you want to get nice and fancy, try a high-side switch like this http://www.micrel.com/_PDF/mic2514.pdf. Couldn’t get them from Digikey without buying a million, but Micrel sampled me four of them without a fuss.
I don’t know much about MOSFET but do they have a voltage drop like a diode? I decided to try a N-channel MOSFET, but I am worried because I am powering the GPS with 3.3V and it needs 3.1-3.5v so the MOSFET can’t drop too much. What do you think? I could only find things like on resistance, nothing on voltage drops. Does that mean they are like a resistor when they are on?
Thanks,
Justin