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GS405 GPS powered down

Tips and questions relating to the GPS modules from SFE

GS405 GPS powered down

By CommanderBob
-  Sat Jul 05, 2008 4:23 pm #51372
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

High side switch

By jpopadic
-  Wed Aug 20, 2008 7:18 am #53982
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.

By CommanderBob
-  Wed Aug 20, 2008 12:47 pm #54005
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
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