Re: current through FET

On Mon, 7 Apr 2008 15:11:41 -0700 (PDT), blanko <electrone2@xxxxxxxxx>
wrote:


I am currently using this FET to toggle the power to a device. The
device wants 3.3V.

http://www.zetex.com/3.0/pdf/ZXM61P03F.pdf

I have pin 1 (gate) going to my microcontroller, pin 2(source) going
to a 3.3V regulator, and pin 3 (drain) goes to the device I am
powering. The 3.3V regulator can provide 800 mA of output current
and I need all of that going through the FET to the device I am
powering. The problem is that when I take a look at the data***
(page 5 , 2nd graph) I will only be getting a few hundred milliamps.

Does anyone have a different part they can recommend or an easy way to
modify my current setup to allow for a higher current?

Thanks!

-Mike


Assuming configured like the switching time test circuit on the
data***....

Rdson = 0.35ohm...ok... Say 0.28V drop @ 800mA.
So load only gets ~3V @ 800mA

The transfer shows Id ~ 800mA @ Vgs ~ -2.0V.

Does that microcontroller output apply >-2.0Vouts with respect to the
source?
Notice the on resistance spec. When Vg= -5V then you get the 350ohm
Rdson. At Vg = -3V, it's a crappy 1 ohm or more.

Make sure Vg is right.


D from BC
British Columbia
Canada
.