On Sun, 18 Oct 2009, Isaac Marino Bavaresco wrote: > M.L. escreveu: >> On Sun, Oct 18, 2009 at 8:27 AM, Kevin wrote: >> >>> What's the difference between Vgs and Vgs(th) I thought the >>> Vgs(th) was the voltage to turn it on fully ? >>> >>> >> >> Vgs(th) is the voltage where a pre-defined level of current can flow. >> To turn it on fully you need a higher voltage. Check the Ids vs. Vgs >> graphs in the datasheet. You want the voltage to be well above >> whatever your maximum current will be. Most of the time this ends up >> being 12v or sometimes 15v (for normal MOSFETs) >> Logic-level MOSFETs have a lower Vth so you can get by with a lower >> gate voltage, but the Rd-s resistance is higher. >> > > Vgs(th) (threshold) is the gate voltage below that no current flows at all. > > > Isaac > OK, thanks to all for clearing that up. I am going to use 2SJ412 for the P channel and IRLU024N for the N channel. I checked the Id versus Vgs graphs and both are about 15 Amps at 5V. Since the motor stall current is 10 Amps these should work fine. Thanks, Kevin http://pdf.chinaicmart.com/2SJ/2SJ412_1095041.pdf http://pdf1.alldatasheet.com/datasheet-pdf/view/93649/IRF/IRLU024N.html -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist