Looked it up, but it only has 170mA continuous drain current compared to the BSH111's 335mA. But that brings up a question ... for a pulsed application (max 33% duty-cycle at ~120hz multiplexing in this case), how does one calculate the proper current/power rating required of the FET? For the BSH123 for example, Rds(On) = 10ohms max at Vgs=4.5V. With 250mA (max drawn by LEDs), that means .625W dissipated. This violates the BSH123's max power rating of .36W. But at 33% duty-cycle, average current dissipated = .208W. So would this be acceptable? Also, Id (pulsed) = 0.68A on the datasheet. The confusing part here (for me) is that they don't specify the freq & duty-cycle that defines "pulsed". Cheers, -Neil. > -------- Original Message -------- > Subject: Re: [EE] Logic-level mosfet? BSH111? > From: "Richard Prosser" > Date: Sun, April 23, 2006 12:11 am > To: "Microcontroller discussion list - Public." > > BSS123 ? > > RP > > On 22/04/06, Picdude wrote: > > Any of you used the BSH111 before? The specs indicate that it would serve as a good logic level mosfet for my purposes, and at a decently low price, but I thought I'd check here first. Intention is to drive the columns on multiplexed LED displays, with 250mA max at 33% duty-cycle max. I've been using the BSS138 or MMBF170 for this, but availability & price have me looking for these other options. Any other suggestions? I'm picking up a few thousand, so cost is important. > > > > Datasheet: http://www.semiconductors.philips.com/acrobat/datasheets/BSH111-02.pdf > > > > Cheers, > > -Neil. > > > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist