svanderschyf@zodiac.rutgers.edu (05/06/91)
Here's another one-
I've designed and prototyped a circuit which controls high current
outputs. I'm feeding a low voltage source through a few power MOSFETs that
pass up to 8 Amps max. I'd like to get a few PCB printed, and am doing the
CAD work myself (ORCAD). However, I am concerned about how to handle these
high currents with a printed circuit board.. What is the usual technique
when high current is involved??? The MOSFETs are housed in a TO-220 package.
Thanks in advance.
-- Nickjeff@hpuplca.nsr.hp.com ( Jeff Gruszynski ) (05/08/91)
>/ hpuplca:sci.electronics / svanderschyf@zodiac.rutgers.edu / 6:31 pm May 5, 1991 / > Here's another one- > > > I've designed and prototyped a circuit which controls high current >outputs. I'm feeding a low voltage source through a few power MOSFETs that >pass up to 8 Amps max. I'd like to get a few PCB printed, and am doing the >CAD work myself (ORCAD). However, I am concerned about how to handle these >high currents with a printed circuit board.. What is the usual technique >when high current is involved??? The MOSFETs are housed in a TO-220 package. >Thanks in advance. > >-- Nick >---------- Quick & Dirty OK? Traces that are too thin for the current is the first problem. 1. find out the copper thickness of the boards you might use 2. multiply by first pass line widths of high current traces 3. divide this cross sectional area into maximum current 4. take this current density and compare to maximum current _density_ limits for copper wire derived from electrical codes, handbooks, etc. (max I / circ. cross sect area) 5. if pcb current density is too big, increase linewidth or use thick copper clad. I did something like this for a switcher I built. A secondary consideration (at least for switching P/S) is RFI from switching mondo currents. That gets more complex. Jeff Gruszynski T&M STE SE Santa Clara Sales Hewlett Packard -----------------