On 8 February 2015 at 16:39, Josh Koffman wrote: .... > For the GS diode, following your suggestion of a Zener rated a volt or > so above the gate voltage (in my case 5V), I am looking at this one > from Bourns: > http://www.digikey.ca/product-detail/en/CD0603-Z6V2/CD0603-Z6V2CT-ND/3534= 311 > - I like it because it's an 0603 package, which is great for board > space. It's rated at 6.2V, 150mW. There are 6.8V and 7.5V versions > from a company called Comchip Technology if you think I should go > higher. > It just needs to be comfortably higher than Vgs_drive max and well enough celar of Vgs_absmax. As you know, zeners have very round shoulders indeed - which varies with voltage (not linearly - there are good and bad areas). Without If you care about absolutely crisp gate drive I'd suspect 6V2 was a tad close to 5V. .... looks at data sheet ... Hmmm. Not too bad for the 6V2 part. The 5V6 is a shocker. See datasheet 4th page (unnumbered) http://www.bourns.com/data/global/pdfs/CD0603_1005-Z.pdf 6V2 is down to 0.01 mA at maybe 5V8. The 5V6 is down to about 4V2 at 0.01 mA and somewhat under 0.1 mA at 5V. Truth be known a gate driver would not notice them at those levels. FWIW the 7V5 is close to ruler straight (if you have a fairly rough ruler). At the upper end you want to be far enough away from Vgsabsmax that a decent spike of Millar capacitance energy does not carry the gate over the limit. Murphy says gate oxides may fails scant volts above rated value. R --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .