Hi all,

I have a circuit which needs to switch a 48V supply (which can rise as
high as 80V). The load is ground referenced and can draw as much as
100 Amps. The switch, however, need not open while any more than 1 Amp
is flowing.

To accomplish this, I was planning on using several N channel FETs in
parallel (because of their low Rds_on). Because the load can be on for
hours or days, I need a true DC high-side drive (normal bootstrap-type
drivers will not work because the bootstrap cap will discharge
slowly).

Based on a web search, I thought that the Intersil ISL6801 would do
this, but the datasheet is confusing and ambiguous, and my actual
prototype test showed that it cannot handle this situation (acts like
a normal bootstrap driver).

Most of the other ICs I found which claim to do this are limited to
less than 80V at the FET source.

I designed up a circuit to do it using a transformer and optocouplers,
but it is not pretty or cheap.

Anyone know of an IC to do gate drive for something like this?

Thanks,

Sean
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist