RE: Digest Number 206

On Thu, 14 Oct 1999, you wrote:

> From: "Elliot Burke" <elliot@...>
>
> Why are opto-isolators needed? Would the high voltage from the output stage
> get back to the IC, or is this just to protect the IC when the output stage
> pops?

> > Have you thought of replacing the MOSFETS on Dan's board with some
> >opto-isolator chips and using the output from these to drive a high voltage
> >bridge ?

Hi Elliot

The voltages required to turn on and off the MOSFETs on the high side of a H
bridge at 80V are way above the max limits of th IC's. In fact only two
opto-isolators would be needed on each bridge - just to act as level shifters.

Regards, Paul.

BTW How do they manage to squeeze so much smoke into a tiny peice of silicon ?