[email protected] wrote: > Gerald Coley <[email protected]> wrote: > > [-- text/plain, encoding quoted-printable, charset: ISO-8859-1, 56 lines --] > > > > Not really. The idea of powering a chip via an I/O pin will > > always cause damage. It means voltage as specified by the datasheet of > > the component. > > > I don't aim to 'power' it via the I/O pin! Maybe that's your way of > saying it but it's a very odd way. The likelihood is that there will > be a biggish resistor in series with the input to limit current and > there will probably also be some clamping diodes or maybe a buffer > amplifier but whatever you do there *cannot* be 'no voltage'. > > What I'm asking really is what will be tolerated with no problems, > every chip spec I have ever seen specifies some sort of minimum, not > zero. > ... and the processor spec *does* tell me!
The limits are specifically stated (as I expected) as follows:- "Steady state max. voltage at all I/O pins" "-0.5 volts to IO supply voltage +0.3 volts" So, even with power off, some voltage *is* allowed and in fact it should be fairly easy to keep the voltage within these limits using Schottky diodes for clamping. *This* is what I've been asking for. -- Chris Green ยท -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
