> On Oct 24, 2016, at 3:55 PM, David Bridgham <d...@froghouse.org> wrote: > > On 10/24/2016 12:01 PM, Paul Koning wrote: > >> I don't know about the receiver part, but I'd expect that the drivers could >> very easily be done with a simple transistor circuit. > > Agreed. However ... > >> As for slew rates, unless you have antique transistors, that's not going to >> be an issue given that you meet the current sink spec; the slew rate of an >> OC circuit is determined by the system capacitance and the sink current of >> the driver. > > I think you read this part backwards. The slew rate requirement is not > a minimum slew rate but a maximum one. That is, any modern transistor > (probably ancient ones too) will be way too fast. You have to do > something to slow it down. Still, I think this one is easily met as > it's just a series resistor on the gate of the driver MOSFET working > against the gate capacitance. Some FPGAs have current limiting on their > output which may obviate the need for the resistor even.
I don't see any max slew rate spec in the driver specs in the peripherals handbook. paul