Re: OT - TTL Circuit: Pullup vs Supply

Jess,

I can't imagine an application where it would make much difference,
especially with pull-ups. If they were pull-downs, then you might need
slightly more power without resistors - at least with vanilla TTL. With
CMOS, it makes no difference. Which exact logic family are you using?
(I assume it's not "original TTL")

Thanks,
-Frank

Jess Askey wrote:
> can anyone explain what any pro's or con's there might be on tying
> static input pins on a TTL device 'high' through a pull-up resistor vs
> straight to the +5V supply? Im working on laying out a ASIC replacement
> PCB and I had the board designed with pull-up resistors but tracing them
> is becoming a PITA so I thought about just tying them to the +5V rail as
> an alternative.
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Received on Wed Sep 6 20:44:13 2006