jaikanth

:cry:
i'm doing jamming program in flash ic (target board) through a jamming device which connected in printer port.(25 pin)
is there any protection circuit that can control the voltage flow in my printer port cable below 5v and 63mA.
mostly my jamming device(which is going to program in flash)gone bad.
simply i need a buffer circuit for parellel printer port.

Nigel Goodwin

Parallel port programmers usually use 7407 or 7406 open-collector buffers, these give you the capability to switch higher voltage supply rails (via PNP transistors) and also protect the port. There's nothing going to provide total protection, particularly if you do something stupid, but buffer chips provide a reasonable amount of protection at low cost.