Hi,
I'm working on a circuit that drives a termal printer. The printer has 8 output signals which activate the heaters. This signals connected to the CPU through a latch (74HC573). The sequence of the process is to enable the OE signal of the latch for about 2ms (at which the heaters are activated), then disable the OE and write new information to the printer via serial interface (takes about 100uS) and activate the OE again...
I want to add a protection circuit that will recognize a situation that the OE of the latch is enabled for too much time (more then 4mS - that might burn the heaters) and will disable it.
Of course, I'm looking for the simplest circuit possible.
Any ideas?
Thanks! Eyal.