PIC output drive

Sometimes you need more output drive than a single PIC output pin is spec'd to handle. You could use a transistor or a buffer, but if you have any extra output pins to spare, you can simply wire multiple outputs in parallel.

Of course, you must make sure that the software always drives the parallel pins to the same state at the same time. Otherwise you would have contention between the output drivers in the PIC, which at the very least will waste current heating up the part, and may permanently damage it.

Note that in addition to the per-pin output drive spec, there is also a per-port spec. This means that there is generally no benefit to tying very many port lines together. For example, the PIC16C5x family is spec'd for a maximum current sink per port pin of 25 mA, and a maximum current sink for a whole port of 50 mA.

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Last updated September 9, 1995

Copyright 1995 Eric Smith