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Altera_Forum
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17 years ago

Is it safe to use I/O pins like an H-bridge?

I am working on a board with an EP3C16E144 that has a RJ-45 with integrated LED's. One of the LED's is bi-color, with the two diodes wired in opposite directions. If you forward bias the LED, it glow...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
17 years ago

This is completely safe, as long as the maximum ratings for the individual pins and the pin group aren't exceeded.

You should consider, that Quartus reduces the drive strength for EP3C to 2 mA with the CMOS3.3V I/O standard, so you should calculate an effective output resistance of 50 to 70 ohms for each pin. In other words, you achieve the intended LED current at best with a zero ohms external resistor.