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Altera_Forum's avatar
Altera_Forum
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13 years ago

Driving LEDs from 1.8V outputs

Hello,

I need to drive some LEDs from the 1.8V outputs on my Arria II GX device.

The plan is to simply connect the LEDS to 3.3V (through a resistor) and make the ouptut open drain. Will this be OK?

It will of course cause the ouptut to be pulled up to 3.3V when the LED is off. The datasheet suggests that the output can stand up to 3.6V.

Thanks

-Tim

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    13 years ago

    The output can stand up to 3.6V but why risk it. Can’t you reverse the polarity of the LEDs and give a ground signal from the controller. That way the LEDs will work at 1.8V when you give them a ground signal.