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Altera_Forum's avatar
Altera_Forum
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13 years ago

external pull-up resistors

I am working on an old design using an EXP880. I have an output pin which I need to be high during power up. Is there a recommended value for external pull-ups, or can you program an internal pull-up? Thanks!

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

    Hi,

    I'm not aware with this type of ALTERA chip, but as long as the device is not configured (during power up), the programming option is no solution, isn't it?

    Thus I would recommend the external pull-up - the upper value is given by the leakage current of the circuits on power up to ensure the level is a logic "high", the min value is given by the max. current the EXP can carry to ensure a stable "low". Nevertheless I would recommend (on engingeering judgement) 1 to 10KOhm :-D