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external pull-up resistors

Altera_Forum
Honored Contributor II
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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
Honored Contributor II
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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
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