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Altera_Forum's avatar
Altera_Forum
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14 years ago

DC Characteristics

In the cyclone II handbook,page 5-4,pin pull-up resistance values will be lower if an external source drivers the pin higher than Vccio. i don't understand it . Please explain it . Thanks
Altera_Forum's avatar
Altera_Forum
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14 years ago

If you drive the pin at a higher voltage than Vccio, the clamping diode will start drawing current, thus lowering the impedance seen from outside.