CPLD input

Does a CPLD Input source current ? When I measure the voltage at my CPLD input pin, it is somewhere in the 3V range. When I connect it to ground, it sources about 50 mA. Is that normal ? I thought an input should not behave like this ..!?

Reply to
Hans Maier
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I would call that an output, or a broken input.

Aust> Does a CPLD Input source current ? When I measure the voltage

Reply to
Austin Lesea

Yes, this is driving me mad ....

It is configured as input, and it WORKS as input. If I pull it down to ground, the logic detects the low level.

Could it still be broken ? How could I break an input ? There are only 5V on the board ....And the rest of the chip works just fine ....

Reply to
Hans Maier

You could clarify if your 50mA meant 50 microamps, or

50 milliamps. Many times I've seen the greek 'u' in uA morph into mA on the internet as it jumps fonts.... 50uA could be a normal pin pullup, 50mA sounds like the PFET is on.

A simple test is to try moving the function to another pin, or simply swap the pin allocates (two same-class pins). If the problem stays with the pin, it's likely to be chip related, if it moves with the function, suspect something in your code...


Reply to
Jim Granville

it is 0.050 A or 50 milliamps

Thanks I will do that.

code is very simple:

VCC_SENSE: in std_logic; -- sense power

Reply to
Hans Maier

Here's a weird thought... Try VOLT_SENSE: in -- sense power

Reply to

Thanks for your help, It actually WAS a broken input. The behaviour is OK when I use a new chip ..

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