QG8 internal pullup = 150uA???

[UtopiaTim]

Hi Folks,

I must be missing something - I'm working on reducing current consumption on a

battery device, and it's drawing about 150 uA more than it should in STOP3 mode.

I narrowed it down to when I select an internal pullup with PTAPE.  If no pullup is

selected, the current is basically nothing.  With it, it is 150uA.  It is PTA1, and I'm

using it as a keyboard interrupt.

If I put an external pullup on it (for a switch), the circuit works fine, and there

is no extra current.

Ideas?

Thanks,

Tim

[admin]

You wouldn't happen to have the KBEDG1 bit set, do you? If set this would make the internal resistor a pulldown rather than a pullup. Not having seen your circuit I don't know if this is relevant or not.

[UtopiaTim]

Hi Wingsy,

Checked, and the bit is clear - set for falling edge.

Tim

[Lundin]

150uA seems resonable to me. 3.3V / 150u = 22kOhm.

I might have misunderstood the problem, but how exactly do you expect a pull-up to work with 0A current through it?

[peg]

Ah, I presume he meant with the switch open.
With it closed you should see something like this (probably a fair bit less)
A pullup will work with virtually no current when it is pulling up a CMOS input gate.
A Utopian one

[UtopiaTim]

Cute!

Yes, it's with the switch open.

I'm not worried about the current when the switch is closed (it's minimal

compared to what the rest of the circuit is drawing).

Guess I'll put a pullup on the board, & if I figure it out before production,

it'll just be a no populate.

Thanks,

Tim