GPIO Impedance in Standby mode

ngaylard · ‎2009-06-15

Posted on June 15, 2009 at 12:04

ngaylard · ‎2011-05-17

Posted on May 17, 2011 at 13:13

Hello,

We are using an STM32F103 device and need to know the impedance of the GPIO pins so that we can place external pull-downs that reliably disable certain features of our board. Current consumption is critical so we can't simply use 10k/100k pulldown resistors they must be as high as possible.

We know that the STM32 GPIO go high-impedance but is there a specification in terms of what the maximum current leakage is at 85 Celsius through a pin?

Many thanks

ngaylard · ‎2011-05-17

Posted on May 17, 2011 at 13:13

Quote:

On 03-06-2009 at 12:59, Anonymous wrote:

Hello,

We are using an STM32F103 device and need to know the impedance of the GPIO pins so that we can place external pull-downs that reliably disable certain features of our board. Current consumption is critical so we can't simply use 10k/100k pulldown resistors they must be as high as possible.

We know that the STM32 GPIO go high-impedance but is there a specification in terms of what the maximum current leakage is at 85 Celsius through a pin?

Many thanks

Well I am quite disappointed that no-body from ST answers forum posts. Regardless we have pursued our own testing and with a 470 ohm resistor from a gpio to ground and another from a different gpio to supply and measured the current to see if it was affected - we maintained 2.3uA @ 2.7V which was very good.

st3 · ‎2011-05-17

Posted on May 17, 2011 at 13:13

Quote:

Well I am quite disappointed that no-body from ST answers forum posts.

There are very few (large) manufacturers that provide support via their user forums. :(

The forums are strictly a user-to-user discussion.

You are expected to seek support via your distributor or, if you're really lucky, your FAE.

See also:

http://www.st.com/mcu/forums-cat-8476-23.html

Yes I realise that and we are very lucky to be well supported by EBV in general. I agree that it is not common for manufacturers to provide decent levels of support to the everyday user (and I understand the financial reasons and justifications). By only providing user-to-user support ST are effectively forcing clients to subsidise them as their engineers sit on-line helping other people out. There is not a-lot of traffic on the forum and I would have thought it was cost effective to provide forum level support.