AM6548: Internal pull resistors

Anil Dali

I just wanted to know the purpose of pullup and pulldown enable bits in the PADCONFIG registers(reffered AM65XX TRM). We are configuring them in the hardware. Will the pullup and pulldown enable bits effect the hardware configuration?

over 5 years ago

0 Biser Gatchev-XID over 5 years ago

TI__Guru**** 393215 points

If you have external pullup/pulldown resistors you should keep the internal ones disabled. Otherwise they may form undesired dividers with the external ones.

0 Anil Dali over 5 years ago in reply to Biser Gatchev-XID

Prodigy 250 points

Hi Biser,

Thank you for your valuable response.

My Intention is to know why we need internal pullup/pulldown when we have external pullup/pulldown resistors. Or if we have internal pullup/pulldown resistors enable option in software, there is no need of external pullup/pulldown resistors to be connected right?

Regards,

Anil

0 Biser Gatchev-XID over 5 years ago in reply to Anil Dali

TI__Guru**** 393215 points

This depends on the external hardware connected to the processor. Internal resistors are weak (approx. 18kOhm at 1.8V, resp. 33kOhm at 3.3V), so in some use cases they may not be sufficient.

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AM6548: Internal pull resistors