Typical pull-up resistance value

[sreejithrnair]

Hi,

 

Greetings @Peter BENSCH 

 

I am using STM32G431MB controller in my project. I am configuring PB4 as my General purpose Input pin. Ports PB5-PB9 as well as PC8,PC9, PA8 and PA9 are assigned as General purpose outputs connected to Analog HART Mux. In the datasheet, the recommended pull up values are minimum:25K; Typical 40K and Maximum 60K for I/O pins.

 

Can you kindly suggest if we could use minimum value of 25K as pull up resistors for the pins.

 

Regards<
Sreejith

[waclawek.jan]

That's value of the internal pullup, and *not* some recommended external pullup.

Whether its value (taking into account the spread given by technology) is adequate for your application, is up to you to judge.

JW

 

[Danish1]

I think you misunderstand the data-sheet.

Those are not "recommended" pull-up values. That is the effective resistance of built-in pull-up resistors, which you can choose to turn on (or not) when the pin is programmed as digital-input or open-drain-output.

There are circumstances where you might choose to have your own external pull-up resistors. These include ensuring the pin is in a certain state even when the stm32 is reset or in its lowest-power shutdown. Or if the value of the built-in pull-up is not appropriate for your application. (You could want a lower value if you need a certain minimum current to maintain healthy switch contacts or better noise-immunity, or a higher value if you wish to have lower current drain when the pin is driven low externally).

[Billy OWEN]

Hi @sreejithrnair 

 

This post has been escalated to the ST Online Support Team for additional assistance.  We'll contact you directly.

 

Regards,

Billy