nR21540 MODE pin

[Rashid Talib]

Hi

According to the errata at https://docs-be.nordicsemi.com/bundle/errata_nRF21540_Rev2/attach/nRF21540_Revision_2_Errata_v1.2.pdf?_LANG=enus, a 33k resistor is required when pulling the MODE pin high.

Question:

How critical is the resistor value? We have old hardware that has the MODE pin connected to the nRF5340 IO directly and we think about using the internal pull-up as a workaround. According to the nRF5340 datasheet, the internal pull-up is around 13k ohms.

What is the acceptable resistance range?

Thanks for your help & best regards

Rashid

[Priyanka]

Hi Rashid,

I don't think there is any "acceptable range" for this. I would suggest you to follow the errata and use a 33kOhm series resistance to the MODE pin itself to mitigate the anomaly. 

-Priyanka

[Rashid Talib]

Hi Priyanka

Thanks for your reply. So I guess the 33k value was determined empirically and is not calculated according to known criteria?

Best regards
Rashid

[Priyanka]

Hi Rashid,

The 33kOhm is what we recommend to use for ideal power consumption, in order to keep the current draw minimum.

Theoretically speaking you could use any other value if this is not a big concern, but 33kOhm is what we have tested and recommend.

-Priyanka