Current spike from sleep mode to using twi

[corentind]

Hello,

I am running S140 on an nRF52840 custom board. While doing some power profiling, I noticed a spike of current of ~15mA when going from sleep mode to waking-up due to an interrupt and then performing some TWI operations. See attached screenshot.

After having performed several tests, it looks like the spike only occurs when the TWI module turns on. Is that something that is known to happen? Is there anyway to mitigate it?

Thank you.

[Jared]

Hi,

The TWI peripheral should only consume about 1 mA current when it's active (transmitting). 

• Are you able to replicate the current on a development kit? Could you provide a minimal project that will reproduce the current and will run on the development kit and doesn't require a specific TWI slave. 
• Are you using the DC/DC regulator?
• Could you try to capture with trigger level set to 10 mA so that we get a better resolution.
• Do you start the HF clock before you enable the TWI peripheral?

regards

Jared

[corentind]

Hi Jared,

Thanks for your help.

• I would need a bit more time to reproduce the issue on a development kit.
• We are not using the DC/DC regulator. What is the implication of enabling the DC/DC regulator?
• I attached a screenshot with higher resolution

• How can I start the HF clock?

[Jared]

Hi,

Using the DC/DC regulator should decrease the current consumption of the CPU compared to using the LDO. Could you update the case with the result from the development kit? Could you share the designs files of your custom board if the issue won't reproduce on the development kit? I can make the case private if you prefer it. 

regards

Jared