nRF54L15 + MX25R64 Idle Power Consumption

[Patrick]

Hi there,

I'm working with a custom board based on the Raytac AN54L15Q module and encountering higher-than-expected power consumption when trying to profile using the system_off example from the nRF Connect SDK.

Current Status

• Running the system_off sample with modifications to power down the external flash (MX25R64).
• Power drops from ~1.86 mA to ~16 μA after powering down the flash.
• I'm unable to get below ~16 μA, which seems too high for full system_off state.

Board Configuration

• RGB LED connected to GPIOs P1.09, P1.10, P1.11, configured as GPIO_ACTIVE_LOW | GPIO_PULL_UP.
• Button connected to GPIO P0.03, configured as GPIO_ACTIVE_LOW | GPIO_PULL_UP.
• MX25R64 flash connected via Port 2 (same as the nrf54l15dk reference)
• SHT41 sensor on P1.04 and P1.05.
• LFXO is mounted and using internal load capacitors.
• No UARTs enabled in the device tree.
• Same result whether building against nrf54l15dk_nrf54l15_cpuapp or using my own board definitions.
• I do not have a devkit, so I’m unable to cross-check behavior on official hardware.

I have not explicitly power managed the SHT41, but its idle current is far lower than what I am seeing. In another project, I have explicitly disabled all peripherals except SPI00 and still cannot break the ~16uA barrier so I am at a loss.

Any guidance on what to double-check for getting down to expected power levels in system_off greatly appreciated. 

[Kazi Afroza Sultana]

Hello,

There could be several reasons to get higher current than expected. One of the reasons can be the enable state of RAM retention.

You can add the following lines before main() function

NRF_MEMCONF->POWER[0].RET = 0;
NRF_MEMCONF->POWER[1].RET = 0;
NRF_MEMCONF->POWER[0].RET2 = 0;
NRF_MEMCONF->POWER[1].RET2 = 0

 

''LFXO is mounted and using internal load capacitors'' Is the load capacitor of your crystal same as the one on nRF54L15DK? 

No UARTs or unnecessary peripherals should be enabled in the device tree. You have already mentioned this, can you share the application file with build folder so I can check if any enabled drivers or background tasks that could keep clocks or regulators on?

[Patrick]

Hi Kazi,

I have attached the application with build folder included as requested. Adding the lines you suggested before main resulted in a build failure, so they have been added inside of main for now, but did not result in any change to device power consumption.

I am using this LXFO, and have the internal load capacitors set to the same as the nRF54L15DK. In my post above you will also find a copy of my board files. The configuration has changed a little compared to the uploaded application, but the changes had no effect.

I did notice this other case that might have some similarities, though my power consumption is still higher than they were able to reach. There did not seem to be a clear conclusion to that case but I do wonder if the external flash is ultimately responsible.

4101.system_off.zip