Hi Nordic team,
I’m evaluating the sleep current of the nRF54LM20A using the nRF54LM20A DK and I’m seeing a large discrepancy compared to the datasheet numbers.
According to the product specification, the typical sleep currents at 3 V are:
-
System ON idle (wake on pin, 512 KB RAM retained): about 4.0 µA (
IONIDLE). -
System OFF, 0 KB RAM retained, wake on pin: about 0.7 µA (
IOFF0). [Current consumption]
My test setup:
-
Board: nRF54LM20A DK
-
Measurement point: I removed the jumper on the VDD nRF CURRENT MEASURE header and inserted a multimeter in series there, so I believe I am measuring the SoC’s VDD_nRF current only (similar to how the nRF54L15 DK VDDM current measure header is used to measure only the SoC current).[54L15 DK external power]
-
Power: DK is otherwise powered in the default way (USB connected to the debugger).
-
Firmware: bare‑metal, no peripherals explicitly initialized, just trying to put the CPU into a low‑power System ON idle state using
WFE.
Test code:
int main(void)
{
while (1)
{
__WFE();
__SEV();
__WFE();
}
return 0;
}Measured result:
-
With this code running, the current measured on the VDD nRF CURRENT MEASURE header is about 89 µA (steady state).
-
This is more than an order of magnitude higher than the ~4 µA typical value from the datasheet for System ON idle. [Current consumption]
My questions:
-
Is there anything wrong with the way I’m using
WFE/SEVhere if the goal is to keep the CPU in low‑power System ON idle most of the time? -
On the nRF54LM20A DK, can you confirm that measuring in series on the VDD nRF CURRENT MEASURE header indeed gives (only) the SoC current, and not other on‑board circuitry?
-
Given this setup and code, is ~89 µA a reasonable number for the DK, or does it indicate that I am not actually in the intended low‑power state?
-
Are there any specific steps recommended for nRF54L‑series devices (similar to the nRF54L15 DK guidance) to minimize current when using System ON idle – for example, any default peripherals, debug interface, or RAM retention settings that I should explicitly disable or change on the DK to get closer to the datasheet value?
Any guidance, or a minimal known‑good example for measuring near‑datasheet System ON idle current on the nRF54LM20A DK, would be greatly appreciated.
Thank you!
