High PWM Power Consumption

RE: High PWM Power Consumption

SwRa — Wed, 29 Oct 2025 14:21:02 GMT

Hi Andrew,

It should be possible to change the PWM frequency to use 400 Hz frequency. In the sample blinky_pwm, you can update the code where the PWM period is set, for example using the pwm_set_dt() function and using the PWM_HZ(x) macro, where x is your desired frequency: https://docs.nordicsemi.com/bundle/zephyr-apis-latest/page/group_pwm_interface.html#ga4a5edbee48c4a5706cf75524aef2364a:~:text=PWM_DT_SPEC_GET_OR-,%E2%97%86%C2%A0PWM_HZ,-%23define%20PWM_HZ ..

Turning off logging when measuring current should also help in reducing the power consumption. The following blog explains what can be done to optimize the power consumption: Optimizing Power on nRF52 Designs

Regards,

Swathy

RE: High PWM Power Consumption

andrew55529 — Tue, 21 Oct 2025 13:39:30 GMT

Thank you for the explanation.
But maybe it’s possible to reduce the PWM frequency — would that lower the current consumption?
I only need about 400 Hz for LED brightness control. It’s hard to believe that the PWM peripheral draws almost as much current as the Bluetooth radio — is there really no way to reduce that?

RE: High PWM Power Consumption

SwRa — Tue, 21 Oct 2025 12:45:32 GMT

Hi Andrew,

The increased current consumption you observe when enabling PWM is expected behavior for Nordic SoCs. When the PWM peripheral is active, it requires a high-frequency clock, which significantly increases current draw—even if the output is low or high.

This current is drawn as long as the PWM peripheral is enabled, regardless of the output state. Setting the duty cycle to 0% or 100% (i.e., always low or always high) can allow the hardware or driver to disable the PWM peripheral and simply set the GPIO, which returns the current consumption to the baseline, which is what you observed. See here: (+) How to completely disable PWM in the nRF Connect SDK? - Nordic Q&A - Nordic DevZone - Nordic DevZone

Regards,

Swathy