NRF54L15- Using external 32kHz source for LFCLK

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Tue, 03 Mar 2026 12:01:56 GMT

There is currently no support for rail-to-rail 32.768kHz external clock sources on the nRRF54H20. Please contact the sales representative of your area for possible future features, as we focus on currently available features/solutions here on DevZone.

Best regards,

Simon

RE: NRF54L15- Using external 32kHz source for LFCLK

AriPP — Tue, 03 Mar 2026 07:57:35 GMT

nRF54H20 preliminary datasheet was also missing that information.

Is rail-to-rail 32.768kHz input from external clock also supported in the nRF54H20? If so and connected to XL1, should XL2 be floating or grounded?

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Thu, 02 Oct 2025 13:43:08 GMT

I'm sorry, but I can't comment on upcoming additions to the nRF Connect SDK, but I assume it will be added soon, and suggest that you follow the main branch of the nRF Connect SDK: https://github.com/nrfconnect/sdk-nrf

If you need some sort of road map or date on this, please contact your regional sales manager, and they can help escalate your question to the right people. Let me know if you need help reaching out.

Best regards,

Simon

RE: NRF54L15- Using external 32kHz source for LFCLK

yanbingyu — Wed, 01 Oct 2025 18:21:46 GMT

We are trying to use an external 32.768KHz crystal oscillator, which is shared with other components in the system, and came across this thread. Good information.

The nRF54L15 datasheet v1.0 defined the register BYPASS in XOSC32KI, but in SDK v3.1.1, the register is not defined yet. When will this be updated into SDK? Thanks!

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Thu, 18 Sep 2025 09:17:38 GMT

As of the nRF54L15 datasheet v1.0 released last week the rail-to-rail source for the 32.768kHz crystal oscillator is now supported on the nRF54L15.

Best regards,

Simon

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Tue, 20 May 2025 11:36:42 GMT

Okay, some bad news here, as we currently do not support rail-to-rail clock sources on the nRF54L15. For more details you can reach out to the Nordic sales representative of your area. Let me know if you need help getting in touch with them.

Best regards,

Simon

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Mon, 19 May 2025 13:50:58 GMT

The following is also just what was true for the nRF52 series, so it will also need confirmation from the product management team. The config to enable or disable the external LF clock will set both XL1 and XL2 I'm afraid, so you can't use P1.01 as a GPIO while using an external 32kHz source. It must be left floating.

Best regards,

Simon

RE: NRF54L15- Using external 32kHz source for LFCLK

JTP — Fri, 16 May 2025 21:37:08 GMT

Thank you Simon,
Another question, if we are using an external oscillator as a 32k source on XL1, could P1.01 be used as GPIO or is it always set as XL2?

RE: NRF54L15- Using external 32kHz source for LFCLK

Simonr — Fri, 16 May 2025 12:32:02 GMT

Hi James

I think this should be possible (similar to the nRF52 series) by just connecting the oscillator to XL1, but I need to check with the product manager. Most likely it just hasn't been added to the datasheet yet. I'll let you know when I hear from them.

Best regards,

Simon