nRF9151 Hardware Enable/Disable by another MCU with least consumption

RE: nRF9151 Hardware Enable/Disable by another MCU with least consumption

Simonr — Thu, 19 Mar 2026 11:47:40 GMT

I would have to recommend option 1 and follow our whitepaper, but the choice will ultimately be yours here.

Best regards,

Simon

RE: nRF9151 Hardware Enable/Disable by another MCU with least consumption

Abomin3v3l — Tue, 17 Mar 2026 18:57:01 GMT

Hi Simon.

We did like this in the PCB, starting with the jumper assembled and the pull-down assembled, and with the pull-up not assembled.

There will be 4 connections among the 54L15 and the 9151: TX, RX, RTS, CTS.

So that we have 2 options:

(1) Implement this what is shown below, disassembling the jumper and the pull-down and assembling a 10K for R1, so the consmption can go down to 2uA according to the document.

devzone.nordicsemi.com/.../Ultra-low-power-PPP-connection-using-nRF9151.pdf

(2) Or keep the circuit as the first picture, so that maybe we can go even lower than 2uA, because when ENABLE = 0 then supposedly almost all internal hardware of 9151 is disabled. The most of time ENABLE would be kept in 0, so no consumption via the pull-down most of time also. The pull-down is just to guarantee level 0 when the board is just powered-up, while the 54L15 is not forcing yet a specific logic level at the ENABLE pin.

RE: nRF9151 Hardware Enable/Disable by another MCU with least consumption

Simonr — Thu, 12 Mar 2026 12:30:25 GMT

Hi Jeferson

Having a pulldown as in alternative 3 here, will likely draw some current, though not a lot. I think it should be fine to connect it to the nRF54L15 without pulldown since the nRF9151 ENABLE pin is a high impedance pin. You can leave the footprint for the pulldown just in case though.

Regarding the current consumption, the System Disabled mode the entire device can be powered down by presenting the appropriate voltage to the ENABLE pin. See page 51 of nRF9151 product specification: https://docs.nordicsemi.com/bundle/ps_nrf9151/page/nRF9151_html5_keyfeatures.html If the system disabled mode is used, there shouldn't be any excess current AFAIK.

Best regards,

Simon