Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Fri, 22 Aug 2025 13:06:46 GMT

Some more data: all on my custom production board with input at 3.44V from an OTII Arc.

1/ running with only BLE GATT service on the nrf5340, no wifi, no other radios, waited for 30s for everything to go to sleep (touch sensor mostly)

- average 4.62mA, min 2.45mA

- little peaks of around 8.8mA every 40mS

- peaks of around 13mA approx avery 300mS : this is the BLE beacon tx I think

2/ running with no radios active, same other conditions:

- average 4.56mA, min 3.22mA

- peaks 8.6mA every 40ms, no others (no BLE tx)

The BLE tx processing on the nrf5340 is pretty low power, not an issue.

I have eliminated about 1.2mA base consumption from previous test due to correctly sleeping my ISO7816 interface chip.

I still have a 2-3mA base load... and I don't know what the regular 40mS peaks could corrospond to?

Any ideas?

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Fri, 22 Aug 2025 09:12:32 GMT

Hi Michael,

I haven't managed to come back to this properly - I had some discussion with the hw guy and have made some changes to hopefully hold more stuff in reset (in particular I have a ISO7816 card driver chip that might be part of the issue); I need to redo my measurements. I'll let you know...

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

Michael Crevier — Fri, 22 Aug 2025 03:08:28 GMT

Hi Brian, did you manage to solve that problem? I’m facing a similar situation, and I’ve reached a point where none of my attempts are giving results.

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Fri, 28 Mar 2025 13:42:57 GMT

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528931"]However, is it necessary for the peripherals to be available when the only threads running are those that the application don't care about?[/quote]

Well, the uart is a case when the uart driver is handling the tx/rx and with all the different methods of api to the uart (interuupt, async, console, etc) its not always clear when it can be powered off. And in fact, I discovered that the enabling of the PM_DRIVER/PM_DRIVER_RUNTIME somehow broke my use of uart2 in interrupt api mode - for now I've just removed these options as I don't see what is making the driver no longer call my isr to handle tx/rx?!

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528931"]However, as mentioned, because the nRF5340 doesn't support PM state anymore, this method is not available.[/quote]

This is IMHO a mistaken decision on Nordic's part and your dev team should seriously reconsider it. But what do I know, I'm just trying to make a product using this stuff....

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528931"]Regarding your current consumption measurements, the numbers you are measuring are definitely not good. We should have under 100uA. [/quote]

Ok. That would be nice..

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528931"]

Are you working with a custom hardware, or a DK?

What is your measuring method? What current draws are included in the measurement?

[/quote]

Custom hardare, so I cannot rule out (right now) the other components on the board being the bad guys - although I have tried to force everything into reset or low power modes (and this has an effect and gets me to the current position).

I'm measuring current draw from the battery connector using an Otii Arc to emulate the battery and show me the measurtement, with no charger connected (obviously!)

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528931"]I think it is helpful to establish a baseline first. I usually start with Hello World, disable CONFIG_SERIAL, and that would give me a baseline for what System ON Idle should look like.[/quote]

Yes, I need to do this, on both the DK and then on my custom hw. This wont be until for 4-5 weeks now, as I am going to be out of the office for a while.... I'll update when I get new data!

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

Hieu — Tue, 25 Mar 2025 21:07:05 GMT

It seems a lot of things happened... I will try to address one point at a time.

[quote user="BrianW"]Ok, so you really need to update or flag the blog post with this information.[/quote]

I agree. I will inform our blog team.

[quote user="BrianW"]I do not want to turn the system off, I want it to be in the lowest possible power state when it is in the idle state in zephyr. I expected this to be automatic, but apparently not....[/quote][quote user="BrianW"]And where do I do this? How does my app code 'know' that zephyr is in the idle state? I understand I can turn off different devices, but I only want (for example) the UART to be off when the app is idle (which I don't know as there are multiple tasks in the system eg for the wifi stack).[/quote]

What you are referring to is the System-managed Device PM method. In this solution, when the system changes PM state, the peripherals can also automatically change state. However, as mentioned, because the nRF5340 doesn't support PM state anymore, this method is not available.

I can see your point about your application doesn't know when the system is or isn't idle, due to there being other SDK stacks like Wi-Fi running.
However, is it necessary for the peripherals to be available when the only threads running are those that the application don't care about?
I think it would be sufficient for most use cases that the application controls peripherals' power states based only on the information it has.

Regarding your current consumption measurements, the numbers you are measuring are definitely not good. We should have under 100uA. Are you working with a custom hardware, or a DK?

What is your measuring method? What current draws are included in the measurement?

I think it is helpful to establish a baseline first. I usually start with Hello World, disable CONFIG_SERIAL, and that would give me a baseline for what System ON Idle should look like.
For a Wi-Fi setup, you can refer to Lesson 6 of our Wi-Fi course for a low-power setup and use it as a baseline.

Could you please try measure those two scenarios and let me know what value you have?

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Tue, 25 Mar 2025 10:32:18 GMT

using the action

PM_DEVICE_ACTION_TURN_OFF

returns me to the case with 3.2mA after the sys_poweroff(), so no impact there (but at least its not worse!)

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Tue, 25 Mar 2025 09:50:03 GMT

I tried to disable all the devices in nrf53 that I use like this:

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(i2c1))), PM_DEVICE_ACTION_SUSPEND);

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(uart2))), PM_DEVICE_ACTION_SUSPEND);

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(spi3))), PM_DEVICE_ACTION_SUSPEND);

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(spi4))), PM_DEVICE_ACTION_SUSPEND);

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(i2s0))), PM_DEVICE_ACTION_SUSPEND);

// pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(pdm0))), PM_DEVICE_ACTION_SUSPEND);

// Wait for logs etc to empty

k_msleep(2000);

pm_device_action_run((struct device *)(DEVICE_DT_GET(DT_NODELABEL(uart0))), PM_DEVICE_ACTION_SUSPEND);

sys_poweroff();

And the power consumption went UP from 4.2mA to 8.9mA!!!! What is the cirrect way to suspend a device using PM_DEVICE_RUNTIME apis?

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Mon, 24 Mar 2025 17:10:48 GMT

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528687"]As for CONFIG_PM_DEVICE, it enables the Device Power Management API, which let you put the "Device" in DeviceTree, so peripherals and/or sensors with drivers, into different power state. [/quote]

So, to be clear, I cannot use the method described: https://docs.nordicsemi.com/bundle/ncs-2.9.1/page/zephyr/services/pm/device.html#system-managed_device_power_management but must call the device power management functions from my app?

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

BrianW — Mon, 24 Mar 2025 17:01:42 GMT

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528687"]Only information regarding CONFIG_PM is outdated. The System Power Management (PM) API controls the CPU state. However, as the nRF5340 only has two states, System ON and System OFF, support for PM has been dropped, and going into System OFF is done via the Power Off API instead.[/quote]

Ok, so you really need to update or flag the blog post with this information.

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528687"]What kind of RAM retention are you looking for? With System OFF, the system reinitializes when it wakes up. Some level of RAM retention is possible, still.[/quote]

I do not want to turn the system off, I want it to be in the lowest possible power state when it is in the idle state in zephyr. I expected this to be automatic, but apparently not....

[quote userid="9456" url="~/f/nordic-q-a/120041/power-consumption-on-nrf5340-when-idle-is-about-4ma-how-to-get-it-lower/528687"]Because the nRF5340 doesn't have System PM, you will need to use the runtime API and manually disable each device.[/quote]

And where do I do this? How does my app code 'know' that zephyr is in the idle state? I understand I can turn off different devices, but I only want (for example) the UART to be off when the app is idle (which I don't know as there are multiple tasks in the system eg for the wifi stack).

Is there a sample showing how to get a proper low power application running, eg one of the ble operational cases? I saw a post here https://github.com/zephyrproject-rtos/zephyr/issues/41382 which makes the same point.... he then goes to hack various parts of the uart code to get it to deal with the idle -> power off case, but I don't want to go changing the core NCS source! (already had to do that for other 'features' and its not sustainable). Also his MCU seems to be a nrf52, and the NCS version is old (2.6 I think)

btw, even if I turn off all my external hardware on my board, including the nrf70, then do sys_poweroff() : its still sucking around 3.2mA....this is not what I expected from a Nordic MCU...

Can you give me some example code that actually gets proper low power operation using the device PM API here?

Brian

RE: Power consumption on nrf5340 when idle is about 4mA, how to get it lower?

Hieu — Mon, 24 Mar 2025 16:26:59 GMT

Hi BrianW,

Only information regarding CONFIG_PM is outdated. The System Power Management (PM) API controls the CPU state. However, as the nRF5340 only has two states, System ON and System OFF, support for PM has been dropped, and going into System OFF is done via the Power Off API instead.

What kind of RAM retention are you looking for? With System OFF, the system reinitializes when it wakes up. Some level of RAM retention is possible, still.

As for CONFIG_PM_DEVICE, it enables the Device Power Management API, which let you put the "Device" in DeviceTree, so peripherals and/or sensors with drivers, into different power state. It supports two methods, runtime and system-managed. Because the nRF5340 doesn't have System PM, you will need to use the runtime API and manually disable each device.
The runtime API is enabled with CONFIG_PM_DEVICE_RUNTIME, and usage of the API is explained in that blog post.

We also have this documentation: Optimizing application.

I think perhaps the peripherals weren't disabled since you misunderstood the Device PM API a little. Could you please check again?

Hieu