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Reducing Power Usage for Adafruit nRF52840 Express
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Reducing Power Usage for Adafruit nRF52840 Express

by xudongzheng on Wed Mar 20, 2019 8:39 pm

The following piece of code is using 0.6mA as I'm measuring on my multimeter, and that seems a bit high. The bootloader is 0.2.6 (s140 6.1.1) along with the Adafruit Arduino package 0.9.3. I would imagine the energy usage here is a lower bound for more complicated stuff. Is there anything that I can do to reduce the power usage here? Are there any board features that I can disable? Is it possible/necessary to use the Nordic SDK with the Adafruit nRF52840 to further reduce power usage?

Code: Select all | TOGGLE FULL SIZE
void setup() {
   suspendLoop();
}

void loop() {
}

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Re: Reducing Power Usage for Adafruit nRF52840 Express

by adafruit_support_mike on Thu Mar 21, 2019 4:36 am

That's a little high, but probably 100uA of that will be parasitic leakage through the components.

If your application can handle a board that wakes up periodically, does its thing, then shuts down again, you might want to look at the TPL5110 breakout:

https://www.adafruit.com/product/3435

It's a low-power timer that controls power to a load. If you cut the trace to the power-on LED, it uses less than 100nA while counting. That's usually at least two orders of magnitude better than anything you can get from microcontroller sleep modes.

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Re: Reducing Power Usage for Adafruit nRF52840 Express

by 42volts on Thu Mar 21, 2019 11:58 am

I cannot agree with that recommendation for reducing power consumption of the device, and it makes me want to scream every time one of these adafruit guys suggests it. The nRF52840 can be reduced in power consumption considerably without resorting to ugly hacks. nRF52's are very commonly used in smart watches, which run for several days or a few weeks on a single charge of the tiny battery built into them.

While the feather itself is not very well designed for reduced power consumption (I am preferring the Nordic PCA10059 dongle over the feather), it should not be too challenging to get the power draw down to ~50 uA.

Note that I'm seeing *average* around 15 uA with the PCA10059, including periodic advertising.


The problem sitting in the way of low power consumption is the adafruit/arduino junk. The Nordic SDK will do a WAY better job.


Note that regarding the PCA10059, one of the big advantages that brings it into extreme low power consumption, is that the nRF52840 has integrated small and efficient linear and buck converters, making it possible to power them directly off of any power source between 3.3 and 5.5 volts. The feather has a fairly inefficient linear, and an additional parasitic loss via the battery charger, BUT, these don't add up to 600 uA.

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Please be positive and constructive with your questions and comments.