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Question regarding power consumption on nrf52840 Express Fea
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Question regarding power consumption on nrf52840 Express Fea

by adreamer on Mon May 10, 2021 2:07 pm

Dear sir/madame
I have a question regarding power consumption on Adafruit nRF52840 Express Feather.
We use this board for rapid prototyping and for demo towards our customer, while developing HW and developing the final code using Nordic SDK and their development board PCA10056.
I have developed a piece of SW utilising the Nordic NUS service (UART over BLE). This code will be used as a reference when it comes to power consumption.
When running this code on PCA10056 and the system are in ‘System ON Idle’ mode (waits for events) the power consumption is 3,2 micro A and in system OFF (deep sleep) mode approx. 0,4 micro A.
If I load the same code to nrf52840 Express feather, the same figures are:
622 micro A on System On Idle
618 micro A on System Off (deep sleep)

I think the problem is connected to some of the circuits outside the MBDT50Q module that use power while in deep sleep and in system ON idle (waiting for an event).
Question: is it possible to turn off some of the additional circuits when putting the board into system OFF mode?

Kind regards
Svein

adreamer
 
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Re: Question regarding power consumption on nrf52840 Express

by adafruit_support_mike on Tue May 11, 2021 1:08 am

You can pull the Feather's EN pin low to shut off its voltage regulator. That will cut power to everything except the LiPo charger.

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Re: Question regarding power consumption on nrf52840 Express

by adreamer on Thu May 13, 2021 3:07 am

adafruit_support_mike wrote:You can pull the Feather's EN pin low to shut off its voltage regulator. That will cut power to everything except the LiPo charger.


Thanks a lot for the information.
I have tested your proposal, but it did not work as expected.
What I thought it would do was to disconnect everything except nRF52840 module and LiPo charger.
This is happening when I am grounding EN pin:
Before grounding I power on nRF52840 Express Feather by using a LiPo battery and then make a connection to a mobile using Nordic nRF Toolbox.
1) Grounding of EN pin gives:
a. Connection lost
b. Power consumption of 117 micro A.
2) De-grounding the EN pin gives the same behaviour as using the reset button

Is there anything I have misunderstood of the usage of the EN pin?
What I want to achieve is a possibility to only power the nrf module; i.e. MBDT50Q

Kind regards Svein

adreamer
 
Posts: 10
Joined: Thu Oct 29, 2020 6:15 pm

Re: Question regarding power consumption on nrf52840 Express

by adafruit_support_mike on Thu May 13, 2021 10:00 pm

The behavior you saw was normal. Shutting off the voltage regulator shuts off the nRF52840.

If you want the nRF52840 to run, you'll need a 3.3V regulator somewhere. It will also contribute to the total current consumption.

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Please be positive and constructive with your questions and comments.