nRF52832 DK sleep mode current consumption too high

[James168]

NCS v2.8.0

nRF52832 DK & nRF52840 DK

peripheral_uart unmodified example

nRF52832 DK with peripheral_uart example has about 1.3 mA current when LED off and sleep mode, but nRF52840 DK with peripheral_uart example just about 600 uA.

How to reduce the nRF52832 DK current consumption to approach the "Online Power Profiler for BLE" value on the web.

[James168]

Hi,

1) I measured the current with system_off sample,

nRF52832 DK

average current is about 322uA

nRF52840 DK, sw6 in DEFAULT

average about 1.9mA

nRF52840DK, sw6 in nRF ONLY

average current about 5.2uA

2) The setup environment is power monitor connected to the External supply pins of the DKs with 3.0V power, 

and I don't have the PPK2 to compare.

3) I do some tests these days, disable the UART can reduce the current consumption, but I need to have both the NUS service AND low power mode.  

[Simonr]

Hi

1. The DKs should also be powered through the USB connector J2 so that the external supply only needs to power the SoC. Make sure the DK is connected to a power source and is turned on and then you can supply the SoC through the P22 header. 

3. The UART peripheral will consume some power, but when the device is not required to be connected to a device over NUS, you can disable the radio and UART peripheral and go into a low power state. What current consumption are you aiming at exactly? There is no way to stay I.E. in single digit µA territory while also maintaining a BLE connection for example.

Best regards,

Simon

[James168]

Hi,

1) Do you mean connect USB J2 and External supply P21 at the same time for current measurement? In this connection will has two power supply? I just connect P21 to power monitor for current measurement before.

2) To use the unmodified peripheral_uart sample, keep 

CONFIG_SERIAL=y

there is a pulse about 0.9ms interval and peak current value about 3.5mA, which code cause this current period?

If this 3.5mA current can be reduced, the current consumption improves a lot.

The ideal goal is approached the "Online Power Profiler for Bluetooth LE" value.

[Simonr]

Hi

1. When a supply is connected to P22 (current measurement header) it will have to power the entire board (debugger MCU included) if you don't also power it using J2. There are voltage detectors on the board that makes P22 only supply the nRF52832 SoC.

P21 is for external supply for the entire DK, and not just the nRF52832.

2. Are you able to get a higher resolution image here, as these spikes seem very low resolution, and hard to tell what is exactly, but if you've powered the board with P21, I assume it's related to some of the other components on the DK, and not the nRF52832 SoC.

Best regards,

Simon

[James168]

Hi,

1) The setup measurement environment is like the following,

The right black line is connected to DK's P21(-), and the right red line is connected to DK's P21(+).

The DK's P22 is connected nothing.

2) The sampling rate is the highest, and can you set up the environment on your end? Just need nRF 52832 DK, PPK2, and peripheral_uart sample, then you can zoom in/out the waveform to watch more clearly.

As your suggestion, I added more waveform graphs.

zoom in

zoom in

zoom in

3) I have changed to use NCS v2.9.0 now.