Current Consumption test on custom board using PPK

[Rishi]

I am using PPK 1.1.0 to compute current draw on a custom hardware.

If I upload ble_app_hrs example on the nRF52-DK and measure it directly, I obtain average reading as 550 uA.

However, running the same application on my custom board yields 1.2 mA of current draw.

The custom board uses Raytac modules: MDBT42 and MDBT42V, and is powered using External DUT connector with SW2 set as External and SW4 set as Regulator.

Do you have any insights on this huge current draw?

Thank you.

[haakonsh]

Hey Rishi,

1. Do you have any other circuits and devices on your custom PCB that can draw additional current?
   If this is the case then you need to electrically isolate the module from the rest of your board when measuring the current.
2. Have you enabled any pull-ups, etc, on the module?
   If this is the case then you need to disable the pull-ups/downs before measurements.
3. Are you running the example as provided or have you made any modification for your custom PCB?
4. Can you show us your schematics and/or Layout files?

Cheers,

Håkon.

[Rishi]

Hey Hakon,

I have isolated the problem. I have a LIS2DH12 accelerometer in my design. Assembling this accelerometer along with three by-pass capacitors (0.1 uF, 0.1 uF, 10 uF) and two pull-up resistors (10K each) for SDA and SCL lines, increases the current consumption to 7 mA.

Removing the pull-up resistors does not reduce the current consumption value either.

I am not even using or enabling the accelerometer. It is just being powered by the VDD rail. I am running ble_app_hrs example.

Any suggestions, what are the possible sources of this huge rise in current?

Thanks.

[haakonsh]

I expect 131µA average for advertisements at 100ms intervals with a 27 byte payload. Check out our online power profiler at: https://devzone.nordicsemi.com/power/ 

You should definitely get way less than 750µA at 1600ms intervals. 

[Rishi]

I see. 

Can you please perform a basic test using the stock ble_app_template example from SDK14.2 using nRF52832 DK and tell me the recorded current consumption using PCA63511 Power Profiler Kit? 

Also, can you tell me the parameters that I can tune to reduce the current consumption in that example?

Thank you.

[Rishi]

I have got the current down. Thank you. I shall re-open the ticket in case of further queries.

Thank you

[Rishi]

Updated current draw:

System-On sleep mode = 2.5uA

Advertising = 13uA

Major current draw was due to the NRF_LOG function calls. Disabling NRF_LOG_ENABLED reduced the current drastically.

Board Support Package was disabled as well.

Advertising interval set to 4 seconds.

Additionally, DC-DC converter was enabled using 

sd_power_dcdc_mode_set(1);

[Toyman]

What NRF_LOG backend did you use? UART or RTT?

[Rishi]

Toyman

The default RTT was enabled.

I just disabled the NRF_LOG_ENABLE flag to disable RTT logging.