nrf52840 Power Consumption

[HardwareGuy]

Hi There,

I am doing current measurements on the nrf52840 in sleep mode with no RAM retention and I am getting different values based on how I take the measurements. Please see the various methods and resulted below.

1. Using an amp meter in series with P22 - SW10 = On | SW6 = nRF Only | VP21 = 3.3V
   13.2 micro amp

2. Using and amp meter in series with P22 and power from USB header J2 - SW10 = off | SW6 = nrf ONly 1.3 micro amp

3. Using and amp meter in series with P21 - SW10 = On | SW6 = nRF Only | VP21 = 3.3V 1.46 micro amp

4. Using and amp meter in series with P21 - SW10 = On | SW6 = default | VP21 = 3.3V 0.1 micro amp

5. Using the PPK with jumper SB40 open 33 micro amp

Can you please help me to understand why these numbers are so different. I believe that method 2 above is probably the correct value, even though it does seem a bit high. Isn't the nRF52840 supposed to draw around 500 nA in sleep mode? Your help would be much appreciated.

[glypat22]

Hi,

I did what HardwareGuy did using setup number 2 and also left SB40 open. My current read varies from 2.9 to 2.2uA. I do understand the stable voltage source argument but this still seems high.

Talking about the code - I tried the nrf_pwr_mgmt_pca10056 and changed the main function to, int main(void) { while (true) { __WFE(); __SEV(); __WFE(); } }

So what am I missing?

Following figures suppose to work but they are not working in my case,

1. When using external 32kHz crystal oscillator as clock source for RTC and no RAM retention: 0.7uA (from OPS) + 0.23uA (32kHz crystal oscillator run current) + 0.1uA (RTC run current) = 1.03uA.
2. When using internal 32kHz RC oscillator as clock source for RTC and no RAM retention: 0.7uA + 0.7uA (32kHz RC oscillator run current in normal mode) + 0.1uA = 1.5uA.
3. When using external 32kHz crystal oscillator as clock source for RTC and 64KB RAM retention: 1.03uA + (16 x 0.03) = 1.51uA (Assumption: the power retention is enabled by SD or user application or both)
4. When using internal 32kHz RC oscillator as clock source for RTC and no RAM retention: 1.5uA + (16 x 0.03) = 1.98uA (same assumption as above)

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Your guidance of exact setup and the code will be of immense help. Any setup that will bring the current near to these or lower than what I have will be helpful.