the current variation of nRF52840

[yanning]

Hello,

I have 4Pcs same PCBAs and same firmware, the current values as below:

1. 2.2uA
2. 3.3uA
3. 3.0uA
4. 3.8uA

Condition: Power Supply 3V Battery;  Temperature 22℃; System ON, GPIOTE wakeup;  Measure tool is PPK2.

The maximum is almost double higher than the minimum. 

The following are the value after I change the sleep mode to system OFF:

1. 0.42uA
2. 0.60uA
3. 0.60uA
4. 0.70uA

Condition: Power Supply 3V Battery;  Temperature 29℃; System OFF, GPIO DETECT;  Measure tool is PPK2.

The maximum much higher than the minimum.

Also the time between current spikes vary from device to device. 

I swap nRF52840 between unit 1 and unit 4 and find IC is dominate the current consumption.

 

My questions:

1. The current variation is acceptable?
2. When regulator in refersh mode, is high frequency cause the high current comsunption or the high current casue high frequency?
3. Could anyone let me know the current variation at low power mode?  Only the typical value at different mode is list on specification.

Thanks

[Jared]

Hi,

1. The current variation for the SYSTEM OFF sleep is acceptable. For SYSTEM ON, it depends on what other configuration you are using such as RAM retention, wake up on what event, comparator enabled etc. 
2. Could you elaborate a bit more on this question. Not sure I understand what you're asking about?
3. This hasn't been specified. 

regards

Jared 

[yanning]

Hi Jared

Thanks for your quickly response.  

1.  The more configuration, the more current variation? 

2.  Please see the picture above, in SYSTEM OFF mode, there are some current spikes, means the regulator in refresh mode to maximum the efficiency.  the time between two current spikes is different, the time interval of unit 1 is 300ms, but for unit 4, it is 100ms. why the time interval is different?  Is the higher current consumption short the time interval? Or the time interval is vary with device to device casue the different current consumption?

[Jared]

Hi,

1. The current consumption in System On sleep depends on several factors such as temperature, system voltage, regulator configuration, RAM retention, and wakeup reason. You have specified the first two, but could you also specify the others?
2. Yes this is correct. The interval of the spikes is dependent on the current consumption. The higher consumption the higher the frequency of the spikes

regards

Jared 

[yanning]

helle Jared

The following are details configuration:

Temperaue: 22℃; Voltage: 3V; Regulator: DC/DC; RAM: Power off section 3 and section 4 of RAM[8]; RTC: rtc_tick_disable in sleep mode using nrf_dtv_rtc_tick_disable(&rtc_inst);  WDT: pause in sleep mode; Wakeup reason: push button(GPIOTE). 

Thanks

[Jared]

Hi,

For the regulator configuration, High voltage or Normal mode?

[yanning]

Normal Mode

[Jared]

Hi,

I checked internally, and although that we don't have enough test data to be 100% certain, I would conclude that the current that you measure for SYSTEM ON is acceptable. We don't have enough data to define the variation range. 

regards

Jared