Current consumption depending on temperature

[Andreas]

We are trying to reduce standby current consumption for our application. When measuring the current depending on the environment temperature we can see a rapid increase of the average standby current. Any external circuits were removed for this measurement.

Here are the measurements (VDD = 2.9 V)

T [°C]    I [uA]
-15        8.10
+24       11.15
+49       20.40

The amount of the increasing current is more than we expected. We can also see that the current increases with time at constant environment temperature. It seems that the nRF51 chip is heating up internally.

Do you have any explanation for this behavior?

Regards,

Andreas

[Kenneth]

The leakage current will increase as temperature increase, and decrease with lower temperature. We typically only provide current consumption values at nominal operating conditions, that is 3V and 25degree C. So what you experience is in general natural, however your measured 11uA at +24degree C and 2.9V, this values does not fit with any of the common values in the datasheet, so you should try to find why it is as high as 11uA in nominal operating conditions.

For current consumption measurements a good starting project may be \examples\ble_peripheral\ble_app_pwr_profiling in a recent nRF5 SDK. It is for instance important to make sure you don't have any pins configured as input if there is no external circuitry pulling them high or low. For the nRF51 series a common value is around 4uA in idle state when softdevice is initialized with RTC running. This is lower than all the values you measure.