nRF51 dongle's current consumption

[Johnson]

I programmed a nRF51 dongle as an ESB receiver using the esb_ptx_prx example code. It sleeps most of the time by calling __WFI() in the while loop.

I used an external 3.3 V power supply to VDD and measure the current consumption. The current was quite constant around 50 mA. Why is the current so high?

On the other hand, the transmitter (also a dongle) only drew 14 mA on average. On the scope, the current was 0 most of the time and peak to 15 mA during transmission.

At first, I thought it was the Segger chip that was drawing the extra current but the transmitter drew the expected amount of current.

[Stefan Birnir Sverrisson]

Hi Johnson

How do you measure current on the nRF51-Dongle? I see no documentation in the nRF51-Dongle User Guide on how to measure current, it is only present in the User Guide for nRF51-DK, which is intended for this purpose. Can you please describe your method on how you measure the current consumption on the nRF51-Dongle.

50mA is more than what the chip should be able to draw. If you have the radio in RX mode it should consume around 13mA. If you have everything else enabled as well, you will normally have around 20mA current consumption, maximum 25mA.

I measure the current consumption of the ESB RX example in nRF51 SDK and get current consumption of 17.3mA, and for the ESB TX example I measure 11.9mA on my nRF51-DK board.

After you flash the chip the current consumption is higher, because the chip is in debug mode. After you power reset the chip it should draw normal current.

For troubleshooting, you may benefit from looking at the current consumption guide, the Troubleshooting section.