Current consumption difference nRF51422 and nRF51822

[Bart de Kramer]

I'm had develloped some software and tested it on the nRF51-DK. After that I made my own PCB design where only the nRF51422 is replaced by a nRF51822. When I flash both with exactly the same software, the nRF51-DK consumes about 5.6uA and my own PCB about 2350uA. Is there a difference between the nRF51422 and nRF51822 which can cause this big difference?

I'm using softdevice s110_nrf51_8.0.0.

[Bart de Kramer]

Hung, I've send the schematic and layout trough the support portal. unfortunately this is my last working day before Christmas. So maybe I can do some tests today, otherwise I'll be back at monday 4th January

[Hung Bui]

Hi Bart,

I have received your files. They looked fine for me. (except some improvement can be done with the layout on RF for optimization but we can discuss that after solving this issue)

I would suggest you to test with following firmwares in the nRF51 SDK and report the current consumption, in each test. Please make sure you removed or modified the firmware to match with your board's GPIO pin (the LED pins)

Erase softdevice

1. Test with \examples\peripheral\blinky (modify so that it blink only one LED, if you have no LED you can check if the voltage on one pin is changing)

2. Test with \examples\peripheral\pin_change_int (Add __WFE(); to put CPU to sleep)

Flash softdevice:

3. Test with \examples\ble_peripheral\ble_app_hrs (remove and LED output). Check if the device advertise, if it doesn't you can try to go to debug mode and walkthrough until the advertising start API call.

[Hung Bui]

Wait a sec, I just looking again at the value of the RF components, could you explain why you use L1 =27nH, and C5 = 3.9 pF ? R12 for SWDCLK is also not needed (if you are not using the very old revision 1 chip from 2 years ago)

[Bart de Kramer]

I used the values from the schematics from the PCA100028 (Revision 1.0.0, date 24-10-2014). The SWDCLK pulldown should be removed if I have the N51822QFAA631440BK?

[Hung Bui]

Hi Bart,

The chip on the PCA100028 is the nRF51422 QFAC (revision3+) and has different matching network components' values. Your chip ( I assume N51822QFAAG3 not 63) is revision 2 chip, you can find the reference design for it in the nRF51822 PS. You don't need the pulldown on SWDCLK for it.

Please also try the tests I mentioned above.