Power management- usuing external LFCLK

RE: Power management- usuing external LFCLK

Gili Elias — Mon, 31 Mar 2014 10:41:42 GMT

apologies, didn't see the button...

RE: Power management- usuing external LFCLK

Ole Morten — Mon, 31 Mar 2014 09:08:42 GMT

Great! If you found the answer useful, as I said I would be happy if you could click the "Accept as answer" button below it, to clear up this question. :-)

RE: Power management- usuing external LFCLK

Gili Elias — Sun, 30 Mar 2014 11:48:15 GMT

thanks, the original reply is useful. I will post a separate question if we run into problems.

Gili

RE: Power management- usuing external LFCLK

Ole Morten — Fri, 28 Mar 2014 16:31:16 GMT

When you go to system off, everything will be turned off automatically, so no manual turning off is needed. However, when you go to system on sleep, everything that's already enabled will stay enabled, so in this mode you should absolutely disable everything you don't need.

However, if you found my original reply useful, I'd be happy if you could accept it, to clear up this question. :-) If you have any further problems next week, I suggest you post them separately.

RE: Power management- usuing external LFCLK

Gili Elias — Fri, 28 Mar 2014 16:09:52 GMT

Hi Ole,

we are measuring without a debugger and next think we will look at next week are IOs and any fast peripherals which may still be active. we have been able to get to below 2uA in OFF mode before, so I guess that now since we are enabling the softdevice we need to disable peripherals properly before we go to OFF state.

regards, Gili

RE: Power management- usuing external LFCLK

Ole Morten — Fri, 28 Mar 2014 10:48:38 GMT

130 µA was an odd level, and I can't say I immediately have any good suggestions on which peripheral combination would draw that. I'd recommend you to also make sure that all I/Os have a defined level (i.e. not input without pull; either output, input with pull or input buffer disconnected).

Also, you should make sure to do the measurement without a debugger connected, either physically disconnect it or turn it off with the SW4 switch or removing the P8 jumpters on the Evaluation Kit.

Finally, if you have the Development Kit, you should not use the CSM to do low-current measurements, but instead measure current directly on P7.

RE: Power management- usuing external LFCLK

Gili Elias — Tue, 25 Mar 2014 15:02:28 GMT

Hi Ole,

Thanks for the reply. We are currently at ~130uA and probably what is going on is we still have some fast clock peripheral on, so we will take a look.

Regards, Gili

RE: Power management- usuing external LFCLK

Ole Morten — Fri, 21 Mar 2014 10:08:21 GMT

1.6 mA is way too high than you should have between connection events, so there's definitely something wrong. As you can see in the SDS, you should see I_on, I_RTC and either I_X32k or I_RC32k depending on clock source used. This should be about ~3 µA in total.

There are a couple of things that you should check when seeing problems like this:

Make sure to power cycle the nRF51822 after debugging/programming, or else the debug interface will stay enabled, which consumes a lot of power.
If you use the Evaluation Kit, make sure to disconnect/turn off the Segger. Depending on kit version, either turn off SW4 (2.0+) or remove jumpers on P8 (1.0).
Make sure to disable all serial interfaces or other peripherals requiring the 16 MHz clock. Take a look at section 8.3 in the PS, as well as this question.

To use a 32 kHz crystal with the softdevice, all you have to do is pass the correct initialization parameter. Take a look at this question for examples.