RE: Power Down Options

Øyvind Karlsen — Thu, 21 Jul 2016 06:52:58 GMT

Hi,

You always want to sleep as much as possible to reduce current consumption, start off by calling sd_app_evt_wait() whenever your application is done processing, eg in main.

while(1)
{
    sd_app_evt_wait();
}

There's no problem with sleeping with the code you describe above, it will wake up "automatically" whenever there is an interrupt.

Before going to sleep you should turn off unused peripherals.

You should also consider if you need to use the TIMER module, are the TWI events so frequent or require so high precision that it is not possible to use RTC from the Low Frequency clock?

The main difference between TIMER and RTC (Real-time counter) is that:

TIMER uses the high-frequency clock source (HFCLK, 16 MHz), which means better resolution (62.5 ns) and higher power consumption.
RTC uses the low-frequency clock source (LFCLK, 32 KHz), which means less resolution (~30 us) and lower power consumption.

Common practice is to route the power separately to each device, preferably using a star configuration from a common capacitor bank (each device has its own VDD branch from the reservoir), this alleviates voltage drop from high loads. In other words each device becomes independent of the other devices.

Best regards,

Øyvind