power up
#define BUTTONPIN 4
...
nrf_gpio_cfg_sense_input(g_ADigitalPinMap[BUTTONPIN], NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW); //wake from deep sleep
power down
sd_power_system_off();
However, the DCDC providing 3v3 to my peripherals remains powered on. Is there a way to shut it down?