High current consumption offset when using internal RC oscillator as compared to crystal oscillator for low frequency clock.

Question

Describe the bug When trying to sleep core on NRF52805 using low frequency internal rc oscillator, average current consumption is ~189.50 uA while when using external crystal oscillator, average current consumption is ~ 8 uA. I can't provide actual application code that I'm running, however, the only difference at Kconfig level it's whether to decide which low frequency crystal is used. I tried to get into the errata section to find out if it was something related to it but it doesn't. Also, I do not have UART enabled, and verification have been made to confirm that there is no GPIO line floating. How to reproduce Chip model: NRF52805 CAAA os: Linux / GNU sdk-nrf tag: v1.5.1, v1.4.0 Microcontroller is using System ON and DC-DC is enabled Use internal rc crystal oscillator remove extra capacitors and crystal connected to xtal pins leave extra capacitors and crystal connected to xtal pins Measure current consumption going into NRF52805 prj.conf: CONFIG_CLOCK_CONTROL_NRF_K32SRC_RC=y CONFIG_CLOCK_CONTROL_NRF_K32SRC_XTAL=n CONFIG_CLOCK_CONTROL_NRF_K32SRC_SYNTH=n Extra configurations: CONFIG_CLOCK_CONTROL_NRF_CALIBRATION_LF_ALWAYS_ON=n When device sleeps and debugger is connected these are the register values: Fields in CLOCK > LFCLKSTAT: SRC: RC 32.768 kHz RC oscillator - Source of LFCLK STATE: Running LFCLK running - LFCLK state Fields in CLOCK > HFCLKSTAT: SRC: RC 64 MHz internal oscillator (HFINT) - Source of HFCLK STATE: Running HFCLK running - HFCLK state Fields in CLOCK > LFCLKSRC: SRC: RC 32.768 kHz RC oscillator - Clock source Fields in CLOCK > HFCLKSTAT: SRC: RC 64 MHz internal oscillator (HFINT) - Source of HFCLK STATE: Running HFCLK running - HFCLK state One way to quickly reproduce the behavior it's modifying system off sample on zephyr samples: /* * Copyright (c) 2019 Nordic Semiconductor ASA * * SPDX-License-Identifier: Apache-2.0 */ #include #include #include #include #include #include #define CONSOLE_LABEL DT_LABEL(DT_CHOSEN(zephyr_console)) /* Prevent deep sleep (system off) from being entered on long timeouts * or `K_FOREVER` due to the default residency policy. * * This has to be done before anything tries to sleep, which means * before the threading system starts up between PRE_KERNEL_2 and * POST_KERNEL. Do it at the start of PRE_KERNEL_2. */ static int disable_ds_1(const struct device *dev) { ARG_UNUSED(dev); pm_ctrl_disable_state(POWER_STATE_DEEP_SLEEP_1); return 0; } SYS_INIT(disable_ds_1, PRE_KERNEL_2, 0); void main(void) { int rc; uint8_t i; const struct device *all_devices; static volatile uint16_t devices_count; devices_count = z_device_get_all_static(&all_devices); for(i = 0; i < devices_count; ++i) { rc = device_set_power_state(&(all_devices[i]), DEVICE_PM_LOW_POWER_STATE, 0, 0); } k_sleep(K_MSEC(1000000)); printk("ERROR: System off failed "); while (true) { /* spin to avoid fall-off behavior */ } } Expected behavior To have similar results on current consumption as when using external crystal oscillator with slightly offset.