Texas Instruments SimpleLink CC2620 Technical Reference Manual page 1214

Power Management
NOTE: TI RTOS forces AUX into active whenever the MCU system is in active mode to ensure fast
access to the oscillator interface in the AUX domain.
There are three power modes available for the AUX domain: active, power down, and power off.
17.5.2.1 Active Mode
Active mode is requested when there is no request set for power down or power off. When active system
mode is entered, the AUX clock source is derived from the high-speed system clock, which can be divided
down by configuring the AON_WUC:AUXCLK.SCLK_HF_DIV register.
The maximum frequency is 24 MHz, and the configuration of clock division must be done by the system
CPU.
When the AUX_PD is in active mode, the device is prevented from entering standby or shutdown power
modes because the AUX_PD is requesting system resources from the supply system.
17.5.2.2 Power Down
Power down is requested when AUX has been disconnected from the system BUS.
In power down mode, the AUX_PD is on and the sensor controller can still execute programs. The AUX
domain receives a clock defined in the AON_WUC:AUXCLK.PWR_DWN_SRC register.
To have the AUX enter power-down mode, a 4-phase handshake with the AON_WUC is necessary, using
the AUX_WUC register bank by completing the following sequence:
1. Write AUX_WUC:PWRDWNREQ = 1
2. Wait for AUX_WUC:PWRDWNACK = 1
3. Write AUX_WUC:PWRDWNREQ = 0
4. Wait until AUX_WUC:PWRDWNACK = 0
When the PWRDWNACK register goes low, the AUX starts receiving the power-down clock instead of the
active-mode clock.
By default, the entire AUX domain has full retention in the power-down mode. TI recommends using this
low-power mode to save execution time by not having to reconfigure AUX every time it is used.
If the entire CC26xx and CC13xx device must be put in a low-power mode, the AUX must first disconnect
from the MCU system bus before completing the power-down sequence. Refer to
Bus Connection for more details.
17.5.2.3 Power Off
The AUX domain can be fully powered off (power disconnected) from the domain to reduce the leakage
current from the domain. To fully power off the AUX domain, the system must first disconnect from the
MCU system bus (refer to
To request the domain to be powered off, write AON_WUC:PWROFFREQ = 1.
Even if the entire domain is powered off, the contents of AUX SRAM are retained by default, which is
configurable in the AON_WUC:AUXCFG.SRAM_RET_EN register field.
NOTE: Powering off the entire AUX domain is usually not needed because the extra current being
drawn compared to power down is minimal (just a few nA).
1214
AUX – Sensor Controller with Digital and Analog Peripherals
Section 17.5.4, MCU Bus Connection for more details).
Copyright © 2015, Texas Instruments Incorporated
Section
SWCU117C – February 2015 – Revised September 2015
Submit Documentation Feedback
www.ti.com
17.5.4, MCU