Functional Description
213
SLAU723A – October 2017 – Revised October 2018
Copyright © 2017–2018, Texas Instruments Incorporated
System Control
To provide the lowest possible deep-sleep power consumption and the ability to wake the processor from
a peripheral without reconfiguring the peripheral for a change in clock, some of the communications
modules have a clock control register at offset 0xFC8 in the module register space. The CS field in the
clock control register lets the user select the PIOSC or ALTCLK as the clock source for the baud clock of
the module. When the microcontroller enters deep-sleep mode, the PIOSC or ALTCLK becomes the
source for the module clock as well, which allows the transmit and receive FIFOs to continue operation
while the microcontroller is in deep-sleep mode.
shows how the clocks are selected.
Figure 4-6. Module Clock Selection
Additional power-management modes are available that lower the power consumption of the peripheral
memory, flash memory, and SRAM. However, the lower power consumption modes have slower deep-
sleep and wake-up times.
NOTE:
If one or more wait states are configured for run mode, when the device enters deep-sleep
mode, it achieves its lowest possible current. If no wait states are applied in run mode, the
lowest possible current is not achieved.
4.1.6.4
Dynamic Power Management
In addition to the sleep and deep-sleep modes and the clock gating for the on-chip modules, other power
mode options let the LDO, flash memory, and SRAM enter different levels of power savings while in sleep
or deep-sleep mode. In addition, software can control the LDO settings to gain a power advantage when
running at slower speeds. These features may not be available on all devices; the System Properties
(SYSPROP) register provides information on whether a mode is supported on a given MCU. The following
registers provide these capabilities:
•
Peripheral Power Control (PCx): Controls power to peripheral if that peripheral has the ability to
respond to a power request
•
Peripheral Memory Power Control (xMPC): Provides power control to some the peripheral memory
arrays
•
LDO Sleep Power Control (LDOSPCTL): Controls the LDO value in sleep mode
•
LDO Deep-Sleep Power Control (LDODPCTL): Controls the LDO value in deep-sleep mode
•
LDO Sleep Power Calibration (LDOSPCAL): Provides factory recommendations for the LDO value in
sleep mode
•
LDO Deep-Sleep Power Calibration (LDODPCAL): Provides factory recommendations for the LDO