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Deep Sleep Mode
198
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Power Management
9.9.2 Entering/Exiting Deep Sleep Mode Using RTC Controlled Wake-Up
9.9.2.1
Entering Deep Sleep Mode
Use the following procedure to enter the Deep Sleep state if the RTC is used to wake-up the device:
1. To preserve DDR2/mDDR memory contents, activate the self-refresh mode and gate the clocks to the
DDR2/mDDR memory controller. You can use partial array self-refresh (PASR) for additional power
savings for mDDR memory.
2. The SATA PHY should be disabled (see
3. The USB2.0 (USB0) PHY should be disabled, if this interface is used and internal clocks are selected
(see
).
4. The USB1.1 (USB1) PHY should be disabled, if this interface is used and internal clocks are selected
(see
).
5. PLL/PLLC0 and PLL/PLLC1 should be placed in bypass mode (clear the PLLEN bit in the PLL control
register (PLLCTL) of each PLLC to 0).
6. PLL/PLLC0 and PLL/PLLC1 should be powered down (set the PLLPWRDN bit in PLLCTL of each
PLLC to 1).
7. Configure the desired wake-up time as an alarm in the RTC.
8. Configure the DEEPSLEEP/RTC_ALARM pin to output RTC_ALARM using the PINMUX0_31_28 bits
in the PINMUX0 register in the
System Configuration (SYSCFG) Module
chapter. The pin is driven low
since the alarm has not yet occurred.
9. Configure the desired delay in the SLEEPCOUNT bit field in the deep sleep register (DEEPSLEEP) in
the
System Configuration (SYSCFG) Module
chapter. This count determines the delay before the
Deep Sleep logic releases the clocks to the device during wake up (allowing the oscillator to stabilize).
10. Set the SLEEPENABLE bit in DEEPSLEEP to 1. This automatically clears the SLEEPCOMPLETE bit.
Also, the device now enters the Deep Sleep mode since the DEEPSLEEP pin is low.
For more details on the clock stop procedure of the DDR2/mDDR memory controller, see the
DDR2/mDDR Memory Controller
chapter.
9.9.2.2
Exiting Deep Sleep Mode
Use the following procedure to exit the Deep Sleep state if the RTC is used to wake-up the device:
1. The RTC alarm occurs and the RTC_ALARM pin is driven high (which is internally connected to the
DEEPSLEEP pin). This causes the Deep Sleep logic to exit the Deep Sleep mode.
2. When the SLEEPCOUNT delay is complete, the Deep Sleep logic releases the clock to the device and
sets the SLEEPCOMPLETE bit in the deep sleep register (DEEPSLEEP) in the
System Configuration
(SYSCFG) Module
chapter.
3. Clear the SLEEPENABLE bit in DEEPSLEEP to 0. This automatically clears the SLEEPCOMPLETE
bit.
4. Initialize the PLL controllers as described in
. Note that the state of the PLL controller
registers is preserved during Deep Sleep mode. Therefore, it is not necessary to reprogram all the PLL
controller registers unless a new setting is desired. At minimum, steps 3, 4, and 7-10 of the PLL
initialization procedure must be followed.
5. Enable the clocks to the DDR2/mDDR memory controller, reset the DDR PHY, and then take the
DDR2/mDDR out of self-refresh mode.
6. Configure the desired states to the peripherals and enable as required.
For more details on the clock enable procedure of the DDR2/mDDR memory controller, see the
DDR2/mDDR Memory Controller
chapter.