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PRCM Functional Description
NOTE:
DPLL1 and DPLL3 cannot be manually forced to switch to low-power stop mode from any
other power mode. They must be in Locked state with automatic transition to low-power stop
mode configured and the hardware condition for the transition (identified in
) must
be satisfied, in order to switch to the low-power stop mode.
lists the bit fields that must be programmed for manual and automatic mode control of the five
DPLLs.
Table 3-41. DPLL Power Mode Control
Mode
Manual Control
Auto Control
DPLL1
[2:0] AUTO_MPU_DPLL
EN_MPU_DPLL
DPLL2
[2:0]
[2:0] AUTO_IVA2_DPLL
EN_IVA2_DPLL
DPLL3
[2:0] AUTO_CORE_DPLL
EN_CORE_DPLL
DPLL4
[5:3] AUTO_PERIPH_DPLL
EN_PERIPH_DPLL
DPLL5
[2:0]
[2:0] AUTO_PERIPH2_DPLL
EN_PERIPH2_DPLL
NOTE:
The DPLL automatically enters locked mode on a power domain wakeup only if the DPLL is
locked before the sleep transition and one of the automatic modes is enabled.
3.5.3.6.3 DPLL Low-Power Mode
The DPLL can operate in a low-power mode by reducing the operating frequency range. This reduces the
power consumption of the DPLL. In this mode, however, there is a period and phase jitter effect.
The DPLL can enter this mode only if the targeted lock frequency of the DPLL is less than 600 MHz. This
implies locking or relocking the DPLL to a new targeted locked-frequency when entering or exiting
low-power mode. Software must ensure that the DPLL lock frequency does not exceed 600 MHz in
low-power mode.
Software can enable/disable automatic switching of the DPLL between normal mode and low-power
mode. The new mode is effective only after the DPLL is relocked. Low-power mode control is considered
only during the following transitions:
•
Bypass mode to lock
•
Stop mode to lock
•
Lock to relock
lists the bit fields that must be programmed for manual control of the five DPLLs.
Table 3-42. LP Mode Control
Mode
Manual Control
DPLL1
PRCM.
[10] EN_MPU_DPLL_LPMODE
DPLL2
PRCM.
[10] EN_IVA2_DPLL_LPMODE
DPLL3
PRCM.
[10] EN_CORE_DPLL_LPMODE
DPLL4
PRCM.
[26] EN_PERIPH_DPLL_LPMODE
DPLL5
PRCM.
[10] EN_PERIPH2_DPLL_LPMODE
331
SWPU177N – December 2009 – Revised November 2010
Power, Reset, and Clock Management
Copyright © 2009–2010, Texas Instruments Incorporated