CLKSTOP_REQ
CLKSTOP_ACK
MODCLK
MODRST
LRST
DDR
PST
PLL0_SYSCLK2/2
VCLKSTOP_REQ
VCLKSTOP_ACK
VCLK
chip_rst_n
mod_g_rst_n
DDR2/mDDR
memory
controller
2X_CLK
PLLC1
/1
Architecture
396
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
DDR2/mDDR Memory Controller
14.2.16 Power Management
Power dissipation from the DDR2/mDDR memory controller may be managed by the following methods:
•
Self-refresh mode (see
)
•
Power-down mode (see
•
Disabling the DDR PHY to reduce power
The DDR2/mDDR memory controller supports low-power modes where the DLL internal to the PHY
and the receivers at the I/O pins can be disabled. These functions are controlled through the
DDR2/mDDR memory controller. Even if the PHY is active, the receivers can be configured to disable
whenever writes are in progress and the receivers are not needed.
•
Gating input clocks to the module off
Gating input clocks off to the DDR2/mDDR memory controller achieves higher power savings when
compared to the power savings of self-refresh mode and power-down mode. The input clocks are
turned off outside of the DDR2/mDDR memory controller through the use of the Power and Sleep
Controller (PSC) and the PLL controller 1 (PLLC1).
shows the connections between the
DDR2/mDDR memory controller, PSC, and PLLC1. For detailed information on power management
procedures using the PSC, see the
Power and Sleep Controller (PSC)
chapter.
Before gating clocks off, the DDR2/mDDR memory controller must place the DDR2/mDDR SDRAM
memory in self-refresh mode. If the external memory requires a continuous clock, the DDR2/mDDR
memory controller clock provided by PLLC1 must not be turned off because this may result in data
corruption. See the following subsections for the proper procedures to follow when stopping the
DDR2/mDDR memory controller clocks. Once the clocks are stopped, to re-enable the clocks follow
the clock stop procedure in each respective subsection in reverse order.
Figure 14-17. DDR2/mDDR Memory Controller Power Sleep Controller Diagram