EMIF Module Architecture
827
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
External Memory Interface (EMIF)
21.2.15 Power Management
Power dissipation from the EMIF memory controller may be managed by following methods:
•
Self-refresh mode
•
Power-down mode
•
Gating input clocks to the module off
Gating input clocks off to the EMIF memory controller achieves higher power savings when compared to
the power savings of self-refresh or power down mode. The input clock VCLK3 can be turned off through
the use of the Global Clock Module (GCM). Before gating clocks off, the EMIF memory controller must
place the SDR SDRAM memory in self-refresh mode. If the external memory requires a continuous clock,
the VCLK3 clock domain 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 EMIF memory controller
clocks.
21.2.15.1 Power Management Using Self-Refresh Mode
The EMIF can be placed into a self-refresh state in order to place the attached SDRAM devices into self-
refresh mode, which consumes less power for most SDRAM devices. In this state, the attached SDRAM
device uses an internal clock to perform its own auto refresh cycles. This maintains the validity of the data
in the SDRAM without the need for any external commands. Refer to
for more details on
placing the EMIF into the self-refresh state.
21.2.15.2 Power Management Using Power Down Mode
In the power down mode, EMIF drives EMIF_CKE low to lower the power consumption. EMIF_CKE goes
high when there is a need to send refresh (REFR) commands, after which EMIF_CKE is again driven low.
EMIF_CKE remains low until any request arrives. Refer to
for more details on placing
EMIF in power down mode.
21.2.16 Emulation Considerations
EMIF memory controller remains fully functional during emulation halts in order to allow emulation access
to external memory.