SH7763 Datasheet, PDF (749/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 18 Power-Down Mode
After the system power supply is turned on, the M_CKE output may remain unstable until the
clock is supplied after the LSI power supply has become stable. Therefore, use the M_BKPRST
signal to keep the M_CKE signal input of the DDR-SDRAM low until the power-on reset is
canceled.
Time
Processing
Confirm that all transactions of
1.
DDRIF caused by on-chip peripheral
modules are completed
SELFS
Command M_CKE
REFA/NOP
High
SDRAM State
Performs auto-refresh at regular
intervals
2.
Set SCR to issue PREALL and REFA
commands
3.
Set MIM to issue self-refresh
command
4.
Set MIM: SELFS = 1
Low
PREALL
REFA
Enters idle state after refreshing
once
REFS
Performs self-refresh
Low
5.
Drive M_BKPRST from high to low
High
6.
Turn off system power supply
Figure 18.2 Sequence for Turning Off System Power Supply after Entering Self-Refresh
Mode
Rev. 1.00 Oct. 01, 2007 Page 683 of 1956
REJ09B0256-0100