SH7641 Datasheet, PDF (419/1036 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7641 Series

Section 12 Bus State Controller (BSC)
CKIO
CKE
Tr
Tc1 Td1
Tde
Tap
Tr
Tc1 Tnop Trwl
Tap
(High)
A25 to A0
A12/A11*¹
CSn
RASL, RASU
CASL, CASU
RD/WR
DQMxx
D31 to D0
BS
DACKn*²
Notes: 1. Address pin to be connected to pin A10 of SDRAM.
2. The waveform for DACKn is when active low is specified.
Figure 12.31 Low-Frequency Mode Access Timing
Power-Down Mode: If the PDOWN bit in the SDCR register is set to 1, the SDRAM is placed in
the power-down mode by bringing the CKE signal to the low level in the non-access cycle. This
power-down mode can effectively lower the power consumption in the non-access cycle.
However, please note that if an access occurs in the power-down mode, a cycle of overhead occurs
because a cycle is needed to assert the CKE in order to cancel the power-down mode.
Figure 12.32 shows the access timing in the power-down mode.
Rev. 4.00 Sep. 14, 2005 Page 369 of 982
REJ09B0023-0400