HD6412320 RENESAS [Renesas Technology Corp], HD6412320 Datasheet - Page 227

• Manufacturer Part Number: HD6412320
• Description: Renesas 16-Bit Single-Chip Microcomputer H8S Family H8S-2300 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Self-Refreshing: A self-refresh mode (battery backup mode) is provided for DRAM as a kind of
standby mode. In this mode, refresh timing and refresh addresses are generated within the DRAM.
To select self-refreshing, set the RFSHE bit and RMODE bit in DRAMCR to 1. Then, when a
SLEEP instruction is executed to enter software standby mode, the CAS and RAS signals are
output and DRAM enters self-refresh mode, as shown in figure 6.27.
When software standby mode is exited, the RMODE bit is cleared to 0 and self-refresh mode is
cleared.
When switching to software standby mode, if there is a CBR refresh request, CBR refreshing is
executed before self-refresh mode is entered.
Note: n = 2 to 5
CAS, LCAS
CSn (RAS)
CAS, LCAS
Note: n = 2 to 5
Figure 6.26 CBR Refresh Timing (When RCW = 1, RLW1 = 0, RLW0 = 1)
CSn (RAS)
HWR (WE)
φ
φ
T
T
Rp
Rp
Figure 6.27 Self-Refresh Timing
T
Rcr
T
Rr
High
T
Rc1
Rev.6.00 Sep. 27, 2007 Page 197 of 1268
Software
standby
T
Rw
Section 6 Bus Controller
T
T
Rc2
Rc3
REJ09B0220-0600