r4f2426 Renesas Electronics Corporation., r4f2426 Datasheet - Page 267

• Manufacturer Part Number: r4f2426
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

In some DRAMs provided with a self-refresh mode, the RAS signal precharge time immediately
after self-refreshing is longer than the normal precharge time. A setting can be made in bits
TPCS2 to TPCS0 in REFCR to make the precharge time immediately after self-refreshing from 1
to 7 states longer than the normal precharge time. In this case, too, normal precharging is
performed according to the setting of bits TPC1 and TPC0 in DRACCR, and therefore a setting
should be made to give the optimum post-self-refresh precharge time, including this time. Figure
6.52 shows an example of the timing when the precharge time immediately after self-refreshing is
extended by 2 states.
φ
Address bus
RASn (CSn)
UCAS, LCAS
OE (RD)
WR (HWR)
Data bus
Note: n = 2 to 5
Figure 6.52 Example of Timing when Precharge Time after Self-Refreshing Is Extended
Software
standby
TR
c3
by 2 States
TR
p1
TR
p2
Rev. 1.00 Sep. 19, 2008 Page 239 of 1270
T
p
DRAM space write
Section 6 Bus Controller (BSC)
T
r
T
c1
REJ09B0466-0100
T
c2