r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 296

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 6 Bus Controller (BSC)
T
T
T
T
T
T
Rp1
Rp2
Rrw
Rr
Rc1
Rc2
φ
SDRAMφ
Address bus
Precharge-sel
RAS
CAS
WE
CKE
High
PALL
NOP
REF
NOP
Figure 6.67 Auto Refresh Timing
(TPC = 1, TPC0 = 1, RCW1 = 0, RCW0 = 1)
When the interval specification from the REF command to the ACTV cannot be satisfied, setting
the RLW1 and RLW0 bits of REFCR enables one to three wait states to be inserted in the refresh
cycle. Set the optimum number of waits according to the synchronous DRAM connected and the
operating frequency of this LSI. Figure 6.68 shows the timing when one wait state is inserted.
Rev. 1.00 Sep. 19, 2008 Page 266 of 1342
REJ09B0467-0100