Table 22-5. DRAM Memory Refresh Timing
Symbol
trref1
trref2
tcrefl
tcrefh
trarf
Parameter
MEMCLK rising to nRAS
MEMCLK falling to nRAS
MEMCLK rising to nCAS[3:0] falling
MEMCLK rising to nCAS[3:0] rising
MEMCLK rising to RA[11:0] changing
CL-PS7500FE
System-on-a-Chip for Internet Appliance
40 MHz
MIN
MAX
12
11
16
16
22
56 MHz
MIN MAX
12
11
16
16
22
Units
ns
ns
ns
ns
ns
LA[28:0]
MEMCLK
nRAS[0]
nRAS[1]
nRAS[2]
nRAS[3]
nCAS[3:0]
RA[11:0]
Address for next instruction
tr r e ß
tr r e f 2
0xF
0x0
tc r e ß
xxx
xxx
tr a r f
tr r e f 1
tr r e f 2
0xF
tc r e f h
xxx
tr a r f
tr a r f
Figure 22-11. DRAM Memory Refresh Timing
208
ELECTRICAL SPECIFICATIONS
ADVANCE DATA BOOK v2.0
June 1997