
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATMTraffic Management Device
Released
Datasheet
79
6.2
DRAM External Memory Timing
NOTE: All inputs are the minimum required. All outputs are the minimum expected. All inputs and outputs
are assume to have a 30 pf capacitive loading. The RX_DRAM_CLK and TX_DRAM_CLK are
assume to have a 22 ohm series terminated resister connected to a combined capacitive load of 36
pf.
Figure 52 shows the receive DRAM external memory 100 MHz read timing.
Figure 52. Receive DRAM External Memory 100 MHz Read Timing
Symbol
Parameter
Signals
Min
Max
Unit
Tcyc
Tch
Tcl
Taddrsu
Tbasu
Taddrh
Tbah
Tckh
Tcksu
Trassu
Trash
Tcassu
Tcash
Tcssu
Tcsh
Trdh
Clock period
Clock high period
Clock low period
Address setup time
Bank address setup time
Address hold time
Bank address hold time
Enable hold time *
Enable setup time *
RAS setup time
RAS hold time
CAS setup time
CAS hold time
Chip select setup time
Chip select hold time
Required hold time required (read data)
RX_DRAM_CLK
RX_DRAM_CLK
RX_DRAM_CLK
RX_DRAM_ADD(8:0)
RX_DRAM_BA
RX_DRAM_ADD(8:0)
RX_DRAM_BA
DRAM_CKE
DRAM_CKE
/RX_DRAM_RAS
/RX_DRAM_RAS
/RX_DRAM_CAS
/RX_DRAM_CAS
/RX_DRAM_CS(1:0)
/RX_DRAM_CS(1:0)
RX_DRAM_DATA(31:0)
10
3
3
2.7
2.9
1.3
1.5
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
3.1
1.5
3.2
1.5
2.4
2.2
2.7
Tcyc
Tch
Tcl
Tcksu
Tckh
Tcssu
Tcsh
Trassu
Trash
Tcassu
Tcash
Taddrsu
Taddrh
Twesu
Tweh
Trds
Trdh
Tbasu
Tbah
ROW
COLUMN
VALID DATA
RX_DRAM_CLK
DRAM_CKE
/RX_DRAM_CS(1:0)
/RX_DRAM_RAS
/RX_DRAM_CAS
RX_DRAM_ADD(8:0)
/RX_DRAM_WE
RX_DRAM_DATA(31:0)
RX_DRAM_BA