Hardware Design Guide
57
IXP28XX Network Processor
QDR SRAM
4.3
QDR SRAM Connections
Figure 22
illustrates the QDR SRAM connections.
4.4
QDR SRAM Interface
The IXP28XX network processor has four independent SRAM subsystems, each of which supports
pipelined QDRII-synchronous static RAM (QDRII SRAM). There may also be – in addition to or
as a replacement for the pipelined QDR SRAM – a coprocessor with QDR signaling capability.
Figure 22.
QDR SRAM Connections
B3414-01
C/C#0
K/K#0
Q[17:0]
D[17:0]
D[17:0]
Q[17:0]
SA[21:0]
ZQ
SA[21:0]
BW[1:0]
BW#[1:0]
W#/R#
W#0/R#0
W#/R#1
ZQ[0]
ZQ[1]
CIN/CIN#0
C/C#1
K/K#1 CIN/CIN#1
C/C# K/K# CQ/CQ#
D[17:0]
Q[17:0]
ZQ
SA[21:0]
BW#[1:0]
NW#[1:0]
NW#[1:0]
W#/R#
C/C# K/K# CQ/CQ#
250 Ohms
250 Ohms
50 Ohms
50 Ohms
0 Ohms
1.5 V
Not
Used
Not Used
Intel
®
IXP2800
QDR
Channe
l
QDR-II
SRAM
1 of 2
Clamshelled
QDR-II
SRAM
2 of 2
Clamshelled
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