LH540235U-20 データシートの表示（PDF） - Sharp Electronics
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LH540235U-20 Datasheet PDF : 46 Pages
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LH540235/45
2048 x 18/4096 x 18 Synchronous FIFOs
DESCRIPTION OF SIGNALS AND OPERATING SEQUENCES
Table 1. Grouping-Mode Determination
During a Reset Operation 5
EMODE WXI/WEN2 RXI/REN2 FL/RT
MODE
WXO/HF
USAGE
WXI/WEN2
USAGE
RXI/REN2
USAGE
FL/RT
USAGE
RXO/EF2
USAGE
H1
H
H
Cascaded
H
Slave 2
WXO WXI
RXI
FL
RXO
H1
H
H
L
Cascaded
Master 2
WXO WXI
RXI
FL
RXO
H
H
L
X
(Reserved)
–
–
–
–
–
H
L
H
X
(Reserved)
–
–
–
–
–
H
L
H
L
(Not
L
H3
Allowed
During
(HF)
(none)
(none) (RT)
(none)
Reset)
L
L 3 Standalone HF
(none)
(none) RT
(none)
L
X
(Not
X
H3
Allowed
During
(HF)
(WEN2) (REN2) (RT)
(EF2)
Reset)
L
X
X
L3
Interlocked
Paralleled 4
HF
WEN2
REN2
RT
EF2
NOTES:
1. In IDT-compatible cascading, a reset operation forces WXO/HF and RXO/EF2 HIGH for the nth FIFO, thus forcing WXI/WEN2 and RXI/REN2
HIGH for the (n + 1)st FIFO.
2. The terms ‘master’ and ‘slave’ refer to IDT-compatible cascading. In pipelined cascading4, there is no such distinction.
3. Once grouping mode has been determined during a reset operation, FL/RT then may go HIGH to activate a retransmit operation.
4. EMODE must be asserted for access to the Control Register to be enabled. Also, FIFOs being used in a pipelined-cascading
configuration should be in Interlocked Paralleled mode.
5. Setup-time and recovery-time specifications apply during a reset operation.
Table 2. Expansion-Pin Usage According to
Grouping Mode
I/O
PIN
I WXI /WEN2
O WXO/HF
I RXI/REN2
O RXO/EF2
I FL/RT
IDT-COMPATIBLE OPERATING MODE
DEPTH-CASCADED
MASTER
From WXO ((n-1)st FIFO)
To WXI ((n+1)st FIFO)
From RXO ((n-1)st FIFO)
To RXI ((n+1)st FIFO)
Grounded (Logic LOW)
DEPTH-CASCADED
SLAVE
From WXO ((n-1)st FIFO)
To WXI ((n+1)st FIFO)
From RXO ((n-1)st FIFO)
To RXI ((n+1)st FIFO)
Logic HIGH
STANDALONE
Grounded
Becomes HF
Grounded
Unused
Becomes RT1
ENHANCED
OPERATING MODE
INTERLOCKED
PARALLELED
From FF (other FIFO)
Becomes HF
From EF (other FIFO)
Becomes EF2
Becomes RT1
NOTE:
1. FL/RT may be grounded if the Retransmit facility is not being used.
BOLD ITALIC = Enhanced Operating Mode
10
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