
Table 5. Output-Port Word-Width Selection
WSO
1
WSO
0
FUNCTION
L
L
9-Bit Data-Path
Width
Output data Q[8:0]
L
H
18-Bit Data-Path
Width
Output data Q[17:0]
H
L
36-Bit Data-Path
Width With Byte-
Order-Reversal
Output data Q[35:0]
H
H
36-Bit Data-Path
Width
Output data Q[35:0]
Table 6. Retransmit Operation Modes
RTMD
1
RTMD
0
OPERATION
ACTION TAKEN
L
L
Depth
Cascade
Mode
The Almost-Empty
Flag is a handshake
signal for cascading
L
H
Retransmit
(RBASE) +
(ROFFSET)
RP
H
L
Retransmit
and Mark
(RBASE) +
(ROFFSET)
RP
and
(RBASE) +
(ROFFSET)
RBASE
H
H
Mark
(RP)
RBASE
PIN NAME
DESCRIPTION
CONTROL SIGNALS SYNCHRONOUS TO THE OUTPUT CLOCK (cont’d)
WSO[1:0]
Output-Port Word-Width Selection.
WSO[1:0] is synchronous to the rising edge of CKO.
WSO[1:0] selects the Output-Port Word-Width and controls byte-order-reversal according to
Table 5.
RTMD[1:0]
Retransmit Mode Control.
RTMD[1:0] is synchronized to the rising edge of CKO. RTMD[1:0]
controls the placement of new contents into the Read Pointer (RP) and/or the Retransmit Base
(RBASE) registers. Whenever Retransmit (RT) is asserted, one of three operations is performed
according to the setting of RTMD[1:0]. See Table 6.
NOTES:
1. When RTMD[1:0] is set to 0, the FIFO is in depth cascade mode, and the Retransmit
mechanism can not be used. In cascade mode, the Almost-Empty Flag is a handshake signal for
cascading. The Almost-Empty Flag is used as an input to the ENI of the next FIFO in the chain.
2. In standard FIFO operation RTMD[1:0] must not be set to 0 and the Retransmit signal must be
HIGH.
RT
Retransmit.
RT is synchronized to the rising edge of CKO. When asserted LOW, RT causes one
of the Retransmit Mode operations to be performed, according to the encoding of RTMD[1:0]. See
Table 6.
NOTE
: When RTMD[1:0] = 0 (FIFO is in cascade mode) RT is ignored.
LH543620
1024
×
36 Synchronous FIFO
12