21
COMMERCIAL TEMPERATURE RANGE
IDT72V3686/72V3696/72V36106 3.3V CMOS TRIPLE BUS SyncFIFO
TM
WITH BUS-MATCHING 16,384 x 36 x 2, 32,768 x 36 x 2, 65, 536 x 36
Figure 9. Serial Programming of the Almost-Full Flag and Almost-Empty Flag Offset Values after Reset (IDT Standard and FWFT Modes)
NOTES:
1. tSKEW1 is the minimum time between the rising CLKA edge and a rising CLKC edge for FFC/IRC to transition HIGH in the next cycle. If the time between the rising edge of CLKA and rising
edge of CLKC is less than tSKEW1, then FFC/IRC may transition HIGH one CLKC cycle later than shown.
2. It is not necessary to program Offset register bits on consecutive clock cycles. FIFO write attempts are ignored until FFA/IRA, FFC/IRC is set HIGH.
3. Programmable offsets are written serially to the SD input in the order AFA offset (Y1), AEB offset (X1), AFC offset (Y2), and AEA offset (X2).
NOTES:
1. tSKEW1 is the minimum time between the rising CLKA edge and a rising CLKC edge for FFC/IRC to transition HIGH in the next cycle. If the time between the rising edge of CLKA and rising
edge of CLKC is less than tSKEW1, then FFC/IRC may transition HIGH one CLKC cycle later than shown.
2. CSA = LOW, W/RA = HIGH, MBA = LOW. It is not necessary to program Offset register on consecutive clock cycles.
Figure 8. Parallel Programming of the Almost-Full Flag and Almost-Empty Flag Offset Values after Reset (IDT Standard and FWFT Modes)
4676 drw10
CLKA
MRS1,
MRS2
FFA/IRA
CLKC
FFC/IRC
A0-A35
FS1,FS0
ENA
t
FSH
t
WFF
t
ENH
t
ENS2
t
SKEW1
t
DS
t
DH
t
WFF
4
0,0
AFA Offset
(Y1)
AEB Offset
(X1)
AFC Offset
(Y2)
AEA Offset
(X2)
First Word to FIFO1
1
2
(1)
t
FSH
t
FSS
t
FSS
FS2
CLKA
FFA/IRA
t
SENS
t
SENH
FS0/SD
(3)
t
SPH
t
SENS
t
SENH
t
FSS
t
WFF
FS1/SEN
AEA Offset
(X2) LSB
t
SDS
t
SDH
t
SDS
t
SDH
AFA Offset
(Y1) MSB
MRS1,
MRS2
4
4676 drw11
t
FSS
t
FSH
CLKC
4
FS2
FFC/IRC
t
WFF
t
SKEW
(1)
