COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
IDT72V261LA/72V271LA
3.3 VOLT CMOS SuperSync FIFO™ 16,384 x 9 and 32,768 x 9
24
NOTES:
1. Use an AND gate in IDT Standard mode, an OR gate in FWFT mode.
2. Do not connect any output control signals directly together.
3. FIFO #1 and FIFO #2 must be the same depth, but may be different word widths.
WRITE CLOCK (WCLK)
m + n m n
MASTER RESET (MRS)
READ CLOCK (RCLK)
DATA OUT
n
m + n
WRITE ENABLE (WEN)
FULL FLAG/INPUT READY (FF/IR)
PROGRAMMABLE (PAF)
PROGRAMMABLE (PAE)
EMPTY FLAG/OUTPUT READY (EF/OR) #2
OUTPUT ENABLE (OE)
READ ENABLE (REN)
m
LOAD (LD)
IDT
72V261LA
72V271LA
EMPTY FLAG/OUTPUT READY (EF/OR) #1
PARTIAL RESET (PRS)
IDT
72V261LA
72V271LA
4673 drw 22
FULL FLAG/INPUT READY (FF/IR) #2
HALF-FULL FLAG (HF)
FIRST WORD FALL THROUGH/
SERIAL INPUT (FWFT/SI)
RETRANSMIT (RT)
#1
FIFO
#2
GATE
(1)
GATE
(1)
D
0
- Dm
DATA IN
Dm
+1
- Dn
Q
0
- Qm
Qm
+1
- Qn
FIFO
#1
OPTIONAL CONFIGURATIONS
WIDTH EXPANSION CONFIGURATION
Word width may be increased simply by connecting together the
control signals of multiple devices. Status flags can be detected from
any one device. The exceptions are the EF and FF functions in IDT
Standard mode and the IR and OR functions in FWFT mode. Because
of variations in skew between RCLK and WCLK, it is possible for EF/FF
deassertion and IR/OR assertion to vary by one cycle between FIFOs.
In IDT Standard mode, such problems can be avoided by creating
Figure 19. Block Diagram of 16,384 x 18 and 32,768 x 18 Width Expansion
composite flags, that is, ANDing EF of every FIFO, and separately
ANDing FF of every FIFO. In FWFT mode, composite flags can be
created by ORing OR of every FIFO, and separately ORing IR of every
FIFO.
Figure 21 demonstrates a width expansion using two IDT72V261LA/
72V271LA devices. D0 - D8 from each device form a 18-bit wide input
bus and Q0-Q8 from each device form a 18-bit wide output bus. Any
word width can be attained by adding additional IDT72V261LA/72V271LA
devices.
