1CY7C402
CY7C401/CY7C403
CY7C402/CY7C404
64 x 4 Cascadable FIFO
64 x 5 Cascadable FIFO
words. Both the CY7C403 and CY7C404 have an output en-
able (OE) function.
Features
• 64 x 4 (CY7C401 and CY7C403)
64 x 5 (CY7C402 and CY7C404)
The devices accept 4- or 5-bit words at the data input (DI –
0
DI ) under the control of the shift in (SI) input. The stored
n
High-speed first-in first-out memory (FIFO)
words stack up at the output (DO – DO ) in the order they
0
n
• Processed with high-speed CMOS for optimum
speed/power
• 25-MHz data rates
• 50-ns bubble-through time—25 MHz
• Expandable in word width and/or length
• 5-volt power supply ± 10% tolerance, both commercial
and military
• Independent asynchronous inputs and outputs
• TTL-compatible interface
• Output enable function available on CY7C403 and
CY7C404
were entered. A read command on the shift out (SO) input
causes the next to last word to move to the output and all data
shifts down once in the stack. The input ready (IR) signal acts
as a flag to indicate when the input is ready to accept new data
(HIGH), to indicate when the FIFO is full (LOW), and to provide
a signal for a cascading. The output ready (OR) signal is a flag
to indicate the output contains valid data (HIGH), to indicate
the FIFO is empty (LOW), and to provide a signal for cascad-
ing.
Parallel expansion for wider words is accomplished by logical-
ly ANDing the IR and OR signals to form composite signals.
Serial expansion is accomplished by tying the data inputs of
one device to the data outputs of the previous device. The IR
pin of the receiving device is connected to the SO pin of the
sending device, and the OR pin of the sending device is con-
nected to the SI pin of the receiving device.
• Capable of withstanding greater than 2001V electro-
static discharge
• Pin compatible with MMI 67401A/67402A
Functional Description
Reading and writing operations are completely asynchronous,
allowing the FIFO to be used as a buffer between two digital
machines of widely differing operating frequencies. The
25-MHz operation makes these FIFOs ideal for high-speed
communication and controller applications.
The CY7C401 and CY7C403 are asynchronous first-in
first-out (FIFOs) organized as 64 four-bit words. The CY7C402
and CY7C404 are similar FIFOs organized as 64 five-bit
Logic Block Diagram
Pin Configurations
DIP
DIP
(CY7C401) NC
(CY7C403) OE
IR
(CY7C402) NC
(CY7C404) OE
IR
SI
V
V
CC
1
2
3
4
5
6
7
8
16
15
14
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
CC
INPUT
SO
OR
DO
DO
SO
OR
DO
DO
DO
DO
DO
MR
CONTROL
WRITE POINTER
SI
SI
LOGIC
IR
CY7C402
CY7C404
CY7C401
DI
DI
13
CY7C403
12
0
0
OUTPUT
0
1
0
1
OE
DO
WRITE MULTIPLEXER
ENABLE
DI
1
DI
1
DI
DI
11 DO
2
2
2
3
2
3
4
DI
DI
DI
DI
0
1
2
3
10
9
DI
3
GND
DI
3
DI
4
GND
DO
MR
0
DATAIN
C401–2
MEMORY
ARRAY
DO
1
C401–4
DO
2
DATAIN
LCC
LCC
(DI
)
4
DO
3
(DO )
4
READ MULTIPLEXER
READ POINTER
MASTER
RESET
3 2 1 2019
18
3 2 1 2019
18
MR
OR
DO
DO
DO
NC
4
4
SI
SI
0
1
SO
OR
5
17 OR
16 DO
15 DO
5
6
7
8
17
16
15
14
0
1
2
DI
DI
DI
DI
DI
DI
DI
OUTPUT
CONTROL
LOGIC
0
1
2
CY7C401
CY7C403
CY7C402
CY7C404
6
7
8
0
1
2
2
3
NC
14
DO
DO
3
910111213
910111213
C401–1
C401–3
C401–5
Selection Guide
7C401/2–5
7C40X–10
7C40X–15
7C40X–25
Operating Frequency (MHz)
5
10
75
90
15
75
90
25
75
90
Maximum Operating
Current (mA)
Commercial
Military
75
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
March 1986 – Revised April 1995
•
408-943-2600