CY7C4421/4201/4211/4221
CY7C4231/4241/4251
64/256/512/1K/2K/4K/8K x 9 Synchronous FIFOs
Features
Functional Description
• High-speed, low-power, First-In, First-Out (FIFO)
memories
The CY7C42X1 are high-speed, low-power FIFO memories
with clocked Read and Write interfaces. All are 9 bits wide. The
CY7C42X1 are pin-compatible to IDT722X1. Programmable
features include Almost Full/Almost Empty flags. These FIFOs
provide solutions for a wide variety of data buffering needs,
including high-speed data acquisition, multiprocessor inter-
faces, and communications buffering.
— 64 × 9 (CY7C4421)
— 256 × 9 (CY7C4201)
— 512 × 9 (CY7C4211)
— 1K × 9 (CY7C4221)
— 2K × 9 (CY7C4231)
— 4K × 9 (CY7C4241)
— 8K × 9 (CY7C4251)
These FIFOs have 9-bit input and output ports that are
controlled by separate clock and enable signals. The input port
is controlled by a free-running clock (WCLK) and two
Write-enable pins (WEN1, WEN2/LD).
• High-speed 100-MHz operation (10 ns Read/Write cycle
time)
• Low power (ICC = 35 mA)
• Fully asynchronous and simultaneous Read and Write
operation
• Empty, Full, and Programmable Almost Empty and
Almost Full status flags
• TTL-compatible
• Expandable in width
• Output Enable (OE) pin
• Independent Read and Write enable pins
• Center power and ground pins for reduced noise
• Width-expansion capability
• Space saving 7 mm × 7 mm 32-pin TQFP
• 32-pin PLCC
When WEN1 is LOW and WEN2/LD is HIGH, data is written
into the FIFO on the rising edge of the WCLK signal. While
WEN1, WEN2/LD is held active, data is continually written into
the FIFO on each WCLK cycle. The output port is controlled in
a similar manner by a free-running Read clock (RCLK) and two
Read-enable pins (REN1, REN2). In addition, the CY7C42X1
has an output enable pin (OE). The Read (RCLK) and Write
(WCLK) clocks may be tied together for single-clock operation
or the two clocks may be run independently for asynchronous
Read/Write applications. Clock frequencies up to 100 MHz are
achievable.
Depth expansion is possible using one enable input for system
control, while the other enable is controlled by expansion logic
to direct the flow of data.
• Pin-compatible and functionally equivalent to
IDT72421, 72201, 72211, 72221, 72231, and 72241
D
0- 8
Logic Block Diagram
Pin Configuration
PLCC
Top View
INPUT
REGISTER
4
3
2
1 323130
29
28
D
RS
WEN1
1
5
6
7
8
9
D
0
WCLK WEN1 WEN2/LD
PAF
PAE
27 WCLK
26
25
24
23
22
21
WEN2/LD
FLAG
PROGRAM
REGISTER
GND
REN1
RCLK
REN2
OE
V
CC
Q
Q
Q
Q
10
11
12
13
8
7
6
5
Write
CONTROL
EF
14151617181920
PAE
PAF
FF
FLAG
LOGIC
Dual Port
RAM Array
64 x 9
TQFP
Top View
Write
POINTER
Read
POINTER
32 31 30 29 28 27 26 25
8k x 9
1
2
3
4
5
6
7
8
24
WEN1
D
D
1
0
23
WCLK
WEN2/LD
22
21
20
19
PAF
PAE
RESET
LOGIC
RS
V
CC
Q
Q
GND
8
7
REN1
RCLK
REN2
Q
6
Q
5
THREE-STATE
OUTPUTREGISTER
18
17
Read
CONTROL
9 10 11 1213 14 15 16
OE
Q
0- 8
RCLK REN1 REN2
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
Document #: 38-06016 Rev. *A
Revised March 6, 2202