1CYM1821
fax id: 2010
CYM1821
16K x 32 Static RAM Module
constructed from eight 16K x 4 SRAM SOJ packages mount-
ed on an epoxy laminate board with pins. Four chip selects
Features
• High-density 512-Kbit SRAM module
(CS , CS , CS , and CS ) are used to independently enable
1 2 3 4
the four bytes. Reading or writing can be executed on individ-
ual bytes or any combination of multiple bytes through proper
use of selects.
• 32-bit standard footprint supports densities from 16K
x 32 through 1M x 32
• High-speed CMOS SRAMs
— Access time of 12 ns
• Low active power
Writing to each byte is accomplished when the appropriate
chip selects (CS ) and write enable (WE) inputs are both
N
LOW. Data on the input/output pins (I/O ) is written into the
X
— 4W (max.)
memory location specified on the address pins (A through
0
A
).
• SMD technology
13
• TTL-compatible inputs and outputs
• Low profile
Reading the device is accomplished by taking the chip selects
(CS ) LOW, while write enable (WE) remains HIGH. Under
N
these conditions the contents of the memory location specified
on the address pins will appear on the data input/output pins
— Max. height of .50 in.
• Small PCB footprint
— 1.0 sq. in.
(I/O ).The data input/output pins stay in the high-impedance
X
state when write enable (WE) is LOW, or the appropriate chip
selects are HIGH.
• JEDEC-compatible pinout
Two pins (PD and PD ) are used to identify module memory
density in applications where alternate versions of the JEDEC
standard modules can be interchanged.
0
1
Functional Description
The CYM1821 is a high-performance 512-Kbit static RAM
module organized as 16K words by 32 bits. This module is
Logic Block Diagram
Pin Configuration
ZIP
Top View
PD - GND
0
GND
PD1
I/O8
1
3
PD
0
0
I/O
1
PD - OPEN
2
1
I/O
A - A
4
5
0
13
14
6
7
I/O9
OE
I/O
8
9
2
I/O10
I/O11
I/O
3
WE
10
11
12
13
15
16
17
19
20
21
V
A
CC
7
A
0
1
14
A
16K x 4
SRAM
16K x 4
I/O – I/O
0
I/O – I/O
A
8
3
4
7
A
2
SRAM
4
4
4
4
4
4
4
4
18
A
9
I/O
I/O
I/O
I/O
12
13
14
15
I/O
I/O
I/O
I/O
4
5
6
7
CS
1
22
23
24
25
27
28
29
26
GND
NC
CS
2
16K x 4
SRAM
16K x 4
SRAM
I/O – I/O
8
I/O – I/O
WE
NC
CS
1
11
12
15
23
31
30
31
32
33
CS
CS
CS
2
3
4
CS
4
CS
3
34
35
NC
OE
I/O
NC
36
16K x 4
SRAM
16K x 4
SRAM
37
I/O – I/O
16
I/O – I/O
20
19
GND
38
39
24
I/O
I/O
I/O
I/O
A
A
A
16
17
18
19
10
11
12
13
20
21
22
23
40
41
I/O
I/O
I/O
25
26
27
42
43
44
45
46
A
47
3
48
49
16K x 4
SRAM
16K x 4
SRAM
I/O – I/O
28
I/O – I/O
24
A
4
A
5
27
50
51
52
53
V
CC
A
54
55
A
6
I/O
I/O
I/O
I/O
56
57
I/O
I/O
I/O
I/O
28
29
30
31
1821–1
58
59
60
61
62
63
GND
64
1821–2
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
•
CA 95134
•
408-943-2600
November 1988 – Revised January 1995