CY7C148_09 Datasheet, PDF (1/9 Pages) Cypress Semiconductor – 1Kx4 Static RAM

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CY7C148
CY7C149
1Kx4 Static RAM
Features
• Automatic power-down when deselected (7C148)
• CMOS for optimum speed/power
• 25-ns access time
• Low active power
— 440 mW (commercial)
— 605 mW (military)
• Low standby power (7C148)
— 82.5 mW (25-ns version)
— 55 mW (all others)
• 5-volt power supply ± 10% tolerance, both commercial
and military
• TTL-compatible inputs and outputs
Functional Description
sion is provided by an active LOW chip select (CS) input and
three-state outputs. The CY7C148 remains in a low-power
mode as long as the device remains unselected; i.e., (CS) is
HIGH, thus reducing the average power requirements of the
device. The chip select (CS) of the CY7C149 does not affect
the power dissipation of the device.
Writing to the device is accomplished when the chip select
(CS) and write enable (WE) inputs are both LOW. Data on the
I/O pins (I/O₀ through I/O₃) is written into the memory loca-
tions specified on the address pins (A₀ through A₉).
Reading the device is accomplished by taking chip select (CS)
LOW while write enable (WE) remains HIGH. Under these
conditions, the contents of the location specified on the
address pins will appear on the four data I/O pins.
The I/O pins remain in a high-impedance state when chip se-
lect (CS) is HIGH or write enable (WE) is LOW.
The CY7C148 and CY7C149 are high-performance CMOS
static RAMs organized as 1024 by 4 bits. Easy memory expan-
Logic Block Diagram
INPUTBUFFER
A₉
A₈
A₇
64 x 64
A₆
ARRAY
A₅
A₄
COLUMN
DECODER
POWER
DOWN
(7C148)
A₃ A₂ A₁ A₀
Pin Configurations
DIP
Top View
A6 ₁
A5 ₂
18 ^VCC
17 ^A7
A4 3
A3 ₄
16 A8
15 A9
A0 ₅
14 I/O 0
A1 ₆
13 ^I/O 1
A2 ₇
12 ^I/O 2
I/O₀
CS ₈
11 ^I/O 3
I/O₁
GND 9
10 WE
I/O₂
LCC
C148–2
Top View
I/O₃
CS
WE
C148–1
2 1 1817
A4 3
16 A8
A13 4
15 A9
A10 5
A11 6
A12 ₇
14 I/O ₀
13 I/O ₁
12 I/O2
8 91011
C148–3
Selection Guide
Maximum Access Time (ns)
Maximum Operating
Current (mA)
Commercial
Military
Maximum Standby
Current (mA)
Commercial
Military
7C148−25
25
90
15
7C148−35
35
80
110
10
10
7C148−45
45
80
110
10
10
7C149−25
25
90
7C149−35
35
80
110
7C149−45
45
80
110
Cypress Semiconductor Corporation • 3901 North First Street • San Jose • CA 95134 • 408-943-2600
Document #: 38-05059 Rev. **
Revised September 18, 2001
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