CYM1851 Datasheet, PDF(1/9 Page) Cypress Semiconductor

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CYM1851 Datasheet, PDF (1/9 Pages) Cypress Semiconductor – 1,024K x 32 Static RAM Module

CYM1851

1,024K x 32 Static RAM Module

Features

â¢ High-density 32-megabit SRAM module

â¢ 32-bit Standard Footprint supports densities from 16K

x 32 through 1M x 32

â¢ High-speed SRAMs

â Access time of 12 ns

â¢ Low active power

â 8.36W (max.) at 12 ns

â¢ 72 pins

â¢ Available in ZIP, SIMM, or angled SIMM format

Functional Description

The CYM1851 is a high-performance 32-megabit static RAM

module organized as 1,024K words by 32 bits. This module is

constructed from eight 1,024K x 4 SRAMs in SOJ packages

mounted on an epoxy laminate substrate. Four chip selects are

used to independently enable the four bytes. Reading or writ-

ing can be executed on individual bytes or any combination of

multiple bytes through proper use of selects.

The CYM1851 is designed for use with standard 72-pin SIMM

sockets. The pinout is downward compatible with the 64-pin

JEDEC ZIP/SIMM module family (CYM1821, CYM1831,

CYM1836, and CYM1841). Thus, a single motherboard de-

sign can be used to accommodate memory depth ranging from

16K words (CYM1821) to 1,024K words (CYM1851). The

CYM1851 is offered in vertical and angled SIMM configura-

tions and both are available with either tin-lead or 10 mi-

cro-inches of gold flash on the edge contacts.

Presence detect pins (PD0âPD3) are used to identify module

memory density in applications where modules with alternate

word depths can be interchanged.

Logic Block Diagram

A0 âA19

CS1

CS2

CS3

CS4

1M x 4

SRAM 4

I/O0â I/O3

1M x 4

SRAM 4

I/O8â I/O11

1M x 4

SRAM 4

I/O16â I/O19

1M x 4

SRAM 4

I/O24â I/O27

Pin Configuration

PD0 - GND

PD1 - OPEN

PD2 - GND

PD3 - OPEN

1M x 4

SRAM

I/O4â I/O7

1M x 4

SRAM

I/O12â I/O15

1M x 4

SRAM

I/O20â I/O23

1M x 4

SRAM

I/O28â I/O31

ZIP/SIMM

Top View

PD3

PD0

I/O0

I/O1

I/O2

I/O3

VCC

AA78

I/O4

I/O5

I/O6

I/O7

A14

CS1

CS3

A16

GND

I/O16

I/O17

I/O18

I/O19

A10

A11

A12

A13

I/O20

I/O21

I/O22

I/O23

GND

A19

10 11

12 13

14 15

16 17

18 19

20 21

22 23

24 25

26 27

28 29

30 31

34 35

38 39

40 41

42 43

44 45

46 47

48 49

50 51

52 53

54 55

56 57

58 59

60 61

62 63

64 65

66 67

68 69

70 71

PD2

GND

PD1

I/O8

I/O9

I/O10

I/O11

I/O12

I/O13

I/O14

I/O15

GND

A15

CS2

CS4

A17

I/O24

I/O25

I/O26

I/O27

VCC

I/O28

I/O29

I/O30

I/O31

A18

Cypress Semiconductor Corporation â¢ 3901 North First Street â¢ San Jose â¢ CA 95134 â¢ 408-943-2600

Document #: 38-05274 Rev. **

Revised March 15, 2002

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