DS2227 Maxim, DS2227 Datasheet

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DS2227

Manufacturer Part Number
DS2227
Description
The DS2227 combines voltage monitoring circuitry with lithium-backed memory in a flexible architecture that can be accessed as 128k x 32, 256k x 16, or 512k x 8 bits
Manufacturer
Maxim
Datasheet

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FEATURES
DESCRIPTION
The DS2227 Flexible NV SRAM Stik is a self-contained 4,194,304-bit nonvolatile static RAM which can
be flexibly organized as 128k x 32 bits, 256k x 16 bits, or 512k x 8 bits. The nonvolatile memory contains
all necessary control circuitry and lithium energy sources to maintain data integrity in the absence of
power for more than 10 years. The DS2227 employs the popular JEDEC standard 72-position SIMM
connection scheme requiring no additional circuitry.
OPERATION
The DS2227 Flexible NV SRAM Stik is used like any standard static RAM. All nonvolatile circuitry is
transparent to the user. The flexibility of the part is achieved by providing separate read, write, and chip
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Flexibly organized as 128k x 32, 256k x 16,
or 512k x 8 bits
Data retention >10 years in the absence of
V
Nonvolatile circuitry transparent to and
independent from host system
Automatic write protection circuitry
safeguards against data loss
Separate chip enables allow access by byte,
word, or long word
Fast access times: 70 ns, 100 ns, or 120 ns
Unlimited write cycles
Read cycle time equals write cycle time
Employs popular JEDEC standard 72-position
SIMM connection scheme
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
CC
1 of 10
PIN ASSIGNMENT
Flexible NV SRAM Stik
72-Pin SIP STIK
DS2227
112099

DS2227 Summary of contents

Page 1

... The DS2227 employs the popular JEDEC standard 72-position SIMM connection scheme requiring no additional circuitry. OPERATION The DS2227 Flexible NV SRAM Stik is used like any standard static RAM. All nonvolatile circuitry is transparent to the user. The flexibility of the part is achieved by providing separate read, write, and chip Flexible NV SRAM Stik ...

Page 2

... Normal RAM operation can resume after V The DS2227 checks lithium status to warn of potential data loss. Each time that V the DS2227, the battery voltage is checked with a precision comparator. If the battery supply is less than 2.0 volts, the second memory access to the device is inhibited. determined by a three-step process. First, a read cycle is performed to any location in memory, in order to save the contents of that location ...

Page 3

... DS2227 SIGNAL NAME 4-D0 4-D1 4-D2 4-D3 4-D4 4-D5 4-D6 4- GND A10 A11 A12 A13 A14 A15 A16 NC NC ...

Page 4

... SCHEMATIC (1 CELL) Figure DS2227 ...

Page 5

... 2.0 3 4.25 4.37 TP SYMBOL MIN TYP OUT MAX UNITS 5 +0.8 V (0°C to 70° MAX UNITS +1.0 µA +5.0 µ 280 mA 4 MAX UNITS DS2227 NOTES 10%) NOTES = 25°C) NOTES ...

Page 6

... MIN MAX MIN MAX MIN MAX 70 100 70 100 100 100 DS2227-120 UNITS NOTES 120 ns 120 120 120 4,5,10 DS2227 ...

Page 7

... READ CYCLE SEE NOTE 1 WRITE CYCLE 1 SEE NOTES AND 8 WRITE CYCLE 2 SEE NOTES AND DS2227 ...

Page 8

... Slew from after Power- PARAMETER Expected Data Retention SYMBOL MIN TYP 300 REC SYMBOL MIN TYP DS2227 MAX UNITS NOTES µs µs µs 125 25°C) A MAX UNITS NOTES years ...

Page 9

... If the is low or the WE transition, the output buffers remain in a high impedance state in this period. 9. Each DS2227 is marked with a 4-digit date code AABB. AA designates the year of manufacture. BB designates the week of manufacture. The minimum expected t date of manufacture. 10. Timings are valid only when DC TEST CONDITIONS ...

Page 10

... DS2227 72-PIN SIP STIK NOTE: DIMENSIONS ARE SHOWN IN INCHES. DIM DS2227 72-PIN MIN MAX 4.245 4.255 3.979 3.989 0.845 0.855 0.395 0.405 0.245 0.255 0.050 BASIC 0.075 0.085 0.245 0.255 1.750 BASIC ...

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