DS1243Y
64K NV SRAM with Phantom Clock
www.dalsemi.com
FEATURES
§
Real time clock keeps track of hundredths of
seconds, seconds, minutes, hours, days, date
of the month, months, and years
§
8K x 8 NV SRAM directly replaces volatile
static RAM or EEPROM
§
Embedded lithium energy cell maintains
calendar operation and retains RAM data
§
Watch function is transparent to RAM
operation
§
Month and year determine the number of days
in each month; valid up to 2100
§
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
§
Standard 28–pin JEDEC pinout
§
Full ±10% operating range
§
Operating temperature range 0°C to 70°C
§
Accuracy is better than ±1 minute/month @
25°C
§
Over 10 years of data retention in the absence
of power
§
Available in 120, 150 and 200 ns access time
PIN ASSIGNMENT
RST
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
V
CC
WE
NC
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
28-Pin Encapsulated Package
720-Mil Extended
PIN DESCRIPTION
A
0
–A
12
CE
GND
DQ
0
–DQ
7
V
CC
WE
OE
ORDERING INFORMATION
DS1243Y–XXX
–120 120 ns access
–150 150 ns access
200 ns access
NC
RST
– Address Inputs
– Chip Enable
– Ground
– Data In/Data Out
– Power (+5V)
– Write Enable
– Output Enable
– No Connect
– Reset
DS1243Y
DESCRIPTION
The DS1243Y 64K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 8192
words by 8 bits) with a built–in real time clock. The DS1243Y has a self–contained lithium energy source
and control circuitry which constantly monitors V
CC
for an out–of–tolerance condition. When such a
condition occurs, the lithium energy source is automatically switched on and write protection is
unconditionally enabled to prevent corrupted data in both the memory and real time clock.
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080299
DALLAS [ DALLAS SEMICONDUCTOR ]
