PRELIMINARY
DS1244/DS1244P
256K NV SRAM with Phantom Clock
www.dalsemi.com
FEATURES
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PIN ASSIGNMENT
Real time clock keeps track of hundredths of
seconds, minutes, hours, days, date of the
month, months, and years
32K 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
=Full 10% operating range
=Operating temperature range 0°C to 70°C
Over 10 years of data retention in the
absence of power
Lithium energy source is electrically
disconnected to retain freshness until power
is applied for the first time
DIP Module only
– Standard 28–pin JEDEC pinout
PowerCap Module Board only
– Surface mountable package for direct
connection to PowerCap containing battery
and crystal
– Replaceable battery (PowerCap)
– Pin for pin compatible with DS1248P and
DS1251P
A14/RST
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
1
2
3
4
5
6
7
8
9
10
11
12
28
27
26
25
24
23
22
21
20
19
18
17
VCC
DQ2
13
16
DQ4
DQ3
14
15
DQ3
WE
A13
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
28-Pin Encapsulated Package
740-Mil Extended
NC
A15
A16
RST
VCC
WE
OE
CE
DQ7
DQ6
DQ5
DQ4
DQ3
DQ2
DQ1
DQ0
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
X1
GND VBAT
X2
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
NC
NC
A14
A13
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
34-PIN POWERCAP MODULE BOARD
(USES DS9034PCX POWERCAP)
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012500