DS1643/DS1643P
Nonvolatile Timekeeping RAM
www.dalsemi.com
FEATURES
Integrated NV SRAM, real time clock,
crystal, power-fail control circuit and lithium
energy source
Clock registers are accessed identically to the
static RAM. These registers are resident in the
eight top RAM locations.
Totally nonvolatile with over 10 years of
operation in the absence of power
Access times of 70 ns and 100 ns
BCD coded year, month, date, day, hours,
minutes, and seconds with leap year
compensation valid up to 2100
Power-fail write protection allows for ±10%
V
CC
power supply tolerance
Lithium energy source is electrically
disconnected to retain freshness until power is
applied for the first time
DS1643 only (DIP Module)
– Standard JEDEC byte-wide 8K x 8 RAM
pinout
DS1643P only (PowerCap Module Board)
– Surface mountable package for direct
connection to PowerCap containing
battery and crystal
– Replaceable battery (PowerCap)
– Power-fail output
– Pin-for-pin compatible with other
densities of DS164XP Timekeeping RAM
PIN ASSIGNMENT
NC
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
VCC
WE
CE2
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
28-PIN Encapsulated Package
(700-mil Extended)
NC
NC
NC
PFO
V
CC
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 V
BAT
X2
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
NC
NC
NC
NC
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
34-PIN PowerCap Module Board
(USES DS9034PCX PowerCap)
ORDERING INFORMATION
DS1643-XXX
28-pin DIP module
-70
70 ns access
-100
100 ns access
34-pin PowerCap Module Board
-70
70 ns access
-100
100 ns access
PowerCap
(Required; must be ordered
separately)
1 of 14
022101
*DS1643P-XXX
*DS9034PCX
DALLAS [ DALLAS SEMICONDUCTOR ]
