19-5058; Rev 5/10
DS1643/DS1643P
Nonvolatile Timekeeping RAMs
www.maxim-ic.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 Reside in the
Eight Top RAM Locations.
Totally Nonvolatile with Over 10 Years of
Operation in the Absence of Power
Access Times of 85ns and 100ns
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
UL Recognized
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 CONFIGURATIONS
TOP VIEW
N.C.
A12
A7
A6
A5
A4
A3
A2
A1
A0
DQ0
DQ1
DQ2
GND
1
28
27
2
DS1643
26
3
4
25
5
24
6
23
7
22
8
21
9
20
10
19
11
18
12
17
13
14
16
15
V
CC
WE
CE2
A8
A9
A11
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
Encapsulated DIP
(700-mil Extended)
N.C.
N.C.
N.C.
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
DS1643P
X1
GND V
BAT
X2
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
N.C.
N.C.
N.C.
N.C.
A12
A11
A10
A9
A8
A7
A6
A5
A4
A3
A2
A1
A0
PowerCap Module Board
(Uses DS9034PCX PowerCap)
ORDERING INFORMATION
PART
DS1643-85+
DS1643-100+
DS1643P-85+
DS1643P-100+
VOLTAGE RANGE
(V)
5.0
5.0
5.0
5.0
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
PIN-PACKAGE
28 EDIP (0.740)
28 EDIP (0.740)
34-PowerCap*
34-PowerCap*
TOP MARK
DS1643+85
DS1643+100
DS1643P+85
DS1643P+100
*
DS9034I-PCX+ and DS9034-PCX+ required (must be ordered separately).
+Denotes a lead(Pb)-free/RoHS-compliant package. The top mark will include a “+” symbol on lead-free devices.
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