DS1642 Datasheet, PDF (1/13 Pages) Dallas Semiconductor – Nonvolatile Timekeeping RAM

19-5266; Rev 5/10
DS1642
Nonvolatile Timekeeping RAM
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FEATURES
 Integrated NV SRAM, Real-Time Clock,
Crystal, Power-Fail Control Circuit, and
Lithium Energy Source
 Standard JEDEC Bytewide 2k x 8 Static
RAM Pinout
 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 85ns and 100ns
 Quartz Accuracy ±1 Minute a Month at
+25°C, Factory Calibrated
 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
 UL Recognized
PIN CONFIGURATION
TOP VIEW
A7 1
24
A6 2 ^DS1642 23
A5 3
22
A4 4
21
A3 5
20
A2 6
19
A1 7
18
A0 8
17
DQ0 9
16
DQ1 10
15
DQ2 11
14
GND 12
13
V_CC
A8
A9
WE
OE
A10
CE
DQ7
DQ6
DQ5
DQ4
DQ3
ENCAPSULATED DIP
ORDERING INFORMATION
VOLTAGE
PART
RANGE TEMP RANGE
(V)
DS1642-85+
5.0
0°C to +70°C
DS1642-100+
5.0
0°C to +70°C
PIN-PACKAGE TOP MARK
24 EDIP (0.720a) DS1642+85
24 EDIP (0.720a) DS1642+100
+Denotes a lead(Pb)-free/RoHS-compliant package.
A “+" indicates a lead(Pb)-free product. The top mark will include a “+” symbol on lead-free devices.
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