DS1284/DS1286
Watchdog Timekeepers
www.maxim-ic.com
GENERAL DESCRIPTION
The DS1284/DS1286 watchdog timekeepers are
self-contained real-time clocks, alarms, watchdog
timers, and interval timers in a 28-pin JEDEC DIP
and encapsulated DIP package. The DS1286
contains an embedded lithium energy source and a
quartz crystal, which eliminates the need for any
external circuitry. The DS1284 requires an external
quartz crystal and a V
BAT
source, which could be a
lithium battery. Data contained within 64 8-bit
registers can be read or written in the same manner
as byte-wide static RAM. Data is maintained in the
watchdog timekeeper by intelligent control circuitry
that detects the status of V
CC
and write protects
memory when V
CC
is out of tolerance. The lithium
energy source can maintain data and real time for
over 10 years in the absence of V
CC
. Watchdog
timekeeper information includes hundredths of
seconds, seconds, minutes, hours, day, date, month,
and year. The date at the end of the month is
automatically adjusted for months with fewer than
31 days, including correction for leap year. The
DS1284/DS1286 operate in either 24-hour or 12-
hour format with an AM/PM indicator. The devices
provide alarm windows and interval timing between
0.01 seconds and 99.99 seconds. The real-time
alarm provides for preset times of up to one week.
FEATURES
Keeps Track of Hundredths of Seconds,
Seconds, Minutes, Hours, Days, Date of the
Month, Months, and Years; Valid Leap Year
Compensation Up to 2100
Watchdog Timer Restarts an Out-of-Control
Processor
Alarm Function Schedules Real-Time-Related
Activities
Embedded Lithium Energy Cell Maintains
Time, Watchdog, User RAM, and Alarm
Information
Programmable Interrupts and Square-Wave
Outputs Maintain JEDEC Footprint
All Registers are Individually Addressable via
the Address and Data Bus
Accuracy is Better than ±1 Minute/Month at
+25°C (EDIP)
Greater than 10 Years of Timekeeping in the
Absence of V
CC
50 Bytes of User NV RAM
Underwriters Laboratory (UL) Recognized
-40°C to +85°C Industrial Temperature Range
Option
Pin Configurations appear at end of data sheet.
ORDERING INFORMATION
PART
TEMP RANGE
0°C to +70°C
DS1284
-40°C to +85°C
DS1284N
0°C to +70°C
DS1284Q
0°C to +70°C
DS1284Q+
0°C to +70°C
DS1284Q/T&R
0°C to +70°C
DS1284Q+T&R
-40°C to +85°C
DS1284QN
-40°C to +85°C
DS1284QN+
-40°C to +85°C
DS1284QN/T&R
-40°C to +85°C
DS1284QN+T&R
0°C to +70°C
DS1286
-40°C to +85°C
DS1286I
-40°C to +85°C
DS1286I+
+
Denotes a lead-free/RoHS-compliant package.
VOLTAGE (V)
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
5.0
PIN-PACKAGE
28 DIP (600 mils)
28 DIP (600 mils)
28 PLCC
28 PLCC
28 PLCC/Tape and Reel
28 PLCC/Tape and Reel
28 PLCC
28 PLCC
28 PLCC/Tape and Reel
28 PLCC/Tape and Reel
28 EDIP (720 mils)
28 EDIP (720 mils)
28 EDIP (720 mils)
TOP MARK*
DS1284
DS1284 N
DS1284Q
DS1284Q
DS1284Q
DS1284Q
DS1284QN
DS1284QN
DS1284QN
DS1284QN
DS1286
DS1286 IND
DS1286 IND
* A “+” anywhere on the top mark indicates a lead-free package.
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REV: 032406
DALLAS [ DALLAS SEMICONDUCTOR ]
