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 VBAT 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 VCC and write protects memory when VCC is out of tolerance. The lithium

FEATURES

ƒ Keeps Track of Hundredths of Seconds, Seconds, Minutes, Hours, Days, Date of the Month, Months, and Years; Valid Leap Year Compensation Up to 2100

ƒ Watchdog Timer Restarts an Out-of-Control Processor

ƒ Alarm Function Schedules Real-Time-Related Activities

ƒ Embedded Lithium Energy Cell Maintains Time, Watchdog, User RAM, and Alarm Information

ƒ Programmable Interrupts and Square-Wave Outputs Maintain JEDEC Footprint

ƒ All Registers are Individually Addressable via the Address and Data Bus

ƒ Accuracy is Better than ±1 Minute/Month at +25°C (EDIP)

ƒ Greater than 10 Years of Timekeeping in the Absence of VCC

ƒ 50 Bytes of User NV RAM

ƒ Underwriters Laboratory (UL) Recognized

ƒ -40°C to +85°C Industrial Temperature Range Option