Watchdog Timekeepers

Part Number	Status	Replacement	Explanation
DS1284	This product is No Longer Available. See Ordering Information for recommended replacements.	DS1501	There is no direct replacement. The DS1501 offers similar features, but has no hundredth second.
DS1286	This product is No Longer Available. See Ordering Information for recommended replacements.	DS1511	There is no direct replacement. The DS1511 offers similar features, but has no hundredth second.

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.

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