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General Description

The DS12885, DS12887, and DS12C887 real-time clocks (RTCs) are designed to be direct replacements for the DS1285 and DS1287. The devices provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of battery backed static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12887 integrates a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package.

Features

? Drop-In Replacement for IBM AT Computer Clock/Calendar

? RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap Year Compensation Through 2099

? Binary or BCD Time Representation

? 12-Hour or 24-Hour Clock with AM and PM in 12-Hour Mode

? Daylight Saving Time Option

? Selectable Intel or Motorola Bus Timing

? Interfaced with Software as 128 RAM Locations

? 14 Bytes of Clock and Control Registers

? 114 Bytes of General-Purpose, Battery-Backed RAM (113 Bytes in the DS12C887 and DS12C887A)

? RAM Clear Function (DS12885, DS12887A, and DS12C887A)

? Interrupt Output with Three Independently Maskable Interrupt Flags

? Time-of-Day Alarm Once Per Second to Once Per Day

? Periodic Rates from 122¦Ìs to 500ms

? End-of-Clock Update Cycle Flag

? Programmable Square-Wave Output

? Automatic Power-Fail Detect and Switch Circuitry

? Optional 28-Pin PLCC Surface Mount Package or 32-Pin TQFP (DS12885)

? Optional Encapsulated DIP (EDIP) Package with Integrated Crystal and Battery (DS12887, DS12887A, DS12C887, DS12C887A)

? Optional Industrial Temperature Range Available

? Underwriters Laboratory (UL) Recognized