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 122μs 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