DESCRIPTION

The DS12885 real-time clock plus RAM is designed to be a direct replacement for the DS1285. The DS12885 is identical in form, fit, and function to the DS1285, and has an additional 64 bytes of general purpose RAM. Access to this additional RAM space is determined by the logic level presented on AD6 during the address portion of an access cycle.

FEATURES

■ Drop-in replacement for IBM AT computer clock/calendar

■ Pin configuration closely matches MC146818B and DS1285

■ Counts seconds, minutes, hours, days, day of the week, date, month, and year with leapyear compensation valid up to 2100

■ Binary or BCD representation of time, calendar, and alarm

■ 12-hour or 24-hour clock with AM and PM in 12-hour mode

■ Daylight Savings Time option

■ Selectable between Motorola and Intel bus timing

■ Multiplex bus for pin efficiency

■ Interfaced with software as 128 RAM locations

■ 14 bytes of clock and control registers

■ 114 bytes of general purpose RAM

■ Programmable square-wave output signal bus-compatible interrupt signals (IRQ )

■ Three interrupts are separately softwaremaskable and testable

■ Time-of-day alarm once/second to once/day

■ Periodic rates from 122ms to 500ms

■ End-of-clock update cycle

■ Optional 28-pin PLCC surface mount package or 32-pin TQFP

■ Optional industrial temperature range available

■ Underwriters Laboratory (UL) recognized