●DESCRIPTION
●The DS1287 Real Time Clock is designed to be a direct replacement for the MC146818A. For a complete
●description of operating conditions, electrical and mechanical characteristics, bus timing, and pin descriptions see the DS12887 data sheet.
●FEATURES
●•Drop-in replacement for IBM AT computer clock/calendar
●•Pin compatible with the MC146818A
●•Totally nonvolatile with over 10 years of operation in the absence of power
●•Self-contained subsystem includes lithium, quartz, and support circuitry
●•Counts seconds, minutes, hours, day of the week, date, month, and year with leap year compensation
●•Binary or BCD representation of time, calendar, and alarm
●•12- 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 64 RAM locations
●– 14 bytes of clock and control registers
●– 50 bytes of general purpose RAM
●•Programmable square wave output signal
●•Bus-compatible interrupt signals (IRQ)
●•Three interrupts are separately software-maskable and testable
●– Time-of-day alarm once/second to once/day
●– Periodic rates from 122 µs to 500 ms
●– End of clock update cycle
