DESCRIPTION
The DS1385/DS1387 RAMified Real Time Clocks (RTCs) are upward–compatible successors to the in
dustry standard DS1285/DS1287 RTC’s for PC applications. In addition to the basic DS1285/DS1287 RTC
functions, 4K bytes of on–chip nonvolatile RAM have been added.

FEATURES
•Upgraded IBM AT computer clock/calendar with 4K x 8 extended RAM
•Totally nonvolatile with over 10 years of operation in the absence of power
•Counts seconds, minutes, hours, day of the week, date, month and year with leap year compensation
•Binary or BCD representations of time, calendar and alarm
•12– or 24–hour clock with AM and PM in 12–hour mode
•Daylight Savings Time option
•Multiplex bus for pin efficiency
•Interfaced with software as 64 user RAM locations plus 4K x 8 of static RAM
– 14–bytes of clock and control registers
– 50–bytes of general purpose RAM
– 4K x 8 SRAM accessible by using separate control pins
•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
•Available as chip (DS1385 or DS1385S) or stand alone module with embedded lithium battery and crystal (DS1387)