VT82887

www.DataSheet4U.com VT82887 VIA Technologies, Inc. Real Time Clock FEATURES Drop-in replacement for IBM AT computer clock/calendar. Pin configuration closely matches the DS12887 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, days, 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 12hour mode Daylight Savings Time option 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 - Times-of-day alarm once/second to once/day - Periodic rates from 122 µs to 500 ms - End of clock update cycle DESCRIPTION The VT82887 Real Time Clock is designed to be a direct replacement for the DS12887. The VT82887 is identical in form, fit and function to the DS12887. It has 114 bytes of general purpose RAM. Access to this RAM space is OPERATION determined by the logic level presented on AD6 during the address portion of an access cycle. An external crystal and battery are the only components required to maintain time-ofday and memory status in the absence of power. A compl...