12C887

DS12C887 Real Time Clock www.dalsemi.com FEATURES Drop-in replacement for IBM AT computer clock/calendar Pin compatible with the MC146818B and DS1287 www.DataSheet4U.com 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 valid up to 2100 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 128 RAM locations – 15 bytes of clock and control registers – 113 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 ms to 500 ms – End of clock update cycle Century register PIN ASSIGNMENT MOT NC NC AD0 AD1 AD2 AD3 AD4 AD5 AD6 AD7 GND 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 VCC SQW NC NC NC IRQ RESET DS NC R/W AS CS DS12C887 24-Pin ENCAPSULATED PACKAGE PIN DESCRIPTION AD0-AD7 - Multiplexed Address/Data Bus NC - No Connect MOT - Bus Type Selection CS - RTC Chip Select Input AS - Address Strobe - Read/Write Input R/ W DS - Data Strobe RESET - Reset Input IRQ - Interrupt Request Output SQ...