DS1285Q

DS1285/DS1285Q DS1285/DS1285Q Real Time Clock FEATURES www.DataSheet4U.com PIN ASSIGNMENT MOT X1 X2 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 RCLR VBAT IRQ RESET DS GND R/W AS CS Drop-in replacement for IBM AT computer clock/calendar Pin configuration closely matches MC146818A Counts seconds, minutes, hours, day of the week, date, month, and year with leap year compensation alarm Binary or BCD representation of time, calendar, and 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 DS1285 24–PIN DIP VCC SQW MOT NC NC X2 4 AD0 AD1 AD2 AD3 AD4 AD5 NC 5 6 7 8 9 10 X1 3 2 1 28 27 26 25 24 23 22 21 20 RCLR VBAT IRQ RESET DS GND R/W 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 19 11 12 13 14 15 16 17 18 AD6 AD7 GND NC NC CS AS DS1285Q 28-PIN PLCC Optional 28-pin PLCC surface mount package DESCRIPTION The DS1285 Real Time Chip is a direct replacement for the MC146818A in IBM AT computer clock/calendar and other applications. For a complete desc...