DS12B887

DS12B887 DS12B887 Real Time Clock FEATURES www.DataSheet4U.com PIN ASSIGNMENT NC 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 RCLR NC IRQ NC DS NC R/W AS CS Drop-in replacement for IBM AT computer clock/calendar Pin compatible with the MC146818B and DS1287 Totally nonvolatile with over 10 years of operation in the absence of power Self-contained Counts subsystem includes lithium, quartz, and support circuitry seconds, minutes, hours, days, 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 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 24 PIN ENCAPSULATED PACKAGE PIN DESCRIPTION AD0-AD7 NC CS AS R/W DS IRQ SQW VCC GND RCLR – – – – – – – – – – – Multiplexed Address/Data Bus No Connection Chip Select Address Strobe Read/Write Input Data Strobe Interrupt Request Output Square Wave Output +5 Volt Supply Ground RAM Clear 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 DESCRIPTION The DS12B887 Real Time Clock plus R...