BQ4287 Datasheet

Direct clock/calendar replacement for IBM? AT-compatible computers and other applications
Functionally compatible with the DS1287/DS1287A and MC146818A
114 bytes of general nonvolatile storage
Automatic backup supply and write-protection to make external SRAM nonvolatile
Integral lithium cell and crystal
160 ns cycle time allows fast bus operation
Intel bus timing
14 bytes for clock/calendar and control
BCD or binary format for clock and calendar data
Calendar in day of the week, day of the month, months, and years with automatic leap-year adjustment
Time of day in seconds, minutes, and hours - 12- or 24-hour format - Optional daylight saving adjustment
Programmable square wave output
Three individually maskable interrupt event flags: - Periodic rates from 122us to 500ms - Time-of-day alarm once per second to once per day - End-of-clock update cycle
Better than one minute per month clock accuracy

BQ4287