The DS12887A+ is a Real-time Clock is designed to be direct replacements for the DS1285 and DS1287. The devices provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave and 114 bytes of battery-backed static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12C887 adds a century byte at address 32h. For all devices, the date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The devices also operate in either 24-hour or 12-hour format with an AM/PM indicator. A precision temperature-compensated circuit monitors the status of VCC. If a primary power failure is detected, the device automatically switches to a backup supply. A Lithium coin-cell battery can be connected to the VBAT input pin on the DS12885 to maintain time and date operation when primary power is absent.
● Drop-in replacement for IBM AT computer clock/calendar
● Binary or BCD time representation
● Selectable Intel or Motorola bus timing
● Interfaced with software as 128 RAM locations
● 14 Bytes of clock and control registers
● Interrupt output with three independently maskable interrupt flags
● Time-of-day alarm once per second to once per day
● Periodic rates from 122µs to 500ms
● End-of-clock update cycle flag
● Programmable square-wave output
● Automatic power-fail detect and switch circuitry
