DS12CR887

Rev 2; 12/04 RTC with Constant-Voltage Trickle Charger General Description The DS12R885 is a functional drop-in replacement for the DS12885 real-time clock (RTC). The device provides an RTC/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of batterybacked static RAM. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. It also operates 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. The VBACKUP pin supports a rechargeable battery or a super cap and includes an integrated, always enabled trickle charger. The DS12R885 is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes. The DS12CR887 and DS12R887 integrate the DS12R885 die with a crystal and battery. Features ♦ Trickle-Charge Capability for a Rechargeable Battery or Super Cap ♦ Selectable Intel or Motorola Bus Timing ♦ RTC Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap-Year Compensation to 2100 ♦ Interrupt Output with Three Independently Maskable Interrupt Flags ♦ Time-of-Day Alarm is Once-per-Second to Onceper-Day ♦ Periodic Rates from 122µs to 500ms ♦ End-of-Clock Update Cycle Flag ♦ 14 Bytes of Clock and Control Regist...