DS1386

The DS1386 is a nonvolatile static RAM with a full-function real-time clock (RTC), alarm, watchdog timer, and interval timer that are all accessible in a byte-wide format. The DS1386 contains a lithium energy source and a quartz crystal, which eliminates the need for any external circuitry. Data contained within 8k or 32k by 8-bit memory and the timekeeping registers can be read or written in the same manner as byte-wide static RAM. The timekeeping registers are located in the first 14 bytes of memory space. Data is maintained in the RAMified timekeeper by intelligent control circuitry, which detects the status of V_CC and write protects memory when V_CC is out of tolerance. The lithium energy source can maintain data and real time for over ten years in the absence of V_CC. Timekeeper information includes hundredths of seconds, seconds, minutes, hours, day, date, month, and year. The date at the end of the month is automatically adjusted for months with less than 31 days, including correction for leap year.

The RAMified timekeeper operates in either 24-hour or 12-hour format with an AM/PM indicator. The watchdog timer provides alarm interrupts and interval timing between 0.01 seconds and 99.99 seconds. The real-time alarm provides for preset times of up to one week. Interrupts for both watchdog and RTC operate when the system is powered down. Either can provide system "wakeup" signals.