The DS1500 is a full-function, year 2000-compliant, real-time clock/calendar (RTC) with an alarm, watchdog timer, power-on reset, battery monitors, 256 bytes of on-board nonvolatile (NV) SRAM, NV control for backing up an external SRAM, and a 32.768kHz output. User access to all registers within the DS1500 is accomplished with a byte-wide interface as shown in Figure 7. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for day of month and leap year are made automatically. Applications * Battery-Backed Systems * Consumer Electronics * Office Equipment * Remote Systems * Telecom Switches * BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap-Year Compensation Valid Up to the Year 2100 * Programmable Watchdog Timer and RTC Alarm * Century Register; Y2K-Compliant RTC * Automatic Battery Backup and Write Protection to External SRAM * +5V or +3.3V Operation * Precision Power-On Reset * Power-Control Circuitry Supports System Power-On from Date/Day/Time Alarm or Key Closure * 256 Bytes User NV RAM * Auxiliary Battery Input * Accuracy Better than ±1 Minute/Month at +25°C * Day-of-Week/Date Alarm Register * Battery Voltage-Level Indicator Flags * Optional Industrial Temperature Range: -40°C to +85°C