DESCRIPTION
The DS1558 is a full-function, year 2000-compliant (Y2KC), real-time clock/calendar with an RTC alarm, watchdog timer, power-on reset, battery monitor, and NV SRAM controller. User access to all registers within the DS1558 is accomplished with a byte-wide interface as shown in Figure 1. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for day of month and leap year are made automatically.

FEATURES
■ Integrated Real-Time Clock (RTC), PowerFail Control Circuit, and NV RAM Controller
■ Clock Registers are Accessed Identically to the Static RAM; These Registers are Resident in the 16 Top RAM Locations
■ Century Register
■ Greater than 10 Years of Timekeeping and Data Retention in the Absence of Power with Small Lithium Coin Cell(s) and Low-Leakage SRAM
■ Precision Power-On Reset
■ Programmable Watchdog Timer and RTC Alarm
■ BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic LeapYear Compensation Valid Up to the Year 2100
■ Battery Voltage-Level Indicator Flag
■ Power-Fail Write Protection Allows for ±10% VCC Power-Supply Tolerance
■ Underwriters Laboratory (UL) Recognized