DESCRIPTION

The DS1743 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 8k x 8 nonvolatile static RAM. User access to all registers within the DS1743 is accomplished with a bytewide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for the day of the month and leap year are made automatically. The RTC clock registers are double buffered to avoid access of incorrect data that can occur during clock update cycles.

FEATURES

■ Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source

■ Clock Registers are Accessed Identically to the Static RAM. These Registers Reside in the Eight Top RAM Locations.

■ Century Byte Register

■ Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power

■ BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds with Automatic Leap Year Compensation Valid through 2099

■ Low-Battery-Voltage Level Indicator Flag

■ Power-Fail Write Protection Allows for ±10 VCC Power-Supply Tolerance

■ Lithium Energy Source is Electrically Disconnected to Retain Freshness Until Power is Applied for the First Time

■ DIP Module Only Standard JEDEC Bytewide 8k x 8 Static RAM Pinout

■ PowerCap Module Board Only

??? Surface-Mountable Package for Direct

??????? Connection to PowerCap Containing

??????? Battery and Crystal

??? Replaceable Battery (PowerCap)

??? Power-On Reset Output

??? Pin-for-Pin Compatible with Other Densities

??????? of DS174XP Timekeeping RAM

■ Underwriters Laboratories (UL) Recognized to Prevent Charging of the Internal Lithium Battery