DESCRIPTION
The DS1642 is a 2k x 8 nonvolatile static RAM and a full-function real-time clock (RTC), both of which are accessible in a bytewide format. The nonvolatile time keeping RAM is pin and function equivalent to any JEDEC-standard 2k x 8 SRAM. The device can also be easily substituted in ROM, EPROM, and EEPROM sockets, providing read/write nonvolatility and the addition of the real-time clock function. The real-time clock information resides in the eight uppermost RAM locations.

FEATURES
● Integrated NV SRAM, Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source
● Standard JEDEC Bytewide 2k x 8 Static RAM Pinout
● Clock Registers are Accessed Identically to the Static RAM. These Registers are Resident in the Eight Top RAM Locations
● Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
● Access Times of 85ns and 100ns
● Quartz Accuracy ±1 Minute a Month at +25°C, Factory Calibrated
● BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Leap Year Compensation Valid Up to 2100
● 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
● UL Recognized