DESCRIPTION
The DS1643 is an 8K x 8 nonvolatile static RAM with a full function Real Time Clock (RTC) that are both accessible in a byte-wide format. The nonvolatile timekeeping RAM is functionally equivalent to any JEDEC standard 8K 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 eightuppermost RAM locations.

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.
Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
Access Times of 85ns and 100ns
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% VCCPower Supply Tolerance
Lithium Energy Source is Electrically
Disconnected to Retain Freshness Until Power is Applied for the First Time
DS1643 Only (DIP Module)
  Standard JEDEC Byte-Wide 8K x 8 RAM Pinout
UL Recognized
DS1643P Only (PowerCap Module Board) Surface Mountable Package for Direct
    Connection to PowerCap Containing
    Battery and Crystal Replaceable Battery (PowerCap) Power-Fail Output
Pin-for-Pin Compatible with Other Densities of
DS164XP Timekeeping RAM