DESCRIPTION
The DS1643 is a 8K x 8 nonvolatile static RAM with a full function Real Time Clock (RTC) which are both acces
sible in a Byte–wide format. The nonvolatile timekeep ing RAM is function equivalent to any JEDEC standard
8K x 8 SRAM.

FEATURES
•Integrated NV SRAM, real time clock, crystal, power–fail control circuit and lithium energy source
•Clock registers are accessed identical 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 120 ns and 150 ns
•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
•DS1643 only (DIP Module)
– Standard JEDEC Byte–wide 8K x 8 RAM pinout
•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