Maxim Integrated DS1644-120

Description
The DS1644/DS1644P is a nonvolatile timekeeping RAM with an integrated real-time clock, crystal, power-fail control circuit, and lithium energy source. The clock registers are accessed identically to the static RAM, and are resident in the eight top RAM locations. The device is totally nonvolatile, with over 10 years of operation in the absence of power. The BCD-coded year, month, date, day, hours, minutes, and seconds with leap year compensation are valid up to 2100. The power-fail write protection allows for ±10% Vcc power supply tolerance.

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
Totally nonvolatile with over 10 years of operation in the absence of power
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
DS1644 only (DIP module) upward compatible with the DS1643 timekeeping RAM to achieve higher RAM density
Standard JEDEC bytewide 32k x 8 static RAM pinout
DS1644P 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
Underwriters Laboratory (UL) recognized

Applications
Timekeeping and date stamping
Industrial control
Medical equipment
Point-of-sale systems
Security systems
Telecommunications