DESCRIPTION

The DS1644L is a low profile module that requires a PLCC surface mountable socket and is functionally equivalent to the DS1644. The DS1644L is a 32K x 8 nonvolatile static RAM with a full function real time clock which are both accessible in a Byte–wide format. The real time clock information resides in the eight upper most RAM locations. The RTC registers contain year, month, date, day, hours, minutes, and seconds data in 24 hour BCD format. Corrections for the day of the month and leap year are made automatically.

FEATURES

• Upward compatible with the DS1643AL Timekeeping RAM to achieve higher RAM density

• Integrated NV SRAM, real time clock, crystal, power–fail control circuit and lithium energy source

• Low profile socketable module

– 255 mil package height

• 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 time of 120 ns and 150 ns

• Quartz accuracy ±1 minute a month @ 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