DESCRIPTION

The DS1244Y 256K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 32,768 words by 8 bits) with a built–in real time clock. The DS1244Y has a self–contained lithium energy source and control circuitry which constantly monitors VCC for an out–of–tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent garbled data in both the memory and real time clock.

FEATURES

? Real time clock keeps track of hundredths of seconds, minutes, hours, days, date of the month, months, and years

? 32K x 8 NV SRAM directly replaces volatile static RAM or EEPROM

? Embedded lithium energy cell maintains calendar operation and retains RAM data

? Watch function is transparent to RAM operation

? Month and year determine the number of days in each month; volid up to 1200

? Standard 28–pin JEDEC pinout

? Full 10 operating range

? Operating temperature range 0°C to 70°C

? Accuracy is better than ±1 minute/month @ 25°C

? Over 10 years of data retention in the absence of power

? Available in 120, 150 and 200 ns access time