The M48T251Y and M48T251V are 5.0 or 3.3V, 4096K TIMEKEEPER® SRAM with PHANTOM. The features are: 5.0V or 3.3V operating voltage, real-time clock keeps track of tenths/hundredths of seconds, seconds, minutes, hours, days, date of the month, months, and years, automatic leap year correction, valid up to the year 2100, automatic switch-over and deselect circuitry, choice of power-fail deselect voltages: M48T251Y: 4.25V ≤ VPFD ≤ 4.50V, M48T251V: 2.80V ≤ VPFD ≤ 2.97V, full 10% VCC operating range, over 10 years’ data retention in the absence of power, watch function is transparent to RAM operation, 512K x 8 NV SRAM directly replaces volatile static RAM or EEPROM