SUMMARY DESCRIPTION

The M41T256Y Serial TIMEKEEPER® SRAM is a low power 256 Kbit static CMOS SRAM organized as 32K words by 8 bits. A built-in 32.768kHz oscillator (external crystal controlled) and 8 bytes of the SRAM (see Table 3., page 14) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format.

FEATURES SUMMARY

■ 5V OPERATING VOLTAGE

■ SERIAL INTERFACE SUPPORTS EXTENDED I2C BUS ADDRESSING (400kHz)

■ AUTOMATIC SWITCH-OVER AND DESELECT CIRCUITRY

■ POWER-FAIL DESELECT VOLTAGES:

– M41T256Y: VCC = 4.5 to 5.5V;

VPFD = 4.2 < VPFD < 4.5V

■ COUNTERS FOR TENTHS/HUNDREDTHS OF SECONDS, SECONDS, MINUTES, HOURS, DAY, DATE, MONTH, and YEAR

■ PROGRAMMABLE SOFTWARE CLOCK CALIBRATION

■ 32,752 BYTES OF GENERAL PURPOSE RAM

■ MICROPROCESSOR POWER-ON RESET

■ HOLDS MICROPROCESSOR IN RESET UNTIL SUPPLY VOLTAGE REACHES STABLE OPERATING LEVEL

■ AUTOMATIC ADDRESS-INCREMENTING

■ TAMPER INDICATION CIRCUIT WITH TIMESTAMP

■ SLEEP MODE FUNCTION

■ PACKAGING INCLUDES A 44-LEAD SOIC AND SNAPHAT® TOP (to be ordered separately)

■ SOIC PACKAGE PROVIDES DIRECT CONNECTION FOR A SNAPHAT® TOP WHICH CONTAINS THE BATTERY AND CRYSTAL