SUMMARY DESCRIPTION The M48T08/18/08Y TIMEKEEPER® RAM is an 8K x 8 non-volatile static RAM and real time clock which is pin and functional compatible with the DS1643. The monolithic chip is available in two special packages to provide a highly integrated battery backed-up memory and real time clock solution. FEATURES SUMMARY ■ INTEGRATED ULTRA LOW POWER SRAM, REAL TIME CLOCK, POWER-FAIL CONTROL CIRCUIT, AND BATTERY ■ BYTEWIDE™ RAM-LIKE CLOCK ACCESS ■ BCD CODED YEAR, MONTH, DAY, DATE, HOURS, MINUTES, and SECONDS ■ TYPICAL CLOCK ACCURACY OF ±1 MINUTE A MONTH, AT 25°C ■ AUTOMATIC POWER-FAIL CHIP DESELECT AND WRITE PROTECTION ■ WRITE PROTECT VOLTAGES (VPFD= Power-fail Deselect Voltage): – M48T08: VCC= 4.75 to 5.5V 4.5V ≤VPFD ≤4.75V – M48T18/T08Y: VCC= 4.5 to 5.5V 4.2V≤VPFD ≤4.5V ■ SOFTWARE CONTROLLED CLOCK CALIBRATION FOR HIGH ACCURACY APPLICATIONS ■ SELF-CONTAINED BATTERY AND CRYSTAL IN THE CAPHAT™ DIP PACKAGE ■ PACKAGING INCLUDES A 28-LEAD SOIC AND SNAPHAT® TOP (to be ordered separately) ■ SOIC PACKAGE PROVIDES DIRECT CONNECTION FOR A SNAPHAT TOP WHICH CONTAINS THE BATTERY AND CRYSTAL ■ PIN AND FUNCTION COMPATIBLE WITH DS1643 and JEDEC STANDARD 8K x 8 SRAMs ■ RoHS COMPLIANCE Lead-free components are compliant with the RoHS Directive.
The DS1243Y-120+ is a 64K NV SRAM with Phantom clock in 28 pin EDIP package. The 64K NV SRAM with Phantom clock is a fully static non-volatile RAM (organized as 8192 words by 8 bits) with a built-in real time clock. The DS1243Y 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, lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent corrupted data in both the memory and real time clock. The Phantom clock provides timekeeping information for hundredths of seconds, seconds, minutes, hours, day, date, month and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The Phantom clock operates in either 24hour or 12hour format with an AM/PM indicator.
The M48T08-100PC1 is a 5V, 64Kbit (8Kb x 8) TIMEKEEPER non volatile static RAM and real time clock in 28 pin DIP package. This real time clock is pin and function compatible with DS1643. It provides highly integrated battery backed memory and real time clock solution. The M48T08-100PC1 is a non volatile pin and function equivalent to any JEDEC standard 8K x 8 SRAM. It also easily fits into many ROM, EPROM and EEPROM sockets providing the non-volatility of PROMs without any requirement for special WRITE timing or limitations on number of WRITEs that can be performed.