M48T36

The M48T36 TIMEKEEPERE^TM RAM is a 32K x 8 non-volatile static RAM and real time clock. The monolithic chip is available in a special package to provide a highly integrated battery backed-up memory and real time clock solution. The M48T36 is a non-volatilepin and function equivalent to any JEDEC standard 32K x 8 SRAM. It also easily fits into many ROM, EPROM, and EEPROMsockets, providing the non-volatility of PROMs without any requirementfor specialwrite timing or limitations on the number of writes that can be performed.

The 44 pin 330mil SO provides sockets with gold plated contacts at both ends for direct connection to a separate SNAPHATE^TM housing containing the battery and crystal. The unique design allows the SNAPHAT battery package to be mounted on top of the SO package after the completion of the surface mount process.

Insertion of the SNAPHAT housing after reflow prevents potential battery and crystal damage due to the high temperatures required for device surface- mounting.The SNAPHAT housing is keyed to prevent reverse insertion.

The SO and battery packages are shipped separately in plastic anti-static tubes. The SO package is also available to ship in Tape & Reel form. For the 44 lead SO, the battery package (i.e. SNAPHAT) part number is "M4T44-BR12SH1".

As Figure 3 shows, the staticmemory array and the quartz controlled clock oscillator of theM48T36 are integrated on one silicon chip. The two circuits are interconnectedat theupper eightmemorylocations to provide user accessible BYTEWIDEE^TM clock information in the bytes with addresses 7FF9h- 7FFFh. The clock locations contain the year, month, date, day, hour, minute, and second in 24 hour BCD format. Corrections for 28, 29 (leap year), 30, and 31 day months are made automatically.