M41T93

The M41T93 is a low power Serial SPI Bus Real Time Clock with a built-in 32.768kHz oscillator (external crystal-controlled for the QFN16 package, and embedded crystal for the SOX18 package). Eight bytes of the Register Map (see Table 3 on page 18) are used for the clock/calendar function and are configured in binary coded decimal (BCD) format. An additional 17 bytes of the Register Map provide status/control of the two Alarms, Watchdog,8-Bit Counter, and Square Wave functions. An additional seven bytes are made available as user SRAM.

Addresses and data are transferred serially via a serial SPI bus-compatible interface. The built-in address register is incremented automatically after each WRITE or READ data byte. The M41T93 has a built-in power sense circuit which detects power failures and automatically switches to the battery supply when a power failure occurs. The energy needed to sustain the clock operations can be supplied by a small lithium button battery when a power failure occurs.

Functions available to the user include a non-volatile, time-of-day clock/calendar, Alarm interrupt, Watchdog Timer, programmable 8-bit Counter, and Square Wave outputs. The eight clock address locations contain the century, year, month, date, day, hour, minute, second, and tenths/hundredths of a second in 24 hour BCD format. Corrections for 28, 29 (leap year), 30, and 31 day months are made automatically. The M41T93 is supplied in either a QFN16 or an SOX18 (MY), 300mil SOIC which includes an embedded 32kHz crystal. The SOX18 package requires only a user-supplied battery to provide non-volatile operation.