M41T00S Serial real-time clock Datasheet - production data Description The M41T00S is a low-power serial real-time 8 clock (RTC) with a built-in 32.768 kHz oscillator (external crystal controlled). Eight bytes of the SRAM are used for the clock/calendar function 1 and are configured in binary coded decimal (BCD) format. Addresses and data are transferred serially via a two line, bidirectional IC interface. SO8, 8-pin SOIC The built-in address register is incremented automatically after each WRITE or READ data byte. Features The M41T00S has a built-in power sense circuit 2.0 to 5.5 V clock operating voltage which detects power failures and automatically Counters for seconds, minutes, hours, day, switches to the battery supply when a power date, month, year, and century failure occurs. The energy needed to sustain the clock operations can be supplied by a small Software clock calibration lithium button supply when a power failure occurs. Automatic switchover and deselect circuitry The eight clock address locations contain the (fixed reference) century, year, month, date, day, hour, minute, and V = 2.7 to 5.5 V CC second in 24-hour BCD format. Corrections for 2.5 V V 2.7 V PFD 28, 29 (leap year - valid until year 2100), 30 and 31 day months are made automatically. Serial interface supports IC bus (400 kHz protocol) The M41T00S is supplied in an 8-pin SOIC. Low operating current of 300 mA Oscillator stop detection TM Battery or SuperCap backup Operating temperature of - 40 to 85 C Ultra-low battery supply current of 0.6 mA October 2021 DocID10772 Rev 6 1/28 This is information on a product in full production. www.st.com 28Contents M41T00S Contents 1 Diagram . 5 2 Operation 7 2.1 2-wire bus characteristics 7 2.1.1 Bus not busy 7 2.1.2 Start data transfer 7 2.1.3 Stop data transfer 8 2.1.4 Data valid . 8 2.1.5 Acknowledge 8 2.2 READ mode 9 2.3 WRITE mode 10 2.4 Data retention mode 11 3 Clock operation 12 3.1 Clock registers . 12 3.2 Calibrating the clock . 13 3.2.1 Century bit . 15 3.2.2 Oscillator fail detection 15 3.2.3 Output driver pin 16 3.2.4 Preferred initial power-on default 16 4 Maximum ratings . 17 5 DC and AC parameters 18 6 Package mechanical information . 22 7 Part numbering 26 8 Revision history . 27 2/28 DocID10772 Rev 6