M41T60 Low-power serial real-time clock (RTC) Datasheet - production data Features Counters for seconds, minutes, hours, day, date, month, years, and century 32 KHz crystal oscillator integrating load capacitance and high crystal series resistance QFN16 operation 3 mm x 3 mm Oscillator stop detection monitors clock operation 2 Serial interface supports I C bus (400 kHz) 2 VSOJ20 (47.6mm ) 350 nA timekeeping current at 3 V 2 (21.5mm ) GND Plane Guard Ring Low operating current of 35 A (at 400 kHz) Timekeeping down to 1.0 V 1 XI SMT 2 XO 2 CRYSTAL 1.3 V to 4.4 V I C bus operating voltage 3 4 ST QFN16 Software clock calibration to compensate deviation of crystal due to temperature Software programmable output (OUT) Operating temperature of 40 to 85 C Footprint comparison of STs QFN16 with Automatic leap year compensation SMT crystal vs. competing VSOJ20 package Lead-free 16-pin QFN package Li-ion rechargeable operation February 2013 DocID10396 Rev 14 1/28 This is information on a product in full production. www.st.com 28Table of contents M41T60 Table of contents 1 Description . 5 2 Operation 8 2.1 2-wire bus characteristics 8 2.1.1 Bus not busy 8 2.1.2 Start data transfer 8 2.1.3 Stop data transfer 8 2.1.4 Data valid . 9 2.1.5 Acknowledge 9 2.2 READ mode . 10 2.3 WRITE mode 12 3 Clock operation 13 3.1 Calibrating the clock . 13 3.2 Century bits . 16 3.3 Leap year . 17 3.4 Output driver pin 17 3.5 Oscillator stop detection 17 3.6 Initial power-on defaults 17 4 Maximum ratings . 18 5 DC and AC parameters 19 6 Package mechanical data 23 7 Part numbering 26 8 Revision history . 27 2/28 DocID10396 Rev 14