M41T66Q6F STMicroelectronics

M41T66 Serial real-time clock with alarms Features Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, year, and century 32 KHz crystal oscillator integrating load capacitance and high crystal series resistance operation Oscillator stop detection monitors clock operation QFN16 3 mm x 3 mm 2 Serial interface supports I C bus (400 kHz) 525 nA timekeeping current at 3 V Low operating current of 35 A (at 400 kHz) Timekeeping down to 1.0 V 2 1.3 V to 4.4 V I C bus operating voltage Allows use in lithium ion rechargeable applications 32 KHz square wave on power-up to drive a microcontroller in low-power mode Programmable (1 Hz to 32 KHz) square wave Programmable alarm with interrupt function Accurate programmable watchdog (from 62.5 ms to 31 min) Software clock calibration to compensate deviation of crystal due to temperature Automatic leap year compensation Operating temperature of 40 to 85 C Lead-free 16-pin QFN package October 2011 Doc ID 15108 Rev 2 1/41 www.st.com 1Contents M41T66 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 Clock registers . 14 3.2 Calibrating the clock . 16 3.3 Setting alarm clock registers 18 3.4 Watchdog timer 19 3.5 Square wave output . 20 3.6 Century bits . 20 3.7 Output driver pin 21 3.8 Oscillator stop detection 21 3.9 Initial power-on defaults 22 4 Maximum ratings . 23 5 DC and AC parameters 24 6 Package mechanical data 28 7 Part numbering 32 8 Revision history . 33 2/34 Doc ID 15108 Rev 2