M41T81SM6F STMicroelectronics

M41T81S Serial access real-time clock (RTC) with alarms Datasheet production data Features Counters for tenths/hundredths of seconds, seconds, minutes, hours, day, date, month, 8 year, and century 1 32 KHz crystal oscillator with integrated load capacitance (12.5 pf) which provides SO8 exceptional oscillator stability and high crystal 8-pin SOIC series resistance operation) Oscillator stop detection (monitors clock operation) 2 Serial interface supports I C bus (400 kHz protocol) 18 Ultra-low battery supply current of 0.6 A (typ) 1 2.0 to 5.5 V clock operating voltage Automatic switchover and deselect circuitry SOX18 (fixed reference) which provides full operation 18-pin (300 mil) SOIC with embedded crystal in 3.0 V applications) V = 2.7 to 5.5 V CC 2.5 V V 2.7 V PFD Power-down time-stamp (HT bit) which allows determination of time elapsed in battery backup Battery low flag Programmable alarm and interrupt function (valid even during battery backup mode) Accurate programmable watchdog timer (from 62.5 ms to 128 s) Software clock calibration (to compensate for crystal deviation due to temperature) Operating temperature of 40 to 85 C Package options include an 8-lead SOIC or 18-lead embedded crystal SOIC May 2012 Doc ID 10773 Rev 7 1/32 This is information on a product in full production. www.st.com 1Contents M41T81S Contents 1 Description . 6 2 Operation 9 2-wire bus characteristics 9 Bus not busy . 10 Start data transfer . 10 Stop data transfer . 10 Data valid . 10 Acknowledge . 10 READ mode . 11 WRITE mode 13 Data retention mode . 13 3 Clock operation 14 Power-down time-stamp 14 Clock registers . 14 Calibrating the clock . 16 Setting alarm clock registers . 17 Watchdog timer . 19 Square wave output . 20 Century bit . 20 Battery low warning 21 Oscillator fail detection . 21 Oscillator fail interrupt enable 21 Output driver pin 22 Preferred initial power-on default . 22 4 Maximum ratings . 23 5 DC and AC parameters 24 6 Package mechanical data 28 2/32 Doc ID 10773 Rev 7