M41T56M6E STMicroelectronics

M41T56 Serial real-time clock (RTC) with 56 bytes NVRAM Features Counters for seconds, minutes, hours, day, date, month, years, and century 32 KHz crystal oscillator integrating load capacitance (12.5 pF) providing exceptional 8 oscillator stability and high crystal series resistance operation 2 1 Serial interface supports I C bus (100 kHz protocol) Ultra-low battery supply current of 450 nA (typ at 3 V) 5 V 10% supply voltage SO8 150-mil width Timekeeping down to 2.5 V Automatic power-fail detect and switch circuitry 56 bytes of general purpose RAM Software clock calibration to compensate crystal deviation due to temperature Automatic leap year compensation Operating temperature of 40 C to 85 C Available in an 8-lead, 150-mil, plastic SOIC (SO8) RoHS compliant Lead-free second level interconnect December 2011 Doc ID 6104 Rev 9 1/27 www.st.com 1Contents M41T56 Contents 1 Description . 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 10 2.3 Write mode 12 2.4 Data retention mode . 12 3 Clock operation 13 3.1 Clock calibration 14 3.2 Output driver pin 15 3.3 Initial power-on defaults 15 4 Maximum ratings . 16 5 DC and AC parameters 17 6 Package mechanical data 20 7 Part numbering 24 8 References 25 9 Revision history . 26 2/27 Doc ID 6104 Rev 9