This part is a kind of semiconductor called AB1805.

Function of this product has Real-Time Clock Module.

Manufacturers : Abracon

Image and pinout :

Some of the text within the PDF file :

AB08XX Real-Time Clock Family Date of Issue: November 7, 2013 3.0 x 3.0 mm Page 1 of 34 Abracon Drawing #453567 Revision : A Features • Ultra-low supply current (all at 3V): - 14 nA with RC oscillator - 22 nA with RC oscillator and Autocalibration - 55 nA with crystal oscillator • Baseline timekeeping features: - 32.768 kHz crystal oscillator with integrated load capacitor/resistor - Counters for hundredths, seconds, minutes, hours, date, month, year, century, and weekday - Alarm capability on all counters - Programmable output clock generation (32.768 kHz to 1 year) - Countdown timer with repeat function - Automatic leap year calculation • Advanced timekeeping features: - Integrated power optimized RC oscillator - Advanced crystal calibration to ± 2 ppm - Advanced RC calibra [ ... ]

AB1805 PDF Datasheet Download