Clock chip: high-precision clock chip DS3231SN; The DS3231 is an RTC IC developed by Maxim Integrated. It is a low cost, extremely accurate RTC IC with communication over I2C Interface. An interesting feature of DS3231 RTC IC is that it has integrated crystal oscillator and temperature sensor and hence you don’t have to connect an external crystal. It is a low cost, extremely accurate RTC IC with communication over I2C Interface. An interesting feature of DS3231 RTC IC is that it has integrated crystal oscillator and temperature sensor and hence you don’t have to connect an external crystal. A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, provide a reset output. In addition, RST pin is monitored as generating a μP reset. The DS3231 is available in commercial and industrial temperature ranges, using a 16-pin 300mil SO package.