Low-cost, highly accurate I2C real-time clock (RTC) with integrated temperature-compensated crystal oscillator (TCXO) and crystal. Features battery backup input to maintain accurate timekeeping when main power is disconnected. Integrated oscillator improves long-term accuracy and reduces component count on the production line. Available in commercial and industrial temperature ranges; packaged in a 16-pin 300-mil SOIC. Maintains seconds, minutes, hours, day, date, month, and year. Automatically adjusts for months with fewer than 31 days, including leap year correction. Operates in either 24-hour or 12-hour format with AM/PM indicator. Includes two configurable alarms and a programmable square-wave output. Address and data transfer via I2C bidirectional serial bus. Precision temperature-compensated voltage reference and comparator monitor VCC to detect power failure, provide reset output, and automatically switch to backup power when needed. /RST pin supports manual microprocessor reset. Includes an integrated digital temperature sensor accessible via the same I2C interface as the RTC; temperature accuracy: ±3°C. On-chip power supply control circuit automatically detects and manages main and backup (battery) power sources. Continues accurate timekeeping and temperature measurement during main power failure without performance degradation. Automatic system reset is triggered when main power is restored or voltage returns within specification. Battery not included. Module specifications: Size: 38 mm (L) × 22 mm (W) × 14 mm (H) Operating voltage: 3.3 V to 5.5 V RTC chip: DS3231 Timekeeping accuracy: ±2 ppm from 0°C to +40°C (~1 minute per year) Calendar and alarm functions with two alarms Programmable square-wave output Real-time clock with leap-year compensation, valid through year 2100 Integrated temperature sensor with ±3°C accuracy Memory chip: AT24C32 (32 Kbit EEPROM) I2C interface, up to 400 kHz max speed at 5 V Supports I2C bus addressing via A0/A1/A2 pins; default address: 0x57 Compatible with rechargeable LIR2032 coin cell (battery not included) for continuous timekeeping during power loss Typical wiring: SCL → A5, SDA → A4, VCC → 5 V, GND → GND Quantity: 1 pc