Low-current, I2C, serial real-time clock for high-ESR crystals

The DS1339B serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output. Address and data are transferred serially through an I²C bus. The clock/date provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The device has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply, maintaining time, date, and alarm operation.

Key Features
-Drop-In Replacement for DS1339
-Supports High-ESR Crystals Up to 100kΩ
-Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Day, Date, Month, and Year with Leap-Year Compensation up to 2200
-I²C Serial Interface
-Two Time-of-Day Alarms
-Programmable Square-Wave Output
-Oscillator Stop Flag
-Automatic Power-Fail Detect and Switch Circuitry
-Trickle-Charge Capability