DS1308U-18+T

The DS1308U-18+T from Analog Devices is a serial real-time clock (RTC) IC designed for low-power applications. It integrates a full binary-coded decimal (BCD) clock/calendar with 56 bytes of non-volatile RAM (NVRAM).

Data transfer occurs serially via an I2C interface. The clock manages seconds, minutes, hours, day, date, month, and year, with automatic adjustments for month lengths and leap years. It supports both 24-hour and 12-hour formats with an AM/PM indicator. A built-in power-sense circuit automatically switches to a backup supply during power failures, ensuring continuous timekeeping.

Key features include low timekeeping current of 250nA (typical), automatic power-fail detection, and support for external clock sources. The device is compatible with crystal ESR up to 100kΩ, allowing for optimized crystal selection. It also offers a programmable square-wave output signal.

This RTC operates within an industrial temperature range of -40°C to +85°C and supports a voltage range of 1.3V to 5.5V. It is available in an 8-uMAX/uSOP package, suitable for surface mount applications. The DS1308U-18+T is recognized by Underwriters Laboratories (UL®).

Applications include handheld devices, consumer electronics, office equipment, medical devices, and telecommunications infrastructure.