Active RTC with I²C interface and 56-byte NVSRAM
The DS1308U-33+T from Analog Devices is an active-production real-time clock (RTC) in the 8-uMAX/uSOP package, providing a complete clock/calendar function with 56 bytes of NVSRAM for data logging or alarm configuration.
Timekeeping features and NVSRAM for system context
The clock tracks time in HH:MM:SS format with 12-hour or 24-hour mode, and the calendar maintains YY-MM-DD-dd with automatic leap-year correction through 2099. 56 bytes of NVSRAM retain user data across power cycles — enough for a calibration constant, serial number, or last-event timestamp without external EEPROM. A square-wave output pin provides a programmable frequency reference (1 Hz, 4 kHz, 8 kHz, or 32 kHz) that can clock an external MCU or drive a status LED without an additional oscillator.
Package options and board integration
The DS1308U-33+T is supplied in the 8-uMAX/uSOP package (3.00 mm body width, 0.65 mm pitch), which is footprint-compatible with the 8-TSSOP and 8-MSOP land patterns — a single PCB layout serves both package variants. Ordering code suffix -33+T indicates the tape-and-reel (TR) and cut-tape (CT) packaging options; the TR variant is suited for automated pick-and-place assembly, while CT is available for prototype or low-volume builds.
Fully ROHS3 compliant (lead-free, no exemptions), the part meets the EU RoHS directive for unrestricted shipment into European markets without a hazardous-substance declaration.