DS1391U-18

Real Time Clock Overview

The DS1391U-18+ is a low-voltage serial real-time clock (RTC) manufactured by Analog Devices Inc./Maxim Integrated. It operates within a supply voltage range of 1.71 V to 1.89 V and features an SPI bus interface for data communication. The device provides binary date formats and supports both 12-hour and 24-hour time formats. It includes a trickle charger function, alarm capabilities, and calendar counting. The component is housed in a uSOP-10 package and is designed for surface mount installation. It functions reliably across a temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Low-voltage operation with power supply range of 1.71 V to 1.89 V
• SPI serial interface for efficient data transfer
• Integrated trickle charger for battery backup maintenance
• Calendar and alarm functionality with binary date format

Real Time Clock Applications

• Portable electronic devices requiring precise timekeeping
• Battery-powered systems needing low standby current
• Industrial equipment operating in extended temperature ranges

Real Time Clock Procurement Notes

Verify the specific suffix '18' indicates the 1.8V nominal voltage variant. Confirm availability status as distribution channels may list this part as obsolete or limited stock. Ensure the uSOP-10 package footprint matches the design requirements before procurement.

Real Time Clock Selection Notes

Select the DS1391U-18+ when a low-voltage SPI RTC is required. Compare against the DS1391U-33+ if a higher voltage range (2.97 V to 5.5 V) is needed instead. Verify that the system's main power rail aligns with the 1.71 V to 1.89 V operating window.

Real Time Clock Part Context

This component belongs to the DS1391 series of low-voltage serial RTCs from Maxim Integrated. It shares functional similarities with the DS1392 but differs in interface type, offering SPI connectivity compared to the 3-wire interface of other variants in the family.