DS1339BU+

Real Time Clock Overview

The DS1339BU+ is a low-power serial real-time clock (RTC) manufactured by Analog Devices Inc./Maxim Integrated. It provides seconds, minutes, hours, day, date, month, and year information with leap-year compensation valid up to the year 2200. The device features two programmable time-of-day alarms and a programmable square-wave output. Address and data are transferred via an I²C bus interface. It includes automatic power-fail detection and switching circuitry to maintain operation on a backup supply. The component operates within a supply voltage range of 1.71V to 5.5V and supports high-ESR crystals up to 100kΩ. It is housed in an 8-pin µSOP package.

Real Time Clock Feature Summary

• I²C Serial Interface for simple microcontroller connection
• Automatic Power-Fail Detect and Switch Circuitry
• Supports High-ESR Crystals Up to 100kΩ
• Two Time-of-Day Alarms and Programmable Square-Wave Output

Real Time Clock Applications

• Handhelds (GPS, POS Terminals)
• Consumer Electronics (Set-Top Box, Digital Recording, Network Appliance)
• Office Equipment (Fax/Printers, Copier)
• Medical (Glucometer, Medicine Dispenser)
• Telecommunications (Routers, Switches, Servers)

Real Time Clock Procurement Notes

Verify the specific suffix 'BU+' corresponds to the µSOP-8 package and lead-free compliance when sourcing. Confirm that the ordering code matches the exact voltage and temperature specifications required for the target application environment.

Real Time Clock Selection Notes

Select this component for applications requiring drop-in replacement for the DS1339 while supporting higher ESR crystals. Ensure the design accommodates the 1.71V to 5.5V VCC range and utilizes an external 32.768kHz crystal with a 6pF load capacitance for accurate timing.

Real Time Clock Part Context

The DS1339B series is designed as a low-current RTC optimized for battery-backed systems. The BU+ variant specifically denotes the µSOP surface-mount package. This part belongs to the broader DS1339 family, which shares core functionality but differs in packaging and specific electrical characteristics like crystal support.

Real Time Clock Replacement Considerations

The datasheet identifies the DS1339B as a drop-in replacement for the standard DS1339. Verify pin compatibility and ensure the host system can handle the specific I²C timing requirements and power-fail voltage thresholds defined in the DS1339B specifications.