DS1339U-2+T&R

Real Time Clock Overview

The DS1339U-2+T&R 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 2100. The device operates on a primary supply voltage range of 1.8V to 5.5V and supports a backup supply between 1.3V and 3.7V. It features an I2C serial interface, two programmable time-of-day alarms, and a programmable square-wave output. The unit includes automatic power-fail detection and switching circuitry to maintain timekeeping during main power loss.

Real Time Clock Feature Summary

• I2C Serial Interface: Supports standard mode (100kHz) and fast mode (400kHz) communication protocols for efficient data transfer.
• Automatic Power-Fail Switching: Built-in circuit detects power failures and seamlessly switches to the VBACKUP pin to maintain operation.
• Dual Alarms and SQW Output: Features two programmable time-of-day alarms and a configurable square-wave/interrupt output pin.
• Trickle-Charge Capability: Includes a programmable trickle charger register to safely charge backup batteries or supercapacitors.

Real Time Clock Applications

• Handheld devices such as GPS units and POS terminals
• Consumer electronics including set-top boxes and digital recorders
• Office equipment like fax machines, printers, and copiers
• Medical devices such as glucometers and medicine dispensers
• Telecommunications infrastructure including routers, switches, and servers

Real Time Clock Procurement Notes

Verify that the ordering suffix T&R indicates tape-and-reel packaging, distinct from tube packaging. Confirm the -2 suffix corresponds to the 2.0V nominal voltage variant with a 1.8V minimum operating limit. Ensure the component meets RoHS compliance standards as indicated by the + designation in the part number.

Real Time Clock Selection Notes

Select this model when a low-voltage operation down to 1.8V is required compared to the 3.0V or 3.3V variants. The µSOP-8 package offers a compact surface-mount solution suitable for space-constrained designs. Ensure the external crystal matches the specified 6pF load capacitance for accurate timing performance.

Real Time Clock Part Context

This component belongs to the DS1339 family of serial real-time clocks. The U suffix denotes the 8-pin µSOP package, while the -2 indicates the specific voltage rating. The T&R suffix specifies the reel packaging format used for automated assembly processes.

Real Time Clock Replacement Considerations

The DS1339A is documented as a drop-in replacement for the DS1339 series. Verify pin compatibility and electrical specifications before substituting other RTC models.