DS1337U+

Real Time Clock Overview

The DS1337U+ is a low-power I2C serial real-time clock and calendar manufactured by Analog Devices Inc./Maxim Integrated. It tracks seconds, minutes, hours, day, date, month, and year with leap-year compensation valid through 2100. The device operates within a supply voltage range of 1.8V to 5.5V for full functionality, maintaining timekeeping down to 1.3V. Key features include two programmable alarms, a programmable square-wave output defaulting to 32kHz, and an oscillator stop flag. It utilizes an I2C interface for data transfer and is housed in an 8-pin µSOP package.

Real Time Clock Feature Summary

• I2C Serial Interface: Supports standard (100kHz) and fast mode (400kHz) communication protocols.
• Dual Alarms: Two programmable time-of-day/date alarms with interrupt capabilities.
• Low Power Consumption: Active current up to 150µA; standby current 1.5µA; timekeeping current 600nA at 1.8V.
• Integrated Oscillator Stop Flag: Detects crystal failure or insufficient voltage to ensure data validity.

Real Time Clock Applications

• Handheld devices such as GPS units, POS terminals, and MP3 players.
• Consumer electronics including set-top boxes and digital recording equipment.
• 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 the ordering suffix '+', which indicates a lead-free/RoHS-compliant device. Confirm the package type 'U' corresponds to the 8-pin µSOP format. Ensure compatibility with the required I2C bus speed (standard or fast mode) and check that the operating temperature range (-40°C to +85°C) meets system requirements. Cross-reference the specific revision against manufacturer errata if necessary.

Real Time Clock Selection Notes

Select the DS1337U+ when an external 32.768kHz quartz crystal is preferred over the integrated crystal version (DS1337C). This model requires external components for the oscillator circuit but offers flexibility in crystal selection. Ensure the design supports the open-drain outputs on SDA, INTA, and SQW/INTB pins with appropriate pull-up resistors. Verify that the microcontroller can handle the BCD register format and alarm mask configurations.

Real Time Clock Part Context

The DS1337U+ is part of the Maxim Integrated DS1337 family of serial real-time clocks. It shares functional similarities with the DS1338 and DS1339 but differs in power specifications and feature sets, such as the absence of NVSRAM found in the DS1338. The 'U+' designation specifically identifies the 8-pin µSOP package variant with RoHS compliance, distinguishing it from DIP (DS1337+) or SO (DS1337S+) packages.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers are not provided in the source material. Designers should verify pinout and register compatibility if considering alternative RTC ICs from other manufacturers.