DS1337S/T&R

Real Time Clock Overview

The DS1337S/T&R is a low-power serial real-time clock and calendar manufactured by Analog Devices Inc./Maxim Integrated. It provides seconds, minutes, hours, day, date, month, and year information with automatic leap-year compensation valid up to the year 2100. The device operates via an I2C bus interface and supports both 12-hour and 24-hour time formats. Full access is maintained when VCC ranges from 1.8V to 5.5V, while timekeeping continues at voltages as low as 1.3V. Key electrical parameters include an active supply current of 150µA maximum, standby current of 1.5µA maximum, and timekeeping current of 600nA maximum.

Real Time Clock Feature Summary

• I2C Serial Interface: Supports standard (100kHz) and fast mode (400kHz) communication protocols for microcontroller integration.
• Dual Alarms: Features two programmable time-of-day alarms with configurable mask bits for second, minute, hour, day, or date matching.
• Square-Wave Output: Provides a programmable square-wave output on the SQW/INTB pin with selectable frequencies including 1Hz, 4.096kHz, 8.192kHz, and 32.768kHz.
• Oscillator Stop Flag: Includes an OSF bit in the status register to detect oscillator failure due to power loss or insufficient voltage.

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 that the ordering suffix 'T&R' corresponds to the specific tape-and-reel packaging configuration required for automated assembly processes. Confirm that the component meets lead-free/RoHS compliance standards indicated by the '+' designation in the part number. Ensure compatibility with the intended surface-mount placement specifications for the SOIC-8 package.

Real Time Clock Selection Notes

Select this component when a low-power RTC with dual alarms and an integrated oscillator stop flag is required. The DS1337S variant specifically utilizes an 8-SOIC package suitable for surface-mount applications. Designers must account for the need for external pull-up resistors on the SDA and SCL lines, as well as a 32.768kHz quartz crystal with a 6pF load capacitance connected to the X1 and X2 pins.

Real Time Clock Part Context

The DS1337S+T&R belongs to the DS1337 family of serial real-time clocks. The 'S' suffix denotes the 8-pin Small Outline (SOIC) package, distinguishing it from the DIP or µSOP variants. The '+T&R' suffix indicates a lead-free/RoHS-compliant device supplied in a tape-and-reel format for high-volume manufacturing.

Real Time Clock Replacement Considerations

The DS1337U+ is a verified substitute offering identical functionality in an 8-µSOP package. Other family members include the DS1337+ in an 8-DIP package and the DS1337C+ in a 16-SO package with an integrated crystal.