DS1337+

Overview

The DS1337+ is a low-power I2C serial real-time clock and calendar manufactured by Analog Devices Inc./Maxim Integrated. It counts seconds, minutes, hours, day, date, month, and year with leap-year compensation valid up to the year 2100. The device operates within a supply voltage range of 1.8V to 5.5V for full functionality, while maintaining timekeeping at voltages as low as 1.3V. It features two programmable time-of-day alarms, a programmable square-wave output defaulting to 32kHz, and an oscillator stop flag. The component is housed in an 8-pin DIP package and supports industrial temperature ranges from -40°C to +85°C.

Feature Summary

• I2C Serial Interface: Supports standard mode (100kHz) and fast mode (400kHz) communication protocols.
• Dual Power Supply Operation: Full access at 1.8V–5.5V; timekeeping maintained at 1.3V–1.8V.
• Calendar Functions: Automatically adjusts for months with fewer than 31 days and includes leap-year correction through 2100.
• Alarm and Output Features: Includes two programmable alarms and a programmable square-wave output.

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

Procurement Notes

Verify that the ordering suffix '+' indicates a lead-free and RoHS-compliant device. Confirm the package type corresponds to the 8-pin DIP configuration. Ensure the operating environment falls within the specified -40°C to +85°C industrial temperature range. Check for any specific errata associated with device revisions before finalizing procurement specifications.

Selection Notes

Select the DS1337+ when an 8-pin DIP package is required for through-hole mounting. This variant is suitable for applications needing low power consumption during standby and timekeeping modes. Ensure the system design accommodates an external 32.768kHz quartz crystal with a 6pF load capacitance. Verify that the microcontroller interface supports the I2C protocol and can handle the open-drain outputs with appropriate pull-up resistors.

Part Context

The DS1337+ belongs to the DS1337 family of serial real-time clocks. Other variants in this series include the DS1337S+ in an 8-pin SO package, the DS1337U+ in an 8-pin µSOP package, and the DS1337C# which integrates a crystal in a 16-pin SO package. All variants share the same core RTC functionality but differ in physical packaging and pin configurations.

Replacement Considerations

Direct replacements within the same family include the DS1337S+ (SO-8), DS1337U+ (µSOP-8), and DS1337C# (SO-16). These parts offer identical electrical characteristics and register maps but require different footprint adaptations on the PCB due to varying package types.

FAQ

What is the minimum voltage required to maintain timekeeping?

Timekeeping operation is maintained when VCC is as low as 1.3V, provided the I2C interface is inactive.

How does the device handle leap years?

The DS1337 automatically adjusts for months with fewer than 31 days and includes leap-year compensation valid up to the year 2100.

What is the default frequency of the square-wave output?

The programmable square-wave output defaults to 32kHz upon power-up.