DS1338U-33

Real Time Clock Overview

The DS1338U-33 is a low-power serial real-time clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It features full binary-coded decimal (BCD) timekeeping with leap-year compensation valid up to the year 2100. The device includes 56 bytes of battery-backed NV SRAM for general-purpose data storage. It communicates via an I2C serial interface and operates within a supply voltage range of 3.0V to 5.5V on VCC, with a backup supply range of 1.3V to 3.7V on VBAT. The component supports both 12-hour and 24-hour formats and includes an automatic power-fail detection circuit that switches operation to the backup supply. It is housed in an 8-pin uSOP package and functions across an industrial temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Integrated BCD clock/calendar with automatic month-end adjustments and leap-year correction through 2100.
• 56-byte battery-backed NV SRAM accessible via I2C interface.
• Built-in power-fail detect and switch circuitry ensures continuous timekeeping during primary power loss.
• Programmable square-wave output signal available at SQW/OUT pin.

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 the specific suffix 'U-33' corresponds to the 8-pin uSOP package and 3.3V nominal supply rating. Confirm RoHS compliance status indicated by the '+' symbol in the ordering part number. Check manufacturer documentation for current production status, as older variants may be discontinued or subject to product change notices.

Real Time Clock Selection Notes

Select this model when a 3.0V to 5.5V operating voltage is required. Ensure the system design accommodates the 8-pin uSOP footprint. Verify that the external 32.768kHz crystal meets the specified load capacitance of 12.5pF for accurate timing. Consider the DS1338C variant if an integrated crystal solution is preferred to save board space.

Real Time Clock Part Context

The DS1338U-33 belongs to the DS1338 family of serial RTCs. The 'U' designation indicates the 8-pin micro-small outline package (uSOP), while '33' specifies the 3.3V nominal supply voltage version. Other variants include the Z-series for SOIC packages and different voltage ratings such as 1.8V or 3.0V.

Real Time Clock Replacement Considerations

Publicly confirmed substitute part numbers are not provided in the source material. Designers should consult official manufacturer channels for end-of-life notifications or recommended replacements for discontinued inventory.