DS1338Z-18+T&R

Real Time Clock Overview

The DS1338Z-18+T&R 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 supports both 12-hour and 24-hour formats. The part operates on a primary supply voltage range of 1.71V to 5.5V, with a typical nominal voltage of 1.8V. It incorporates a built-in power-fail detect circuit that automatically switches to a backup supply to maintain timekeeping during main power loss.

Real Time Clock Feature Summary

• Full BCD clock/calendar with automatic month-end adjustments and leap-year compensation valid through 2100.
• 56-byte battery-backed NV SRAM supporting unlimited write cycles.
• Built-in power-fail detection and automatic switching between VCC and VBAT supplies.
• Programmable square-wave output signal at selectable frequencies: 1Hz, 4.096kHz, 8.192kHz, or 32.768kHz.

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify the specific ordering suffix '+T&R' indicates tape-and-reel packaging when sourcing this component. Confirm the 'Z' designation corresponds to the SOIC-8 package variant. Ensure the '-18' suffix matches the required 1.8V nominal operating voltage range for the target application design.

Real Time Clock Selection Notes

Select the DS1338Z-18+T&R when a lower nominal supply voltage of 1.8V is required compared to the standard 3.0V or 3.3V variants. Verify that the system's primary power rail falls within the 1.71V to 5.5V operating range. Ensure the I²C bus speed requirements are compatible with the standard (100kHz) or fast mode (400kHz) specifications defined in the datasheet.

Real Time Clock Part Context

This component belongs to the DS1338 family of serial RTCs from Maxim Integrated, now part of Analog Devices. The 'Z' suffix denotes the SOIC-8 package, while the '-18' specifies the 1.8V nominal voltage grade. Other variants include the -3 (3.0V) and -33 (3.3V) versions, as well as the U-series for µSOP packages and the C-series which integrates an onboard crystal.

Real Time Clock Replacement Considerations

Direct replacements within the same family include DS1338Z-3+T&R and DS1338Z-33+T&R, provided the system voltage supports their respective nominal ranges. For applications requiring an integrated crystal, the DS1338C series offers a 16-pin SOIC package option. Cross-voltage substitution requires verification of the power-fail threshold levels.