DS1374U-18+

Real Time Clock Overview

The DS1374U-18+ is a real-time clock (RTC) IC featuring a 32-bit binary counter and an I²C serial interface. Designed for low-voltage operation, it functions within a supply voltage range of 1.71V to 1.89V. The device includes a precision power-fail detect circuit that automatically switches to a backup supply when VCC drops below the trip point. It supports trickle charging for backup batteries or super capacitors and provides separate interrupt and square-wave outputs. The component operates across a temperature range of -40°C to +85°C and is housed in a 10-pin µSOP package.

Real Time Clock Feature Summary

• 32-bit binary time-of-day counter with automatic data latching during I²C reads
• Integrated watchdog timer or alarm counter with selectable reset steering
• Automatic power-fail detection and seamless switching to VBACKUP supply
• Trickle charger capability for maintaining rechargeable backup sources

Real Time Clock Applications

• Portable instruments requiring precise timekeeping
• Point-of-sale equipment needing reliable system clocks
• Medical equipment with strict timing requirements
• Telecommunications systems utilizing watchdog functionality

Real Time Clock Procurement Notes

Verify the specific voltage suffix '18' corresponds to the required 1.8V operating range, as other variants like DS1374U-33+ exist. Confirm the package type is 10-pin µSOP. Check RoHS compliance status if lead-free soldering is mandatory for the assembly process. Ensure the design accounts for the internal pullup resistor on the RST pin.

Real Time Clock Selection Notes

Select this part when a low-voltage 1.8V RTC is required alongside watchdog or alarm features. The DS1374U-18+ is suitable for designs where space is limited due to its small µSOP footprint. Consider the DS1374C variant if an integrated crystal is preferred to save board space and simplify BOM management. Verify I²C bus speed compatibility with the host microcontroller.

Real Time Clock Part Context

The DS1374U-18+ belongs to the Maxim Integrated DS1374 family of real-time clocks. It shares functional similarities with the DS1374C but differs in packaging and external crystal requirements. The 'U' designation indicates the surface-mount µSOP package, while the '+18' specifies the 1.8V voltage grade. This component is distinct from the DS1392 series, which utilizes a different 3-wire interface.

Real Time Clock Replacement Considerations

The DS1374C-18# is a pin-compatible alternative that integrates a 32.768kHz crystal within the 16-pin SO package. Designers must account for the pin count difference (10 vs. 16) and layout changes when substituting between the U and C series.