DS1340U-3+T&R

Real Time Clock Overview

The DS1340U-3+T&R is a low-power I2C real-time clock/calendar manufactured by Analog Devices/Maxim Integrated. It operates within a supply voltage range of 2.7V to 5.5V and supports a backup supply from 1.3V to 3.7V. The device provides timekeeping for seconds, minutes, hours, day, date, month, and year in BCD format with automatic leap-year correction. Key features include software clock calibration, an oscillator stop flag, and trickle-charger capability on the VBACKUP pin. It utilizes a fast-mode (400kHz) I2C interface and is housed in an 8-pin µSOP package.

Real Time Clock Feature Summary

• I2C Serial Interface: Supports standard (100kHz) and fast mode (400kHz) bidirectional communication.
• Trickle-Charger Capability: Configurable charging circuitry on the VBACKUP pin for batteries or supercapacitors.
• Software Clock Calibration: Digital adjustment via control register bits to compensate for crystal and temperature variations.
• Oscillator Stop Flag: Detects power failures or oscillator stops to indicate data validity.

Real Time Clock Applications

• Portable Instruments
• Point-of-Sale Equipment
• Medical Equipment
• Telecommunications

Real Time Clock Procurement Notes

Verify the specific ordering suffix '+T&R' corresponds to the tape-and-reel packaging configuration as indicated by distributor listings. Confirm that the 'DS1340U-3' designation aligns with the required 3.0V nominal supply voltage range (2.7V to 5.5V). Ensure compatibility with the 8-pin µSOP surface-mount package dimensions for the target PCB layout.

Real Time Clock Selection Notes

Select this component when a pin-compatible replacement for the ST M41T00 is required. Choose the '-3' variant specifically for systems operating with a 3.0V nominal supply rail. Consider the integrated trickle charger if battery maintenance is needed without external components. Verify that the 8-pin µSOP footprint meets space constraints compared to the SO package options.

Real Time Clock Part Context

This part belongs to the DS1340 series of real-time clocks. The 'U' suffix denotes the 8-pin µSOP package, while the '3' indicates the 3.0V supply voltage variant. The '+' signifies lead-free/RoHS compliance. It serves as an enhanced second source for the ST M41T00, offering functional equivalence with additional features like the oscillator stop flag and improved trickle-charging options.

Real Time Clock Replacement Considerations

The DS1340U-3+T&R is functionally equivalent to the ST M41T00. Other variants in the same family include DS1340U-18+ (1.8V) and DS1340U-33+ (3.3V), which share the same package but differ in supply voltage ranges. The DS1340Z series offers the same functionality in an 8-pin SO package.