UM3304QS 4-Bit Bidirectional Voltage-Level Translator

Overview

Union’s UM3304QS is a 4-bit, dual-supply bidirectional voltage-level translator designed for open-drain and push-pull applications. It supports a wide range of operating voltages and features automatic direction sensing, enabling seamless interface between devices operating at different logic levels. Compared to Texas Instruments’ TXB0104RGYR, a popular 4-bit bidirectional level shifter, the UM3304QS delivers enhanced drive strength, better tolerance to capacitive loads, and broader design flexibility in real-world applications.

Voltage Range and Compatibility

The UM3304QS supports VCCA from 1.2V to 3.6V and VCCB from 1.65V to 5.5V, enabling voltage-level shifting between ultra-low-voltage logic and standard 5V logic. This provides superior compatibility for mixed-voltage systems commonly found in industrial, automotive, and consumer electronics.

In contrast, TXB0104 operates over a narrower supply voltage range of 1.2V to 3.6V on both VCCA and VCCB, which limits its capability to interface directly with 5V logic. Therefore, UM3304QS offers greater voltage domain flexibility, particularly in systems where legacy 5V logic must coexist with modern low-voltage processors.

Drive Strength and Capacitive Load Handling

A notable limitation of the TXB0104 is its weak output drive and internal edge accelerators, which make it unsuitable for driving capacitive loads >70pF or pull-up resistors <50kΩ. This significantly restricts its use in practical scenarios involving longer trace lengths, connector-driven buses, or heavily loaded signal lines.

The UM3304QS, by contrast, is engineered to support higher capacitive loading and stronger drive strength, allowing stable operation even in more demanding board layouts and IO conditions. This makes it ideal for robust embedded systems and industrial signal translation where TXB0104 may fail or become unreliable.

Automatic Direction Sensing

Both UM3304QS and TXB0104 feature automatic bidirectional direction sensing, eliminating the need for a dedicated direction control signal. However, while TXB0104 uses weak one-shots that can lead to signal integrity issues when connected to slow or high-impedance drivers, UM3304QS incorporates an optimized internal detection mechanism that supports reliable operation across a wider range of signal speeds and driver types.

This ensures fewer transmission errors and improved data integrity, especially in systems with variable edge rates or asynchronous interfaces.

Data Rate and Performance

Union’s UM3304QS supports data rates up to 100 Mbps (push-pull) and 2 Mbps (open-drain), enabling compatibility with SPI, I2C, GPIO, and other high-speed digital protocols. This is on par with the performance of TXB0104, which specifies 110 Mbps max (push-pull) and 24 Mbps (open-drain) under ideal conditions.

However, due to better capacitive load handling, UM3304QS tends to maintain its high-speed capability more consistently across practical PCB designs, while TXB0104 often shows degraded performance outside of lab conditions.

Package and Pin Compatibility

Both devices are available in 16-pin QFN (3x3 mm) packages, with the UM3304QS fully pin-compatible with the TXB0104RGYR. This allows for drop-in replacement without board changes, making it convenient for design updates or cost optimization.

Moreover, Union offers strong local support, flexible lead times, and competitive pricing, ensuring better supply chain security and lower total cost of ownership in volume production.

Conclusion

Union’s UM3304QS delivers compelling advantages over the TI TXB0104RGYR, especially in real-world application environments where capacitive loading, voltage domain diversity, and robust data transfer are critical. Key highlights include:

• Wider voltage support (VCCB up to 5.5V)

• Stronger drive for capacitive loads and low-impedance pull-ups

• Stable performance under practical layout and load conditions

• Pin-compatible with TXB0104, enabling easy migration

• Excellent local support and supply reliability

As a result, UM3304QS is a superior alternative to TXB0104RGYR in both technical performance and deployment flexibility, especially for industrial, consumer, and automotive-level translation applications.