74ACT138TTR

Signal Switches, Multiplexers, Decoders Overview

The STMicroelectronics 74ACT138TTR is an obsolete advanced high-speed CMOS 3-to-8 line inverting decoder fabricated with sub-micron silicon gate and double-layer metal wiring C2MOS technology. It operates within a supply voltage range of 4.5V to 5.5V, featuring symmetrical output impedance with minimum drive currents of 24mA for both high and low states. The device provides balanced propagation delays, typically 5ns at VCC=5V, and includes three enable inputs to facilitate cascade connections for memory address decoding applications.

Signal Switches, Multiplexers, Decoders Feature Summary

• Features three enable inputs (G1, G2A, G2B) that allow flexible cascading for expanded address decoding systems.
• Designed with improved latch-up immunity and protection circuits against static discharge providing 2KV ESD immunity.
• Capable of driving 50Ω transmission lines with symmetrical output impedance ensuring balanced signal integrity.

Signal Switches, Multiplexers, Decoders Applications

• Memory system address decoders
• Cascaded 3-to-8 line decoding configurations
• High-speed CMOS logic interfacing

Signal Switches, Multiplexers, Decoders Procurement Notes

This component is officially classified as an obsolete product by the manufacturer. Verify availability through authorized distributors or secondary markets, as new production has ceased. Ensure compatibility with existing designs before sourcing replacements from alternative suppliers.

Signal Switches, Multiplexers, Decoders Selection Notes

Select this part only if legacy design compatibility with the standard 74 series 138 pinout is required. Consider the operating voltage constraints strictly between 4.5V and 5.5V. Evaluate performance requirements against modern alternatives due to the discontinued status of this specific package variant.

Signal Switches, Multiplexers, Decoders Part Context

The 74ACT138TTR belongs to the 74ACT family of high-speed CMOS logic devices. This series bridges the gap between standard TTL logic levels and CMOS power efficiency. The TTR suffix indicates the TSSOP surface-mount packaging format, which was commonly used for compact circuit board implementations requiring small footprint solutions.

Signal Switches, Multiplexers, Decoders Replacement Considerations

Direct substitutes include the SN74ACT138PWR from Texas Instruments and the MC74ACT138ADTR2G from onsemi. These components maintain functional and pin compatibility while offering current manufacturing availability.