M74HC138TTR

Overview

The M74HC138TTR is a high-speed CMOS 3-to-8 line decoder fabricated with silicon gate C2MOS technology. It accepts three binary address inputs (A, B, and C) to select one of eight low-active outputs (Y0 to Y7). The device features three enable inputs: two low-active (G2A, G2B) and one high-active (G1). Functional operation requires G1 high and G2A/G2B low; otherwise, all outputs remain high. It operates within a supply voltage range of 2V to 6V, providing symmetrical output impedance of 4mA minimum at VCC=5V.

Feature Summary

• High-speed decoding capability utilizing advanced silicon gate C2MOS technology
• Three enable inputs facilitate cascade connection and memory system addressing
• Outputs go low when enabled based on binary address selection
• All inputs include protection circuits against static discharge and transient excess voltage

Applications

• Memory systems requiring address decoders
• Data routing applications
• Industrial control systems
• Consumer electronics

Procurement Notes

Verify the specific package type matches the design requirements, as the M74HC138TTR designation corresponds to the TSSOP-16 package in the official ordering codes. Confirm that the tape and reel quantity aligns with manufacturing needs. Ensure the operating temperature range of -55°C to +125°C meets environmental specifications for the intended application environment.

Selection Notes

Select this component when a 3-to-8 inverted decoder is required with high noise immunity and low power dissipation. The wide operating voltage range from 2V to 6V allows compatibility with various logic families. Consider the propagation delay characteristics relative to system timing requirements, noting that delays vary with supply voltage and load conditions.

Part Context

This part belongs to the M74HC138 series of 3-to-8 line decoders manufactured by STMicroelectronics. It is pin and function compatible with standard 74 series 138 devices. The TTR suffix indicates it is supplied in a Tape & Reel format within a TSSOP-16 package, distinguishing it from tube-packaged variants like the DIP or SOP versions.

Replacement Considerations

Direct replacements must maintain 3-to-8 decoding functionality with compatible pinouts. Verify that substitute components support the same 2V to 6V operating voltage range and offer similar propagation delays under equivalent load conditions to ensure signal integrity in existing designs.