SN74HCT138PWRG4

Overview

The SN74HCT138PWRG4 is a 3-line to 8-line decoder/demultiplexer from the HCT logic family, manufactured by Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and features TTL-compatible inputs. The device incorporates three enable inputs (one active-high G1 and two active-low G2A, G2B) to simplify cascading and data reception. It provides eight active-low outputs capable of driving up to 10 LSTTL loads with ±4-mA drive current at 5 V. Typical propagation delay is 17 ns, with maximum delays of 34 ns at 5.5 V. The component is housed in a 16-pin TSSOP package.

Feature Summary

• TTL-voltage compatible inputs for direct interfacing with standard logic systems
• Three enable inputs designed to facilitate system expansion and demultiplexing applications
• Active-low outputs suitable for high-performance memory decoding and data routing

Applications

• High-speed memory decoders
• Data transmission systems
• System decoding in high-performance memory architectures

Procurement Notes

Verify the specific ordering suffix 'G4' corresponds to the desired RoHS-compliant variant and lead finish configuration as defined in the manufacturer's orderable addendum. Confirm that the TSSOP-16 package dimensions align with the target PCB land pattern requirements. Ensure the operating temperature range of -40°C to +85°C meets the environmental specifications of the intended deployment scenario.

Selection Notes

Select this component when TTL input compatibility is required alongside CMOS low power consumption. The HCT series is appropriate for designs needing to interface directly with older TTL logic families without level shifting. Consider the three-enable architecture if the design requires complex cascading or gating functions without additional external gates.

Part Context

This part belongs to the SNx4HCT138 family of 3-line to 8-line decoders and demultiplexers. The 'SN74' prefix indicates commercial grade availability, while the 'HCT' designation specifies High-speed CMOS technology with TTL-compatible inputs. The 'PWR' suffix identifies the TSSOP surface-mount package, and 'G4' denotes the Green/RoHS-compliant manufacturing version.

Replacement Considerations

Direct functional equivalents include SN74HCT138DR, SN74HCT138PW, and SN74HCT138DRE4. Verify package compatibility and electrical characteristics against the original design requirements before substitution.