TC74VHC138F(EL,K,F

Overview

The TC74VHC138F is a 3-to-8 line decoder fabricated with silicon gate C2MOS technology. It operates within a supply voltage range of 2.0 V to 5.5 V and supports an operating temperature from -40°C to 85°C. The device features balanced propagation delays, typically 5.7 ns at 5 V with 15 pF load. Quiescent current is 4 μA maximum at 25°C. It includes power-down protection on all inputs and provides three enable inputs (G1, 2AG, 2BG) for cascading or memory addressing.

Feature Summary

• High-speed operation comparable to Bipolar Schottky TTL while maintaining CMOS low power dissipation.
• Power down protection provided on all inputs to prevent device destruction due to mismatched supply voltages.
• Three enable inputs facilitate cascade connections and address decoding for memory systems.
• Pin and function compatible with the 74ALS138 standard.

Applications

• Address decoding for memory systems
• Cascaded logic circuit designs
• Interface between 5 V and 3 V systems

Procurement Notes

Verify the specific package suffix required for the application: 'F' denotes SOP16-P-300-1.27A, while 'FK' denotes VSSOP16-P-0030-0.50. Confirm that the selected variant meets the mechanical footprint constraints of the target PCB layout. Ensure compliance with RoHS directives as applicable to the manufacturing batch.

Selection Notes

Select this component when a high-speed decoder with low quiescent current is required. The wide input voltage range allows interfacing between different logic families without level shifting. Verify that the output drive capability of 8 mA is sufficient for the connected loads. Consider the 74ALS138 compatibility if replacing legacy designs.

Part Context

This part belongs to Toshiba's advanced high-speed CMOS VHC series. It utilizes silicon gate C2MOS technology to achieve performance levels similar to Bipolar Schottky TTL. The device is designed for general-purpose digital applications requiring efficient signal routing and decoding capabilities in compact surface-mount packages.

Replacement Considerations

The datasheet explicitly states pin and function compatibility with the 74ALS138. Designers replacing older bipolar logic should verify that the new CMOS input thresholds and drive currents meet the system requirements.