CD74HC138SM

Signal Switches, Multiplexers, Decoders Overview

The CD74HC138SM is a high-speed silicon-gate CMOS decoder/driver manufactured by Harris Corporation. It features three binary address inputs and eight active-low outputs, designed for memory address decoding or data routing applications. The device operates within a voltage range of 2V to 6V and includes three enable inputs: two active-low (E1, E2) and one active-high (E3). These enables facilitate cascading multiple units without additional logic gates. The component utilizes a 16-pin Small Outline package.

Signal Switches, Multiplexers, Decoders Feature Summary

• Features three binary address inputs and eight mutually exclusive active-low outputs
• Includes composite enable inputs (two active-low, one active-high) to simplify cascading
• Provides low power consumption typical of CMOS technology with speed comparable to Low-Power Schottky TTL
• Offers balanced propagation delays and transition times

Signal Switches, Multiplexers, Decoders Applications

• Memory address decoding
• Data routing
• I/O port selection
• Cascaded decoding systems

Signal Switches, Multiplexers, Decoders Procurement Notes

Verify the manufacturer designation as Harris Corporation, noting that Texas Instruments acquired Harris Semiconductor assets. Confirm the specific suffix 'SM' corresponds to the Small Outline package variant. Ensure compliance requirements are checked against the original datasheet specifications, particularly regarding RoHS status which may vary based on production date and revision.

Signal Switches, Multiplexers, Decoders Selection Notes

Select this component when a high-speed CMOS 3-to-8 decoder is required with active-low outputs. It serves as a direct functional replacement for other HC138 variants from different manufacturers, provided pin compatibility and electrical characteristics match the system design. Consider the operating temperature range and supply voltage limits during integration.

Signal Switches, Multiplexers, Decoders Part Context

This part belongs to the HC/UH series of high-speed CMOS logic devices. It is functionally related to the CD74HC238, which provides active-high outputs instead of inverted ones. The device is compatible with LSTTL logic levels, allowing it to interface directly with legacy TTL components while maintaining CMOS power efficiency advantages.

Signal Switches, Multiplexers, Decoders Replacement Considerations

Compatible substitutes include CD74HC138, SN74HC138, and equivalent parts from other manufacturers such as NXP or STMicroelectronics. Verify package dimensions and pinout alignment before substitution.