SN74F138D

Overview

The SN74F138D is a high-speed 3-line to 8-line decoder/demultiplexer from Texas Instruments. It operates within a supply voltage range of 4.5 V to 5.5 V and supports data rates up to 1 MHz. The device features three address inputs and eight active-low outputs, designed for high-performance memory decoding or data-routing applications. It is housed in a 16-pin SOIC package with surface mount installation. Operating temperatures range from 0°C to +70°C.

Feature Summary

• High-speed operation suitable for performance-critical memory decoding
• Active-low output configuration for direct interface compatibility
• Three address inputs enable efficient 1-of-8 line selection

Applications

• High-performance memory chip select address decoding
• Data-routing applications requiring fast signal switching
• Industrial control systems utilizing TTL-compatible logic

Procurement Notes

Verify the specific suffix 'D' confirms the SOIC-16 package variant. Confirm the manufacturer is Texas Instruments to ensure original component quality. Check RoHS compliance status if required by project specifications. Validate that the operating temperature range meets environmental requirements. Ensure pinout compatibility with existing PCB footprints before integration.

Selection Notes

Select this component when high-speed decoding is required within standard 5V logic levels. Compare propagation delays against system timing constraints. Consider the SOIC package size for board space limitations. Evaluate power consumption relative to other logic families like LS or HC variants. Verify input voltage thresholds match the driving source signals.

Part Context

This part belongs to the SN74F series, representing high-speed CMOS/TTL compatible logic. It is functionally similar to the SN74LS138 but offers faster switching speeds. The 138 family is widely used for address decoding in digital systems. Other variants include LVC for low voltage and HCS for automotive applications.

Replacement Considerations

SN74LS138D: Slower speed, lower power consumption. SN74HC138D: Higher noise immunity, wider voltage range. SN74HCT138D: TTL-compatible inputs with CMOS outputs.