74ACT138PC

Signal Switches, Multiplexers, Decoders Overview

The Fairchild Semiconductor 74ACT138PC is a high-speed 1-of-8 decoder and demultiplexer integrated circuit belonging to the 74ACT logic series. It features three binary address inputs that select one of eight mutually exclusive outputs, which are active-low. The device operates within a supply voltage range of 4.5V to 5.5V and supports output drive currents of 24mA for both high and low states. It is housed in a 16-pin Plastic Dual-In-Line (DIP) package with a standard pin pitch of 0.300 inches (7.62mm). The component is rated for an operating temperature range from -40°C to +85°C.

Signal Switches, Multiplexers, Decoders Feature Summary

• Provides high-speed decoding capabilities suitable for memory chip select applications
• Converts three binary input lines into eight mutually exclusive active-low outputs
• Features robust output drive capability with 24mA source and sink current

Signal Switches, Multiplexers, Decoders Applications

• High-speed bipolar memory chip select address decoding
• Digital system address decoding
• Demultiplexing data streams in digital circuits

Signal Switches, Multiplexers, Decoders Procurement Notes

Verify the manufacturer origin carefully, as Fairchild Semiconductor has undergone corporate integration. Confirm the specific suffix 'PC' corresponds to the 16-pin DIP package variant rather than surface-mount options. Check RoHS compliance status against current regulatory requirements. Ensure the part status is active or available through authorized distributors, as legacy logic parts may have limited availability or obsolescence risks.

Signal Switches, Multiplexers, Decoders Selection Notes

Select this component when a 1-of-8 decoding function is required with CMOS-compatible speeds and bipolar-level drive strength. The 74ACT series offers faster switching than standard 74LS logic while maintaining compatible power consumption levels relative to older technologies. Ensure the design accommodates the 4.5V to 5.5V supply requirement and the physical space constraints of the 16-pin DIP footprint.

Signal Switches, Multiplexers, Decoders Part Context

This device is part of the widely adopted 74ACT family, designed to bridge the performance gap between TTL and CMOS logic families. The 74ACT138 specifically addresses the need for efficient address decoding in systems utilizing fast memory or I/O ports. Its mutual exclusivity ensures that only one output is active at any given time based on the input code, simplifying control logic design.

Signal Switches, Multiplexers, Decoders Replacement Considerations

Direct substitutes include the onsemi MC74ACT138DTR2G and 74ACT138SCX, though these utilize surface-mount packages (TSSOP and SOIC respectively) rather than the through-hole DIP format. For equivalent DIP packaging, verify cross-manufacturer equivalents such as those from Texas Instruments or NXP that maintain the 74ACT specification and 16-DIP form factor.