Renesas 74ACT138FPEL-E

Overview

74ACT138FPEL-E from Renesas (formerly Hitachi) is a high-speed 1-of-8 decoder/demultiplexer with TTL-compatible inputs, active-Low mutually exclusive outputs, 24 mA output drive capability, and three enable inputs (E1, E2 active-Low; E3 active-High). It is used in memory address decoding, bus demultiplexing, and logic expansion circuits operating at 5 V.

For engineers reviewing the 74ACT138FPEL-E datasheet, 74ACT138FPEL-E pinout, 74ACT138FPEL-E application, or 74ACT138FPEL-E equivalent, key selection criteria include propagation delay (≤11.5 ns @ 5 V), output sink/source strength (24 mA), enable input logic polarity, DC supply current (≤8.0 µA @ 25°C), and compatibility with TTL-level control signals.

Technical Context

The 74ACT138FPEL-E implements a 3-to-8 binary decoder with fully decoded active-Low outputs. Its triple-enable architecture (E1, E2, E3) enables hierarchical expansion-e.g., four devices + one inverter achieve 1-of-32 decoding without external logic gates beyond the inverter.

It functions as an 8-output demultiplexer when one enable input (e.g., E1) serves as data input while others act as strobes. All outputs remain HIGH unless E1 = LOW, E2 = LOW, and E3 = HIGH-ensuring strict mutual exclusivity and predictable state control under valid enable conditions.

Key Specifications

Pinout & Package

74ACT138FPEL-E uses a 16-pin plastic DIP (Dual In-line Package) with 0.3-inch body width and 0.1-inch lead pitch, compliant with JEDEC MS-001 and EIAJ FP-16DA standards. Weight: 0.24 g.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 1-of-8 decoder/demultiplexer applications.

Compared with SN74ACT138N and 74HCT138N, the 74ACT138FPEL-E delivers superior speed (11.5 ns vs. 19 ns) and output strength (24 mA vs. 4 mA), making it the preferred choice for timing-critical address decoding and direct-load driving-while maintaining full functional equivalence with SN74ACT138N in pin-compatible designs.

Availability

74ACT138FPEL-E is available at Aetrix Electronics and suitable for memory address decoding, bus demultiplexing, and logic expansion systems requiring stable component supply, long-term industrial lifecycle support, and verified 5 V TTL/CMOS interoperability.

Supply support for 74ACT138FPEL-E includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Renesas Electronics Corporation is a global semiconductor leader formed from the merger of NEC Electronics and Renesas Technology, specializing in microcontrollers, analog, power, and logic solutions for automotive, industrial, and infrastructure markets.

The 74ACT138FPEL-E belongs to Renesas' legacy high-speed CMOS logic family, designed specifically for low-latency, high-drive digital interfacing in memory subsystems and industrial control backplanes.

FAQ

What logic family does the 74ACT138FPEL-E belong to, and how does it differ from 74HC or 74HCT variants?

The 74ACT138FPEL-E is part of the Advanced CMOS Technology (ACT) family, featuring TTL-compatible inputs and 24 mA output drive. Unlike 74HC (high-speed CMOS, CMOS input thresholds) or 74HCT (TTL-compatible inputs but only 4 mA drive), the 74ACT138FPEL-E combines fast propagation (≤11.5 ns) with robust output strength-making it uniquely suited for driving multiple TTL loads without buffers. Its VCC rating is strictly 5.0 V ± 0.5 V.

Can the 74ACT138FPEL-E be used as a demultiplexer, and how is that configured?

Yes-the 74ACT138FPEL-E can operate as an 8-output demultiplexer. To do so, assign one active-Low enable input (e.g., E1) as the data input, and tie the remaining enables (E2 and E3) to fixed logic states (E2 = LOW, E3 = HIGH) to activate the device. The A0–A2 address inputs then route the data to one of eight active-Low outputs. This configuration is explicitly supported in the functional description and truth table of the 74ACT138FPEL-E datasheet.

What is the maximum propagation delay of the 74ACT138FPEL-E across its full industrial temperature range?

The maximum propagation delay of the 74ACT138FPEL-E is 11.5 ns for address-to-output transitions (An → On) and 13.0 ns for enable-to-output transitions (E3 → On), measured at VCC = 5.0 V ± 0.5 V and CL = 50 pF over –40°C to +85°C. These values are specified in the "AC Characteristics: HD74ACT138" section of the official Renesas datasheet for the 74ACT138FPEL-E.

Does the 74ACT138FPEL-E support 3.3 V operation?

No-the 74ACT138FPEL-E is rated exclusively for 5.0 V ± 0.5 V operation. Its AC characteristics, input thresholds, and output drive specifications are defined only at 5 V. The datasheet provides no timing or DC parameters for 3.3 V, and attempting 3.3 V operation may result in undefined behavior, excessive propagation delay, or failure to meet output voltage specifications. Use 74LVC138 or similar for 3.3 V systems.

How many 74ACT138FPEL-E devices are needed to implement a 1-of-32 decoder, and what additional component is required?

Four 74ACT138FPEL-E devices are required to implement a 1-of-32 decoder, along with one 74ACT04 hex inverter. The inverter generates the complement of the highest-order address bit (e.g., A4), which drives the E3 inputs of two decoder groups-enabling full 5-bit (A0–A4) to 32-line decoding. This configuration is illustrated in Figure a of the 74ACT138FPEL-E datasheet and requires no additional logic gates beyond the inverter.