Texas Instruments CD74AC138M96

Overview

CD74AC138M96 from Texas Instruments is a 3-line to 8-line decoder/demultiplexer in SOIC-16 package, operating from 1.5 V to 5.5 V with ±24 mA output drive, balanced propagation delays, and SCR-latchup-resistant CMOS process. It features three enable inputs (G1, G2A, G2B) for cascading and is designed for high-speed memory decoding and data-routing systems.

For engineers reviewing the CD74AC138M96 datasheet, CD74AC138M96 pinout, CD74AC138M96 application, or CD74AC138M96 equivalent, key selection criteria include supply voltage range (1.5–5.5 V), worst-case propagation delay of 11 ns at 5 V, 3-state outputs with active-low enables, ESD rating of ±2000 V HBM, and compatibility with high-density memory address decoding in industrial control and test equipment.

Technical Context

The CD74AC138M96 implements positive-logic 3-to-8 decoding with three independent strobe inputs (G1, G2A, G2B) that must all be asserted-G1 high and G2A/G2B low-for any output Y0–Y7 to activate. Its function table defines eight mutually exclusive active-low outputs based on binary input A/B/C combinations.

It uses a robust CMOS process with Schmitt-trigger inputs on enable pins, ensuring noise immunity at 30% of VCC, and supports fanout to 15 F-type devices. Propagation delays are balanced across all paths (tPLH ≈ tPHL), and output drive capability remains stable across –55°C to 125°C operating temperature.

Key Specifications

Pinout & Package

CD74AC138M96 is housed in a 16-pin SOIC (D) package measuring 9.9 mm × 6.0 mm body size, with gull-wing leads and RoHS-compliant NiPdAu plating. Thermal performance is characterized by RθJA = 106.6°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-to-8 decoder applications.

Compared with SN74AC138DR and CD74HC138M96, CD74AC138M96 uniquely combines extended temperature operation, ±24 mA drive, and latchup resistance-making it the sole choice for ruggedized memory decoding and industrial signal routing where reliability and timing margin are critical.

Availability

CD74AC138M96 is available at Aetrix Electronics and suitable for memory address decoding, industrial PLC I/O expansion, test equipment signal routing, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74AC138M96 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions, with decades of heritage in high-reliability logic families and industrial-grade qualification.

CD74AC138M96 belongs to TI's Advanced CMOS (AC) logic portfolio, engineered specifically for high-speed memory decoding and data-routing applications demanding low propagation delay, wide supply range, and robust latchup immunity.

FAQ

What is the maximum operating frequency supported by CD74AC138M96?

The CD74AC138M96 does not specify a clock frequency-it is a combinational logic device with propagation delay as the key timing parameter. At VCC = 5 V, its worst-case tPD is 11 ns, supporting reliable operation in address decode paths up to ~45 MHz (1/2 × tPD). System-level frequency depends on total path delay including trace length and load capacitance. The CD74AC138M96 itself imposes no fundamental clock limit.

Can CD74AC138M96 operate from a 1.8 V supply?

Yes. CD74AC138M96 is fully specified from 1.5 V to 5.5 V, including 1.8 V operation. At 1.8 V, VIH = 1.44 V and VIL = 0.36 V, providing 20% noise margin. Output drive drops to ±12 mA, but remains sufficient for driving modern low-voltage logic families. The CD74AC138M96 maintains full functionality and timing compliance across this entire range.

Does CD74AC138M96 require pull-up resistors on its outputs?

No. CD74AC138M96 has active-push-pull outputs-not open-drain-so pull-ups are unnecessary. Each Y0–Y7 output actively drives high or low when enabled, and enters high-impedance (Hi-Z) state when disabled. Adding pull-ups would cause contention during active-low output states and is explicitly discouraged in the datasheet.

How does the enable logic work on CD74AC138M96?

CD74AC138M96 requires all three enables to be simultaneously asserted: G1 must be HIGH, and both G2A and G2B must be LOW. Only then will the selected Yx output go LOW (all others HIGH). If any enable condition fails, all outputs go HIGH (not Hi-Z)-a design feature ensuring fail-safe default state. This triple-enable scheme prevents partial decoding during power-up or reset transitions. The CD74AC138M96 implements this logic internally with no external components needed.

Is CD74AC138M96 pin-compatible with CD74HC138M96?

Yes-CD74AC138M96 and CD74HC138M96 share identical SOIC-16 pinout, pin functions, and footprint. However, they are not functionally interchangeable without design review: the AC version offers faster speed (11 ns vs. 29 ns), higher drive (±24 mA vs. ±5.2 mA), and latchup immunity, while the HC version operates down to 2 V and draws less quiescent current. Swapping requires verifying timing margins, load requirements, and environmental conditions. The CD74AC138M96 delivers superior performance where speed and drive strength matter.