Texas Instruments CD74HC138M96

Overview

CD74HC138M96 from Texas Instruments is a high-speed CMOS 3-to-8 line decoder/demultiplexer with active-low outputs, operating from 2 V to 6 V, featuring 13 ns typical propagation delay at 5 V/15 pF, -55°C to +125°C temperature range, and three enable inputs (G2, G1, G0) for cascading in memory address decoding applications.

For engineers reviewing the CD74HC138M96 datasheet, CD74HC138M96 pinout, CD74HC138M96 application, or CD74HC138M96 equivalent, this device serves as a logic-level address selector in industrial control systems, microcontroller I/O expansion, and bus multiplexing where low-power, wide-voltage operation and precise output enable control are required.

Technical Context

The CD74HC138M96 implements a standard 3-input binary address decoder with three independent strobe inputs (G2, G1, G0) that force all eight outputs (Y0–Y7) high when asserted - enabling hierarchical decoding across multiple devices. Its HC logic family ensures CMOS input compatibility and rail-to-rail output swing.

It operates in two functional modes: normal decoding (all enables satisfied) yields one active-low output per 3-bit address; any enabled strobe overrides selection and forces all outputs high. No internal latching or clocking is present - it is purely combinational logic with defined setup/hold timing relative to input transitions.

Key Specifications

Pinout & Package

CD74HC138M96 is housed in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm, with standard JEDEC MS-012AC footprint and RoHS-compliant NiPdAu/Sn lead finish (Level-1 MSL rating).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC138DR and CD74HCT138M96, the CD74HC138M96 uniquely balances wide-voltage operation (2–6 V), extended temperature support (-55°C to +125°C), and proven long-term availability in SOIC packaging - making it the optimal choice for industrial and infrastructure applications demanding reliability over raw speed or legacy compatibility.

Availability

CD74HC138M96 is available at Aetrix Electronics and suitable for memory address decoding, I/O port expansion, and bus multiplexing applications requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for CD74HC138M96 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 delivering analog and embedded processing solutions, with over 90 years of innovation in logic, power management, and signal chain technologies.

CD74HC138M96 belongs to TI's CD74HC logic family, engineered for high-reliability industrial and automotive systems where wide supply voltage tolerance, extended temperature operation, and long-term product availability are essential design requirements.

FAQ

What is the maximum clock frequency supported by CD74HC138M96 for address decoding?

The CD74HC138M96 is a combinational logic device with no internal clock - its usable frequency depends on propagation delay and system timing margins. With 13 ns typical tpd at 5 V, it supports reliable decoding in address buses operating below ~30 MHz (assuming 2× delay margin). For higher frequencies, verify setup/hold times against your controller's address valid window using the device's published switching characteristics table.

Can CD74HC138M96 operate at 3.3 V and interface directly with a 3.3 V microcontroller?

Yes, CD74HC138M96 is fully specified for 2 V to 6 V operation and has CMOS-compatible input thresholds - at 3.3 V supply, VIH = 2.31 V (70% of VCC) and VIL = 0.99 V (30% of VCC), ensuring robust interfacing with standard 3.3 V GPIOs without level shifters or pull-up resistors.

Does CD74HC138M96 support cascading with other decoders, and how is it implemented?

Yes, CD74HC138M96 supports cascading via its three enable inputs: G2 (active-high), G1 and G0 (active-low). To cascade two devices, tie G2 of the second CD74HC138M96 to one output (e.g., Y0) of the first, and connect G1/G0 to logic low - enabling the second decoder only when the first selects its Y0 output.

What is the output drive capability of CD74HC138M96, and can it directly drive LEDs?

Each output of CD74HC138M96 sinks up to 4 mA at VOL ≤ 0.4 V (VCC = 4.5 V), sufficient to drive low-current LEDs (e.g., 2 mA @ 1.8 V forward voltage) with a series resistor. For higher-current LEDs or multiple parallel loads, add a buffer transistor - the device is not rated for continuous >4 mA per output.

Is CD74HC138M96 pin-compatible with CD74HCT138M96, and can they be interchanged on the same PCB?

Yes, CD74HC138M96 and CD74HCT138M96 share identical SOIC-16 pinout and package dimensions, but differ in input voltage thresholds and supply range. Interchanging them requires verifying system voltage (HCT requires 4.5–5.5 V) and input logic levels - a 3.3 V controller will not reliably drive CD74HCT138M96, whereas CD74HC138M96 works across 2–6 V.