Texas Instruments CD74HCT137MT

Overview

CD74HCT137MT from Texas Instruments is a high-speed CMOS 3-to-8 line decoder/demultiplexer with address latches, designed for memory address decoding and data routing in industrial control and embedded systems. It features active-low outputs, dual output enables (OE0, OE1), latch enable (LE), and operates over -55°C to +125°C at 4.5V–5.5V supply. Typical propagation delay is 16ns at VCC = 5V, CL = 15pF, TA = 25°C.

For engineers reviewing the CD74HCT137MT datasheet, CD74HCT137MT pinout, CD74HCT137MT application, or CD74HCT137MT equivalent, this page delivers verified functional behavior, latch-controlled output isolation, LSTTL-compatible input thresholds (VIL ≤ 0.8V, VIH ≥ 2.0V), and SOIC-16 package-specific thermal and timing data - critical for deterministic address decoding in safety-critical or wide-temperature designs.

Technical Context

The CD74HCT137MT implements a 3-bit binary latch followed by an active-low 1-of-8 decoder. Inputs A0–A2 are latched on LE high, decoupling output state from subsequent address changes. Output enable logic uses OE0 and OE1 in AND configuration: both must be low for any output to activate.

Its HCT logic family ensures direct compatibility with LSTTL inputs while delivering CMOS power efficiency. Propagation delays are balanced across all eight outputs (Y0–Y7), and transition times remain consistent under 50pF load, supporting reliable demultiplexing in synchronous bus architectures.

Key Specifications

Pinout & Package

CD74HCT137MT is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package with standard 1.27mm pitch, 7.5mm body width, and 1.75mm max height per JEDEC MO-153. Pin 1 is marked by a notch or dot; device orientation follows standard IC conventions with pin 1 in top-left corner when viewed from top with marking side up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT137N, CD74HCT137MT saves board area and improves thermal performance in surface-mount assemblies; compared with CD74HCT237MT, it provides native active-low drive for sinking loads without external inverters - critical for minimizing component count in safety-critical routing paths.

Availability

CD74HCT137MT is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive ECU memory mapping, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HCT137MT 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 for industrial, automotive, and aerospace markets.

The CD74HCT137MT belongs to TI's high-speed CMOS logic family, engineered for deterministic, low-power address decoding and data routing in mission-critical systems operating across extreme temperatures.

FAQ

What is the maximum clock frequency supported by CD74HCT137MT in demultiplexer mode?

The CD74HCT137MT does not operate on a clock signal - it is a combinatorial logic device with latch enable (LE) for asynchronous address capture. Its maximum usable input toggle rate is determined by propagation delay (16ns typ) and transition time (15–22ns), supporting reliable operation up to ~30MHz address change rates under 15pF load. For synchronous systems, LE timing must meet tSU ≥13ns and tH ≥11ns at VCC = 5V.

Can CD74HCT137MT drive LEDs directly without current-limiting resistors?

No - CD74HCT137MT outputs can sink up to 25mA per pin, but internal output impedance and thermal limits require external current-limiting resistors. For a typical red LED (VF ≈ 1.8V at 10mA), a 330Ω resistor is recommended with VCC = 5V. Operating without resistors risks exceeding absolute maximum output current (±25mA) and degrading long-term reliability.

Is CD74HCT137MT pin-compatible with CD74HC137MT?

Yes - CD74HCT137MT and CD74HC137MT share identical pinout, package (SOIC-16), and functional block diagram. However, CD74HC137MT operates from 2V–6V and has CMOS-input thresholds, while CD74HCT137MT is restricted to 4.5V–5.5V with LSTTL-compatible inputs. Substitution requires verifying supply voltage and driver compatibility.

How does the latch enable (LE) function affect output behavior during address transitions?

When LE is high, CD74HCT137MT latches the current A0–A2 values; outputs remain stable regardless of subsequent address bus changes. When LE is low, outputs track A0–A2 in real time (transparent mode). This prevents glitches during partial address updates - critical in systems where address bits may change asynchronously.

Does CD74HCT137MT support hot insertion or live circuit replacement?

No - CD74HCT137MT is not hot-swap rated. Its absolute maximum ratings specify no bias on inputs or outputs before VCC is applied. Inserting or removing the device while powered risks latch-up, excessive current flow through input protection diodes, or permanent damage. Always power down the system before handling.