Texas Instruments CD74HC137E

Overview

CD74HC137E 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), three binary select inputs (A0–A2), and operates from 2V to 6V with propagation delay of 31ns (typ) at VCC = 6V, CL = 15pF.

For engineers reviewing the CD74HC137E datasheet, CD74HC137E pinout, CD74HC137E application, or CD74HC137E equivalent, this page delivers verified functional behavior, latch-controlled output isolation, cascading support via dual enables, and design-critical timing specs across -55°C to +125°C.

Technical Context

The CD74HC137E integrates a 3-bit address latch followed by a 1-of-8 decoder, enabling transparent input-to-output operation when LE is low and latched selection when LE is high. Its two independent output enables (OE0, OE1) allow hierarchical cascading and flexible demultiplexing - one enable serves as data input while the other remains active.

It uses silicon-gate CMOS technology for low power consumption (ICC ≤ 160 µA over full temperature range) and high noise immunity (NIL/NIH = 30% of VCC at 5V), with balanced propagation delays and transition times optimized for synchronous digital systems requiring deterministic address decoding.

Key Specifications

Pinout & Package

CD74HC137E is supplied in a 16-pin plastic dual in-line package (PDIP), with 0.3-inch body width and standard through-hole mounting footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC237E and CD74HCT137E, the CD74HC137E uniquely combines active-low outputs with wide 2V–6V operation - making it optimal for low-voltage embedded controllers driving reset or chip-select lines directly without pull-ups or translators.

Availability

CD74HC137E is available at Aetrix Electronics and suitable for industrial automation, avionics subsystems, and test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC137E 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, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The CD74HC137E belongs to TI's High-Speed CMOS Logic family, engineered for low-power, high-noise-immunity digital interfacing in mission-critical systems operating across extreme temperatures.

FAQ

What is the primary function of the CD74HC137E?

The CD74HC137E is a 3-to-8 line decoder/demultiplexer with integrated address latches. It accepts three binary inputs (A0–A2), latches them on the rising edge of LE, and drives exactly one of eight active-low outputs (Y0–Y7) based on the latched address - provided both OE0 (low) and OE1 (high) are asserted. This makes CD74HC137E ideal for memory chip-select generation and data routing in synchronous digital systems.

How does the latch enable (LE) pin affect CD74HC137E operation?

When LE is low, the CD74HC137E operates in transparent mode: outputs respond immediately to changes on A0–A2. When LE transitions high, the current address is latched, freezing the output state regardless of subsequent address changes - isolating downstream circuitry from bus activity. This behavior is essential for glitch-free chip selection during multi-cycle address setup, and is a defining feature of the CD74HC137E.

Can CD74HC137E operate at 3.3V supply voltage?

Yes, CD74HC137E supports 2V to 6V operation, including standard 3.3V logic rails. At VCC = 3.3V, its input thresholds scale proportionally (VIH ≈ 2.31V min, VIL ≈ 0.99V max), and propagation delay increases to ~45ns (typ) at CL = 15pF. This allows direct interfacing with 3.3V microcontrollers and FPGAs without level-shifting, distinguishing CD74HC137E from TTL-compatible variants like CD74HCT137E.

What is the difference between CD74HC137E and CD74HC237E?

The CD74HC137E and CD74HC237E share identical pinout, package, and latch/decode architecture, but differ in output polarity: CD74HC137E has active-low outputs (Yx = LOW when selected), while CD74HC237E has active-high outputs (Yx = HIGH when selected). This affects downstream interface design - CD74HC137E directly drives reset or chip-select inputs expecting active-low assertion, whereas CD74HC237E suits enable lines requiring active-high logic.

Does CD74HC137E support cascading with other decoders?

Yes, CD74HC137E supports cascading via its dual output enables: OE0 (active-low) and OE1 (active-high). One CD74HC137E can use its Y outputs to control OE0/OE1 of downstream units, enabling hierarchical decoding trees - e.g., a master unit selects one of eight slave decoders, each managing eight sub-peripherals. This eliminates external AND/OR logic and simplifies large-scale address decoding in CD74HC137E-based systems.