Texas Instruments CD74HC147PW

Overview

CD74HC147PW from Texas Instruments is a high-speed CMOS 9-input priority encoder performing 10-line-to-4-line active-low encoding with decimal zero implied, operating across 2V–6V supply range, featuring 13ns typical propagation delay at 5V/15pF, -55°C to +125°C temperature rating, and buffered inputs/outputs for industrial keypad scanning and fault-tolerant control logic.

For engineers reviewing the CD74HC147PW datasheet, CD74HC147PW pinout, CD74HC147PW application, or CD74HC147PW equivalent, this page delivers verified functional identity, TSSOP-16 package mapping, truth table behavior under simultaneous input assertion, noise immunity specs (NIL/NIH = 30% at VCC = 5V), and real-world implementation guidance for priority-based digital encoding in safety-critical embedded systems.

Technical Context

The CD74HC147PW implements combinational priority encoding logic where input I9 holds highest priority and forces Y3–Y0 to binary 1001 (active-low), with all outputs HIGH only when all nine inputs (I0–I9) are HIGH - representing the implied "zero" state. It uses silicon-gate CMOS technology with no internal latches or clocks.

Its operation requires no external timing components; propagation delay (tPLH/tPHL) is load-dependent (CL = 15pF or 50pF), and transition times (tTLH/tTHL) remain balanced across temperature extremes (-55°C to 125°C), ensuring deterministic response in asynchronous control paths.

Key Specifications

Pinout & Package

TSSOP-16 package (PW), 5.00 mm × 4.40 mm body size, 1.2 mm max height, 0.65 mm lead pitch, exposed metal not present - suitable for compact PCB layouts with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar priority encoder applications.

Compared with SN74HC147N, CD74HC147PW saves 60% board area and enables reflow-soldered reliability; compared with CD74HCT147PW, it offers broader supply flexibility but requires CMOS-compatible input sources - making CD74HC147PW optimal for mixed-voltage industrial controllers.

Availability

CD74HC147PW is available at Aetrix Electronics and suitable for industrial keypad interfaces, automotive fault prioritization circuits, PLC input modules, and legacy system bus retrofits requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC147PW 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 logic solutions for industrial, automotive, and communications markets.

CD74HC147PW belongs to TI's HC-series high-speed CMOS logic family, designed specifically for low-power, wide-voltage, and high-noise-immunity digital encoding in harsh-environment control systems.

FAQ

What is the function of the NC pin on CD74HC147PW?

Pin 15 is designated NC (No Connection) and has no internal bond wire or circuit connection. It must remain unconnected on the PCB - neither tied to VCC, GND, nor left floating with stub traces - to prevent parasitic coupling or solder bridging during reflow. This is confirmed in TI's official pin function table and mechanical drawings for PW package.

Does CD74HC147PW support 3.3V operation?

Yes, CD74HC147PW fully supports 3.3V operation as part of its 2V–6V supply range. At VCC = 3.3V, it maintains valid logic thresholds (VIH ≥ 2.1V, VIL ≤ 1.1V), 100% tested functionality across -55°C to 125°C, and typical propagation delay of ~18ns (CL = 15pF), making it suitable for mixed-voltage industrial controllers interfacing with 3.3V microcontrollers.

How does CD74HC147PW handle simultaneous active inputs?

CD74HC147PW implements strict hardware priority: when multiple inputs go LOW simultaneously, only the highest-priority input determines the output code - I9 > I8 > … > I0. This behavior is hardwired in silicon and requires no clock or enable signal, ensuring deterministic encoding even during power-up or reset transitions.

What is the maximum capacitive load CD74HC147PW can drive?

CD74HC147PW is characterized up to CL = 50pF in switching specifications, with tPLH/tPHL = 27ns max at VCC = 6V. For loads exceeding 50pF, propagation delay increases linearly - e.g., at CL = 100pF, delay degrades by ~15%. Layout best practices (short traces, ground plane) are essential to maintain timing integrity at higher capacitance.

Is CD74HC147PW pin-compatible with CD74HCT147PW?

Yes, CD74HC147PW and CD74HCT147PW share identical TSSOP-16 pinout, pin functions, and truth table behavior. The sole difference is input threshold compatibility: CD74HC147PW uses CMOS thresholds (VIH = 70% VCC), while CD74HCT147PW uses TTL thresholds (VIH = 2V min). Both are drop-in replacements electrically if supply and driving logic match their respective input requirements.