Texas Instruments 8406401EA

Overview

8406401EA from Texas Instruments is a CD54HC147 high-speed CMOS 10-to-4-line priority encoder in a 16-pin CDIP (J) package, operating from 2V to 6V with -55°C to +125°C temperature range. It accepts nine active-low inputs (I0–I9), encodes decimal "zero" when all inputs are high, and delivers active-low 4-bit binary outputs (Y0–Y3) with priority resolution (I9 highest). Used in industrial control panels for keypad scan encoding and fault prioritization logic.

For engineers reviewing the 8406401EA datasheet, 8406401EA pinout, 8406401EA application, or 8406401EA equivalent, this page delivers verified electrical specs (13ns typical propagation delay at 5V), thermal data (RθJA = 67°C/W), input/output voltage thresholds, fanout capability (15 LSTTL loads), and precise pin mapping for layout and validation - all confirmed against TI's SCHS149G production datasheet.

Technical Context

The 8406401EA implements a silicon-gate CMOS priority encoder with active-low input and output logic, where I9 holds highest priority and forces Y3–Y0 = LHLH. Its truth table defines encoding behavior across all nine inputs, including the implied "zero" state when all inputs are high (outputs all high).

It supports wide supply operation (2V–6V) with CMOS-level noise immunity (NIL/NIH = 30% of VCC at 5V), balanced propagation delay and transition times, and quiescent current as low as 8µA at 25°C - enabling direct replacement of LSTTL encoders while reducing system power consumption significantly.

Key Specifications

Pinout & Package

8406401EA is housed in a 16-pin Ceramic Dual In-line Package (CDIP, J), body size 21.34mm × 6.92mm, with through-hole mounting and SNPB (tin-lead) lead finish. Pin 1 index area located at top-left corner; pins 1–8 on left side, 9–16 on right side (top view).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC147E and CD74HCT147E, the 8406401EA provides superior moisture resistance and thermal cycling endurance via ceramic packaging, making it the sole choice for mission-critical military and space-grade systems where long-term reliability under extreme conditions is non-negotiable.

Availability

8406401EA is available at Aetrix Electronics and suitable for industrial control panels, avionics test equipment, and automotive diagnostic modules requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 8406401EA 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 with emphasis on reliability, longevity, and industrial/military qualification.

The CD54HC147 product line was designed specifically for high-reliability, wide-temperature applications in defense, aerospace, and harsh-environment industrial systems - prioritizing hermetic packaging, extended thermal range, and proven radiation-tolerant process technology.

FAQ

What is the absolute maximum supply voltage rating for 8406401EA?

The absolute maximum supply voltage (VCC) for 8406401EA is 7V, as specified in Section 4.1 of the TI SCHS149G datasheet. Operation above this voltage risks permanent damage. Recommended operating range remains 2V to 6V. Always observe this limit during power-up sequencing, transient events, or hot-swap scenarios to ensure long-term reliability of the 8406401EA.

Does 8406401EA support true "zero" encoding when all inputs are high?

Yes, the 8406401EA implements implied decimal "zero" encoding: when all nine inputs (I0–I9) are high, all four outputs (Y0–Y3) go high. This behavior is defined in the truth table (Table 6-1) and functional description of the 8406401EA. It enables compact representation of ten states (0–9) using only nine physical inputs - a key feature distinguishing it from basic binary encoders.

What is the meaning of "NC" on pin 15 of 8406401EA?

Pin 15 of the 8406401EA is marked "NC" (No internal connection) per Table 3-1 in the TI datasheet. It is an unconnected die pad with no bond wire or circuit tie. This pin must remain floating - neither tied to VCC nor GND - to prevent mechanical stress on the ceramic package or unintended capacitive coupling that could affect timing margins in the 8406401EA.

How does the 8406401EA handle simultaneous assertion of multiple inputs?

The 8406401EA resolves simultaneous input assertions using fixed priority: I9 (pin 10) has highest priority, followed by I8 (pin 5), I7 (pin 4), down to I0 (pin 9). When two or more inputs are low, only the highest-priority active input determines the output code. This priority logic is hardwired in the silicon and requires no configuration - a deterministic behavior guaranteed across all operating conditions for the 8406401EA.

Is 8406401EA compatible with 3.3V logic systems?

Yes, the 8406401EA operates fully within 2V–6V supply range, including 3.3V nominal systems. At VCC = 3.3V, its VIH is 2.31V (70% of 3.3V) and VIL is 1.1V (30% of 3.3V), providing robust noise margins. Output VOH exceeds 3.2V and VOL stays below 0.1V, ensuring clean interfacing with 3.3V CMOS receivers - confirmed by electrical characteristics tables in the 8406401EA datasheet.