Texas Instruments CD74HC147MT

Overview

CD74HC147MT from Texas Instruments is a high-speed CMOS 9-input priority encoder that implements 10-line-to-4-line encoding with active-low inputs (I0–I9) and active-low binary outputs (Y3–Y0), supporting implied decimal "zero" encoding when all inputs are high. It operates from 2V to 6V, delivers 13ns typical propagation delay at 5V/15pF, and functions across -55°C to 125°C for industrial control panel key encoding and fault-priority logic in legacy TTL-compatible systems.

For engineers reviewing the CD74HC147MT datasheet, CD74HC147MT pinout, CD74HC147MT application, or CD74HC147MT equivalent, this page provides verified functional identity, validated SOIC-16 pin mapping, confirmed HC-series voltage and timing specs, and two technically documented alternative encoders - all directly applicable to discrete logic design, keypad interface, and priority interrupt encoding tasks.

Technical Context

The CD74HC147MT implements combinational priority encoding logic where input I9 has highest priority and I0 lowest; when multiple inputs are low, only the highest-priority active-low input determines the 4-bit active-low binary output. Its silicon-gate CMOS architecture ensures rail-to-rail output swing, buffered I/O, and noise immunity of 30% of VCC at 5V.

It uses no internal latches or clocks - operation is purely asynchronous and level-sensitive. Input loading follows HC-type unit load definitions (1.1–1.5 loads per input), and quiescent current remains ≤160 µA over full temperature range, enabling low-power embedded logic without external pull-ups.

Key Specifications

Pinout & Package

CD74HC147MT is supplied in a 16-pin SOIC (D) package measuring 9.90 mm × 3.90 mm, with standard 1.27 mm pitch and gull-wing leads compatible with IPC-7351 land patterns.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC147MT, CD74HC147M96 offers identical functionality in production-ready packaging, while SN74HC147N trades extended temperature range for broader commercial availability - making CD74HC147MT most suitable for legacy high-reliability designs requiring full military-grade thermal qualification.

Availability

CD74HC147MT is available at Aetrix Electronics and suitable for industrial keypad interfaces, priority interrupt encoding, and legacy TTL-to-CMOS logic translation requiring stable component supply across extended temperature ranges.

Supply support for CD74HC147MT 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, with over 50 years of innovation in high-reliability logic ICs.

The CD74HC147MT belongs to TI's CD74HC high-speed CMOS logic family, engineered for low-power, wide-voltage, and extended-temperature operation in industrial automation, aerospace, and instrumentation systems.

FAQ

What is the logic function implemented by the CD74HC147MT?

The CD74HC147MT is a 9-input active-low priority encoder that converts up to nine simultaneous low inputs (I0–I9) into a 4-bit active-low binary output (Y3–Y0), with I9 having highest priority. It implements the 10-line-to-4-line encoding function using implied decimal "zero", meaning all outputs go high when all inputs are high - a behavior confirmed in the device truth table and functional description.

Does the CD74HC147MT support 3.3V operation?

Yes, the CD74HC147MT supports 3.3V operation as part of its 2V–6V supply range. At 3.3V, it maintains valid HC logic thresholds (VIH ≈ 2.1V, VIL ≈ 1.1V), delivers typical propagation delay <20 ns, and draws <100 µA quiescent current - making it suitable for mixed-voltage systems interfacing with 3.3V microcontrollers without level shifters.

Is CD74HC147MT pin-compatible with the 74LS147?

No - while functionally equivalent as a 10-line-to-4-line priority encoder, CD74HC147MT is not pin-compatible with 74LS147. The 74LS147 uses a different pinout (e.g., I0 on pin 1, Y0 on pin 14), whereas CD74HC147MT places I0 on pin 9 and Y0 on pin 13. Direct replacement requires PCB modification or adapter wiring.

What does the "MT" suffix indicate in CD74HC147MT?

The "MT" suffix denotes a discontinued SOIC-16 package variant supplied in tube packaging (as opposed to "M96" for tape-and-reel). Per TI's packaging addendum, CD74HC147MT is marked "Obsolete" with no current production status, though functional specifications and pinout match active variants like CD74HC147M96 - confirming identical electrical behavior where available.

Can CD74HC147MT drive LED indicators directly?

No - CD74HC147MT outputs are designed for logic-level interfacing, not direct LED drive. Its absolute maximum output sink/source current is ±25 mA per pin, but recommended operating conditions limit continuous output current to ±6 mA to maintain VOH/VOL specs. For LED indication, use an external transistor or buffer stage to avoid violating DC electrical characteristics.