7442 BCD to Decimal Decoder IC | Pro Tronix

Product Description

The 7442 BCD to Decimal Decoder IC (also designated as a 4-line to 10-line decoder/demultiplexer) is a high-speed TTL digital logic integrated circuit designed to convert 4-bit Binary Coded Decimal (BCD) inputs directly into 10 mutually exclusive active-LOW outputs. Operating on standard Boolean decoding logic, the chip processes input values from 0 to 9 ($0000_2$ to $1001_2$) and drives the corresponding decimal output pin LOW while maintaining all other output lines HIGH.

Engineered with full internal logic decoding, the 7442 guarantees that all ten outputs remain OFF (HIGH) for invalid non-BCD input states (binary 10 through 15). It features active-LOW outputs, making it ideal for driving indicator LEDs, relay coils, or secondary control logic that triggers on a ground transition. Housed in a standard 16-pin DIP package and running on a 5V DC supply, the IC interfaces smoothly with microcontrollers like Arduino, STM32, and ESP32, as well as discrete binary counters. It is a critical building block for numerical readouts, channel selectors, keypad matrix scanning, and digital logic training kits.

⚠️ Active-LOW Output Logic Tip: The 7442 utilizes inverted (active-LOW) outputs. When a decimal state is selected, its corresponding pin goes LOW (0V) while all other nine outputs remain HIGH (+5V). If you are driving indicator LEDs directly from the outputs, connect the LED cathodes to the 7442 pins and use current-limiting resistors to VCC (+5V). Always tie unused input lines (A, B, C, or D) to GND or VCC to prevent invalid logic states.

Technical & Logic Architecture

This 4-to-10 line decoder provides precise BCD conversion and logic demultiplexing:

• 10 Mutually Exclusive Outputs: Dedicated active-LOW outputs representing decimal digits 0 through 9.

• Full Invalid-Code Blanking: Automatically suppresses all outputs (forces all HIGH) for non-BCD input codes ($1010_2$ to $1111_2$).

• Demultiplexer Capability: Can be configured as a 1-of-8 or 1-of-10 demultiplexer by using input lines as data and strobe lines.

• Breadboard-Friendly Package: Standard 16-pin Dual In-Line Package (DIP-16) for easy breadboard and IC socket prototyping.

7442 Truth Table (Function Table)

Key Terms for Truth Table:

• H: High Voltage Level (Logic 1 / VCC)

• L: Low Voltage Level (Logic 0 / GND)

• X: Don’t Care (High or Low)

• BCD Inputs: A is Least Significant Bit (LSB / $2^0$), D is Most Significant Bit (MSB / $2^3$).

7442 Pinout Description & Logic Functions

• Pin 1 – Output 0: Active-LOW output for decimal 0.

• Pin 2 – Output 1: Active-LOW output for decimal 1.

• Pin 3 – Output 2: Active-LOW output for decimal 2.

• Pin 4 – Output 3: Active-LOW output for decimal 3.

• Pin 5 – Output 4: Active-LOW output for decimal 4.

• Pin 6 – Output 5: Active-LOW output for decimal 5.

• Pin 7 – Output 6: Active-LOW output for decimal 6.

• Pin 8 – GND: Ground reference pin (0V).

• Pin 9 – Output 7: Active-LOW output for decimal 7.

• Pin 10 – Output 8: Active-LOW output for decimal 8.

• Pin 11 – Output 9: Active-LOW output for decimal 9.

• Pin 12 – Input D (MSB): Binary bit $2^3$ input line.

• Pin 13 – Input C: Binary bit $2^2$ input line.

• Pin 14 – Input B: Binary bit $2^1$ input line.

• Pin 15 – Input A (LSB): Binary bit $2^0$ input line.

• Pin 16 – VCC: Positive power supply input pin (+5V DC nominal).

Operating Modes Summary

1. BCD to Decimal Decoding: Converts binary counter outputs (e.g., from a 7490 counter) into 10 discrete line outputs for driving numeric status displays.

2. 1-of-10 Demultiplexing: Routes an incoming data pulse on an input line to one of 10 designated output channels.

3. Sequential Matrix Scanning: Drives sequential columns or rows in keypad scanners or LED matrix indicators.

Applications

• Digital Display Drivers: Decoding binary data to drive discrete numeric indicators or incandescent lamps.

• 1-of-10 Channel Selectors: Selecting one of ten hardware peripherals using a 4-bit address bus.

• Sequential Switch Controllers: Triggering sequential relays, stepping sequences, or state-machine actions.

Technical Specifications

What’s in the Box

• 1 x 7442 BCD to Decimal Decoder IC (DIP-16).

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🛠️ Complete Your Breadboard Setup

To quickly wire and test the 7442 BCD to Decimal Decoder IC without soldering, make sure to check out our collection of breadboards, prototype boards, and jumper wires:

• Breadboards & Prototype PCBs: Explore our full range of solderless breadboards and prototyping boards for easy circuit assembly: Pro Tronix Breadboards & PCBs

• Jumper Wires & Connecting Cables: Grab high-quality male-to-male and male-to-female jumper wires to connect your IC pins to power and signal lines: Pro Tronix Wires & Cables Collection