74156 IC Dual 2-Line to 4-Line Decoders/Demultiplexer DIP-16

The 74156 IC is a dual 2-line to 4-line decoder/demultiplexer designed for digital logic applications. It comes in a standard DIP-16 package and is part of the TTL logic family. Each decoder within the IC can decode a 2-bit binary input into one of four mutually exclusive outputs, making it useful in memory addressing, data routing, and control applications. The IC includes enable inputs that allow independent control of each decoder, supporting flexible circuit designs. With active-low outputs, the 74156 is commonly employed in systems requiring efficient selection of data lines, expansion of I/O, or implementation of demultiplexing functions. Its reliable performance, compatibility with standard TTL devices, and ease of integration make it suitable for educational projects, digital circuits, and microprocessor-based systems.

• Dual 2-to-4 line decoder/demultiplexer in a single package.
• Active-low outputs for easy integration with TTL logic systems.
• Independent enable inputs for each decoder, allowing flexible control.
• Can be used for decoding binary inputs or for demultiplexing data lines.
• Standard DIP-16 package for easy handling and prototyping.
• High-speed TTL logic compatibility.
• Low power consumption relative to older logic families.
• Reliable operation for memory addressing, data routing, and control applications.
• Widely used in digital systems, microprocessor interfacing, and educational electronics.

Pin Layout

Pin Configuration

Pin No.	Pin Name	Description
1	1C	Data / Select Input C for Decoder 1
2	1G’	Enable Input (Active Low) for Decoder 1
3	1B	Select Input B for Decoder 1
4	1Y3	Output Y3 of Decoder 1 (Active Low)
5	1Y2	Output Y2 of Decoder 1 (Active Low)
6	1Y1	Output Y1 of Decoder 1 (Active Low)
7	1Y0	Output Y0 of Decoder 1 (Active Low)
8	GND	Ground (0V Reference)
9	2Y0	Output Y0 of Decoder 2 (Active Low)
10	2Y1	Output Y1 of Decoder 2 (Active Low)
11	2Y2	Output Y2 of Decoder 2 (Active Low)
12	2Y3	Output Y3 of Decoder 2 (Active Low)
13	2B	Select Input B for Decoder 2
14	2G’	Enable Input (Active Low) for Decoder 2
15	2C	Data / Select Input C for Decoder 2
16	VCC	Supply Voltage (+5V for TTL)

Specifications

Parameter	Test Conditions / Notes	Typical Value	Units
VOL (when IOL = 4 mA)	VCC = 4.5 V, output low current = 4 mA	0.25	V
VOL (when IOL = 8 mA)	VCC = 4.5 V, output low current = 8 mA	0.35	V
IOH (High-level output current)	VCC = 4.5 V, VOH = 5.5 V	0.1	mA
ICCL (Supply current, low outputs)	VCC = 5.5 V	5	mA
Input leakage current, high (IIH)	VCC = 5.5 V, VI = 2.7 V	20	µA
Input leakage current, low (IIL)	VCC = 5.5 V, VI = 0.4 V	–0.1	µA
Propagation delay, tPLH / tPHL	A, B → any Y (CL = 50 pF, RL = 500 Ω)	25 to 55	ns

Applications

• Memory Address Decoding.
• Data Routing / Demultiplexing.
• I/O Expansion.
• Microprocessor & Microcontroller Interfacing.
• Signal Selection.
• Control Systems.
• LED / Display Driving.
• Programmable Logic & Digital Systems.
• Educational & Training Kits.

Package Contents

• 1 x  74156 IC Dual 2-Line to 4-Line Decoders/Demultiplexer DIP-16

Datasheet

• 74156