The 7427 Triple 3-Input NOR Gate IC is a high-speed TTL logic device that contains three independent NOR gates, each with three inputs. It performs the logical NOR function, outputting a LOW signal only when any input is HIGH. Designed for reliable digital logic operations, the 7427 offers fast switching speeds and stable performance across a wide range of temperatures. Packaged in a 14-pin DIP, it is ideal for use in combinational logic circuits, signal processing, and general-purpose digital systems.
Features
Three independent 3-input NOR gates in one IC.
High-speed TTL logic operation.
Performs standard NOR logic function.
Wide operating voltage range: 4.75V to 5.25V.
Low power consumption and fast switching.
Compatible with all TTL and CMOS logic families.
High noise immunity for reliable performance.
Standard 14-pin Dual Inline Package (DIP-14).
Suitable for cascading and complex logic designs.
Operating temperature range: 0°C to +70°C.
Pinout Configuration
Pin #
Type
Description
1
Input
Input to the first NOR gate.
2
Input
Input to the first NOR gate.
3
Input
Input to the second NOR gate.
4
Input
Input to the second NOR gate.
5
Input
Input to the second NOR gate.
6
Output
Output from the second NOR gate.
7
Power
Connect to ground (GND).
8
Output
Output from the third NOR gate.
9
Input
Input to the third NOR gate.
10
Input
Input to the third NOR gate.
11
Input
Input to the third NOR gate.
12
Output
Output from the first NOR gate.
13
Input
Input to the first NOR gate.
14
Power
Positive power supply (VCC). Connect to +5V power.
What does the 74HC27 / 74LS27 do?
The 74×27 gives you three 3-input NOR gates.
A NOR gate is a logic gate that outputs 1 (HIGH) if all of its inputs are 0 (LOW). Therefore, if you input a HIGH in any of the inputs, the output will become LOW. Otherwise, the output will be HIGH.
3-input NOR gate symbol
Truth Table for the 3-input NOR gate
Input A
Input B
Input C
Output Q
0
0
0
1
0
0
1
0
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
0
Specifications
Parameter
Description
IC Type
Triple 3-Input NOR Gate
Logic Family
TTL
Datasheet
7427
Number of Gates
3
Inputs per Gate
3
Logic Function
NOR (NOT-OR)
Operating Voltage (Vcc)
4.75V – 5.25V
Input High Voltage (VIH) (min)
2.0V
Input Low Voltage (VIL) (max)
0.8V
Output High Voltage (VOH) (min)
2.7V
Output Low Voltage (VOL) (max)
0.4V
Propagation Delay (typ)
15 nsec
Power Dissipation
10 mW per gate
Operating Temperature Range
0°C to +70°C
Package Type
DIP-14
Mounting Type
Through Hole
Pin Count
14 Pins
Technology
TTL – Transistor-Transistor Logic
How To Use This Chip
The 74HC27 comes in a 14-pin package, and you need to connect it to power before you can use it. Most 7400 ICs support a VCC voltage of 5V. One difference between the HC and LS version of the chip is that the 74HC27 supports 2V to 6V, while the 74LS27 only supports 5V.
The maximum current you can pull out of one output pin is 4 mA when the pin is high (sourcing) or 16 mA when the pin is low (sinking). This can differ between models, so check the datasheet of your model to verify.
Once you’ve connected it to power, you can use any of the three 3-input NOR gates inside.
The 74HC27/74LS27 IC connected to power
Applications
Digital logic and control circuits.
Combinational logic design and implementation.
Signal inversion and logic level control.
Data processing and timing circuits.
Logic decoders and encoders.
Arithmetic and logic unit (ALU) designs.
Digital system design and testing.
Interface and control modules in embedded systems.
