Introduction for The IC LM339N Quad Diff Comparator

/ 2018-09-06 / News

The LM339N is a quadruple differential comparator designed to operate from a single power supply over a wide voltage range. Dual power operation is also possible, as long as the difference between the two supplies is 2 to 36V and the VDC is at least 1.5V more positive than the common mode input voltage. The current consumption is independent of the supply voltage. The outputs can be connected to other open-collector outputs to achieve wired-AND relationships.

Key Features:

Manufacturer: Texas Instruments 

Mounting Style: Through Hole 

Comparator Type: Differential 

Product: Analog Comparators 

Subcategory: Amplifier ICs 

Supply Type: Single, Dual 

Technology: Bipolar 

Number of Channels: 4 Channel 

Output Type: Rail-to-Rail 

Output Current per Channel: 6 mA 

Ib - Input Bias Current: 50 nA 

Vos - Input Offset Voltage: 5 mV 

Supply Voltage - Max: 30 V 

Supply Voltage - Min: 2 V 

Operating Supply Current: 500 uA 

Response Time: 300 ns 

Minimum Operating Temperature: 0 C 

Maximum Operating Temperature: + 70 C 

Dual Supply Voltage: +/- 3 V, +/- 5 V, +/- 9 V, +/- 12 V 

GBP - Gain Bandwidth Product: - 

Ios - Input Offset Current: 50 nA 

Maximum Dual Supply Voltage: +/- 15 V 

Minimum Dual Supply Voltage: 1 V 

Operating Supply Voltage: 2 V to 30 V 

Pd - Power Dissipation: 1050 mW 

Voltage Gain dB: 106.02 dB


High-Precision Comparators

Reduced VOS Drift Overtemperature

Eliminates Need for Dual Supplies

Allows Sensing Near GND

Compatible With All Forms of Logic

Power Drain Suitable for Battery Operation


The pinout is very simple.


The 4 operational amplifiers have 3 pins each. They have 2 inputs to compare the input is greater. And they have an output whose voltage depends on the comparison of the 2 inputs. If the reversing voltage is higher, the output will be raised to high Vdc. If the non-reversed voltage is greater, then the output will be pulled down to GND. This applies to each of the 4 op-amps. If each of the op-amps has higher reversing voltages than the non-reversing ones, all outputs will be set to a high Vdc value. If all non-inverting voltages are higher, all outputs will be conducted at GND.

Apart from the op-amps inputs and outputs, the LM393 has 2 pins for power supply. One pin is Vdc, where the positive voltage is connected and the other is GND, where it is connected to GND or negative voltage. This serves a dual purpose. This gives the LM393 power so that the chip can work. Second, the voltage that is fed into these power supply pins serve as a polarization of the circuit. The amount of voltage fed to the power pins is applied to the output pins to power any load connected to the output terminals of the op amps. Therefore, sufficient power must be supplied to the op amp's power pins to power any load connected to the chip's output terminals. This means that if you are powering a 9V motor, at least 9V must be plugged into the power pin of the LM393.

Then, to demonstrate the LM393, we will build a circuit that will show how it works. 


• Limit Comparators

• Simple Analog-to-Digital Converters (ADCs)

• Pulse, Squarewave, and Time Delay Generators

• Wide Range VCO; MOS Clock Timers

• Multivibrators and High-Voltage Digital Logic Gates

LM339 Circuit diagram

Below is the circuit diagram of the LM339 quadruple voltage comparator circuit that we are going to build.


This circuit was built for demonstration purposes, just to show you how to connect an LM339 and how it works. In this circuit, there are 4 LEDs of different colors, so you can demonstrate each of the 4 op-amps one at a time. At each of the operational reversing terminals, we connect the wiper terminal of a potentiometer. One end of the potentiometer goes to Vdc and the other end goes to ground. At each of the non-inverter terminals of the op-amps, we connect +2V power.

To power the LM339 chip, we connect the Vcc terminal (pin 3) of the +5V chip and the GND terminal (pin 12) to the ground. This gives the LM339 the power it needs to work, as well as providing the polarization of our circuitry. This is because when the reversing terminal is greater than the non-inverting terminal for an operational, the output will be brought to Vdc.

To each of the output pins, we connect a current limiting resistor (about 330Ω) and an LED. The LEDs are all of different colors, but if you don't have all of the different colors, using the same color is fine. It will still work the same. The colors serve to distinguish the different outputs, but if you use the same colors, you can still easily observe how this circuits.

With all the pins connected, we can now go beyond the circuit works. And it's very simple.

First, before demonstrating the circuit, adjust all the potentiometers so that they emit almost 0Ω of resistance. This will ensure that all outputs are turned off the first time you use the circuit. If you turn on the circuit now, all LEDs should be off. Now take the potentiometer regulator and adjust the potentiometer so that its resistance increases. When you turn it at a certain point, the point where it goes beyond 2V, the first LED will light up. This is because the voltage of the inverting terminal is now greater than the voltage of the non-inverting terminal. Thus, the output fluctuates from VDC to ground and the load turns on. If we repeat this for the next 3 operational amplifiers (potentiometer adjustment), the same result will occur. Each of the output LEDs will light when the voltage exceeds the 2V reference value entered in the non-inverting terminal.

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