LM339 – Voltage Comparator IC

24 October 2018 - 0 Comments

LM339 Voltage Comparator IC

LM339 Pinout

LM339 is a voltage comparator IC from LMx39x series and is manufactured by many industries. The devices consist of four independent voltage comparators that are designed to operate from a single power supply. Also operation from dual supplies is possible, as long as the difference between the two supplies is 2 V to 36 V.

LM339 Pin Configuration

LM339 is a 14 pin device as shown in above pin diagram. Here we will name the pinout of all four comparators on the chip and describe function of each pin.

Pin	Name	Description
1	1OUT	Output pin of the comparator 1
2	2OUT	Output pin of the comparator 2
3	VCC	Power supply
4	2IN-	Negative input pin of the comparator 2
5	2IN+	Positive input pin of the comparator 2
6	1IN-	Negative input pin of the comparator 1
7	1IN+	Positive input pin of the comparator 1
8	3IN-	Negative input pin of the comparator 3
9	3IN+	Positive input pin of the comparator 3
10	4IN-	Negative input pin of the comparator 4
11	4IN+	Positive input pin of the comparator 4
12	GND	Ground
13	4OUT	Output pin of the comparator 4
14	3OUT	Output pin of the comparator 3

The device is available in many packages; a designer can choose one depending on their requirement.

Features and Electrical Characteristics of LM339

Four individually operated voltage comparators
Low noise interference among comparators
Single Supply Operation: +3.0 V to +36 V
Dual Supply Operation: +18V and -18V
Low Input Bias Current: 25 nA
Low Input Offset Current: ±5.0 nA
Low Input Offset Voltage
Input Common Mode Voltage Range to GND
Low Output Saturation Voltage: 130 mV @ 4.0 mA
TTL and CMOS compatible
ESD Clamps on the inputs increase reliability without affecting device operation
Pb−Free, Halogen Free/BFR Free and RoHS compliant

Similar to LM339 Voltage Comparators

LM311, LM324, LM397, LM139, LM239, LM2901 etc.

LM339 IC Overview

LM339 is used in applications where a comparison between two voltage signals is required. In addition with four of those comparators on board the device can compare four pairs of voltage signals at a time which comes in handy in some applications. The comparator is popular among makers and engineers for being low cost and good performance. The device response is also fast enough to satisfy many applications.

How to use LM339 Voltage Comparator

First let us consider the internal connection of four comparators in the device as shown below.

LM339 Internal Connections

Now let us take a single comparator from the four and construct a simple application circuit as show below.

LM339 Voltage Comparator Circuit

Here the comparison between voltages V1 and V2 is done by the device and an output is provided as Vo. Also the device is powered from single voltage source of VCC as shown above.

In the circuit the comparison output goes as,

If V1>V2 then Vo = VCC

If V2>V1 the Vo = 0V or GND

Based on the state of the output we can determine whether V1 is higher or V2 is higher at the input.