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 |
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
How to use LM339 Voltage Comparator
First let us consider the internal connection of four comparators in the device as shown below.
Now let us take a single comparator from the four and construct a simple application circuit as show below.
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.
Applications
- Oscillators
- Voltage comparators
- Peak detectors
- Logic voltage translation
- Power supervision
- Industrial
- Measuring instruments
- Automotive
