Introduction
The LM339 is a popular quad voltage comparator IC that integrates four independent comparators into a single package. Unlike operational amplifiers, comparators are designed to switch quickly and decisively, producing a digital (binary) output that indicates which of two analog input voltages is higher. The LM339 is optimized for such applications: it can operate from a single supply voltage (or dual supplies) over a wide voltage range, and its outputs are open-collector to allow interfacing with different logic levels and wiring configurations.

One of the standout features of the LM339 is its ability to include the ground (0 V) within its input common-mode voltage range when used on a single supply. This means it can compare signals down to 0 V, which is very useful in many embedded and mixed-signal circuits. Because the outputs are open-collector, the LM339 cannot drive the output high by itself; instead, an external pull-up resistor is required, and multiple outputs can be wired together (wired-AND logic) if needed.
LM339 Quad Comparator IC

While the LM339 is widely used in hobby and industrial circuits, designers must consider its propagation delay, output saturation level, and input bias currents in more demanding designs. For many threshold detection, under-voltage protection, and sensor interface roles, it remains a go-to choice thanks to its robustness, wide supply voltage range, and low cost.
LM339 Pinout

LM339 Key Features
- Quad comparator: four independent comparators in one IC
- Single-supply operation: typically 3.0 V to 36 V
- Dual (split) supply operation supported: ±1.5 V to ±18 V (i.e. ± range)
- Low input bias current: ~25 nA typical
- Low input offset current: typically ±5 nA
- Low output saturation voltage: ~130 mV at 4 mA
- Input common-mode range includes ground
- TTL/CMOS compatible output (via pull-ups)
- ESD protection/clamps on input pins for reliability
- Ability to wire outputs for wired-AND logic
- Available in various packages (DIP-14, SOIC-14, TSSOP etc.)
LM339 Specifications/Characteristics
- Supply Voltage Range: 3 V to 36 V (single supply) or ±1.5 V to ±18 V (dual supply)
- Quiescent Supply Current: ~0.8 mA typical, independent of supply voltage
- Input Offset Voltage (Vos): typically 2 mV, maximum up to 5 mV
- Input Bias Current: around 25 nA typical
- Input Offset Current: about ±5 nA typical
- Input Common-Mode Voltage Range: from ground (0 V) up to (VCC – 1.5 V)
- Output Saturation Voltage: ~130 mV at 4 mA sink current
- Maximum Output Sink Current: up to 16 mA (depends on load and pull-up)
- Propagation Delay (Response Time): typically 1.3 µs with overdrive
- Operating Temperature Range: 0 °C to +70 °C
- Package Options: 14-pin DIP, SOIC, TSSOP, and other variants
Note: DATASHEET DOWNLOAD button is provided end of this article.
Pin Configuration of LM339 Quad Comparator IC
Pin# | Pin Name | Pin Description |
---|---|---|
1 | OUTPUT2 | Output of comparator channel 2 (open-collector) |
2 | OUTPUT1 | Output of comparator channel 1 |
3 | V+ (VCC) | Positive supply voltage input |
4 | INPUT1– | Inverting input (–) of comparator channel 1 |
5 | INPUT1+ | Non-inverting input (+) of comparator channel 1 |
6 | INPUT2– | Inverting input (–) of comparator channel 2 |
7 | INPUT2+ | Non-inverting input (+) of comparator channel 2 |
8 | INPUT3– | Inverting input (–) of comparator channel 3 |
9 | INPUT3+ | Non-inverting input (+) of comparator channel 3 |
10 | INPUT4– | Inverting input (–) of comparator channel 4 |
11 | INPUT4+ | Non-inverting input (+) of comparator channel 4 |
12 | GND | Ground / negative supply reference (0 V) |
13 | OUTPUT4 | Output of comparator channel 4 |
14 | OUTPUT3 | Output of comparator channel 3 |

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Key Applications of LM339 Quad Comparator IC
- Voltage threshold detection, window comparators
- Battery monitoring / under voltage protection
- Zero-crossing detectors, AC waveform discrimination
- Oscillators, pulse generation, timing circuits
- Sensor interfaces (thermistor, photo-diode comparators)
- Logic-level translation and interfacing to TTL/CMOS
- Peak detectors, envelope detectors
- Control systems, industrial automation
- Power supply supervision, fault detection
- Multi-channel analog decision blocks in embedded systems
LM339 Equivalent ICs / Alternatives
- LM2901 – quad comparator similar to LM339, often rated for wider temperature range (–40 °C to +125 °C)
- LM239 / LM139 – earlier or variant families of comparators with similar topology
- LM311 – single comparator, can be used as alternative when one comparator is needed (but you’ll need four for equivalent)
- LM393 – dual comparator (you’d need two to match functionality)
- MC3302 – another quad comparator family sometimes used in similar roles
- MAX/Kia-brand comparators (various single/dual types) depending on speed, input range, etc.
In newer versions, LM339B is offered as a drop-in upgrade with improved performance (lower offset, faster, extended voltage) compared to older LM339 versions.
(The pinout for certain ICs can vary from that of the LM339).
Datasheet of LM339 Quad Comparator IC
Click the following Button below to download the datasheet of LM339 :
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