The LM339 IC functions as a quad voltage comparator. This means it contains four independent comparators in one package. Engineers use the LM339 to compare voltages and detect changes in electronic signals. It offers high precision with a low input bias current of 25 nA and an input offset current of ±5 nA. The device supports a wide supply voltage range from 3 V to 36 V and works well with both TTL and CMOS logic circuits. Its low output saturation voltage of 130 mV at a 4 mA load ensures energy efficiency, making it a popular choice for low-power and precise applications. For more details, designers often refer to the LM339 datasheet.
Key Takeaways
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The LM339 IC contains four separate voltage comparators in one chip, allowing multiple voltage checks in a small space.
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It works with a wide supply voltage range from 2V to 36V, making it flexible for many electronic devices and power sources.
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The LM339 uses very little power and has low input bias and offset currents, which helps save energy and improves accuracy.
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Its open-collector output design lets it connect easily with different digital logic circuits like TTL and CMOS.
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Engineers use the LM339 for tasks like voltage monitoring, signal generation, and logic level translation in many practical applications.
LM339 IC Basics
What It Is
The LM339 is a special type of integrated circuit called a quad voltage comparator. This means it has four separate comparators inside one small chip. Each comparator checks two input voltages and decides which one is higher. The chip then sends out a signal based on this comparison. Engineers use the LM339 to help electronic devices make decisions, like turning on a warning light if a battery gets too low.
The LM339 works well in many types of circuits. It can handle a wide range of supply voltages, from as low as 2 volts up to 36 volts. This flexibility makes it useful in battery-powered gadgets, power supplies, and even car electronics. The chip also uses very little power when it is not working hard, which helps save energy.
Note: The Texas Instruments application report SNOAA35A and the LM339 datasheet SLCS006U both provide detailed information about how the LM339 works in real circuits. These documents show that the LM339 meets important standards for accuracy, reliability, and safety.
How It Works
The LM339 compares two voltages at its input pins. If the voltage at the non-inverting input (+) is higher than the voltage at the inverting input (−), the output switches to a low state. If the inverting input (−) is higher, the output stays high. The output does not produce a full voltage by itself. Instead, it needs an external pull-up resistor to connect the output to the supply voltage. This design helps the LM339 work with different types of logic circuits, like TTL and CMOS.
The chip can work with both single and split power supplies. This means it can fit into many different circuit designs. The LM339 also stays stable if the power supply and grounding are set up correctly. In real-world use, engineers often use the LM339 for tasks like monitoring power supplies, creating timing signals, and translating voltage levels between different parts of a circuit.
Here is a table showing some important performance numbers for the LM339:
| Parameter | Value | Description |
|---|---|---|
| Input Offset Voltage (Vos) | 5 mV | Shows how much voltage difference is needed to balance the inputs. |
| Input Bias Current (Max) | 0.25 μA @ 5V | Maximum current flowing into the input pins. |
| Quiescent Current (Max) | 2.5 mA | Current used when the chip is idle. |
| Output Current (Typical) | 18 mA @ 5V | Usual amount of current the output can handle. |
| Max Supply Voltage | 36 V | Highest voltage the chip can safely use. |
| Min Supply Voltage | 2 V | Lowest voltage needed for the chip to work. |
| Operating Temperature | 0°C to 70°C | Temperature range where the chip works best. |
| Voltage Gain | 106.02 dB | Shows how much the chip can amplify a signal. |
| Recommended Operating Limits | Output current ≤ 16 mA | For long life, keep output current below this value. |
| Supply voltage ≤ 28 V | For best results, use a supply voltage below this value. |
The LM339 helps in many practical circuits. For example, it can watch over a power supply and send a signal if the voltage drops too low. It can also create timing signals in oscillator circuits or help different parts of a system talk to each other by changing voltage levels. These uses show how the LM339 compares voltages and controls other parts of a circuit, making it a key part of many electronic systems.
Main Features
Quad Comparator
The LM339 IC contains four independent voltage comparators in a single package. This quad configuration allows engineers to compare four pairs of voltages at the same time. Each comparator works separately, so designers can use them for different tasks within one circuit. This setup saves space on the circuit board and reduces the number of chips needed.
A table below shows how the quad comparator design supports precision and speed:
| Performance Metric | Measured Value | Significance |
|---|---|---|
| Response Time | 1.3 microseconds | Enables fast decisions in real-time circuits |
| Offset Voltage | ~2 mV | Provides accurate voltage comparisons |
| Input Bias Current | 25 nA (typical) | Maintains signal quality |
| Input Offset Current | 3 nA (typical) | Reduces comparison errors |
| Differential Input Voltage Range | Up to ±36 V | Handles a wide range of input signals |
| Output Saturation Voltage | Low | Ensures efficient switching |
The quad comparator feature makes the LM339 ideal for applications like battery monitoring, window detection, and adaptive power control. By comparing multiple voltages at once, the chip helps devices make quick and reliable decisions.
Open-Collector Output
Each comparator in the LM339 uses an open-collector output. This type of output pulls the signal to ground when active but does not drive it high. Instead, an external pull-up resistor connects the output to the supply voltage. This design lets the LM339 work with different logic families, such as TTL, CMOS, and MOS.
The open-collector output offers several advantages:
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It allows multiple outputs to connect together for a wired-AND function.
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It provides clear switching between logic states.
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It keeps the output saturation voltage low, which means less power is wasted as heat.
The LM339’s open-collector outputs also make it easy to interface with other digital circuits. Engineers can choose the right pull-up resistor to match the needs of their design. This flexibility helps the LM339 fit into many types of electronic systems.
Tip: Proper selection of the pull-up resistor ensures correct logic levels and limits current, which protects both the LM339 and other connected devices.
Low Offset Voltage
The LM339 features a low input offset voltage, usually around 1 to 3 millivolts. This small value means the comparator can detect tiny differences between its input voltages. Low offset voltage is important for precision applications, such as sensor circuits and voltage monitoring.
A low input offset current, typically about 3 nA, further improves accuracy. The chip’s low input bias current, around 25 nA, helps maintain the integrity of weak signals from high-impedance sources. These characteristics make the LM339 suitable for sensitive measurements and reliable voltage detection.
Technical articles and datasheets confirm that the LM339’s low offset voltage and current values support its reputation for precision. The device can compare voltages accurately, even when the input signals are very close together.
Wide Voltage Range
The LM339 operates over a wide supply voltage range. It works with single supplies from 2 V to 36 V, or dual supplies up to ±18 V. This flexibility allows the chip to function in many different environments, from battery-powered gadgets to industrial equipment.
A summary table highlights the LM339’s voltage range and related features:
| Feature | Range / Value | Impact in Circuits |
|---|---|---|
| Supply Voltage Range | 2 V to 36 V (single), ±1 V to ±18 V (dual) | Adapts to various power sources |
| Common-Mode Input Range | Includes ground | Useful for low-voltage and sensor circuits |
| Differential Input Range | Up to ±36 V | Handles large voltage differences |
| Output Compatibility | TTL, CMOS, MOS logic | Integrates with many digital systems |
The wide voltage range, combined with low power consumption (about 0.8 mA typical), makes the LM339 energy efficient. It works well in both low-power and high-voltage applications. The chip’s design also supports fast response times, from 165 nanoseconds to 1.3 microseconds, which is important for real-time signal processing.
The LM339’s energy efficiency and precision have been proven in both DIY and industrial projects. Its ability to compare multiple voltages quickly and accurately helps engineers build reliable, space-saving circuits.
LM339 Datasheet and Specs
Key Parameters
The LM339 datasheet provides a detailed look at the most important technical features of this IC. Engineers often check these parameters before choosing the LM339 for a project. The chip comes in a 14-pin Dual In-line Package (DIP), which makes it easy to use on standard circuit boards. The LM339 datasheet lists four independent comparator channels, so one chip can handle several tasks at once.
Here is a table that shows the main parameters from the LM339 datasheet:
| Parameter | Typical / Maximum Value / Range |
|---|---|
| Number of Channels | 4 |
| Package Type | 14-pin DIP |
| Supply Voltage Range | 2 V to 36 V (single), ±1 V to ±18 V (dual) |
| Input Offset Voltage | ±1 mV (typical), max 5 mV at 25°C |
| Input Bias Current | 25 nA (typical), max 250 nA |
| Input Offset Current | ±5 nA (typical) |
| Output Type | Open-collector |
| Output Saturation Voltage | 250 mV (typical at 4 mA sink current) |
| Propagation Delay Time | 1.3 µs |
| Output Compatibility | TTL, DTL, ECL, MOS, CMOS |
The LM339 datasheet also mentions that the chip works well with both single and dual power supplies, making it flexible for many designs.
Electrical Ratings
The LM339 datasheet gives clear limits for safe operation. These ratings help engineers design circuits that last a long time and work reliably. The chip can handle a wide range of temperatures, from 0°C to 70°C, which covers most indoor and outdoor uses. The LM339 datasheet also shows that the chip uses very little current, which helps save energy in battery-powered devices.
Below is a summary of the electrical ratings found in the LM339 datasheet:
| Parameter | Value / Range |
|---|---|
| Operating Temperature Range | 0°C to 70°C |
| Storage Temperature Range | -65°C to 150°C |
| Maximum Supply Voltage | 36 V (single supply) |
| Minimum Supply Voltage | 2 V (single supply) |
| Maximum Output Current (per channel) | 6 mA |
| Static Current per Channel (max) | 0.5 mA |
| Quiescent Current | 1.1 mA (typical) |
| Response Time (Low to High) | 0.3 µs to 1.3 µs |
The LM339 datasheet also lists similar devices, such as the LM239 and LM2901, which offer extended temperature ranges for harsher environments. The detailed tables in the LM339 datasheet help engineers compare these options and pick the right part for their needs.
Tip: Always check the LM339 datasheet before starting a new design. The datasheet gives the most accurate and up-to-date information about the chip’s performance and safety limits.
Applications
Voltage Monitoring
The LM339 IC plays a key role in voltage monitoring circuits. Engineers often use it to check battery levels or power supply voltages. When the voltage drops below a set point, the LM339 can trigger a warning light or shut down a device to prevent damage. This function helps protect sensitive electronics and ensures safe operation.
A table below shows how the LM339 fits into different practical applications:
| Application Area | Practical Use Case Description |
|---|---|
| Voltage Monitoring | Used in voltage level detection circuits such as battery monitoring, where it detects threshold crossings to trigger warnings or system responses. |
| Signal Generation | Employed in pulse generation and shaping circuits, producing precise square waves and pulses for timing and motor control applications. |
| Logic Level Translation | Utilizes open-collector outputs to interface with various logic families, allowing easy integration with different system voltage levels via pull-up resistors. |
| Window Comparator Circuits | Functions as a window comparator to verify if signals lie within set voltage limits, useful in quality control systems. |
| Oscillator Designs | Acts as relaxation oscillators or multivibrators to generate periodic signals for clock, timing, or audio output purposes. |
In battery-powered devices, the LM339 helps extend battery life by signaling when it is time to recharge or replace the battery. This makes it a popular choice in portable electronics and backup power systems.
Signal Generation
The LM339 also works well in signal generation circuits. Designers use it to create square waves and timing pulses. These signals control the timing of motors, lights, and other devices. The LM339 can shape and clean up signals, making them more reliable for digital circuits.
In oscillator designs, the LM339 acts as a relaxation oscillator or multivibrator. It generates periodic signals for clocks, timers, or even simple audio outputs. This versatility allows engineers to use the LM339 in many timing and control applications.
Tip: The LM339’s fast response time and precision make it ideal for generating accurate timing signals in both hobby and industrial projects.
Logic Level Translation
The LM339 stands out in logic level translation tasks. Its open-collector output allows easy interfacing with different logic families. By adding a pull-up resistor, the output can match the voltage levels needed by other parts of the circuit.
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The LM339 comparator IC features an open collector output.
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Open collector outputs allow multiple outputs to be safely wired together.
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This characteristic makes LM339 suitable for interfacing with digital logic levels and logic level translation.
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In contrast, the LM358 op-amp has a totem-pole output, which cannot be connected in parallel with others.
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Therefore, LM339 is preferred over LM358 for applications requiring logic level translation due to its output stage design.
This feature helps engineers connect circuits that use different voltages, such as 3.3V and 5V systems. The LM339 ensures smooth communication between these systems, making it a valuable tool in mixed-voltage designs.
Comparisons
Similar ICs
Engineers often compare the LM339 with other voltage comparator ICs. The LM339N is one of the closest alternatives. Both chips offer four independent comparators and open-collector outputs. However, they show some key differences in performance and application.
The table below highlights important specifications:
| Specification | LM339 | LM339N |
|---|---|---|
| Number of Channels | 4 | 4 |
| Output Type | Open-collector | Open-collector, Open-drain |
| Propagation Delay Time (μs) | 0.3 | 0.7 |
| Maximum Supply Voltage (V) | 30 | 36 |
| Minimum Supply Voltage (V) | 2 | 2 |
| Offset Voltage @ 25°C (mV) | 5 | 5 |
| Typical Quiescent Current (mA) | 0.2 | 0.2 |
| Maximum Input Bias Current (nA) | 50 | 250 |
| Operating Temperature Range (°C) | 0 to 70 | 0 to 70 |
| Common Mode Input Voltage Range (V) | 0 to 28.5 | 0 to 34 |
The LM339 supports a wider supply voltage range and has a faster propagation delay than the LM339N. It also features a much lower input bias current, which helps in precision tasks. Both chips share similar offset voltages and temperature ranges. The LM339N, with its compact packaging and efficient power use, fits well in consumer electronics like induction cookers. The LM339, on the other hand, is better for industrial and high-voltage uses.
Unique Advantages
The LM339 stands out for several reasons:
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Versatility: It works with a wide supply voltage range, from 2V to 36V. This makes it suitable for both low-voltage and high-voltage circuits.
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Precision: Its low input bias current allows for accurate voltage comparisons, even with weak signals.
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Robustness: The LM339 handles demanding environments, making it a top choice for industrial systems.
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Fast Response: With a quick propagation delay, the LM339 can react to changes in signals almost instantly.
The LM339’s combination of speed, precision, and voltage flexibility makes it a favorite for engineers designing reliable and efficient electronic systems. Its robust design ensures stable operation in both simple and complex circuits.
The LM339 IC stands out as a reliable quad voltage comparator for many electronics projects. Its main strengths include:
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Four independent comparators for multiple voltage checks
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Wide supply voltage range for flexible designs
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Low power use with minimal input bias and offset current
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Operation near ground level for sensitive circuits
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Compatibility with TTL and CMOS logic
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Stable output with low saturation voltage
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Built-in ESD protection and RoHS compliance
Engineers use the LM339 in control systems, measuring tools, and automotive safety. For detailed design help, the LM339 datasheet gives complete technical information.
FAQ
What does "open-collector output" mean in the LM339?
The LM339 uses an open-collector output. This means the output can pull the signal to ground but cannot drive it high. An external pull-up resistor connects the output to the supply voltage.
Can the LM339 compare signals close to ground?
Yes. The LM339 can sense voltages that are very close to ground. This feature helps in circuits that need to detect low-level signals or work with single-supply power.
How do engineers connect the LM339 to digital logic circuits?
Engineers add a pull-up resistor to the output pin. This resistor matches the voltage needed by the digital logic circuit. The LM339 then works with TTL, CMOS, or MOS logic families.
What is the main difference between the LM339 and an op-amp?
| LM339 Comparator | Op-Amp |
|---|---|
| Fast switching | Amplifies |
| Open-collector | Push-pull |
| Compares signals | Boosts signals |
The LM339 compares voltages and switches quickly. An op-amp mainly amplifies signals.
Is the LM339 suitable for battery-powered devices?
Yes. The LM339 uses very little current. Its low power use makes it a good choice for battery-powered gadgets and portable electronics.
Written by Jack from AIChipLink.
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