LM331 V-F Converter: Circuit, Price and Pinout
2.54mm 5V PMIC LM331 100kHz 5V 8-DIP (0.300, 7.62mm)
LM331 is a V-F Converter. This article mainly introduce its circuit, price, pinout and other detailed information about Texas Instruments LM331.

LM331 Light to Voltage to Frequency
- LM331 Description
- LM331 Pinout
- LM331 CAD Model
- LM331 Features
- Specifications
- LM331 Functional Block Diagram
- LM331 Schematic Diagram
- LM331 Internal Block Diagram
- LM331 V/F conversion circuit
- LM331 Application circuit
- LM331 Alternatives
- LM331 Applications
- LM331 Package
- LM331 Manufacturer
- Trend Analysis
- Datasheet PDF
LM331 Description
LM331 is a precision voltage/frequency converter integrated circuit produced by American NS company with high cost performance, simple peripheral circuit, single power supply, and low power consumption. The LM331 has a wide dynamic range of 100dB, an operating frequency as low as 0.1Hz, and has good linearity, and a digital resolution of up to 12 bits. The output driver of LM331 adopts the open-collector form, so the logic level of the output pulse can be flexibly changed by selecting the logic current and external resistance to adapt to different logic circuits such as TTL, DTL and CMOS. LM331 can work between 4.0V and 40V, the output can be as high as 40V, and can prevent VCC short circuit.
LM331 Pinout

LM331 CAD Model
Symbol

Footprint

3D Model

LM331 Features
★Guaranteed linearity: 0.01% (maximum)
★Low power consumption: 15mW5V
★Wide comprehensive frequency: 1Hzto100kHz
★Pulse output compatible with all logic forms
★Wide dynamic range: 100db
Specifications
- TypeParameter
- Lifecycle Status
Lifecycle Status refers to the current stage of an electronic component in its product life cycle, indicating whether it is active, obsolete, or transitioning between these states. An active status means the component is in production and available for purchase. An obsolete status indicates that the component is no longer being manufactured or supported, and manufacturers typically provide a limited time frame for support. Understanding the lifecycle status is crucial for design engineers to ensure continuity and reliability in their projects.
ACTIVE (Last Updated: 2 days ago) - Factory Lead Time6 Weeks
- Contact Plating
Contact plating (finish) provides corrosion protection for base metals and optimizes the mechanical and electrical properties of the contact interfaces.
Tin - Mount
In electronic components, the term "Mount" typically refers to the method or process of physically attaching or fixing a component onto a circuit board or other electronic device. This can involve soldering, adhesive bonding, or other techniques to secure the component in place. The mounting process is crucial for ensuring proper electrical connections and mechanical stability within the electronic system. Different components may have specific mounting requirements based on their size, shape, and function, and manufacturers provide guidelines for proper mounting procedures to ensure optimal performance and reliability of the electronic device.
Through Hole - Mounting Type
The "Mounting Type" in electronic components refers to the method used to attach or connect a component to a circuit board or other substrate, such as through-hole, surface-mount, or panel mount.
Through Hole - Package / Case
refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.
8-DIP (0.300, 7.62mm) - Number of Pins8
- Weight930.006106mg
- Packaging
Semiconductor package is a carrier / shell used to contain and cover one or more semiconductor components or integrated circuits. The material of the shell can be metal, plastic, glass or ceramic.
Tube - JESD-609 Code
The "JESD-609 Code" in electronic components refers to a standardized marking code that indicates the lead-free solder composition and finish of electronic components for compliance with environmental regulations.
e3 - Pbfree Code
The "Pbfree Code" parameter in electronic components refers to the code or marking used to indicate that the component is lead-free. Lead (Pb) is a toxic substance that has been widely used in electronic components for many years, but due to environmental concerns, there has been a shift towards lead-free alternatives. The Pbfree Code helps manufacturers and users easily identify components that do not contain lead, ensuring compliance with regulations and promoting environmentally friendly practices. It is important to pay attention to the Pbfree Code when selecting electronic components to ensure they meet the necessary requirements for lead-free applications.
yes - Part Status
Parts can have many statuses as they progress through the configuration, analysis, review, and approval stages.
Active - Moisture Sensitivity Level (MSL)
Moisture Sensitivity Level (MSL) is a standardized rating that indicates the susceptibility of electronic components, particularly semiconductors, to moisture-induced damage during storage and the soldering process, defining the allowable exposure time to ambient conditions before they require special handling or baking to prevent failures
1 (Unlimited) - Number of Terminations8
- ECCN Code
An ECCN (Export Control Classification Number) is an alphanumeric code used by the U.S. Bureau of Industry and Security to identify and categorize electronic components and other dual-use items that may require an export license based on their technical characteristics and potential for military use.
EAR99 - TypeVoltage to Frequency
- Max Operating Temperature
The Maximum Operating Temperature is the maximum body temperature at which the thermistor is designed to operate for extended periods of time with acceptable stability of its electrical characteristics.
70°C - Min Operating Temperature
The "Min Operating Temperature" parameter in electronic components refers to the lowest temperature at which the component is designed to operate effectively and reliably. This parameter is crucial for ensuring the proper functioning and longevity of the component, as operating below this temperature may lead to performance issues or even damage. Manufacturers specify the minimum operating temperature to provide guidance to users on the environmental conditions in which the component can safely operate. It is important to adhere to this parameter to prevent malfunctions and ensure the overall reliability of the electronic system.
0°C - Terminal Position
In electronic components, the term "Terminal Position" refers to the physical location of the connection points on the component where external electrical connections can be made. These connection points, known as terminals, are typically used to attach wires, leads, or other components to the main body of the electronic component. The terminal position is important for ensuring proper connectivity and functionality of the component within a circuit. It is often specified in technical datasheets or component specifications to help designers and engineers understand how to properly integrate the component into their circuit designs.
DUAL - Number of Functions1
- Supply Voltage
Supply voltage refers to the electrical potential difference provided to an electronic component or circuit. It is crucial for the proper operation of devices, as it powers their functions and determines performance characteristics. The supply voltage must be within specified limits to ensure reliability and prevent damage to components. Different electronic devices have specific supply voltage requirements, which can vary widely depending on their design and intended application.
5V - Terminal Pitch
The center distance from one pole to the next.
2.54mm - Frequency
In electronic components, the parameter "Frequency" refers to the rate at which a signal oscillates or cycles within a given period of time. It is typically measured in Hertz (Hz) and represents how many times a signal completes a full cycle in one second. Frequency is a crucial aspect in electronic components as it determines the behavior and performance of various devices such as oscillators, filters, and communication systems. Understanding the frequency characteristics of components is essential for designing and analyzing electronic circuits to ensure proper functionality and compatibility with other components in a system.
100kHz - Base Part Number
The "Base Part Number" (BPN) in electronic components serves a similar purpose to the "Base Product Number." It refers to the primary identifier for a component that captures the essential characteristics shared by a group of similar components. The BPN provides a fundamental way to reference a family or series of components without specifying all the variations and specific details.
LM331 - Pin Count
a count of all of the component leads (or pins)
8 - Power Supplies
an electronic circuit that converts the voltage of an alternating current (AC) into a direct current (DC) voltage.?
5V - Temperature Grade
Temperature grades represent a tire's resistance to heat and its ability to dissipate heat when tested under controlled laboratory test conditions.
COMMERCIAL - Number of Circuits1
- Max Supply Voltage
In general, the absolute maximum common-mode voltage is VEE-0.3V and VCC+0.3V, but for products without a protection element at the VCC side, voltages up to the absolute maximum rated supply voltage (i.e. VEE+36V) can be supplied, regardless of supply voltage.
40V - Min Supply Voltage
The minimum supply voltage (V min ) is explored for sequential logic circuits by statistically simulating the impact of within-die process variations and gate-dielectric soft breakdown on data retention and hold time.
4V - Output Current per Channel
Output Current per Channel is a specification commonly found in electronic components such as amplifiers, audio interfaces, and power supplies. It refers to the maximum amount of electrical current that can be delivered by each individual output channel of the component. This parameter is important because it determines the capacity of the component to drive connected devices or loads. A higher output current per channel means the component can deliver more power to connected devices, while a lower output current may limit the performance or functionality of the component in certain applications. It is crucial to consider the output current per channel when selecting electronic components to ensure they can meet the power requirements of the intended system or setup.
136μA - Supply Type
Supply Type in electronic components refers to the classification of power sources used to operate the component. It indicates whether the component requires DC or AC power, and if DC, specifies the voltage levels such as low, medium, or high. Different supply types can affect the performance, compatibility, and application of the component in electronic circuits. Understanding the supply type is crucial for proper component selection and integration into electronic designs.
Single - Input Offset Voltage (Vos)
Input Offset Voltage (Vos) is a key parameter in electronic components, particularly in operational amplifiers. It refers to the voltage difference that must be applied between the two input terminals of the amplifier to nullify the output voltage when the input terminals are shorted together. In simpler terms, it represents the voltage required to bring the output of the amplifier to zero when there is no input signal present. Vos is an important parameter as it can introduce errors in the output signal of the amplifier, especially in precision applications where accuracy is crucial. Minimizing Vos is essential to ensure the amplifier operates with high precision and accuracy.
4mV - Linearity
In electronic components, linearity refers to the relationship between the input and output signals of the component. A component is said to be linear if its output is directly proportional to its input over a specified range. In other words, when the input signal changes, the output signal changes in a consistent and predictable manner without introducing distortion or non-linear effects.Linearity is an important parameter in electronic components such as amplifiers, filters, and sensors, as it determines the accuracy and fidelity of signal processing. Non-linearities in components can lead to signal distortion, harmonic generation, and other undesirable effects that can degrade the performance of electronic systems.Engineers often characterize the linearity of components by measuring parameters such as gain error, harmonic distortion, and intermodulation distortion. By ensuring that components exhibit good linearity characteristics, designers can create electronic systems that accurately process signals and faithfully reproduce the desired output.
±0.01% - Ambient Temperature Range High
This varies from person to person, but it is somewhere between 68 and 77 degrees F on average. The temperature setting that is comfortable for an individual may fluctuate with humidity and outside temperature as well. The temperature of an air conditioned room can also be considered ambient temperature.
70°C - Positive Input Voltage-Max
Positive Input Voltage-Max refers to the maximum allowable voltage that can be applied to the input of an electronic component without causing damage or malfunction. Exceeding this voltage can result in failure of the component or degraded performance. It is a crucial parameter in designing circuits to ensure reliability and longevity of the electronic device. This value is typically specified in volts and should be carefully considered to maintain safe operation within the specified limits.
3V - Negative Input Voltage-Max
Negative Input Voltage-Max is a parameter in electronic components that specifies the maximum allowable negative voltage that can be applied to the input of the component without causing damage. This parameter is important for ensuring the proper functioning and longevity of the component, as exceeding the specified negative input voltage can lead to breakdown or failure. It is typically expressed in volts and serves as a guideline for users to prevent overvoltage conditions that could potentially harm the component. It is crucial to adhere to the manufacturer's specifications regarding the negative input voltage-max to avoid any potential damage to the electronic component.
-0.2V - Full Scale
In electronics and signal processing, full scale represents the maximum amplitude a system can represent.
±150ppm/°C - Height5.08mm
- Length9.81mm
- Width6.35mm
- Thickness
Thickness in electronic components refers to the measurement of how thick a particular material or layer is within the component structure. It can pertain to various aspects, such as the thickness of a substrate, a dielectric layer, or conductive traces. This parameter is crucial as it impacts the electrical, mechanical, and thermal properties of the component, influencing its performance and reliability in electronic circuits.
3.9mm - REACH SVHC
The parameter "REACH SVHC" in electronic components refers to the compliance with the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulation regarding Substances of Very High Concern (SVHC). SVHCs are substances that may have serious effects on human health or the environment, and their use is regulated under REACH to ensure their safe handling and minimize their impact.Manufacturers of electronic components need to declare if their products contain any SVHCs above a certain threshold concentration and provide information on the safe use of these substances. This information allows customers to make informed decisions about the potential risks associated with using the components and take appropriate measures to mitigate any hazards.Ensuring compliance with REACH SVHC requirements is essential for electronics manufacturers to meet regulatory standards, protect human health and the environment, and maintain transparency in their supply chain. It also demonstrates a commitment to sustainability and responsible manufacturing practices in the electronics industry.
No SVHC - Radiation Hardening
Radiation hardening is the process of making electronic components and circuits resistant to damage or malfunction caused by high levels of ionizing radiation, especially for environments in outer space (especially beyond the low Earth orbit), around nuclear reactors and particle accelerators, or during nuclear accidents or nuclear warfare.
No - RoHS Status
RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.
ROHS3 Compliant - Lead Free
Lead Free is a term used to describe electronic components that do not contain lead as part of their composition. Lead is a toxic material that can have harmful effects on human health and the environment, so the electronics industry has been moving towards lead-free components to reduce these risks. Lead-free components are typically made using alternative materials such as silver, copper, and tin. Manufacturers must comply with regulations such as the Restriction of Hazardous Substances (RoHS) directive to ensure that their products are lead-free and environmentally friendly.
Lead Free
LM331 Functional Block Diagram

LM331 Schematic Diagram

LM331 Internal Block Diagram
The internal circuit composition of LM331 as shown in the figure is composed of input comparator, timing comparator, RS flip-flop, output drive tube, reset transistor, band gap reference circuit, precision current source circuit, current switch, output protection tube, etc. The drive tube adopts the open-collector form, so the logic level of the output pulse can be flexibly changed by selecting the logic current and external resistance to adapt to different logic circuits such as TTL, DTL and CMOS. LM331 can use dual power supply or single power supply, can work between 4.0 ~ 40V, the output can be as high as 40V, and can prevent Vcc short circuit.

LM331 V/F conversion circuit
The circuit used by LM331 for V/F conversion is shown below, where CIN is a filter capacitor, and the size is generally 0.1μF; in order to improve the conversion accuracy, the size of RIN is generally 100 kΩ. All devices should try to use materials with high temperature stability, such as metal film resistors. The capacitor is best to choose materials such as NPO ceramic, polystyrene, polytetrafluoroethylene or polypropylene. Pin 2 can be connected in series with a fixed resistor and an adjustable resistor to adjust the errors caused by Rt, Ct and RL. Connecting a 47Ω resistor and a 1μF capacitor to ground in series can improve linearity. Although the size of CL will not directly affect the conversion result, a capacitor with a small leakage current should be selected as much as possible. R1 and R2 are used to adjust the zero output. The relationship between output frequency and input voltage is:


LM331 Application circuit
Application Circuit(1)

The figure is a voltage/frequency conversion circuit composed of LM331. LM331 is switched by on-chip reference voltage and current of 1·9v. A monolithic voltage/frequency conversion integrated circuit composed of comparators and flip-flops. In order to expand the measuring range, an A1 operational amplifier is added to the circuit. The reference current IR is set by (Rl+R(RPl)). Since the internal reference voltage is 1·9V, IR=l·9V/(Rl+R(RPl)). The usual setting range is 100-500μA . In addition, the current average value I at the output (pin 1) of the current switch. It is equal to the input current Ii. For the on-chip charging and discharging circuit, when the charging voltage reaches 2A of the power supply voltage, the circuit is reset, so the pulse width is equal to 1·1R4C3. Since the input current Ii is equal to 1·lxR4xC3xf0xIR, the input current Ii is proportional to the oscillation frequency f0, that is, the output frequency f0 is proportional to -Ui.
Application Circuit(2)

Application Circuit(3)

Precision Voltage-to-Frequency Converter, 100KHz Full-Scale

Light Intensity to Frequency Converter

Simple Frequency-to-Voltage Converter, 10KHz Full-Scale
LM331 Alternatives

LM331 Applications
★Voltage to Frequency Conversions
★Frequency to Voltage Conversions
★Remote-Sensor Monitoring
★Tachometers
LM331 Package

LM331 Manufacturer
Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally.[6] It is one of the top 10 semiconductor companies worldwide based on sales volume.The company's focus is on developing analog chips and embedded processors, which account for more than 80% of its revenue.TI also produces TI digital light processing technology and education technology products including calculators, microcontrollers and multi-core processors. The company holds 45,000 patents worldwide as of 2016.
Trend Analysis
Datasheet PDF
- Datasheets :
LM331N-NOPB-Texas-Instruments-datasheet-102489952.pdf
LM331N-NOPB-Texas-Instruments-datasheet-39144877.pdf
LM331N-NOPB-Texas-Instruments-datasheet-21076653.pdf
LM331N-NOPB-Texas-Instruments-datasheet-27708916.pdf
NOPB-Texas-Instruments-datasheet-10847788.pdf
LM331N-NOPB-Texas-Instruments-datasheet-7280248.pdf
NOPB-National-Semiconductor-datasheet-40291.pdf
LM331N-NOPB-Texas-Instruments-datasheet-38162684.pdf
pid_4972712_lm331n-nopb-texas-instruments-datasheet-39144877.pdf
- PCN Assembly/Origin :
- PCN Design/Specification :
1.What chip can replace LM331?
LM331 is not a voltage comparator, but a precision voltage-to-frequency converter. It can input different voltage signals and can output different frequency signals. It can be replaced by KA331. The pin functions are exactly the same.
2.What is the allowable range of LM331 input voltage
The working voltage is 40V, input voltage (maximum) 40-0.2 = 39.8V.
3.Do LM321 and LM331 have the same function and what is the difference?
Not the same, 321 is a single op amp, and 331 is a voltage-to-frequency converter.
4.Is there a difference between LM331 and LM131 connection?
LM331 and LM131 are the same kind of chip, precision voltage-frequency converter, the connection standard wiring diagram is the same drawing, there is no difference between the wiring according to the diagram. Difference LM331 is a commercial grade chip, LM131 is a military grade chip.
5.What is the working temperature of LM331?
Working environment temperature range of LM331 is 0 degrees ~ 70 degrees
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