LM2940 voltage regulator[video+FAQ]: Datasheet, circuit and Equivalent
Fixed 2.54mm LM2940 PMIC 4 TO-263-4, D2Pak (3 Leads + Tab), TO-263AA
This article provides you with a basic overview of the LM2940, including its pin descriptions, functions, and specifications, alternative products, etc. to help you quickly understand what LM2940 is.

HOW TO: LM7805 vs LM2940 voltage regulator Comparison plus setup howto
- LM2940 Pinout and Configurations
- LM2940 Introduction
- Specifications
- LM2940: Features
- LM2940:Applications
- LM2940 Equivalent
- LM2940 Typical Application
- LM2940 Block Diagram
- LM2940 Package
- LM2940 Manufacturer
- LM2940 Recommended Operating Conditions
- LM2940 vs LM7805
- Trend Analysis
- Datasheet PDF
- Parts with Similar Specs
LM2940 Pinout and Configurations

| Name | NDE | KTT | DCY | NGN | I/O | Description |
| IN | 1 | 1 | 1 | 3 | I | Unregulated input voltage |
| GND | 2 | 2 | 2 | 2 | - | Ground |
| OUT | 3 | 3 | 3 | 5,6 | 0 | Regulated output voltage. |
| GND | 4 | 4 | 4 | 7 | - | Ground |
| N/C | - | - | - | 1,4,8 | - | No connection |
LM2940 Introduction
The LM2940 positive voltage regulator features the ability to source 1A of output current with a dropout voltage of typically 0.5V and a maximum of 1V over the entire temperature range. Furthermore, a quiescent current reduction circuit has been included which reduces the ground current when the differential between the input voltage and the output voltage exceeds approximately 3V.


Specifications
- TypeParameter
- 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.
Surface Mount - 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.
Surface Mount - Package / Case
refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.
TO-263-4, D2Pak (3 Leads + Tab), TO-263AA - Number of Pins3
- Operating Temperature
The operating temperature is the range of ambient temperature within which a power supply, or any other electrical equipment, operate in. This ranges from a minimum operating temperature, to a peak or maximum operating temperature, outside which, the power supply may fail.
-40°C~125°C - 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.
e0 - 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.
no - Part Status
Parts can have many statuses as they progress through the configuration, analysis, review, and approval stages.
Obsolete - 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
3 (168 Hours) - Number of Terminations3
- 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 - Terminal Finish
Terminal Finish refers to the surface treatment applied to the terminals or leads of electronic components to enhance their performance and longevity. It can improve solderability, corrosion resistance, and overall reliability of the connection in electronic assemblies. Common finishes include nickel, gold, and tin, each possessing distinct properties suitable for various applications. The choice of terminal finish can significantly impact the durability and effectiveness of electronic devices.
Tin/Lead (Sn/Pb) - Packing Method
The packing method in electronic components refers to the technique used to package and protect the component during shipping and handling. It encompasses various forms including tape and reel, tray, tube, or bulk packaging, each suited for different types of components and manufacturing processes. The choice of packing method can affect the ease of handling, storage, and the efficiency of assembly in automated processes. Additionally, it plays a crucial role in ensuring the reliability and integrity of the components until they are used in electronic devices.
RAIL - 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.
SINGLE - Peak Reflow Temperature (Cel)
Peak Reflow Temperature (Cel) is a parameter that specifies the maximum temperature at which an electronic component can be exposed during the reflow soldering process. Reflow soldering is a common method used to attach electronic components to a circuit board. The Peak Reflow Temperature is crucial because it ensures that the component is not damaged or degraded during the soldering process. Exceeding the specified Peak Reflow Temperature can lead to issues such as component failure, reduced performance, or even permanent damage to the component. It is important for manufacturers and assemblers to adhere to the recommended Peak Reflow Temperature to ensure the reliability and functionality of the electronic components.
235 - Number of Functions1
- Terminal Pitch
The center distance from one pole to the next.
2.54mm - 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.
LM2940 - Pin Count
a count of all of the component leads (or pins)
4 - Current - Supply (Max)
The parameter "Current - Supply (Max)" in electronic components refers to the maximum amount of current that a component can draw from a power supply for its operation. This parameter is critical for ensuring that the power supply can adequately meet the demands of the component without causing damage or malfunction. Exceeding this specified maximum current can lead to overheating, reduced performance, or failure of the component. It is essential to consider this value when designing or integrating components into electronic circuits to maintain reliability and functionality.
15mA - Number of Outputs1
- Voltage - Input (Max)
Voltage - Input (Max) is a parameter in electronic components that specifies the maximum voltage that can be safely applied to the input of the component without causing damage. This parameter is crucial for ensuring the proper functioning and longevity of the component. Exceeding the maximum input voltage can lead to electrical overstress, which may result in permanent damage or failure of the component. It is important to carefully adhere to the specified maximum input voltage to prevent any potential issues and maintain the reliability of the electronic system.
26V - Output Voltage
Output voltage is a crucial parameter in electronic components that refers to the voltage level produced by the component as a result of its operation. It represents the electrical potential difference between the output terminal of the component and a reference point, typically ground. The output voltage is a key factor in determining the performance and functionality of the component, as it dictates the level of voltage that will be delivered to the connected circuit or load. It is often specified in datasheets and technical specifications to ensure compatibility and proper functioning within a given system.
9V - Output Type
The "Output Type" parameter in electronic components refers to the type of signal or data that is produced by the component as an output. This parameter specifies the nature of the output signal, such as analog or digital, and can also include details about the voltage levels, current levels, frequency, and other characteristics of the output signal. Understanding the output type of a component is crucial for ensuring compatibility with other components in a circuit or system, as well as for determining how the output signal can be utilized or processed further. In summary, the output type parameter provides essential information about the nature of the signal that is generated by the electronic component as its output.
Fixed - Output Configuration
Output Configuration in electronic components refers to the arrangement or setup of the output pins or terminals of a device. It defines how the output signals are structured and how they interact with external circuits or devices. The output configuration can determine the functionality and compatibility of the component in a circuit design. Common types of output configurations include single-ended, differential, open-drain, and push-pull configurations, each serving different purposes and applications in electronic systems. Understanding the output configuration of a component is crucial for proper integration and operation within a circuit.
Positive - Quiescent Current
The quiescent current is defined as the current level in the amplifier when it is producing an output of zero.
10mA - Output Voltage 1
Output Voltage 1 is a parameter commonly found in electronic components such as voltage regulators, power supplies, and amplifiers. It refers to the voltage level that is produced or delivered by the component at a specific output terminal or pin. This parameter is crucial for determining the performance and functionality of the component in a circuit. The specified output voltage should meet the requirements of the connected devices or components to ensure proper operation and compatibility. It is important to carefully consider and verify the output voltage 1 specification when selecting and using electronic components in a design or application.
9V - Number of Regulators
A regulator is a mechanism or device that controls something such as pressure, temperature, or fluid flow. The voltage regulator keeps the power level stabilized. A regulator is a mechanism or device that controls something such as pressure, temperature, or fluid flow.
1 - Min Input Voltage
The parameter "Min Input Voltage" in electronic components refers to the minimum voltage level that must be applied to the component for it to operate within its specified parameters. This value is crucial as providing a voltage below this minimum threshold may result in the component malfunctioning or not functioning at all. It is important to adhere to the specified minimum input voltage to ensure the proper operation and longevity of the electronic component. Failure to meet this requirement may lead to potential damage to the component or the overall system in which it is used.
10.5V - Protection Features
Protection features in electronic components refer to the built-in mechanisms or functionalities designed to safeguard the component and the overall system from various external factors or internal faults. These features are crucial for ensuring the reliability, longevity, and safety of the electronic device. Common protection features include overvoltage protection, overcurrent protection, reverse polarity protection, thermal protection, and short-circuit protection. By activating these features when necessary, the electronic component can prevent damage, malfunctions, or hazards that may arise from abnormal operating conditions or unforeseen events. Overall, protection features play a vital role in enhancing the robustness and resilience of electronic components in diverse applications.
Over Current, Over Temperature, Reverse Polarity, Short Circuit - Current - Quiescent (Iq)
The parameter "Current - Quiescent (Iq)" in electronic components refers to the amount of current consumed by a device when it is in a quiescent or idle state, meaning when it is not actively performing any tasks or operations. This parameter is important because it represents the baseline power consumption of the device even when it is not actively being used. A lower quiescent current (Iq) value is desirable as it indicates that the device is more energy-efficient and will consume less power when not in use, which can help extend battery life in portable devices and reduce overall power consumption in electronic systems. Designers often pay close attention to the quiescent current specification when selecting components for low-power applications or battery-operated devices.
10mA - Voltage Dropout (Max)
Voltage Dropout (Max) refers to the minimum voltage difference between the input and output of a voltage regulator or linear power supply needed to maintain proper regulation. It indicates the maximum allowable voltage drop across the device for it to function effectively without dropout. If the input voltage falls below this threshold, the output voltage may drop below the specified level, leading to potential operational issues for connected components. This parameter is critical for ensuring stable and reliable power delivery in electronic circuits.
1V @ 1A - PSRR
PSRR stands for Power Supply Rejection Ratio. It is a measure of how well a device, such as an amplifier or a voltage regulator, can reject variations in the power supply voltage. A high PSRR value indicates that the device is able to maintain its performance even when the power supply voltage fluctuates. This parameter is important in ensuring stable and reliable operation of electronic components, especially in applications where the power supply voltage may not be perfectly regulated. A good PSRR helps to minimize noise and interference in the output signal of the device.
64dB (120Hz) - Dropout Voltage
Dropout voltage is the input-to-output differential voltage at which the circuit ceases to regulate against further reductions in input voltage; this point occurs when the input voltage approaches the output voltage.
500mV - Dropout Voltage1-Nom
Dropout Voltage1-Nom is a parameter commonly found in voltage regulators and power management ICs. It refers to the minimum voltage difference required between the input voltage and the output voltage for the regulator to maintain regulation. In other words, it is the minimum voltage drop that the regulator can handle while still providing a stable output voltage. This parameter is important to consider when designing power supply circuits to ensure that the regulator can operate within its specified voltage range and maintain proper regulation under varying load conditions.
0.5V - Voltage Tolerance-Max
Voltage Tolerance-Max is a parameter in electronic components that specifies the maximum allowable deviation from the rated voltage without causing damage or malfunction. It indicates the range within which the component can safely operate without being affected by voltage fluctuations. This parameter is crucial for ensuring the reliability and longevity of the component in various electrical systems. Manufacturers provide this specification to help users understand the limits within which the component can function properly and to prevent potential failures due to overvoltage conditions.
5% - Input Voltage Absolute-Max
The "Input Voltage Absolute-Max" parameter in electronic components refers to the maximum voltage that can be safely applied to the input of the component without causing damage. This specification is crucial for ensuring the reliable operation and longevity of the component. Exceeding the absolute maximum input voltage can lead to permanent damage, malfunction, or even complete failure of the component. It is important for designers and engineers to carefully adhere to this specification to prevent any potential issues and ensure the proper functioning of the electronic system.
60V - Height Seated (Max)
Height Seated (Max) is a parameter in electronic components that refers to the maximum allowable height of the component when it is properly seated or installed on a circuit board or within an enclosure. This specification is crucial for ensuring proper fit and alignment within the overall system design. Exceeding the maximum seated height can lead to mechanical interference, electrical shorts, or other issues that may impact the performance and reliability of the electronic device. Manufacturers provide this information to help designers and engineers select components that will fit within the designated space and function correctly in the intended application.
4.79mm - Width8.64mm
- 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.
Non-RoHS 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.
Contains Lead
LM2940: Features
Dropout Voltage 0.385 V (Typ) at IO = 1A
Output Current in Excess of 1A
Output Voltage Trimmed Before Assembly
Reverse-Battery Protection
Internal Short-Circuit Current Limit
Mirror-Image Insertion Protection
Available in
– Commercial Temperature (0°C to 125°C)
– Extended Temperature (–40°C to 125°C)
LM2940:Applications
Post Regulator for Switching Supplies
Logic Power Supplies
Industrial Instrumentation
LM2940 Equivalent
The equivalent for LM2940 is LM7805.
LM2940 Typical Application

LM2940 Block Diagram

LM2940 Package


LM2940 Manufacturer
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LM2940 Recommended Operating Conditions

LM2940 vs LM7805
The LM7805 is a popular linear voltage regulator because it requires no additional components to operate. It is a very low-cost component.
Because of its characteristics, it reduces the output voltage at the expense of heat dissipation, making it inefficient.
The LM7805 requires a minimum input voltage of 7.3V to function properly. It can handle a maximum current of 1A. Some models can handle up to 1.5A.
It is recommended, and in some cases required, to use capacitors to reduce or eliminate the effects of the frequencies introduced by the other elements of the circuit. They also help to reduce the impact of peak consumption.
While the LM2940 is from a different generation, its pin is still compatible with the LM7805,
It is a Low-dropout (LDO) Linear Regulator that is more efficient than the LM7805. but it will require capacitors.
The main difference between LM2940 and LM7805 is that the maximum output current of LM2940 is 1A. The maximum output current of LM7805 is 1.5A. Others are very close, so if the circuit only requires 1A or below, LM2940 can be used instead of LM7805
What's more, the 7805 is expending the excess power as heat. This is very lossy especially if your project uses batteries. The other chip is a buck converter so it approaches 90% efficiency by switching so there is no waste heat, that's why even though LM7805 is cheaper and easier to use but there are still a lot of people who would go for LM2940.
LM2940 & LM7805 Schematic Comparison


LM2940 Schematic LM7805 Schematic
Trend Analysis
Datasheet PDF
- Datasheets :
Parts with Similar Specs
- ImagePart NumberManufacturerPackage / CaseNumber of PinsNumber of OutputsMin Input VoltageVoltage - Input (Max)Output VoltageDropout VoltageTechnologyView Compare
LM2940S-9.0
TO-263-4, D2Pak (3 Leads + Tab), TO-263AA
3
1
10.5 V
26V
9 V
500 mV
BIPOLAR
TO-263-3, D2Pak (2 Leads + Tab), TO-263AB
3
1
10 V
35V
5 V
2 V
BIPOLAR
TO-263-4, D2Pak (3 Leads + Tab), TO-263AA
3
1
13.6 V
26V
12 V
500 mV
BIPOLAR
TO-263-4, D2Pak (3 Leads + Tab), TO-263AA
3
1
10.5 V
26V
9 V
500 mV
BIPOLAR
TO-263-4, D2Pak (3 Leads + Tab), TO-263AA
3
1
10.5 V
26V
9 V
500 mV
BIPOLAR
What type of linear regulator is the LM2940?
Low-dropout
What can the LM2940 be used with to provide a regulated 5V output?
A 6-volt wall wart
What is the minimum input voltage for the LM7805?
7.3V
What is the maximum current of the LM7805?
1A
What is the purpose of the LM7805?
To reduce or eliminate the effects of the frequencies introduced by the other elements of the circuit
What does the LM7805 help to do?
Reduce the impact of peak consumption
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