A General Introduction to LM25145 Synchronous Buck DC-DC Controller
20 Terminals 6V~42V 20-Pin LM25145 DC to DC converter IC SWITCHING CONTROLLER 1 Outputs 100kHz~1MHz Transistor Driver









20 Terminals 6V~42V 20-Pin LM25145 DC to DC converter IC SWITCHING CONTROLLER 1 Outputs 100kHz~1MHz Transistor Driver
The LM25145 is a 42-V synchronous buck controller. This post mainly covers its pinout, datasheet, application circuit and more details about LM25145.
LM25145 Pinout

LM25145RGYR Pinout
LM25145 CAD Model
Symbol

LM25145 Symbol
Footprint

LM25145 Footprint
3D Model

LM25145 3D Model
LM25145 Description
The LM25145 is a 42-V synchronous buck controller that features all of the functions necessary to implement a high-efficiency step-down power supply with an output voltage ranging from 0.8 V to 40 V. The voltage-mode control architecture uses input feedforward for excellent line transient response over a wide VIN range. Voltage-mode control supports the wide duty cycle range for high input voltage and low dropout applications as well as when a high voltage conversion ratio (for example, 10-to-1) is required. Current sensing for cycle-by-cycle current limit can be implemented with either the low-side FET RDS(on) or a current sense resistor. The operating frequency is programmable from 100 kHz to 1 MHz.
The LM25145 drives external high-side and low-side NMOS power switches with robust 7.5-V gate drivers suitable for standard threshold MOSFETs. Adaptive dead-time control between the high-side and low-side drivers is designed to minimize body diode conduction during switching transitions. An external bias supply can be connected to the VCC pin to improve efficiency in high-voltage applications. A user-selectable diode emulation feature enables discontinuous conduction mode operation for improved efficiency and lower dissipation at light-load conditions.
LM25145 Feature
Versatile synchronous buck DC-DC controller
Wide input voltage range of 6V to 42V
Adjustable output voltage From 0.8V to 40V
Lossless RDS(on) or shunt current sensing
Switching frequency from 100kHz to 1MHz
SYNC In and SYNC out capability
40ns Minimum on-time for high VIN / VOUT ratio
140ns minimum off-time for low dropout
0.8V Reference with ±1% feedback accuracy
7.5V Gate drivers for standard VTH MOSFETs
14ns Adaptive dead-time control
2.3A Source and 3.5A sink capability
Low-side soft-start for pre-biased start-up
Adjustable soft-start or optional voltage tracking
Fast line and load transient response
Voltage-mode control with line feedforward
The high gain-bandwidth error amplifier
A precision enables input and open-drain power good indicator for sequencing and control
Inherent protection features for robust design
Hiccup mode overcurrent protection
Input UVLO with hysteresis
VCC and Gate drive UVLO protection
Thermal shutdown protection with hysteresis
VQFN-20 Package with wettable flanks
LM25145 Application
Telecom infrastructure
Factory automation
Test and measurement
Industrial motor drives
LM25145 Functional Block Diagram
LM25145 Typical Application Circuit
The following figure shows a typical application circuit and efficient performance of LM25145:

LM25145 Typical Application Circuit and Efficiency Performance, VOUT = 5 V, FSW = 225 kHz
LM25145 Package

LM25145 Package
Buck Converter vs. Boost Converter
A buck or step-down converter is a DC/DC switch mode power supply designed to buck (or lower) an unregulated DC supply's input voltage to a stabilized lower output voltage. Buck converters are highly appreciated for their extraordinarily high efficiency, which can easily surpass 95 per cent when compared to ordinary voltage regulators. The simplified circuit schematic below depicts how current flows across the circuit during a buck converter switching event.

Buck Converter Circuit
A boost converter is a DC/DC switch mode power supply designed to boost (or enhance) an unregulated DC supply's input voltage to a stabilized higher output voltage. A boost converter, like a buck converter, uses an inductor, diode, capacitor, and power switch to adjust the output voltage, but they are organized differently. The simplified circuit schematic below depicts how current travels through the circuit during a boost converter switching event.

Boost Converter Circuit
The output voltage of a boost converter is controlled by the mark-space ratio of the PWM signal to be equal to or greater than V in. Because power is conserved, a boost converter that supplies three times the input voltage can only supply one-third of the current that it pulls from the supply. Boost converters, on the other hand, are highly popular in battery-powered devices, where a pair of batteries may give 3V but must power a 5V circuit.
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: 3 days ago) - Factory Lead Time6 Weeks
- 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, Wettable Flank - Package / Case
refers to the protective housing that encases an electronic component, providing mechanical support, electrical connections, and thermal management.
20-VFQFN Exposed Pad - Surface Mount
having leads that are designed to be soldered on the side of a circuit board that the body of the component is mounted on.
YES - Number of Pins20
- 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 TJ - 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.
Tape & Reel (TR) - 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
2 (1 Year) - Number of Terminations20
- 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.
Matte Tin (Sn) - Additional Feature
Any Feature, including a modified Existing Feature, that is not an Existing Feature.
ADJUSTABLE OUTPUT VOLTAGE FROM 0.8 V TO 40 V - 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.
QUAD - Terminal Form
Occurring at or forming the end of a series, succession, or the like; closing; concluding.
NO LEAD - 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.
260 - Terminal Pitch
The center distance from one pole to the next.
0.5mm - Time@Peak Reflow Temperature-Max (s)
Time@Peak Reflow Temperature-Max (s) refers to the maximum duration that an electronic component can be exposed to the peak reflow temperature during the soldering process, which is crucial for ensuring reliable solder joint formation without damaging the component.
NOT SPECIFIED - 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.
LM25145 - Function
The parameter "Function" in electronic components refers to the specific role or purpose that the component serves within an electronic circuit. It defines how the component interacts with other elements, influences the flow of electrical signals, and contributes to the overall behavior of the system. Functions can include amplification, signal processing, switching, filtering, and energy storage, among others. Understanding the function of each component is essential for designing effective and efficient electronic systems.
Step-Down - Number of Outputs1
- 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.
Transistor Driver - Input Voltage-Nom
Input Voltage-Nom refers to the nominal or rated input voltage that an electronic component or device is designed to operate within. This parameter specifies the voltage level at which the component is expected to function optimally and safely. It is important to ensure that the actual input voltage supplied to the component does not exceed this nominal value to prevent damage or malfunction. Manufacturers provide this specification to guide users in selecting the appropriate power supply or input voltage source for the component. It is a critical parameter to consider when designing or using electronic circuits to ensure reliable performance and longevity of the component.
24V - Analog IC - Other Type
Analog IC - Other Type is a parameter used to categorize electronic components that are integrated circuits (ICs) designed for analog signal processing but do not fall into more specific subcategories such as amplifiers, comparators, or voltage regulators. These ICs may include specialized analog functions such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), voltage references, or signal conditioning circuits. They are typically used in various applications where precise analog signal processing is required, such as in audio equipment, instrumentation, communication systems, and industrial control systems. Manufacturers provide detailed specifications for these components to help engineers select the most suitable IC for their specific design requirements.
SWITCHING CONTROLLER - 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 - Voltage - Supply (Vcc/Vdd)
Voltage - Supply (Vcc/Vdd) is a key parameter in electronic components that specifies the voltage level required for the proper operation of the device. It represents the power supply voltage that needs to be provided to the component for it to function correctly. This parameter is crucial as supplying the component with the correct voltage ensures that it operates within its specified limits and performance characteristics. It is typically expressed in volts (V) and is an essential consideration when designing and using electronic circuits to prevent damage and ensure reliable operation.
6V~42V - Control Features
Control features in electronic components refer to specific functionalities or characteristics that allow users to manage and regulate the operation of the component. These features are designed to provide users with control over various aspects of the component's performance, such as adjusting settings, monitoring parameters, or enabling specific modes of operation. Control features can include options for input/output configurations, power management, communication protocols, and other settings that help users customize and optimize the component's behavior according to their requirements. Overall, control features play a crucial role in enhancing the flexibility, usability, and performance of electronic components in various applications.
Enable, Frequency Control, Ramp, Soft Start - Input Voltage (Min)
Input Voltage (Min) is a parameter in electronic components that specifies the minimum voltage level required for the component to operate properly. It indicates the lowest voltage that can be safely applied to the component without causing damage or malfunction. This parameter is crucial for ensuring the reliable and safe operation of the component within its specified operating range. It is important for designers and engineers to consider the minimum input voltage requirement when selecting and using electronic components in their circuits to prevent potential issues such as underperformance or failure.
6V - Topology
In the context of electronic components, "topology" refers to the arrangement or configuration of the components within a circuit or system. It defines how the components are connected to each other and how signals flow between them. The choice of topology can significantly impact the performance, efficiency, and functionality of the electronic system. Common topologies include series, parallel, star, mesh, and hybrid configurations, each with its own advantages and limitations. Designers carefully select the appropriate topology based on the specific requirements of the circuit to achieve the desired performance and functionality.
Buck - Control Mode
In electronic components, "Control Mode" refers to the method or mode of operation used to regulate or control the behavior of the component. This parameter determines how the component responds to input signals or commands to achieve the desired output. The control mode can vary depending on the specific component and its intended function, such as voltage regulation, current limiting, or frequency modulation. Understanding the control mode of an electronic component is crucial for proper integration and operation within a circuit or system.
VOLTAGE-MODE - Frequency - Switching
"Frequency - Switching" in electronic components refers to the rate at which a device, such as a transistor or switching regulator, turns on and off during operation. This parameter is crucial in determining the efficiency and performance of power converters, oscillators, and other circuits that rely on rapid switching. Higher switching frequencies typically allow for smaller component sizes but may require more advanced design considerations to manage heat and electromagnetic interference.
100kHz~1MHz - Input Voltage (Max)
Input Voltage (Max) refers to the maximum voltage that an electronic component can safely handle without getting damaged. This parameter is crucial for ensuring the proper functioning and longevity of the component. Exceeding the maximum input voltage can lead to overheating, electrical breakdown, or even permanent damage to the component. It is important to carefully consider and adhere to the specified maximum input voltage when designing or using electronic circuits to prevent any potential issues or failures.
42V - Control Technique
In electronic components, "Control Technique" refers to the method or approach used to regulate and manage the operation of the component. This parameter is crucial in determining how the component functions within a circuit or system. Different control techniques can include analog control, digital control, pulse-width modulation (PWM), and various feedback mechanisms. The choice of control technique can impact the performance, efficiency, and overall functionality of the electronic component. It is important to select the appropriate control technique based on the specific requirements and characteristics of the application in which the component will be used.
PULSE WIDTH MODULATION - Synchronous Rectifier
Synchronous rectification is a technique for improving the efficiency of rectification by replacing diodes with actively controlled switches, usually power MOSFETs or power bipolar junction transistors (BJT).
Yes - Height1mm
- Length4.5mm
- Width3.5mm
- 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.
900μm - RoHS Status
RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.
ROHS3 Compliant
Datasheet PDF
- Datasheets :
What is the LM25145?
42-V synchronous buck controller.
What is the operating frequency programmable from LM25145?
100 kHz to 1 MHz.
The LM25145 drives external high-side and low-side NMOS power switches with what?
7.5-V gate drivers.
What can the LM25145 be powered from?
The output of the switching regulator or another available source.
What does the LM25145 controller have for optical inspection of solder joint fillets?
Wettable flanks.
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