UC3843N SMPS Controller: Pinout, Equivalent and Datasheet
8 Terminals 7.6V~30V DC to DC converter IC SWITCHING CONTROLLER 1 Outputs Up to 500kHz Transistor Driver









8 Terminals 7.6V~30V DC to DC converter IC SWITCHING CONTROLLER 1 Outputs Up to 500kHz Transistor Driver
The UC3843N is fixed frequency current-mode PWM controller. It is specially designed for Off-Line and DC to DC converter applications with minimum external components. Furthermore, Huge range of Semiconductors, Capacitors, Resistors and IcS in stock. Welcome RFQ.
UC3843N Pinout
The following figure is the diagram of UC3843N Pinout.

Pinout
UC3843N CAD Model
The followings are UC3843N Symbol, Footprint and 3D Model.

PCB Symbol

PCB Footprint

3D Model
UC3843N Overview
The UC3843N is fixed frequency current-mode PWM controller. It is specially designed for Off-Line and DC to DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totem-pole output for driving a Power MOSFET. The UC3843 is 8.5V(on) and 7.9V (off). The UC3843 can operate within 100% duty cycle.
This article provides you with a basic overview of the UC3843N SMPS Controller, including its pin descriptions, features and specifications, etc., to help you quickly understand what UC3843N is.
UC3843N Features
● Low Start up Current
● Maximum Duty Clamp
● UVLO With Hysteresis
● Operating Frequency up to 500KHz
Specifications
- TypeParameter
- 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.
NO - 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) - 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 - 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 - 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.
0°C~70°C TA - 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.
e4 - 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.
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 Terminations8
- 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.
NICKEL PALLADIUM GOLD - 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 - 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.
2.54mm - JESD-30 Code
JESD-30 Code refers to a standardized descriptive designation system established by JEDEC for semiconductor-device packages. This system provides a systematic method for generating designators that convey essential information about the package's physical characteristics, such as size and shape, which aids in component identification and selection. By using JESD-30 codes, manufacturers and engineers can ensure consistency and clarity in the specification of semiconductor packages across various applications and industries.
R-PDIP-T8 - 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-Up, Step-Up/Step-Down - Number of Outputs1
- 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.
5V - 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.
15V - 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.
7.6V~30V - 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.
Frequency Control - 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.
8.2V - 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.
Boost, Flyback - 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.
CURRENT-MODE - Output Current-Max
Output Current-Max is a parameter in electronic components that specifies the maximum amount of current that can be safely drawn from the output of the component without causing damage. It is an important specification to consider when designing circuits to ensure that the component can handle the required current without overheating or failing. Exceeding the maximum output current can lead to performance issues, component damage, or even complete failure of the circuit. It is crucial to adhere to the specified maximum output current to ensure the reliable operation of the electronic component and the overall circuit.
1A - 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.
Up to 500kHz - 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.
25V - 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).
No - Switcher Configuration
Switcher Configuration in electronic components refers to the arrangement or setup of a switcher circuit, which is a type of power supply that converts one form of electrical energy into another. The configuration of a switcher circuit includes the specific components used, such as transistors, diodes, capacitors, and inductors, as well as their interconnections and control mechanisms. The switcher configuration determines the efficiency, voltage regulation, and other performance characteristics of the power supply. Different switcher configurations, such as buck, boost, buck-boost, and flyback, are used for various applications depending on the desired output voltage and current requirements. Understanding and selecting the appropriate switcher configuration is crucial in designing reliable and efficient power supply systems for electronic devices.
SINGLE - Duty Cycle (Max)
The "Duty Cycle (Max)" parameter in electronic components refers to the maximum percentage of time that a signal is active or on within a specific period. It is commonly used in components such as pulse-width modulation (PWM) controllers, oscillators, and timers. A duty cycle of 100% means the signal is always on, while a duty cycle of 0% means the signal is always off. Understanding the maximum duty cycle is important for ensuring proper operation and performance of the electronic component within its specified limits. It is typically expressed as a percentage and helps determine the amount of power or energy being delivered by the signal.
97% - Width7.62mm
- 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.
5.08mm - Length9.59mm
- RoHS Status
RoHS means “Restriction of Certain Hazardous Substances” in the “Hazardous Substances Directive” in electrical and electronic equipment.
ROHS3 Compliant
UC3843N Functional Block Diagram
The following is the Internal Block Diagram of UC3843N.

Internal Block Diagram
UC3843N Equivalent
| Model number | Manufacturer | Description |
| MIC38HC42-1YM | Microchip Technology Inc | IC,SMPS CONTROLLER,CURRENT-MODE,BICMOS,SOP,14PIN,PLASTIC |
| UC3844BVDR2G | Rochester Electronics LLC | 1 A SWITCHING CONTROLLER, 275 kHz SWITCHING FREQ-MAX, PDSO14, ROHS COMPLIANT, SOIC-14 |
| CS3843BGN8 | ON Semiconductor | 1A SWITCHING CONTROLLER, PDIP8, 0.300 INCH, PLASTIC, MS-001, DIP-8 |
| LT1245IJ8 | Linear Technology | IC SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, CDIP8, CERAMIC, DIP-8, Switching Regulator or Controller |
| MIC38HC43-1YM | Microchip Technology Inc | IC,SMPS CONTROLLER,CURRENT-MODE,BICMOS,SOP,14PIN,PLASTIC |
| CS3845BGD8 | ON Semiconductor | 1A SWITCHING CONTROLLER, PDSO8, 0.150 INCH, MS-012, SO-8 |
| LT1241MJ8 | Linear Technology | IC 1 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, CDIP8, 0.300 INCH, HERMETIC SEALED, CERDIP-8, Switching Regulator or Controller |
| TC38C43COE | Microchip Technology Inc | 1.2 A SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO16 |
| UC1844AL/883B | Unitrode Corporation | Switching Controller, Current-mode, 1A, 500kHz Switching Freq-Max, CQCC20 |
| LT1244CS8#PBF | Analog Devices Inc | High Speed Current Mode Pulse Width Modulators |
UC3843N Package
The following diagrams show the UC3843N Package.

View A

View B

View C
UC3843N Manufacturer
Rochester Electronics is the largest continuing source manufacturer of semiconductors in the world. With product licensing from leading manufacturers such as Analog Devices, Altera, Cypress, Fairchild, Freescale, Infineon, Intel, NXP, Renesas and Texas Instruments, Rochester continues to manufacture and distribute mature products. For industrial, transportation and hi-reliability markets, this extension of product life is critical for long term production and maintenance. With over 100,000 products and 15 billion units in stock, no other company compares to our selection, capabilities or solutions.
Datasheet PDF
- Datasheets :
How many pins of UC3843N?
8 Pins.
What’s the operating temperature of UC3843N?
0°C~70°C TA.
What is the essential property of the UC3843N?
The UC3843N is fixed frequency current-mode PWM controller. It is specially designed for Off-Line and DC to DC converter applications with minimum external components.
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