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UC2851N
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UC2851N

Product Overview

  • Category: Integrated Circuit (IC)
  • Use: Voltage Mode PWM Controller
  • Characteristics:
    • High-performance controller for power supply applications
    • Provides precise regulation and control of output voltage
    • Suitable for various power supply topologies
  • Package: DIP-8 (Dual In-line Package)
  • Essence: Regulating and controlling output voltage in power supply applications
  • Packaging/Quantity: Available in reels of 2500 units

Specifications

  • Input Voltage Range: 10V to 30V
  • Output Voltage Range: 0.8V to 5.5V
  • Maximum Duty Cycle: 100%
  • Operating Temperature Range: -40°C to +85°C
  • Frequency Range: 50kHz to 500kHz
  • Output Current: Up to 1A
  • Error Amplifier Bandwidth: 10MHz
  • Soft Start Time: Adjustable from 0ms to 20ms

Pin Configuration

The UC2851N IC has the following pin configuration:

  1. VCC: Power supply input
  2. COMP: Compensation pin for error amplifier
  3. FB: Feedback pin for regulating output voltage
  4. RT/CT: Timing components connection pins
  5. GND: Ground reference
  6. CS: Current sense pin for current limiting
  7. SS: Soft start pin for adjustable soft start time
  8. OUT: Output pin for regulated voltage

Functional Features

  • Voltage mode control with adjustable frequency and duty cycle
  • Error amplifier with high bandwidth for precise regulation
  • Adjustable soft start time for controlled startup
  • Current sense pin for overcurrent protection
  • Internal oscillator for generating switching frequency
  • Protection against overvoltage and undervoltage conditions

Advantages and Disadvantages

Advantages: - Precise regulation and control of output voltage - Suitable for various power supply topologies - Adjustable soft start time for controlled startup - Overcurrent protection for enhanced reliability

Disadvantages: - Limited output current capability (up to 1A) - Requires external timing components for frequency adjustment

Working Principles

The UC2851N is a voltage mode PWM controller that regulates and controls the output voltage of a power supply. It operates by comparing the feedback voltage (FB) with a reference voltage to generate an error signal. This error signal is amplified by the error amplifier and compared with a sawtooth waveform generated by the internal oscillator. The resulting PWM signal is then used to control the duty cycle of the power switch, which in turn regulates the output voltage.

Detailed Application Field Plans

The UC2851N is commonly used in various power supply applications, including:

  1. Switching Power Supplies: Provides precise regulation and control of output voltage in switch-mode power supplies.
  2. DC-DC Converters: Used as a controller in DC-DC converters to regulate the output voltage.
  3. Battery Chargers: Controls the charging process in battery chargers to ensure proper voltage regulation.
  4. LED Drivers: Regulates the output voltage in LED drivers for consistent illumination.

Detailed and Complete Alternative Models

  1. UC3842: Similar voltage mode PWM controller with higher output current capability (up to 2A).
  2. TL494: PWM controller with adjustable frequency and duty cycle, suitable for power supply applications.
  3. SG3525: Voltage mode PWM controller with wide input voltage range and high-frequency operation.

These alternative models offer similar functionality and can be considered as alternatives to the UC2851N based on specific requirements.

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技術ソリューションにおける UC2851N の適用に関連する 10 件の一般的な質問と回答をリストします。

Sure! Here are 10 common questions and answers related to the application of UC2851N in technical solutions:

Q1: What is UC2851N? A1: UC2851N is a high-performance current-mode PWM controller IC used in various power supply applications.

Q2: What are the key features of UC2851N? A2: The key features of UC2851N include adjustable frequency operation, cycle-by-cycle current limiting, soft-start capability, and built-in protection features.

Q3: What is the typical input voltage range for UC2851N? A3: The typical input voltage range for UC2851N is between 8V and 20V.

Q4: How does UC2851N provide cycle-by-cycle current limiting? A4: UC2851N uses a current sensing resistor in series with the power MOSFET to monitor the current flowing through it. It compares this sensed current with a reference value to provide cycle-by-cycle current limiting.

Q5: Can UC2851N be used in both buck and boost converter topologies? A5: Yes, UC2851N can be used in both buck and boost converter topologies, as well as in other power supply configurations.

Q6: Does UC2851N have any built-in protection features? A6: Yes, UC2851N has built-in protection features such as overvoltage protection (OVP), undervoltage lockout (UVLO), and thermal shutdown.

Q7: How can I adjust the switching frequency of UC2851N? A7: The switching frequency of UC2851N can be adjusted by changing the value of an external timing capacitor connected to the RT pin.

Q8: Can UC2851N operate in continuous conduction mode (CCM)? A8: Yes, UC2851N can operate in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM), depending on the application requirements.

Q9: What is the maximum duty cycle supported by UC2851N? A9: The maximum duty cycle supported by UC2851N is typically around 90%.

Q10: Are there any application notes or reference designs available for UC2851N? A10: Yes, Texas Instruments provides application notes and reference designs that can help you understand and implement UC2851N in various technical solutions. These resources can be found on their official website.

Please note that these answers are general and may vary based on specific design considerations and application requirements. It's always recommended to refer to the datasheet and application notes provided by the manufacturer for detailed information.