SLUS515G September   2002  – December 2015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 UVLO and Reference Block
      2. 7.3.2 Error Amplifier
      3. 7.3.3 Zero Current Detection and Re-Start Timer Blocks
      4. 7.3.4 Enable Block
      5. 7.3.5 Zero Power Block
      6. 7.3.6 Multiplier Block
      7. 7.3.7 Overvoltage Protection (OVP) Block
    4. 7.4 Device Functional Modes
      1. 7.4.1 Transition Mode Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
        2. 8.2.2.2 MOSFET Selection
        3. 8.2.2.3 Diode Selection
        4. 8.2.2.4 Capacitor Selection
        5. 8.2.2.5 Multiplier Set-Up
        6. 8.2.2.6 Sense Resistor Selection
        7. 8.2.2.7 Output Voltage Sense Design
        8. 8.2.2.8 Voltage Loop Design
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Bias Current
      2. 10.1.2 Zero Current Detection
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
    2. 11.2 Related Links
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

1 Features

  • Transition Mode PFC Controller for Low Implementation Cost
  • Industry Pin Compatibility With Improved Feature Set
  • Improved Transient Response With Slew-Rate Comparator
  • Zero Power Detect to Prevent Overvoltage Protection (OVP) During Light Load Conditions
  • Accurate Internal VREF for Tight Output Regulation
  • Two UVLO Options
  • OVP, Open-Feedback Protection, and Enable Circuits
  • ±750-mA Peak Gate Drive Current
  • Low Start-Up and Operating Currents
  • Lead (Pb)-Free Packages

2 Applications

  • Single-Stage PFC Flyback Converters for Lighting and Motor Drives
  • Switch-Mode Power Supplies for Desktops, Monitors, TVs, and Set Top Boxes (STBs)
  • AC Adapter Front-End Power Supplies
  • Electronic Ballasts

3 Description

The UCC38050 and UCC38051 are PFC controllers for low-to-medium power applications requiring compliance with IEC 1000-3-2 harmonic reduction standard. The controllers are designed for a boost preregulator operating in transition mode (also referred to as boundary-conduction mode or critical conduction-mode operation). They feature a transconductance voltage amplifier for feedback error processing, a simple multiplier for generating a current command proportional to the input voltage, a current-sense (PWM) comparator, PWM logic, and a totem-pole driver for driving an external FET.

In the transition mode operation, the PWM circuit is self-oscillating, with the turnon being governed by an inductor zero-current detector (ZCD pin), and the turnoff being governed by the current-sense comparator. Additionally, the controller provides features such as peak current limit, default timer, overvoltage protection (OVP) and enable.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
UCC28050, UCC28051, UCC38050, UCC38051 SOIC (8) 3.91 mm × 4.90 mm
PDIP (8) 6.35 mm × 9.81 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Application Diagram

UCC28050 UCC28051 UCC38050 UCC38051 slus515_sch.gif