SLUSBE8B May   2013  – September 2015 UCC28720

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 Detailed Pin Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Primary-Side Voltage Regulation
      2. 7.4.2 Primary-Side Current Regulation
      3. 7.4.3 Valley Switching
      4. 7.4.4 Start-Up Operation
      5. 7.4.5 Fault Protection
  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 Stand-by Power Estimate
        2. 8.2.2.2 Input Bulk Capacitance and Minimum Bulk Voltage
        3. 8.2.2.3 Transformer Turns Ratio, Inductance, Primary-Peak Current
        4. 8.2.2.4 Transformer Parameter Verification
        5. 8.2.2.5 Output Capacitance
        6. 8.2.2.6 VDD Capacitance, CDD
        7. 8.2.2.7 VS Resistor Divider, Line Compensation, and Cable Compensation
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
        1. 11.1.1.1 Definition of Terms
          1. 11.1.1.1.1  Capacitance Terms in Farads
          2. 11.1.1.1.2  Duty Cycle Terms
          3. 11.1.1.1.3  Frequency Terms in Hertz
          4. 11.1.1.1.4  Current Terms in Amperes
          5. 11.1.1.1.5  Current and Voltage Scaling Terms
          6. 11.1.1.1.6  Transformer Terms
          7. 11.1.1.1.7  Power Terms in Watts
          8. 11.1.1.1.8  Resistance Terms in Ω
          9. 11.1.1.1.9  Timing Terms in Seconds
          10. 11.1.1.1.10 Voltage Terms in Volts
          11. 11.1.1.1.11 AC Voltage Terms in VRMS
          12. 11.1.1.1.12 Efficiency Terms
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    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

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

1 Features

  • < 10-mW No-Load Power
  • Primary-Side Regulation (PSR) Eliminates Opto-Coupler
  • ±5% Voltage and Current Regulation Across Line and Load
  • 700-V Start-Up Switch
  • 80-kHz Maximum Switching Frequency Enables High-Power Density Charger Designs
  • Quasi-Resonant Valley-Switching Operation for Highest Overall Efficiency
  • Wide VDD Range Allows Small Bias Capacitor
  • Dynamic BJT Drive
  • Overvoltage, Low-Line, and Overcurrent Protection Functions
  • Programmable Cable Compensation
  • SOIC-7 Package

2 Applications

  • USB-Compliant Adapters and Chargers for Consumer Electronics
    • Smart phones
    • Tablet computers
    • Cameras
  • Standby Supply for TV and Desktop
  • White Goods

3 Description

The UCC28720 flyback power supply controller provides isolated-output Constant-Voltage (CV) and Constant-Current (CC) output regulation without the use of an optical coupler. The devices process information from the primary power switch and an auxiliary flyback winding for precise control of output voltage and current.

An internal 700-V start-up switch, dynamically-controlled operating states and a tailored modulation profile support ultra-low standby power without sacrificing start-up time or output transient response.

Control algorithms in the UCC28720 allow operating efficiencies to meet or exceed applicable standards. The output drive interfaces to a bipolar transistor power switch. Discontinuous conduction mode (DCM) with valley switching reduces switching losses. Modulation of switching frequency and primary current peak amplitude (FM and AM) keeps the conversion efficiency high across the entire load and line ranges.

The controller has a maximum switching frequency of 80 kHz and always maintains control of the peak-primary current in the transformer. Protection features help keep primary and secondary component stresses in check. The UCC28720 allows compensation for voltage drop in the cable to be programmed with an external resistor.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
UCC28720 SOIC (7) 3.91 mm × 4.90 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Typical Application

UCC28720 alt_v13090_lusbe8.gif