SLUSFF2 October   2024 UCG28826

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Detailed Pin Descriptions
      1. 6.3.1  HV - High Voltage Input
      2. 6.3.2  SW - Switch Node
      3. 6.3.3  GND – Ground Return
      4. 6.3.4  FLT - External Overtemperature Fault
      5. 6.3.5  FB ­­– Feedback
      6. 6.3.6  TR - Turns Ratio
      7. 6.3.7  IPK - Peak Current and Dithering
      8. 6.3.8  FCL - Frequency clamp and fault response
      9. 6.3.9  CDX - CCM, drive strength and X-cap discharge
      10. 6.3.10 VCC - Input Bias
    4. 6.4 Feature Description
      1. 6.4.1  Self Bias and Auxless Sensing
      2. 6.4.2  Control Law
        1. 6.4.2.1 Valley Switching
        2. 6.4.2.2 Frequency Foldback
        3. 6.4.2.3 Burst Mode
        4. 6.4.2.4 Continuous Conduction Mode (CCM)
      3. 6.4.3  GaN HEMT Switching Capability
      4. 6.4.4  Soft Start
      5. 6.4.5  Frequency Clamp
      6. 6.4.6  Frequency Dithering
      7. 6.4.7  Slew Rate Control
      8. 6.4.8  Transient Peak Power Capability
      9. 6.4.9  X-Cap Discharge
      10. 6.4.10 Fault Protections
        1. 6.4.10.1 Brownout Protection
        2. 6.4.10.2 Short-Circuit Protection
        3. 6.4.10.3 Output Over Voltage Protection
        4. 6.4.10.4 Over Power Protection (OPP, LPS)
        5. 6.4.10.5 Overtemperature Protection
        6. 6.4.10.6 Open FB Protection
        7. 6.4.10.7 Error Codes for Protections
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Input Bulk Capacitor
        2. 7.2.2.2 Transformer Primary Inductance and Turns Ratio
        3. 7.2.2.3 Output Capacitor
        4. 7.2.2.4 Selection Resistors
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Package Option Addendum
    2. 10.2 Mechanical Data

Package Options

Mechanical Data (Package|Pins)
  • REZ|12
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6.1 Overview

The UCG28826 is a high frequency, quasi-resonant (QR) AC/DC flyback converter with integrated 700V primary-side GaN high electron mobility transistor (HEMT)(hereinafter referred to as GaN HEMT) suitable for use in power supplies up to 65W. This device gives benefit of GaN integration to achieve high power density designs with high switching frequency up to 500kHz.

The UCG28826 features industry's first auxless flyback architecture with self-bias to give a compact and low cost power supply design without the need for an auxiliary winding in the transformer. The self bias feature reduces losses to improve efficiency in wide output voltage applications like USB-PD chargers by eliminating the need for a low dropout regulator (LDO) and its associated losses to generate the device bias.

The UCG28826 supports continuous conduction mode (CCM) operation for upto 4msec for transient output power conditions of min. 130W (two times the 65W nominal output power) in low-line input conditions without the need for a transformer designed for such transient load conditions, saving space and cost. This device also includes frequency foldback and burst modes for higher efficiency operation during light load and no-load conditions, respectively. The X-cap discharge circuit discharges the X-capacitor in the input EMI filter to 0V within less than 1s to prevent the user from an electric shock at the time of unplugging the power supply from the wall socket.

The UCG28826 overcomes the system design limitations of integrated converters by offering resistor programmable options to the user for maximum flexibility to optimize performance at the desired operating point. The device also includes many built-in protections such as output over-voltage protection (OVP), short-circuit protection (SCP), two-level over power protection (OPPH and OPPL) and over-temperature protections (OTP) with auto-restart and latch response for a robust power supply design preventing any damage during such fault conditions.

UCG28826 AC/DC Flyback Converter Schematic using UCG28826 Figure 6-1 AC/DC Flyback Converter Schematic using UCG28826