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

6.3.9 CDX - CCM, drive strength and X-cap discharge

Use the CDX pin to enable/disable CCM mode and X-cap discharge and select the SW node slew rate when turning on the GaN HEMT. Refer to Table 8-4 for values of resistors to connect from this pin to GND for the given operating points. The resistor needs to be 1% accurate.

Table 6-4 CDX Pin Programming Resistor Values
CDX Pin Resistor (kΩ) CCM SW node turn-on slew rate X-cap discharge
5.23 Disabled 7V/ns Enabled
6.34 Disabled 5V/ns Enabled
7.68 Disabled 3V/ns Enabled
9.31 Disabled 7V/ns Disabled
11.5 Disabled 5V/ns Disabled
14.3 Disabled 3V/ns Disabled
17.8 Enabled 7V/ns Enabled
22.6 Enabled 5V/ns Enabled
28.7 Enabled 3V/ns Enabled
36.5 Enabled 7V/ns Disabled
51.1 Enabled 5V/ns Disabled
75 Enabled 3V/ns Disabled