SLUUD92 June   2025

 

  1.   1
  2.   Abstract
  3. 1General TI High Voltage Evaluation User Safety Guidelines
  4. 2Module and Gate Driver Compatibility
    1. 2.1 Supported Wolfspeed Modules and Evaluation Platforms
    2. 2.2 Supported Gate Drivers
  5. 3System Overview and Functions
    1. 3.1 Features
    2. 3.2 Specifications
    3. 3.3 PCB Pinout
    4. 3.4 EVM Information
      1. 3.4.1 Primary-Side Power
      2. 3.4.2 Primary-Side I/O and Diagnostics
      3. 3.4.3 Secondary-Side Bias Supply
      4. 3.4.4 Output Stage Gate Loop
      5. 3.4.5 Current Booster
      6. 3.4.6 Short-Circuit Detection System
        1. 3.4.6.1 Short-Circuit Detection - DESAT
        2. 3.4.6.2 Short-Circuit Detection - OC
  6. 4Using the EVM
    1. 4.1 Equipment List and Board Setup
    2. 4.2 Test Setups and Procedures
      1. 4.2.1 Power-On and Bias Supply Check
      2. 4.2.2 Output Switching
  7. 5Hardware Design Files
    1. 5.1 Schematics
    2. 5.2 PCB Layouts
    3. 5.3 Bill of Materials (BOM)
  8. 6Additional Information
    1. 6.1 Trademarks
  9. 7Revision History

3.4.6.1 Short-Circuit Detection - DESAT

The detailed DESAT, OC protection approach and the design guide is explained in the APP note. Please refer this APP note for the design choise of the compoents and the formulae details,Choosing Appropriate Protection Approach for IGBT and SiC Power Modules.

Equation 1. V DET ⁡ =   V D E S A T - V Z - n ×   V F - I c h g ×   R l i m

The Vds voltage detection threshold can be calculated with the equation,

With the 9V internal DESAT detection threshold, the two STTH122A diode with forward voltage of 0.6 V each, the 475-Ω limiting resistor, the Zener diode with 2.7-V Zener voltage, and the 500-µA internal charging current, the Vds DESAT detection threshold is calculated to be 4.86 V. If another Vds voltage detection threshold is desired, use different Rlim, diodes to create the needed detection voltage.

The DESAT charging current can be increased by installing R25 and R29. Increasing the DESAT charging current can decrease the blanking time of the capacitor and provide better protection for SiC MOSFETs.

UCC218002QEVM-111 DESAT Circuit Figure 3-6 DESAT Circuit