SNOU209 December   2024

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
    5. 1.5 General TI High Voltage Evaluation User Safety Guidelines
      1. 1.5.1 Safety and Precautions
  7. 2Hardware
    1. 2.1 LMG2656EVM-102 Daughtercard
      1. 2.1.1 Test Points
      2. 2.1.2 Integrated Current Sensing
      3. 2.1.3 Enable Pin
      4. 2.1.4 GDH
      5. 2.1.5 Power Pins
      6. 2.1.6 Heat Sink
    2. 2.2 Motherboard
      1. 2.2.1 Bias Supply
      2. 2.2.2 PWM Input
      3. 2.2.3 Fault Protection
    3. 2.3 Recommended Footprint
    4. 2.4 Test Equipment
    5. 2.5 Test Procedure When Paired With LMG342X-BB-EVM
      1. 2.5.1 Setup
      2. 2.5.2 Start-Up and Operating Procedure
      3. 2.5.3 Test Results
      4. 2.5.4 Shutdown Procedure
      5. 2.5.5 Additional Operating Notes
  8. 3Hardware Design Files
    1. 3.1 LMG2656EVM-102 Schematic
    2. 3.2 Motherboard Schematic
    3. 3.3 PCB Layout
    4. 3.4 Bill of Materials
  9. 4Additional Information
    1. 4.1 Trademarks
  10. 5Related Documentation

2.1.4 GDH

The LMG2656EVM-102 only reports a low-side overtemperature fault. A low-side overtemperature fault is reported on the FLT pin when the low-side overtemperature protection function is asserted. The FLT pin is an active low open-drain output so the pin pulls low when there is a low-side overtemperature fault. Refer to the LMG2656 650V 250mΩ GaN Half Bridge with Integrated Driver and Current Sense Emulation data sheet for operation details.

The GDH pin is referenced to SW and is used to turn the high-side GaN power FET on and off. The GDH pin is compatible with controllers that use a high-side referenced signal to control the high-side GaN power FET. The LMG2656 is intended to be used with either the INH pin or the GDH pin controlling the high-side GaN power FET.

The LMG2656EVM-102 uses headers J2 and J3 paired with two jumpers SH-J1 and SH-J2 to set the high-side PWM input signal pin. By default, GDH is shorted to SW and INH is shorted to the digital header J1 which interfaces with either the corresponding TI motherboard or custom circuit.

To use the GDH pin as high-side input signal, INH must be grounded with jumper SH-J2. Move this jumper between pins 2 and 3 of header J3 to connect the INH pin of LMG2656 to AGND. Next, remove the jumper SH-J1 to expose header J2, which is now the input for high-side gate signal. If using a waveform generator, be sure the ground is floating, and connect the signal between pin 1 and 2 of J2. The positive signal connects to GDH and negative to SW.