TIDUF86A January   2025  – July 2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 System Overview
    3. 2.3 Highlighted Products
      1. 2.3.1 LMG3100
      2. 2.3.2 LMR38010
      3. 2.3.3 TMP61
      4. 2.3.4 TPS7B81
      5. 2.3.5 OPA4323
  9. 3System Design Theory
    1. 3.1 Power Stage Design: Three-Phase Inverter
    2. 3.2 LMG3100 GaN-FET Power Stage
    3. 3.3 Power Management
    4. 3.4 Current-Sensing Circuit
    5. 3.5 Overcurrent Protection Circuit
    6. 3.6 Phase Voltage and DC Input Voltage Sensing
    7. 3.7 Power-Stage PCB Temperature Monitor
    8. 3.8 Interface to Host MCU
  10. 4Hardware, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
      1. 4.1.1 TIDA-010276 PCB Overview
      2. 4.1.2 TIDA-010276 Jumper Settings
    2. 4.2 Test Setup
    3. 4.3 Test Results
      1. 4.3.1 Power Management and System Power Up and Power Down
      2. 4.3.2 GaN Inverter Switch Node Voltage
      3. 4.3.3 Switch Node Voltage Transient Response
      4. 4.3.4 Impact of PWM Frequency to DC-Bus Voltage Ripple
      5. 4.3.5 Efficiency Measurements
      6. 4.3.6 Thermal Analysis
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6About the Author
  13. 7Revision History

4.3.3 Switch Node Voltage Transient Response

Figure 4-10 through Figure 4-13 outline the SW transient voltage at hard-switching and soft-switching. PWM frequency (20kHz), LMG3100 propagation delay, as well as the 16.6ns PWM dead band can be well identified. Due to the low phase current there is hard-switching and a combination of soft- and hard-switching as shown in the following waveforms. The turn-on and turn-off slew rate (20% to 80%) of the GaN FETs was configured to around 10V/ns to 15V/ns.


TIDA-010276 Phase U Rising SW, Phase Current 36V, 1A

Figure 4-10 Phase U Rising SW, Phase Current 36V, 1A

TIDA-010276 Phase U Rising SW, Phase Current 36V, –1A

Figure 4-12 Phase U Rising SW, Phase Current 36V, –1A

TIDA-010276 Phase U Falling SW, Phase Current 36V, 1A

Figure 4-11 Phase U Falling SW, Phase Current 36V, 1A

TIDA-010276 Phase U Falling SW, Phase Current 36V, –1A

Figure 4-13 Phase U Falling SW, Phase Current 36V, –1A

Figure 4-14 through Figure 4-17 show the test result of PWM input to GaN-FET propagation delay, tested in output of 1A and 20A. Propagation delay is small enough for a motor control system.


TIDA-010276 Phase U Rising SW, Phase Current 36V, 20A

Figure 4-14 Phase U Rising SW, Phase Current 36V, 20A

TIDA-010276 Phase U Rising SW, Phase Current 36V, –20A

Figure 4-16 Phase U Rising SW, Phase Current 36V, –20A

TIDA-010276 Phase U Falling SW, Phase Current 36V, 20A

Figure 4-15 Phase U Falling SW, Phase Current 36V, 20A

TIDA-010276 Phase U Falling SW, Phase Current 36V, –20A

Figure 4-17 Phase U Falling SW, Phase Current 36V, –20A