SNOSDL1 December   2024 LMG3650R035

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
  8. 7 Parameter Measurement Information
    1. 7.1 Switching Parameters
      1. 7.1.1 Turn-On Times
      2. 7.1.2 Turn-Off Times
      3. 7.1.3 Drain-Source Turn-On and Turn-off Slew Rate
      4. 7.1.4 Zero-Voltage Detection Times (LMG3656R035 only)
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
      1. 8.2.1 LMG3650R035 Functional Block Diagram
      2. 8.2.2 LMG3651R035 Functional Block Diagram
      3. 8.2.3 LMG3656R035 Functional Block Diagram
      4. 8.2.4 LMG3657R035 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Drive Strength Adjustment
      2. 8.3.2 VDD Supply
      3. 8.3.3 Overcurrent and Short-Circuit Protection
      4. 8.3.4 Overtemperature Protection
      5. 8.3.5 UVLO Protection
      6. 8.3.6 Fault Reporting
      7. 8.3.7 Auxiliary LDO (LMG3651R035 Only)
      8. 8.3.8 Zero-Voltage Detection (ZVD) (LMG3656R035 Only)
      9. 8.3.9 Zero-Current Detection (ZCD) (LMG3657R035 Only)
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Slew Rate Selection
        2. 9.2.2.2 Signal Level-Shifting
    3. 9.3 Power Supply Recommendations
      1. 9.3.1 Using an Isolated Power Supply
      2. 9.3.2 Using a Bootstrap Diode
        1. 9.3.2.1 Diode Selection
        2. 9.3.2.2 Managing the Bootstrap Voltage
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

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発注情報

8.3.3 Overcurrent and Short-Circuit Protection

There are two types of current faults which can be detected by the driver: overcurrent fault and short-circuit fault.

The overcurrent protection (OCP) circuit monitors drain current and compares that current signal with an internally set limit IT(OC). Upon detection of the overcurrent, the LMG365xR035 performs cycle-by-cycle protection as shown in Figure 8-2. In this mode, the GaN device is shut off when the drain current crosses the IT(OC) plus a delay toff(OC), but the overcurrent signal clears after the IN pin signal goes low. In the next cycle, the GaN device can turn on as normal. The cycle-by-cycle function can be used in cases where steady-state operation current is below the OCP level but transient response can still reach current limit, while the circuit operation cannot be paused. The cycle-by-cycle function also prevents the GaN device from overheating by overcurrent induced conduction losses.

The short-circuit protection is based on desaturation (de-sat) detection, which monitors the drain-source voltage VDS and compares the voltage with an internally set limit VT(Idsat). If the OC occurs before the de-sat, the VDS is below the threshold, then OC is triggered, else de-sat is triggered as shown in Figure 8-3. Saturation can be damaging for the GaN to continue to operate in that condition. Therefore, if a de-sat is detected, the GaN device is turned off with an intentionally slowed driver so that a lower overshoot voltage and ringing can be achieved during the turn-off event. This fast response circuit helps protect the GaN device even under a hard short-circuit condition. In this protection, the GaN device is shut off and held off until the fault is reset by either holding the IN pin low for a period of time defined in the Specifications or removing power from VDD.

For safety considerations, OCP allows cycle-by-cycle operation while de-sat latches the device until reset. Both faults are reported on the FLT/RDRV pin.

LMG3650R035 LMG3651R035 LMG3656R035 LMG3657R035 Cycle-by-Cycle Overcurrent Protection Operation Figure 8-2 Cycle-by-Cycle Overcurrent Protection Operation
LMG3650R035 LMG3651R035 LMG3656R035 LMG3657R035 Overcurrent Detection vs Desaturation Detection Figure 8-3 Overcurrent Detection vs Desaturation Detection