SNOSDL7A January   2025  – December 2025 LMG3650R070

PRODMIX  

  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
    6. 5.6 Switching Characteristics
    7. 5.7 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Switching Parameters
      1. 6.1.1 Turn-On Times
      2. 6.1.2 Turn-Off Times
      3. 6.1.3 Drain-Source Turn-On and Turn-off Slew Rate
      4. 6.1.4 Zero-Voltage Detection Times (LMG3656R070 only)
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
      1. 7.2.1 LMG3650R070 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Drive Strength Adjustment
      2. 7.3.2 VDD Supply
      3. 7.3.3 Overcurrent and Short-Circuit Protection
      4. 7.3.4 Overtemperature Protection
      5. 7.3.5 UVLO Protection
      6. 7.3.6 Fault Reporting
      7. 7.3.7 Auxiliary LDO (LMG3651R070 Only)
      8. 7.3.8 Zero-Voltage Detection (ZVD) (LMG3656R070 Only)
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Slew Rate Selection
        2. 8.2.1.2 Signal Level-Shifting
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Using an Isolated Power Supply
      2. 8.3.2 Using a Bootstrap Diode
        1. 8.3.2.1 Diode Selection
        2. 8.3.2.2 Managing the Bootstrap Voltage
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Solder-Joint Reliability
        2. 8.4.1.2 Power-Loop Inductance
        3. 8.4.1.3 Signal-Ground Connection
        4. 8.4.1.4 Bypass Capacitors
        5. 8.4.1.5 Switch-Node Capacitance
        6. 8.4.1.6 Signal Integrity
        7. 8.4.1.7 High-Voltage Spacing
        8. 8.4.1.8 Thermal Recommendations
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1.     PACKAGE OPTION ADDENDUM
    2. 11.1 Tape and Reel Information
    3. 11.2 Mechanical, Packaging, and Orderable Information

7.3.3 Overcurrent and Short-Circuit Protection

The driver detects two types of current faults: overcurrent and short-circuit.

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 LMG365xR070 performs cycle-by-cycle protection as shown in Cycle-by-Cycle Overcurrent Protection Operation. 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 turns on as normal. Use the cycle-by-cycle function in cases where steady-state operation current is below the OCP level but transient response still reach current limit, while the circuit operation cannot pause. The cycle-by-cycle function also prevents the GaN device from overheating by overcurrent induced conduction losses. Additionally, the OCP level dynamically adjusts with junction temperature, with the internally set limit IT(OC) being higher at lower temperatures and decreasing as temperature increases, as defined in the Specifications, based on Equation 3. Dynamic adjustment allows customer to operate the device at lower temperatures with higher currents.

Equation 3. ITOC150°CITOC25°C=77%

The short-circuit protection is based on detection of saturation (de-sat), which monitors the drain-source voltage VDS and compares the voltage with an internally set limit VT(Idsat). Saturation can damage the GaN, causing failures if continued to operate in that condition. If saturation is detected, the GaN device is latched off. Turning off the device at high current causes significant voltage overshoot. Therefore, when turning off from saturation, the device is turned off with an intentionally slowed driver to achieve a lower overshoot voltage and ringing 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.

Figure Figure 7-3 shows the behavior of the OC and de-sat protection. In the first two cycles OC limit is triggered without de-sat being triggered, so cycle-by-cycle protection takes place. In the third cycle OC limit is triggered, but within the toff(OC) the de-sat protection is triggers when VDS rises above VT(Idsat). Since de-sat protection triggers, this results in a slowed turn-off and latched protection.

LMG3650R070 LMG3651R070 LMG3656R070 LMG3657R070 Cycle-by-Cycle Overcurrent Protection OperationFigure 7-2 Cycle-by-Cycle Overcurrent Protection Operation
LMG3650R070 LMG3651R070 LMG3656R070 LMG3657R070 Overcurrent Detection vs Desaturation DetectionFigure 7-3 Overcurrent Detection vs Desaturation Detection