JAJSR62 September   2023 LMG3522R050

PRODUCTION DATA  

  1.   1
  2. 特長
  3. アプリケーション
  4. 概要
  5. Revision History
  6. Pin Configuration and Functions
  7. 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
    7. 6.7 Typical Characteristics
  8. 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 Slew Rate
  9. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  GaN FET Operation Definitions
      2. 8.3.2  Direct-Drive GaN Architecture
      3. 8.3.3  Drain-Source Voltage Capability
      4. 8.3.4  Internal Buck-Boost DC-DC Converter
      5. 8.3.5  VDD Bias Supply
      6. 8.3.6  Auxiliary LDO
      7. 8.3.7  Fault Detection
        1. 8.3.7.1 Overcurrent Protection and Short-Circuit Protection
        2. 8.3.7.2 Overtemperature Shutdown
        3. 8.3.7.3 UVLO Protection
        4. 8.3.7.4 Fault Reporting
      8. 8.3.8  Drive-Strength Adjustment
      9. 8.3.9  Temperature-Sensing Output
      10. 8.3.10 Ideal-Diode Mode Operation
        1. 8.3.10.1 Overtemperature-Shutdown Ideal-Diode Mode
    4. 8.4 Start-Up Sequence
    5. 8.5 Safe Operation Area (SOA)
      1. 8.5.1 Repetitive SOA
    6. 8.6 Device Functional Modes
  10. 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
          1. 9.2.2.1.1 Start-Up and Slew Rate With Bootstrap High-Side Supply
        2. 9.2.2.2 Signal Level-Shifting
        3. 9.2.2.3 Buck-Boost Converter Design
      3. 9.2.3 Application Curves
    3. 9.3 Do's and Don'ts
    4. 9.4 Power Supply Recommendations
      1. 9.4.1 Using an Isolated Power Supply
      2. 9.4.2 Using a Bootstrap Diode
        1. 9.4.2.1 Diode Selection
        2. 9.4.2.2 Managing the Bootstrap Voltage
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
        1. 9.5.1.1 Solder-Joint Reliability
        2. 9.5.1.2 Power-Loop Inductance
        3. 9.5.1.3 Signal-Ground Connection
        4. 9.5.1.4 Bypass Capacitors
        5. 9.5.1.5 Switch-Node Capacitance
        6. 9.5.1.6 Signal Integrity
        7. 9.5.1.7 High-Voltage Spacing
        8. 9.5.1.8 Thermal Recommendations
      2. 9.5.2 Layout Examples
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 ドキュメントの更新通知を受け取る方法
    3. 10.3 サポート・リソース
    4. 10.4 Trademarks
    5. 10.5 静電気放電に関する注意事項
    6. 10.6 Export Control Notice
    7. 10.7 用語集

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

Overtemperature-Shutdown Ideal-Diode Mode

Overtemperature-shutdown ideal-diode mode (OTSD-IDM) is implemented in LMG3522R050. As explained in Overtemperature Shutdown, ideal-diode mode provides the best GaN FET protection when the GaN FET is overheating.

OTSD-IDM accounts for all, some, or none of the power system operating when OTSD-IDM is protecting the GaN FET. The power system may not have the capability to shut itself down, in response to the LMG3522R050 asserting the FAULT pin in a GaN OTSD event, and just continue to try to operate. Parts of the power system can stop operating due to any reason such as a controller software bug or a solder joint breaking or a device shutting off to protect itself. At the moment of power system shutdown, the power system stops providing gate drive signals but the inductive elements continue to force current flow while they discharge.

The OTSD-IDM state machine is shown in Figure 8-6. Each state is assigned a state number in the upper right side of the state box. The OTSD-IDM state machine has a similar structure to the OP-IDM state machine. Similar states use the same state number.

GUID-20211117-SS0I-2CGR-M843-JT4BHRWSMPQB-low.svg Figure 8-6 Overtemperature-Shutdown Ideal-Diode Mode (OTSD-IDM) State Machine
  1. The LMG3522R050 GaN FET always goes to state #1 if a falling edge is detected on the IN pin. OTSD-IDM turns off the GaN FET in OTSD-IDM state #1. OTSD-IDM is waiting for the IN falling edge blank time to expire. This time gives the opposite-side FET time to switch to create a positive drain voltage. After the blank time expires, the device moves to OTSD-IDM state #2.
  2. For OTSD-IDM state #2, OTSD-IDM keeps the GaN FET off if it is coming from OTSD-IDM state #1 and turns the GaN FET off if it is coming from OTSD-IDM state #3. OTSD-IDM is monitoring the GaN FET drain voltage in OP-IDM state #2. It is looking for a negative drain voltage which means third-quadrant current is flowing. This is also the starting state when the device enters OTSD. After a negative GaN FET drain voltage is detected, the device moves to OTSD-IDM state #3
  3. OP-IDM turns on the GaN FET in OTSD-IDM state #3. OP-IDM monitors the drain current in this state. If first-quadrant drain current is detected, the device moves to OP-IDM state #2.

State #1 is used to protect against shoot-through current. The state #1 in the OTSD-IDM state machine waits for a fixed time period before proceeding to state #2. The fixed time period is to give the opposite-side switch time to switch and create a positive drain voltage. A fixed time is used to avoid a stuck condition for cases where a positive drain voltage is not created.

State #1 will help protect against shoot-through currents if the converter continues switching when the LMG3522R050 enters OTSD. Meanwhile, if the converter initiates switching with the LMG3522R050 already in OTSD, shoot-through current protection can be obtained by switching the OTSD device first to force it to progress though state #1. For example, the synchronous rectifier in a boost PFC can go into OTSD during initial input power application as the inrush current charges the PFC output cap. A shoot-through current event can be avoided if converter switching begins by switching the synchronous rectifier FET before switching the boost PFC FET.

If there is no IN signal, the state machine only moves between states #2 and #3 as a classic ideal-diode mode state machine. This allows all the inductive elements to discharge, when the power system shuts off, with minimum discharge stress created in the GaN FET.

Note that the OTSD-IDM state machine has no protection against repetitive shoot-through current events. There are degenerate cases, such as the LMG3522R050 losing its IN signal during converter operation, which can expose the OTSD-IDM to repetitive shoot-through current events. There is no good solution in this scenario. If OTSD-IDM did not allow repeated shoot-thru current events, the GaN FET would instead be exposed to excessive off-state third-quadrant losses.