JAJSSX2 February   2025 LMG3650R025

ADVANCE INFORMATION  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  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 (LMG3656R025 only)
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
      1. 8.2.1 LMG3650R025 Functional Block Diagram
      2. 8.2.2 LMG3651R025 Functional Block Diagram
      3. 8.2.3 LMG3656R025 Functional Block Diagram
      4. 8.2.4 LMG3657R025 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 (LMG3651R025 Only)
      8. 8.3.8 Zero-Voltage Detection (ZVD) (LMG3656R025 Only)
      9. 8.3.9 Zero-Current Detection (ZCD) (LMG3657R025 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 ドキュメントの更新通知を受け取る方法
    2. 10.2 サポート・リソース
    3. 10.3 Trademarks
    4. 10.4 静電気放電に関する注意事項
    5. 10.5 用語集
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

8.3.1 Drive Strength Adjustment

The LMG365xR025 allows users to adjust the drive strength of the device and obtain a desired slew rate, which provides flexibility when optimizing switching losses and minimizing EMI. The typical value of turn-on slew rate and the maximum value of turn-off slew rate can be independently controlled by connecting the resistors and capacitor as shown in the Figure 8-1. The resistance and capacitance on FLT/RDRV pin is sensed once at power-up. To do so, the device forces a step-function from 0V to 1.2V on the external RDRVon-RDRVoff-CDRVoff network and measures the resulting current waveform. The DC measurement determines the turn-on slew rate setting, which is programmed by the resistance RDRVon. The AC measurement dependent on RDRVon-RDRVoff-CDRVoff determines the turn-off slew rate setting, which is dependent on the magnitude of the drain-to-source current charging the output capacitance but can be limited to a maximum value programmed by the resistance RDRVoff and capacitance CDRVoff, connected in parallel to RDRVon. Table 8-1 shows the recommended typical resistances and capacitance programming values at each slew rate setting.

The slew rate settings are determined one time at power up, then the FLT/RDRV pin is used as a push-pull 5V digital output for fault monitoring, as described in Fault Reporting. If RDRVoffand CDRVoff are not used, the device turns-off at full-speed and the turn-off slew rate is strictly determined by the Coss and the load current. If RDRVon is not used, the device defaults to the 100V/ns slew rate setting. Using slower turn-on settings results in higher Eon losses, and slower turn-off settings results in higher Eoff losses.

LMG3650R025 LMG3651R025 LMG3656R025 LMG3657R025 Drive Strength Adjustment Circuit Figure 8-1 Drive Strength Adjustment Circuit
Table 8-1 Recommended Typical Programming Resistance (kΩ) and Capacitance (pF) for Adjusting Slew Rates
TYPICAL TURN-ON SLEW RATE (V/ns) MAXIMUM TURN-OFF SLEW RATE (V/ns)
10 20 40 No limit (1)
RDRVon RDRVoff CDRVoff RDRVoff CDRVoff RDRVoff CDRVoff RDRVoff CDRVoff
10 29.4 2 680 4.87 270 9.09 150 high impedance(2)
20 35.7 2 680 4.75 270 8.66 150
40 43.2 2 680 4.64 270 8.25 150
60 53.6 2 680 4.64 270 8.06 150
80 69.8 2 680 4.53 270 7.68 150
100 > 400(2) 2 680 4.22 270 6.98 180
(1) Fully dependent on the magnitude of the drain-to-source current charging the output capacitance
(2) Open-circuit connection for programming resistances is acceptable

For example, setting RDRVon = 53.6kΩ, RDRVoff = 4.64kΩ and CDRVoff= 270pF results in turn-on slew rate of 60V/ns and turn-off slew rate is limited to a maximum of 20V/ns.