ZHCSP68C December   2021  – October 2022 DRV8328

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specification
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings Comm
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information 1pkg
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Three BLDC Gate Drivers
        1. 8.3.1.1 PWM Control Modes
          1. 8.3.1.1.1 6x PWM Mode
          2. 8.3.1.1.2 3x PWM Mode
        2. 8.3.1.2 Device Hardware Interface
        3. 8.3.1.3 Gate Drive Architecture
          1. 8.3.1.3.1 Propagation Delay
          2. 8.3.1.3.2 Deadtime and Cross-Conduction Prevention
      2. 8.3.2 AVDD Linear Voltage Regulator
      3. 8.3.3 Pin Diagrams
      4. 8.3.4 Gate Driver Shutdown Sequence (DRVOFF)
      5. 8.3.5 Gate Driver Protective Circuits
        1. 8.3.5.1 PVDD Supply Undervoltage Lockout (PVDD_UV)
        2. 8.3.5.2 AVDD Power on Reset (AVDD_POR)
        3. 8.3.5.3 GVDD Undervoltage Lockout (GVDD_UV)
        4. 8.3.5.4 BST Undervoltage Lockout (BST_UV)
        5. 8.3.5.5 MOSFET VDS Overcurrent Protection (VDS_OCP)
        6. 8.3.5.6 VSENSE Overcurrent Protection (SEN_OCP)
        7. 8.3.5.7 Thermal Shutdown (OTSD)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Gate Driver Functional Modes
        1. 8.4.1.1 Sleep Mode
        2. 8.4.1.2 Operating Mode
        3. 8.4.1.3 Fault Reset (nSLEEP Reset Pulse)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Three Phase Brushless-DC Motor Control
        1. 9.2.1.1 Detailed Design Procedure
          1. 9.2.1.1.1 Motor Voltage
          2. 9.2.1.1.2 Bootstrap Capacitor and GVDD Capacitor Selection
          3. 9.2.1.1.3 Gate Drive Current
          4. 9.2.1.1.4 Gate Resistor Selection
          5. 9.2.1.1.5 System Considerations in High Power Designs
            1. 9.2.1.1.5.1 Capacitor Voltage Ratings
            2. 9.2.1.1.5.2 External Power Stage Components
            3. 9.2.1.1.5.3 Parallel MOSFET Configuration
          6. 9.2.1.1.6 Dead Time Resistor Selection
          7. 9.2.1.1.7 VDSLVL Selection
          8. 9.2.1.1.8 AVDD Power Losses
          9. 9.2.1.1.9 Power Dissipation and Junction Temperature Losses
      2. 9.2.2 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Bulk Capacitance Sizing
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
      1. 11.3.1 Power Dissipation
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Device Nomenclature
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Community Resources
    6. 12.6 Trademarks
  13. 13Mechanical, Packaging, and Orderable Information

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9.2.1.1.4 Gate Resistor Selection

The slew rate of the SHx connection will be dependent on the rate at which the gate of the external MOSFETs is controlled. The pull-up/pull-down strength of the DRV8328 is fixed internally, hence the slew rate of gate voltage can be controlled with an external series gate resistor. In some applications, the gate charge of the MOSFET, which is the load on gate driver device, is significantly larger than the gate driver peak output current capability. In such applications, external gate resistors can limit the peak output current of the gate driver. External gate resistors are also used to dampen ringing and noise.

The specific parameters of the MOSFET, system voltage, and board parasitics will all affect the final SHx slew rate, so generally selecting an optimal value or configuration of external gate resistor is an iterative process.

To lower the gate drive current, a series resistor RGATE can be placed on the gate drive outputs to control the current for the source and sink current paths. A single gate resistor will have the same gate path for source and sink gate current, so larger RGATE values will yield similar SHx slew rates. Note that gate drive current varies by PVDD voltage, junction temperature, and process variation of the device. Gate resistor values can be estimated with +/-30% accuracy using the Gate Resistor Calculator.

Figure 9-3 Gate driver outputs with series resistors

Typically, it is recommended to have the sink current be twice the source current to implement a strong pulldown from gate to the source to ensure the MOSFET stays off while the opposite FET is switching. This can be implemented discretely by providing a separate path through a resistor for the source and sink currents by placing a diode and sink resistor (RSINK) in parallel to the source resistor (RSOURCE). Using the same value of source and sink resistors results in half the equivalent resistance for the sink path. This yields twice the gate drive sink current compared to the source current, and SHx will slew twice as fast when turning off the MOSFET.

Figure 9-4 Gate driver outputs with separate source and sink current paths