SNOSDF8 December   2024 LM74680

PRODUCTION DATA  

  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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Input and Output Voltage
      2. 7.3.2 Charge Pump
      3. 7.3.3 Gate Drivers
      4. 7.3.4 Enable
    4. 7.4 Device Functional Modes
      1. 7.4.1 Conduction Mode
        1. 7.4.1.1 Regulated Conduction Mode
        2. 7.4.1.2 Full Conduction Mode
      2. 7.4.2 Reverse Current Protection Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Design Considerations
        2. 8.2.2.2 MOSFET Selection
        3. 8.2.2.3 Output Capacitance
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Transient Protection
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      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

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8.3.1 Transient Protection

The TVS at input or output is not required for the LM74680 to operate, but it may be required to clamp the voltage transients caused by lightning, switching surges, or power disturbances that can exceed the voltage ratings of MOSFETs and the controller possibly causing damage. A TVS diode protects against such events by clamping the transient voltages to safe levels. For 24V AC systems, a bidirectional TVS with a standoff voltage above the AC peak and a clamping voltage below the MOSFET's maximum rating is recommended. In well-regulated applications with minimal transient risks, a TVS diode may not be necessary.

To avoid output voltage buildup during input hotplug conditions due to coupling from MOSFET gate capacitance using MOSFETs with input capacitance of at least 1nF is recommended. If the input capacitance of the selected MOSFET is less than 1nF, add a 1nF capacitor between the gate and source of the top-side MOSFETs.