SNVS532D October   2007  – August 2020 LM5067

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 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 Power Up Sequence
      2. 8.3.2 Gate Control
      3. 8.3.3 Current Limit
      4. 8.3.4 Circuit Breaker
      5. 8.3.5 Power Limit
      6. 8.3.6 Fault Timer and Restart
      7. 8.3.7 Undervoltage Lock-Out (UVLO)
      8. 8.3.8 Overvoltage Lock-Out (OVLO)
      9. 8.3.9 Power Good Pin
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown / Enable Control
  9. 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  RIN, CIN
        2. 9.2.2.2  Current Limit, RS
        3. 9.2.2.3  Power Limit Threshold
        4. 9.2.2.4  Turn-On Time
          1. 9.2.2.4.1 Turn-on With Current Limit Only
          2. 9.2.2.4.2 Turn-on With Power Limit and Current Limit
        5. 9.2.2.5  MOSFET Selection
        6. 9.2.2.6  Timer Capacitor, CT
          1. 9.2.2.6.1 Insertion Delay
          2. 9.2.2.6.2 Fault Timeout Period
          3. 9.2.2.6.3 Restart Timing
        7. 9.2.2.7  UVLO, OVLO
          1. 9.2.2.7.1 Option A:
          2. 9.2.2.7.2 Option B:
          3. 9.2.2.7.3 Option C:
          4. 9.2.2.7.4 Option D:
        8. 9.2.2.8  Thermal Considerations
        9. 9.2.2.9  System Considerations
          1. 9.2.2.9.1 System Considerations During Surge Events
        10. 9.2.2.10 Power Good Pin
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Operating Voltage
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.5 MOSFET Selection

It is recommended that the external MOSFET (Q1) selection be based on the following criteria:

  • The BVDSS rating should be greater than the maximum system voltage (VSYS), plus ringing and transients which can occur at VSYS when the circuit card, or adjacent cards, are inserted or removed.
  • The maximum continuous current rating should be based on the current limit threshold (50 mV/RS), not the maximum load current, since the circuit can operate near the current limit threshold continuously.
  • The Pulsed Drain Current spec (IDM) must be greater than the current threshold for the circuit breaker function (100 mV/RS).
  • The SOA (Safe Operating Area) chart of the device, and the thermal properties, should be used to determine the maximum power dissipation threshold set by the RPWR resistor. The programmed maximum power dissipation should have a reasonable margin from the maximum power defined by the FET's SOA chart if the LM5067-2 is used since the FET will be repeatedly stressed during fault restart cycles. The FET manufacturer should be consulted for guidelines.
  • RDS(on) should be sufficiently low that the power dissipation at maximum load current (IL(max)2 x RDS(on)) does not raise its junction temperature above the manufacturer’s recommendation.

If the device chosen for Q1 has a maximum VGS rating less than 13V, an external zener diode must be added from its gate to source, with the zener voltage less than the maximum VGS rating. The zener diode’s forward current rating must be at least 110 mA to conduct the GATE pull-down current during startup and in the circuit breaker mode.