SNOSD95C April   2020  – December 2020 LM7480-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Charge Pump
      2. 9.3.2 Dual Gate Control (DGATE, HGATE)
        1. 9.3.2.1 Reverse Battery Protection (A, C, DGATE)
        2. 9.3.2.2 Load Disconnect Switch Control (HGATE, OUT)
      3. 9.3.3 Overvoltage Protection and Battery Voltage Sensing (VSNS, SW, OV)
      4. 9.3.4 Low Iq Shutdown and Under Voltage Lockout (EN/UVLO)
    4. 9.4 Device Functional Modes
    5. 9.5 Application Examples
      1. 9.5.1 Redundant Supply OR-ing with Inrush Current Limiting, Overvoltage Protection and ON/OFF Control
      2. 9.5.2 Ideal Diode with Unsuppressed Load Dump Protection
  10. 10Applications and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical 12-V Reverse Battery Protection Application
      1. 10.2.1 Design Requirements for 12-V Battery Protection
      2. 10.2.2 Automotive Reverse Battery Protection
        1. 10.2.2.1 Input Transient Protection: ISO 7637-2 Pulse 1
        2. 10.2.2.2 AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06
        3. 10.2.2.3 Input Micro-Short Protection: LV124 E-10
      3. 10.2.3 Detailed Design Procedure
        1. 10.2.3.1 Design Considerations
        2. 10.2.3.2 Charge Pump Capacitance VCAP
        3. 10.2.3.3 Input and Output Capacitance
        4. 10.2.3.4 Hold-Up Capacitance
        5. 10.2.3.5 Overvoltage Protection and Battery Monitor
      4. 10.2.4 MOSFET Selection: Blocking MOSFET Q1
      5. 10.2.5 MOSFET Selection: Hot-Swap MOSFET Q2
      6. 10.2.6 TVS Selection
      7. 10.2.7 Application Curves
    3. 10.3 200-V Unsuppressed Load Dump Protection Application
      1. 10.3.1 Design Requirements for 200-V Unsuppressed Load Dump Protection
      2. 10.3.2 Design Procedure
        1. 10.3.2.1 Charge Pump Capacitance VCAP
        2. 10.3.2.2 Input and output capacitance
        3. 10.3.2.3 VS Capacitance, Resistor and Zener Clamp
        4. 10.3.2.4 Overvoltage Protection and Output Clamp
        5. 10.3.2.5 MOSFET Q1 Selection
        6. 10.3.2.6 Input TVS Selection
        7. 10.3.2.7 MOSFET Q2 Selection
      3. 10.3.3 Application Curves
    4. 10.4 Do's and Don'ts
  11. 11Power Supply Recommendations
    1. 11.1 Transient Protection
    2. 11.2 TVS Selection for 12-V Battery Systems
    3. 11.3 TVS Selection for 24-V Battery Systems
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Receiving Notification of Documentation Updates
    2. 13.2 Support Resources
    3. 13.3 Trademarks
    4. 13.4 Electrostatic Discharge Caution
    5. 13.5 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

11.3 TVS Selection for 24-V Battery Systems

For 24-V battery protection application, the TVS and MOSFET in Figure 10-1 needs to be changed to suit 24-V battery requirements.

The breakdown voltage of the TVS+ should be higher than 48-V jump start voltage, less than the absolute maximum ratings of anode and enable pin of LM7480x-Q1 (70 V) and should withstand 65-V suppressed load dump. The breakdown voltage of TVS- should be lower than maximum reverse battery voltage –32 V, so that the TVS- is not damaged due to long time exposure to reverse connected battery.

During ISO 7637-2 pulse 1, the input voltage goes up to –600 V with a generator impedance of 50 Ω. This translates to 12-A flowing through the TVS-. The clamping voltage of the TVS- cannot be same as that of 12-V battery protection circuit. Because during the ISO 7637-2 pulse, the Anode to Cathode voltage seen is equal to (- TVS Clamping voltage + Output capacitor voltage). For 24-V battery application, the maximum battery voltage is 32 V, then the clamping voltage of the TVS- should not exceed, 85 V – 32 V = 53 V.

Single bi-directional TVS cannot be used for 24-V battery protection because breakdown voltage for TVS+ ≥ 65V, maximum clamping voltage is ≤ 53 V and the clamping voltage cannot be less than the breakdown voltage. Two un-directional TVS connected back-back needs to be used at the input. For positive side TVS+, SMBJ58A with the breakdown voltage of 64.4 V (minimum), 67.8 (typical) is recommended. For the negative side TVS-, SMBJ28A with breakdown voltage close to 32 V (to withstand maximum reverse battery voltage –32 V) and maximum clamping voltage of 42.1 V is recommended.

For 24-V battery protection, a 75-V rated MOSFET is recommended to be used along with SMBJ28A and SMBJ58A connected back-back at the input.