SNOSD98A May   2020  – December 2020 LM7481-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Charge Pump
      2. 8.3.2 Dual Gate Control (DGATE, HGATE)
        1. 8.3.2.1 Reverse Battery Protection (A, C, DGATE)
        2. 8.3.2.2 Load Disconnect Switch Control (HGATE, OUT)
      3. 8.3.3 Over Voltage Protection and Battery Voltage sensing (VSNS, SW, OV)
      4. 8.3.4 Low Iq Shutdown and Under Voltage Lockout (EN/UVLO)
    4. 8.4 Device Functional Modes
    5. 8.5 Application Examples
      1. 8.5.1 Redundant Supply OR-ing with Inrush Current Limiting, Over Voltage Protection and ON/OFF Control
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical 12-V Reverse Battery Protection Application
      1. 9.2.1  Design Requirements for 12-V Battery Protection
      2. 9.2.2  Automotive Reverse Battery Protection
      3. 9.2.3  Input Transient Protection: ISO 7637-2 Pulse 1
      4. 9.2.4  AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06
      5. 9.2.5  Input Micro-Short Protection: LV124 E-10
      6. 9.2.6  Detailed Design Procedure
        1. 9.2.6.1 Design Considerations
        2. 9.2.6.2 Charge Pump Capacitance VCAP
        3. 9.2.6.3 Input and Output Capacitance
        4. 9.2.6.4 Hold-up Capacitance
        5. 9.2.6.5 Over Voltage Protection and Battery Monitor
      7. 9.2.7  MOSFET Selection: Blocking MOSFET Q1
      8. 9.2.8  MOSFET Selection: Hot-Swap MOSFET Q2
      9. 9.2.9  TVS selection
      10. 9.2.10 Application Curves
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
    1. 10.1 Transient Protection
    2. 10.2 TVS Selection for 12-V Battery Systems
    3. 10.3 TVS Selection for 24-V Battery Systems
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2.1 Reverse Battery Protection (A, C, DGATE)

A, C, DGATE comprises of Ideal Diode stage. Connect the Source of the external MOSFET to A, Drain to C and Gate to DGATE. The LM74810-Q1 has integrated reverse input protection down to –65 V.

Before the DGATE driver is enabled, following conditions must be achieved:

  • The EN/UVLO pin voltage must be greater than the specified input high voltage.
  • The CAP to VS voltage must be greater than the undervoltage lockout voltage.
  • Voltage at A pin must be greater than VA POR Rising threshold.
  • Voltage at Vs pin must be greater than Vs POR Rising thershold.
If the above conditions are not achieved, then the DGATE pin is internally connected to the A pin, assuring that the external MOSFET is disabled.

In LM74810-Q1 the voltage drop across the MOSFET is continuously monitored between the A and C pins, and the DGATE to A voltage is adjusted as needed to regulate the forward voltage drop at 9.1 mV (typ). This closed loop regulation scheme enables graceful turn off of the MOSFET during a reverse current event and ensures zero DC reverse current flow. This scheme ensures robust performance during slow input voltage ramp down tests. Along with the linear regulation amplifier scheme, the LM74810-Q1 also integrates a fast reverse voltage comparator. When the voltage drop across A and C reaches V(AC_REV) threshold then the DGATE goes low within 0.5-µs (typ). This fast reverse voltage comparator scheme ensures robust performance during fast input voltage ramp down tests such as input micro-shorts. The external MOSFET is turned ON back when the voltage across A and C hits V(AC_FWD) threshold within 0.85 µs (typ).

For Ideal Diode only designs, connect LM74810-Q1 as shown in Figure 8-2.

GUID-848E3509-3DA5-4B50-ABED-727A12716055-low.gifFigure 8-2 Configuring LM74810-Q1 for Ideal Diode Only