SNOSDD8 December   2022 LM7480

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
      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 Boost Converter Components (C2, C3, L1)
        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
    5. 10.5 Power Supply Recommendations
      1. 10.5.1 Transient Protection
      2. 10.5.2 TVS Selection for 12-V Battery Systems
      3. 10.5.3 TVS Selection for 24-V Battery Systems
    6. 10.6 Layout
      1. 10.6.1 Layout Guidelines
      2. 10.6.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.3.2.1 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 LM7480x 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 LM74800 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 10.5 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 LM74800 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 2.8 µs (typ).

In LM74801, reverse current blocking is by fast reverse voltage comparator only. 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 LM7480 micro-shorts. The external MOSFET is turned ON back when the voltage across A and C hits V(AC_FWD) threshold within 2.8 µs (typ).

For Ideal Diode only designs, connect LM7480x as shown in Figure 9-2.

Figure 9-2 Configuring LM7480x-Q1 for Ideal Diode Only