SNOSDE0A February   2022  – May 2022 LM74502-Q1 , LM74502H-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 Input Voltage (VS)
      2. 9.3.2 Charge Pump (VCAP)
      3. 9.3.3 Gate Driver (GATE an SRC)
        1. 9.3.3.1 Inrush Current Control
      4. 9.3.4 Enable and Undervoltage Lockout (EN/UVLO)
      5. 9.3.5 Overvoltage Protection (OV)
    4. 9.4 Device Functional Modes
      1. 9.4.1 Shutdown Mode
      2. 9.4.2 Conduction Mode
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Design Considerations
        2. 10.2.2.2 MOSFET Selection
        3. 10.2.2.3 Overvoltage Protection
        4. 10.2.2.4 Charge Pump VCAP, Input and Output Capacitance
      3. 10.2.3 Selection of TVS Diodes for 12-V Battery Protection Applications
      4. 10.2.4 Selection of TVS Diodes and MOSFET for 24-V Battery Protection Applications
      5. 10.2.5 Application Curves
    3. 10.3 Surge Stopper Using LM74502-Q1, LM74502H-Q1
      1. 10.3.1 VS Capacitance, Resistor R1 and Zener Clamp (DZ)
      2. 10.3.2 Overvoltage Protection
      3. 10.3.3 MOSFET Selection
    4. 10.4 Fast Turn-On and Turn-Off High Side Switch Driver Using LM74502H-Q1
  11. 11Power Supply Recommendations
  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

10.4 Fast Turn-On and Turn-Off High Side Switch Driver Using LM74502H-Q1

In automotive load driving applications N-Channel MOSFET based high side switch is very commonly used to disconnect the loads from supply line in case of faults such as overvoltage event . LM74502-Q1, LM74502H-Q1 can be used to drive external MOSFET to realize simple high side switch with overvoltage protection. Figure 10-13 shows a typical application circuit where LM74502H-Q1 is used to drive external MOSFET Q1 as a main power path connect and disconnect switch. A resistor divider from input to OV pin to ground can be used the set the overvoltage threshold.

If VOUT node (SRC pin) of the device is expected to drop in case of events such as overcurrent or short-circuit on load side then additional Zener diode is required across gate and source pin of external MOSFET to protect it from exceeding its maximum VGS rating.

Figure 10-13 Fast Turn-ON and OFF High Side Switch Using LM74502H-Q1

Many safety applications require fast switching off of the MOSFET in case of fault events such as overvoltage or overcurrent fault. Some of the load driving path applications also require PWM operation of high side switch. LM74502H-Q1 OV pin can be used as control input to realize fast turn-on and turn-off load switch functionality. With OV pin pulled above VOVR threshold of (1.25-V typical), LM74502H-Q1 turns off the external MOSFET (with Ciss = 4.7 nF) within 1 μs typically. When OV pin is pulled low, LM74502H-Q1 with its peak gate drive strength of 11 mA turns on external MOSFET with turn-on speed of 7-μs typical. Figure 10-14 shows LM74502H-Q1 GATE to SRC response when OV pin is toggled with ON/OFF logic input.

GUID-20220406-SS0I-ZW6N-XNMF-JLTCSPNKZ42L-low.pngFigure 10-14 Fast Turn-On and Turn-Off High Side Switch Driver Using LM74502H-Q1