SNOSDF6 October   2023 LM74930-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Charge Pump
      2. 7.3.2  Dual Gate Control (DGATE, HGATE)
        1. 7.3.2.1 Load Disconnect Switch Control (HGATE, OUT)
        2. 7.3.2.2 Reverse Battery Protection (A, C, DGATE)
      3. 7.3.3  Overcurrent Protection (CS+, CS-, ILIM, IMON, TMR)
      4. 7.3.4  Overcurrent Protection with Circuit Breaker (ILIM, TMR)
      5. 7.3.5  Overcurrent Protection With Latch-Off
      6. 7.3.6  Short-Circuit Protection (ISCP)
        1. 7.3.6.1 Device Wake-Up With Output Short-Circuit Condition
      7. 7.3.7  Analog Current Monitor Output (IMON)
      8. 7.3.8  Overvoltage and Undervoltage Protection (OV, UVLO, OVCLAMP)
      9. 7.3.9  Disabling Reverse Current Blocking Functionality (MODE)
      10. 7.3.10 Device Functional Modes
        1. 7.3.10.1 Low Quiescent Current Shutdown Mode (EN)
  9. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application: 200-V Unsuppressed Load Dump Protection Application
      1. 8.2.1 Design Requirements for 200-V Unsuppressed Load Dump Protection
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  VS Capacitance, Resistor R1 and Zener Clamp (DZ)
        2. 8.2.2.2  Charge Pump Capacitance VCAP
        3. 8.2.2.3  Input and Output Capacitance
        4. 8.2.2.4  Overvoltage and Undervoltage Protection Component Selection
        5. 8.2.2.5  Selection of Scaling Resistor (RSET) and Short-Circuit Protection Setting Resistor (RSCP)
        6. 8.2.2.6  Overcurrent Limit (ILIM), Circuit Breaker Timer (TMR), and Current Monitoring Output (IMON) Selection
        7. 8.2.2.7  Selection of Current Sense Resistor, RSNS
        8. 8.2.2.8  Hold-Up Capacitance
        9. 8.2.2.9  MOSFET Q1 Selection
        10. 8.2.2.10 MOSFET Q2 Selection
        11. 8.2.2.11 Input TVS Selection
      3. 8.2.3 Application Curves
    3. 8.3 Best Design Practices
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 Transient Protection
      2. 8.4.2 TVS Selection for 12-V Battery Systems
      3. 8.4.3 TVS Selection for 24-V Battery Systems
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2.5 Selection of Scaling Resistor (RSET) and Short-Circuit Protection Setting Resistor (RSCP)

RSET is the resistor connected between C and CS+ pin. This resistor scales the overcurrent protection threshold voltage and coordinates with RILIM and RIMON to determine the overcurrent protection threshold and current monitoring output. The recommended range of RSET is 50 Ω to 100 Ω. RSET is selected as 50 Ω, 1% for this design example.

LM74930-Q1 default short circuit threshold of 20 mV can be shifted to higher value as given by Equation 14.

Equation 14. VSNS_SCP=20mV+RISCP× 11 μA

For this application, ISCP pin is shorted directly to C pion (Drain of Q2). User has a flexibility to populate suitable value of RISCP resistor to adjust short circuit protection current limit and also gives flexibility in terms of selecting different current sense resistor value.

An additional de-glitch filter (optional) consisting of RISCP and CSCP can be added from ISCP pin to CS– pin as shown in Figure 8-1 to avoid any false short circuit trigger in case of fast automotive transients such as Input Micro cuts (LV124, E-10), AC superimpose (LV124, E-06), ISO7637-2 Pulse 2 A.