SLVSFD0 September   2019 LM74202-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      ISO16750-2 Load Dump Pulse 5b Performance at 12 V
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 6 Specifications
    1. 6.1      Absolute Maximum Ratings
    2. 6.2      ESD Ratings
    3. 6.3      Recommended Operating Conditions
    4. Table 1. Thermal Information
    5. 6.4      Electrical Characteristics
    6. 6.5      Timing Requirements
    7. 6.6      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 Undervoltage Lockout (UVLO)
      2. 8.3.2 Overvoltage Protection (OVP)
      3. 8.3.3 Reverse Battery Protection
      4. 8.3.4 Hot Plug-In and In-Rush Current Control
      5. 8.3.5 Overload and Short Circuit Protection
        1. 8.3.5.1 Overload Protection
          1. 8.3.5.1.1 Active Current Limiting
          2. 8.3.5.1.2 Electronic Circuit Breaker with Overload Timeout, MODE = OPEN
        2. 8.3.5.2 Short Circuit Protection
          1. 8.3.5.2.1 Start-Up With Short-Circuit On Output
        3. 8.3.5.3 FAULT Response
          1. 8.3.5.3.1 Look Ahead Overload Current Fault Indicator
        4. 8.3.5.4 Current Monitoring
        5. 8.3.5.5 IN, OUT, RTN and GND Pins
        6. 8.3.5.6 Thermal Shutdown
        7. 8.3.5.7 Low Current Shutdown Control (SHDN)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Step by Step Design Procedure
        2. 9.2.2.2 Setting Undervoltage Lockout and Overvoltage Set Point for Operating Voltage Range
        3. 9.2.2.3 Programming the Current-Limit Threshold—R(ILIM) Selection
        4. 9.2.2.4 Programming Current Monitoring Resistor—RIMON
        5. 9.2.2.5 Limiting the Inrush Current
          1. 9.2.2.5.1 Selection of Input TVS for Transient Protection
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Transient Protection
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2 Overvoltage Protection (OVP)

The device incorporates circuitry to protect the system during overvoltage conditions. This device features an overvoltage cut off functionality. A voltage more than V(OVPR) on OVP pin turns off the internal FET and protects the downstream load. To program the OVP threshold, connect a resistor divider from IN supply to OVP terminal to RTN as shown in Figure 21. OVP Overvoltage Cut-off response is shown in Figure 22. OVP pin must not be left floating. If OVP pin could be floating due to dry soldering, an additional zener diode at the output will be required for protection from over voltage.

LM74202-Q1 bd-uvlo-ovp-SLVSFD0.gifFigure 21. OVP Threshold Setting
LM74202-Q1 overvoltage36v-ovp-cutoff-SLVSFD0.pngFigure 22. OVP Overvoltage Cut-Off

Programmable overvoltage clamp can also be achieved using LM74202-Q1 by connecting the resistor ladder from Vout to OVP to RTN as shown in Figure 23 . This results in clamping of output voltage close to OVP set-point by resistors R1 and R2. as shown in Figure 24. This scheme will also help in achieving minimal system Iq during off state. For this OVP configurataion, use R1 > 90 kΩ.

LM74202-Q1 bd-ovp-output-SLVSFD0.gif
Figure 23. Programmable OV Clamp
LM74202-Q1 output-ov-clamp-28vin-rload-16000-SLVSFD0.pngFigure 24. Programmable Overvoltage Clamp Response

If the OVP pin is connected to GND, the device will clamp the output voltage to 37.5 V (typical).