SLVSH18 December   2024 TPS4HC120-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
    1.     6
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 SNS Timing Characteristics
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Pin Current and Voltage Conventions
      2. 6.3.2 Low Power Mode
      3. 6.3.3 Accurate Current Sense
      4. 6.3.4 Adjustable Current Limit
      5. 6.3.5 Inductive-Load Switching-Off Clamp
      6. 6.3.6 Fault Detection and Reporting
        1. 6.3.6.1 Diagnostic Enable Function
        2. 6.3.6.2 Multiplexing of Current Sense
        3. 6.3.6.3 FAULT Reporting
        4. 6.3.6.4 Fault Table
      7. 6.3.7 Full Diagnostics
        1. 6.3.7.1 Short-to-GND and Overload Detection
        2. 6.3.7.2 Open-Load Detection
          1. 6.3.7.2.1 Channel On
          2. 6.3.7.2.2 Channel Off
        3. 6.3.7.3 Short-to-Battery Detection
        4. 6.3.7.4 Reverse-Polarity and Battery Protection
        5. 6.3.7.5 Thermal Fault Detection
          1. 6.3.7.5.1 Thermal Protection Behavior
      8. 6.3.8 Full Protections
        1. 6.3.8.1 UVLO Protection
        2. 6.3.8.2 Loss of GND Protection
        3. 6.3.8.3 Loss of Power Supply Protection
        4. 6.3.8.4 Reverse Polarity Protection
        5. 6.3.8.5 Protection for MCU I/Os
    4. 6.4 Device Functional Modes
      1. 6.4.1 Working Mode
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 EMC Transient Disturbances Test
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Examples
        1. 7.5.2.1 Without a GND Network
        2. 7.5.2.2 With a GND Network
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.5 Inductive-Load Switching-Off Clamp

When switching an inductive load off, the inductive reactance tends to pull the output voltage negative. Excessive negative voltage could cause the power FET to break down. To protect the power FET, an internal clamp between drain and source is implemented, namely VDS(clamp).

Equation 2. TPS4HC120-Q1

During the period of demagnetization (tdecay), the power FET is turned on for inductance-energy dissipation. The total energy is dissipated in the high-side switch. Total energy includes the energy of the power supply (E(VS)) and the energy of the load (E(load)). If resistance is in series with inductance, some of the load energy is dissipated on the resistance.

Equation 3. TPS4HC120-Q1

When an inductive load switches off, E(HSS) causes high thermal stressing on the device. The upper limit of the power dissipation depends on the device intrinsic capacity, ambient temperature, and board dissipation condition.

TPS4HC120-Q1 Drain-to-Source Clamping StructureFigure 6-10 Drain-to-Source Clamping Structure
TPS4HC120-Q1 Inductive Load Switching-Off DiagramFigure 6-11 Inductive Load Switching-Off Diagram

From the perspective of the high-side switch, E(HSS) equals the integration value during the demagnetization period.

Equation 4. TPS4HC120-Q1

When R approximately equals 0, E(HSD) can be given simply as:

Equation 5. TPS4HC120-Q1

Note that for PWM-controlled inductive loads, it is recommended to add the external freewheeling circuitry shown in Figure 6-12 to protect the device from repetitive power stressing. TVS is used to achieve the fast decay. See Figure 6-12 for more details.

TPS4HC120-Q1 Protection With External CircuitryFigure 6-12 Protection With External Circuitry