SLVSFJ6A November   2020  – June 2026 TPS27SA08

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Summary Table
  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 SNS Timing Characteristics
    8. 6.8 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Protection Mechanisms
        1. 8.3.1.1 Thermal Shutdown
        2. 8.3.1.2 Current Limit
          1. 8.3.1.2.1 Current Limit Foldback
          2. 8.3.1.2.2 Undervoltage Lockout (UVLO)
          3. 8.3.1.2.3 VBB during Short-to-Ground
        3. 8.3.1.3 Energy Limit
        4. 8.3.1.4 Voltage Transients
          1. 8.3.1.4.1 Driving Inductive and Capacitive Loads
        5. 8.3.1.5 Reverse Supply
        6. 8.3.1.6 Fault Event – Timing Diagrams
      2. 8.3.2 Diagnostic Mechanisms
        1. 8.3.2.1 VOUT Short-to-supply and Open-Load
          1. 8.3.2.1.1 Detection With Switch Enabled
          2. 8.3.2.1.2 Detection With Switch Disabled
        2. 8.3.2.2 SNS Output
          1. 8.3.2.2.1 RSNS Value
            1. 8.3.2.2.1.1 High Accuracy Load Current Sense
            2. 8.3.2.2.1.2 SNS Output Filter
        3. 8.3.2.3 ST Pin
        4. 8.3.2.4 Fault Indication and SNS Mux
        5. 8.3.2.5 Resistor Sharing
        6. 8.3.2.6 High-Frequency, Low Duty-Cycle Current Sensing
    4. 8.4 Device Functional Modes
      1. 8.4.1 Off
      2. 8.4.2 Standby
      3. 8.4.3 Diagnostic
      4. 8.4.4 Standby Delay
      5. 8.4.5 Active
      6. 8.4.6 Fault
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Ground Protection Network
      2. 9.1.2 Interface With Microcontroller
      3. 9.1.3 I/O Protection
      4. 9.1.4 Inverse Current
      5. 9.1.5 Loss of GND
      6. 9.1.6 Thermal Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Thermal Considerations
        2. 9.2.2.2 Diagnostics
          1. 9.2.2.2.1 Selecting the RISNS Value
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Support
      1. 10.1.1 Related Documentation
    2. 10.2 Trademarks
    3. 10.3 Electrostatic Discharge Caution
    4. 10.4 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.3.1.5 Reverse Supply

In the reverse supply condition, the switch automatically enables (regardless of EN status) to prevent power dissipation inside the MOSFET body diode. In many applications (for example, resistive load), the full load current can be present during reverse supply. To activate the automatic switch on feature, the SEL2 pin must have a path to module ground. This can be path 1 as shown below, or, if the SEL2 pin is unused, the path can be through RPROT to module ground.

Protection features (for example, thermal shutdown) are not available during reverse supply. Take care to verify that excessive power is not dissipated in the switch during the reverse supply condition.

There are two options for blocking reverse current in the system. Option 1 is to place a blocking device (FET or diode) in series with the supply. This blocks all current paths. Option 2 is to place a blocking diode in series with the GND node of the high-side switch. This method protects the controller portion of the switch (path 2), but it does not prevent current from flowing through the load (path 3). The diode used for Option 2 can share amongst multiple high-side switches.

Path 1 shown in Figure 8-3 is blocked inside of the device.

TPS27SA08 Current Path During Reverse supplyFigure 8-3 Current Path During Reverse supply