SLVSFZ1 December   2020 TPS27SA08-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Summary Table
  6. 6 Pin Configuration and Functions
    1. 6.1 Recommended Connections for Unused Pins
  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 SNS Timing Characteristics
    8. 7.8 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 Protection Mechanisms
        1. 9.3.1.1 Thermal Shutdown
        2. 9.3.1.2 Current Limit
          1. 9.3.1.2.1 Current Limit Foldback
          2. 9.3.1.2.2 Undervoltage Lockout (UVLO)
          3. 9.3.1.2.3 VBB during Short-to-Ground
        3. 9.3.1.3 Energy Limit
        4. 9.3.1.4 Voltage Transients
          1. 9.3.1.4.1 Driving Inductive and Capacitive Loads
        5. 9.3.1.5 Reverse supply
        6. 9.3.1.6 Fault Event – Timing Diagrams
      2. 9.3.2 Diagnostic Mechanisms
        1. 9.3.2.1 VOUT Short-to-supply and Open-Load
          1. 9.3.2.1.1 Detection With Switch Enabled
          2. 9.3.2.1.2 Detection With Switch Disabled
        2. 9.3.2.2 SNS Output
          1. 9.3.2.2.1 RSNS Value
            1. 9.3.2.2.1.1 High Accuracy Load Current Sense
            2. 9.3.2.2.1.2 SNS Output Filter
        3. 9.3.2.3 ST Pin
        4. 9.3.2.4 Fault Indication and SNS Mux
        5. 9.3.2.5 Resistor Sharing
        6. 9.3.2.6 High-Frequency, Low Duty-Cycle Current Sensing
    4. 9.4 Device Functional Modes
      1. 9.4.1 Off
      2. 9.4.2 Standby
      3. 9.4.3 Diagnostic
      4. 9.4.4 Standby Delay
      5. 9.4.5 Active
      6. 9.4.6 Fault
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Ground Protection Network
      2. 10.1.2 Interface With Microcontroller
      3. 10.1.3 I/O Protection
      4. 10.1.4 Inverse Current
      5. 10.1.5 Loss of GND
      6. 10.1.6 Thermal Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Thermal Considerations
        2. 10.2.2.2 Diagnostics
          1. 10.2.2.2.1 Selecting the RISNS Value
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Related Documentation
    2. 13.2 Trademarks
    3. 13.3 Electrostatic Discharge Caution
    4. 13.4 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

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

10.1.1 Ground Protection Network

As discussed in the section regarding Reverse supply, DGND may be used to prevent excessive reverse current from flowing into the device during a reverse supply event. Additionally, RGND is placed in parallel with DGND if the switch is used to drive an inductive load. The ground protection network (DGND and RGND) may be shared amongst multiple high-side switches.

A minimum value for RGND may be calculated by using the absolute maximum rating for IGND. During the reverse supply condition, IGND = VBB / RGND:

Equation 1. RGND ≥ VBB / IGND
  • Set VBB = –13.5 V
  • Set IGND = –50 mA (absolute maximum rating)

    RGND ≥ –13.5 V / –50 mA = 270 Ω

In this example, it is found that RGND must be at least 270 Ω. It is also necessary to consider the power dissipation in RGND during the reverse supply event:

Equation 2. PRGND = VBB2 / RGND

PRGND = (13.5 V)2 / 270 Ω = 0.675 W

In practice, RGND may not be rated for such a high power. In this case, a larger resistor value should be selected.