SLVSE18B June   2019  – February 2023 TPS1HB35-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1. 6.1 Recommended Connections for Unused Pins
  7. 7 Specifications
    1. 7.1 Recommended Operating Conditions
    2. 7.2 Electrical Characteristics
    3. 7.3 Absolute Maximum Ratings
    4. 7.4 ESD Ratings
    5. 7.5 Thermal Information
    6. 7.6 SNS Timing Characteristics
    7. 7.7 Switching 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 Programmable Current Limit
          3. 9.3.1.2.3 Undervoltage Lockout (UVLO)
          4. 9.3.1.2.4 VBB During Short-to-Ground
        3. 9.3.1.3 Voltage Transients
          1. 9.3.1.3.1 Load Dump
          2. 9.3.1.3.2 Driving Inductive Loads
        4. 9.3.1.4 Reverse Battery
        5. 9.3.1.5 Current Limit Behavior
        6. 9.3.1.6 Fault Event – Timing Diagrams
      2. 9.3.2 Diagnostic Mechanisms
        1. 9.3.2.1 VOUT Short-to-Battery 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 Fault Indication and SNS Mux
        4. 9.3.2.4 Resistor Sharing
        5. 9.3.2.5 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 Automotive Standards
        1. 10.1.6.1 ISO7637-2
        2. 10.1.6.2 AEC-Q100-012 Short Circuit Reliability
      7. 10.1.7 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 RILIM Calculation
        3. 10.2.2.3 Diagnostics
          1. 10.2.2.3.1 Selecting the RISNS Value
    3. 10.3 Typical Application
      1. 10.3.1 Design Requirements
      2. 10.3.2 Detailed Design Procedure
      3. 10.3.3 Application Curves
    4. 10.4 Power Supply Recommendations
    5. 10.5 Layout
      1. 10.5.1 Layout Guidelines
      2. 10.5.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
10.2.2.3.1 Selecting the RISNS Value

#GUID-BB7C4F86-FBFE-49F5-B121-3C01CC89ADB1/SLVSDZ39361 shows the requirements for the load current sense in this application. The KSNS value is specified for the device and can be found in the Specifications section.

Table 10-5 RSNS Calculation Parameters
PARAMETEREXAMPLE VALUE
Current Sense Ratio (KSNS)2000
Largest diagnosable load current 8 A
Smallest diagnosable load current 40 mA
Full-scale ADC voltage5 V
ADC resolution10 bit

The load current measurement requirements of 8 A ensures that even in the event of a overcurrent surpassing the set current limit, the MCU can register and react by shutting down the TPS1HB35-Q1, while the low level of 40 mA allows for accurate measurement of low load currents.

The RSNS resistor value must be selected such that the largest diagnosable load current puts VSNS at about 95% of the ADC full-scale. With this design, any ADC value above 95% can be considered a fault. Additionally, the RSNS resistor value must ensure that the smallest diagnosable load current does not cause VSNS to fall below 1 LSB of the ADC. With the given example values, a 1.2-kΩ sense resistor satisfies both requirements shown in #GUID-BB7C4F86-FBFE-49F5-B121-3C01CC89ADB1/SLVSDZ33340.

Table 10-6 VSNS Calculation
LOAD (A)SENSE RATIOISNS (mA)RSNS (Ω)VSNS (V)% of 5-V ADC
0.04 20000.0212000.0240.5%
82000412004.80096.0%