SLVSDM4F November   2018  – October 2026 TPS1HA08-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
    1. 5.1 Recommended Connections for Unused Pins
  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
      1. 8.1.1 Device Nomenclature
    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 Selectable Current Limit Threshold
          3. 8.3.1.2.3 Undervoltage Lockout (UVLO)
          4. 8.3.1.2.4 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 Load Dump
          2. 8.3.1.4.2 Driving Inductive and Capacitive Loads
        5. 8.3.1.5 Reverse Battery
        6. 8.3.1.6 Fault Event – Timing Diagrams
      2. 8.3.2 Diagnostic Mechanisms
        1. 8.3.2.1 VOUT Short-to-Battery 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
      3. 8.3.3 Enable Watchdog
    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 Automotive Standards
        1. 9.1.6.1 ISO7637-2
        2. 9.1.6.2 AEC – Q100-012 Short Circuit Reliability
      7. 9.1.7 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 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information
9.2.2.2.1 Selecting the RISNS Value

Table 9-5 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 9-5 RSNS Calculation Parameters
PARAMETEREXAMPLE VALUE
Current Sense Ratio (KSNS)4600
Largest diagnosable load current20A
Smallest diagnosable load current50mA
Full-scale ADC voltage5V
ADC resolution10 bit

The load current measurement requirements of 20A establishes that current can be sensed up to the 20A current limit, while the low level of 100mA 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 90% of the ADC full-scale. With this design, any ADC value above 90% can be considered a fault. Additionally, the RSNS resistor value verifies that the smallest diagnosable load current does not cause VSNS to fall below 1LSB of the ADC. With the given example values, a 1kΩ sense resistor satisfies both requirements shown in Table 9-6.

Table 9-6 VSNS Calculation
LOAD (A)SENSE RATIOISNS (mA)RSNS (Ω)VSNS (V)% OF 5V ADC
0.05046000.01110000.0110.22%
20.00046004.34810004.34887%