SLVSDM4E November   2018  – June 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

9.2.3 Application Curves

Figure 9-4 shows the behavior of the TPS1HA08-Q1 in this application when the MCU provides an enable pulse to beginning heating the resistive element. Shortly after the EN pin goes high, the load current begins to flow and the SNS pin measures the output current.

TPS1HA08-Q1 Heater Turn-on TimeFigure 9-4 Heater Turn-on Time

By measuring the voltage on the SNS pin, the TPS1HA08-Q1 can communicate back to the system MCU what the load current is. Figure 9-5 shows that when the seat heater approaches full load and IOUT jumps from a low load current of 1A up to a 5A load current, the load step is mirrored on the SNS pin.

TPS1HA08-Q1 SNS Response During Heater Load StepFigure 9-5 SNS Response During Heater Load Step

One common concern in these type of applications is that the heating element can accidentally lose connection, creating an open load situation. In this case, it is designed for the TPS1HA08-Q1 to recognize that the load has been removed and report a FLT to the MCU. Figure 9-6 shows the behavior of the TPS1HA08-Q1 when there is no load attached. As soon as the DIAG_EN pin is engaged, the SNS output goes high and the ST output engages low. By monitoring these pins, the MCU can recognize there is a fault and notify the user that maintenance is required.

TPS1HA08-Q1 Open Load Detection If Heating Element is MissingFigure 9-6 Open Load Detection If Heating Element is Missing

Importantly, the TPS1HA08-Q1 also protects the system in the event of a short-circuit. Figure 9-7 shows the behavior of the device if it is enabled into a short circuit condition. If this is using the device option C, the current is clamped to the current limit ICL until it hits an over temperature event, at which point it shuts down. In this way, the system is protected from unchecked overcurrent in the event of a short circuit.

TPS1HA08-Q1 Overcurrent Behavior During Short Circuit EventFigure 9-7 Overcurrent Behavior During Short Circuit Event