SLVSDM4D November   2018  – December 2019 TPS1HA08-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Schematic
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
    2. 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
      1. 9.1.1 Device Nomenclature
    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 Selectable Current Limit Threshold
          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 Energy Limit
        4. 9.3.1.4 Voltage Transients
          1. 9.3.1.4.1 Load Dump
          2. 9.3.1.4.2 Driving Inductive and Capacitive Loads
        5. 9.3.1.5 Reverse Battery
        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 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
      3. 9.3.3 Enable Watchdog
    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 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

10.2.3 Application Curves

Figure 57 shows the behavior of the 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 SS1_TEK00289_SLVSD84.gifFigure 57. Heater Turn-on Time

By measuring the voltage on the SNS pin, the can communicate back to the system MCU what the load current is. Figure 58 shows that when the seat heater approaches full load and IOUT jumps from a low load current of 1 A up to a 5 A load current, the load step is mirrored on the SNS pin.

TPS1HA08-Q1 SS4_TEK00291_SLVSD84.gifFigure 58. 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 ideal for the to recognize that the load has been removed and report a FLT to the MCU. Figure 59 shows the behavior of the 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 SS6_TEK00294_SLVSD84.gifFigure 59. Open Load Detection If Heating Element is Missing

Importantly, the will also protect the system in the event of a short-circuit. Figure 60 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 will be clamped to the current limit ICL until it hits an over temperature event, at which point it will shut down. In this way, the system is protected from unchecked overcurrent in the event of a short circuit.

TPS1HA08-Q1 C_PermShort.gifFigure 60. Overcurrent Behavior During Short Circuit Event