SLVAE30E February   2021  – March 2021 TPS1H000-Q1 , TPS1H100-Q1 , TPS1H200A-Q1 , TPS1HA08-Q1 , TPS25200-Q1 , TPS27S100 , TPS2H000-Q1 , TPS2H160-Q1 , TPS2HB16-Q1 , TPS2HB35-Q1 , TPS2HB50-Q1 , TPS4H000-Q1 , TPS4H160-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Driving Resistive Loads
    1. 2.1 Background
    2. 2.2 Application Example
    3. 2.3 Why Use a Smart High Side Switch?
      1. 2.3.1 Accurate Current Sensing
      2. 2.3.2 Adjustable Current Limiting
    4. 2.4 Selecting the Right Smart High Side Switch
      1. 2.4.1 Power Dissipation Calculation
      2. 2.4.2 PWM and Switching Loss
  4. 3Driving Capacitive Loads
    1. 3.1 Background
    2. 3.2 Application Examples
    3. 3.3 Why Use a Smart High Side Switch?
      1. 3.3.1 Capacitive Load Charging
      2. 3.3.2 Inrush Current Mitigation
        1. 3.3.2.1 Capacitor Charging Time
      3. 3.3.3 Thermal Dissipation
      4. 3.3.4 Junction Temperature During Capacitive Inrush
      5. 3.3.5 Over Temperature Shutdown
      6. 3.3.6 Selecting the Correct Smart High Side Switch
  5. 4Driving Inductive Loads
    1. 4.1 Background
    2. 4.2 Application Examples
    3. 4.3 Why Use a Smart High Side Switch?
    4. 4.4 Turn-On Phase
    5. 4.5 Turn-Off Phase
      1. 4.5.1 Demagnetization Time
      2. 4.5.2 Instantaneous Power Losses During Demagnetization
      3. 4.5.3 Total Energy Dissipated During Demagnetization
      4. 4.5.4 Measurement Accuracy
      5. 4.5.5 Application Example
      6. 4.5.6 Calculations
      7. 4.5.7 Measurements
    6. 4.6 Selecting the Correct Smart High Side Switch
  6. 5Driving LED Loads
    1. 5.1 Background
    2. 5.2 Application Examples
    3. 5.3 LED Direct Drive
    4. 5.4 LED Modules
    5. 5.5 Why Use a Smart High Side Switch?
    6. 5.6 Open Load Detection
    7. 5.7 Load Current Sensing
    8. 5.8 Constant Current Source
      1. 5.8.1 Selecting the Correct Smart High Side Switch
  7. 6Appendix
    1. 6.1 Transient Thermal Impedance Data
    2. 6.2 Demagnitization Energy Capability Data
  8. 7References
  9. 8Revision History

4.5.5 Application Example

Example specifications for a few inductive loads are shown in Table 4-2. This specification is an example of a solenoid or relay that is commonly driven in automotive or industrial applications. The following example will step through determining if TPS4H160-Q1 is capable of driving these loads with no external components. Inductive load profiles will vary over temperature, so typically the profile will be specified across the operating temperature range of the system with the worst case when the system is at its lowest temperature.

Table 4-2 Inductive Load Examples
Load #InductanceResistanceSwitching FrequencyVSUPPLY
-40⁰C25⁰C35⁰C
1205 mH79 Ω150 Ω158 Ω1 Hz24 V
248.4 mH50 Ω67 Ω69.9 Ω1 Hz24 V
335 mH7.5 Ω10 Ω10.4 Ω1 Hz24 V

With these load profiles, we can calculate the current and stored energy during the on-state and demagnetized on transition to the off-state. These parameters allow us to choose the correct high side switch that is capable of safely dissipating the stored inductive energy during switching off.