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

3.3.6 Selecting the Correct Smart High Side Switch

When selecting a Smart High Side Switch for capacitive load driving, there are two critical specifications:

  1. DC Current Range: Ensure that the on resistance of the Smart High Side Switch is low enough to drive the required DC current without significant heating.
  2. Thermal Dissipation: Calculate the thermal energy required for charging the capacitor and then reference the Smart High Side Switch thermal models to make sure that the device can drive the load with minimal thermal shutdowns.

Use Table 3-1 to determine the best device for your application by selecting a device that can support the maximum application DC current requirement:

Table 3-1 TI Smart High Side Switch Portfolio
Device On Resistance Max DC Current
TPS1H000-Q1 1000 mΩ 1 A
TPS2H000-Q1 1000 mΩ 0.75 A
TPS4H000-Q1
TPS1H200-Q1 200 mΩ 2.5 A
TPS2H160-Q1 160 mΩ 2.5 A
TPS4H160-Q1
TPS1H100-Q1 100 mΩ 4 A
TPS27S100
TPS1HB50-Q1 50 mΩ 4 A

TPS2HB50-Q1

4.5 A

TPS1HB35-Q1

35 mΩ

5 A
TPS2HB35-Q1 5 A

TPS1HB16-Q1

 16 mΩ

7 A
TPS2HB16-Q1 7 A
TPS1HA08-Q1 8 mΩ 8 A

TPS1HB08-Q1

11 A

The maximum current listed in the table refers to nominal silicon with a JEDEC standard board. The best practice is to ensure sufficient margin to account for non-ideal layouts or higher than standard ambient temperatures. For an exact calculation, reference the data sheet RθJA specification to calculate the actual thermal diffusion for DC current flow. Once you have a selected a device that can support the output current requirements, ensure that it has the thermal dissipation capability to sufficiently dissipate the heat required for the capacitive charging.

TI Smart High Side Switches provide a reliable and efficient way to safely drive capacitive loads. While driving a capacitive load it is important to safely limit the inrush current while still minimizing the load charging time. By selecting the appropriate current limiting Smart High Side Switch it is possible to efficiently and effectively charge the capacitive load while avoiding thermal issues.