SLVSGL6B July   2022  – October 2026 TPS1HC30-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 SNS Timing Characteristics
    7. 5.7 Switching Characteristics
    8. 5.8 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Accurate Current Sense
      2. 7.3.2 Programmable Current Limit
        1. 7.3.2.1 Current Limit Accuracy Across VDS
        2. 7.3.2.2 Capacitive Charging
      3. 7.3.3 Inductive-Load Switching-Off Clamp
      4. 7.3.4 Full Protections and Diagnostics
        1. 7.3.4.1  Short-Circuit and Overload Protection
        2. 7.3.4.2  Open-Load and Short-to-Battery Detection
        3. 7.3.4.3  Short-to-Battery Detection
        4. 7.3.4.4  Reverse-Polarity and Battery Protection
        5. 7.3.4.5  Latch-Off Mode
        6. 7.3.4.6  Thermal Protection Behavior
        7. 7.3.4.7  UVLO Protection
        8. 7.3.4.8  Loss of GND Protection
        9. 7.3.4.9  Loss of Power Supply Protection
        10. 7.3.4.10 Reverse Current Protection
        11. 7.3.4.11 Protection for MCU I/Os
      5. 7.3.5 Diagnostic Enable Function
    4. 7.4 Device Functional Modes
      1. 7.4.1 Working Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Dynamically Changing Current Limit
        2. 8.2.2.2 EMC Transient Disturbances Test
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
        1. 8.4.2.1 Without a GND Network
        2. 8.4.2.2 With a GND Network
      3. 8.4.3 Thermal Considerations
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.2.2 Capacitive Charging

The following figure shows the typical setup for a capacitive load application and the internal blocks that function when the device is used. Note that all capacitive loads have an associated "load" in parallel with the capacitor that is described as a resistive load but in reality it can be inductive or resistive.

TPS1HC30-Q1 Capacitive Charging Circuit Figure 7-7 Capacitive Charging Circuit
The first thing to check is that the nominal DC current, INOM, is acceptable for the TPS1HC30-Q1 device. This check can easily be done by taking the RθJA from the Thermal Information section and multiplying the RON of the TPS1HC30-Q1 and the INOM with it, add the ambient temperature and if that value is below the thermal shutdown value the device can operate with that load current. For an example of this calculation see the Applications section.

The second key care about for this application is to make sure that the capacitive load can charge up completely without the device hitting thermal shutdown. The reason is because if the device hits thermal shutdown during the charging, the resistive nature of the load in parallel with the capacitor starts to discharge the capacitor over the duration the TPS1HC30-Q1 is off. Note that there are some application with high enough load impedance that the TPS1HC30-Q1 hitting thermal shutdown and trying again is acceptable; however, for most applications, the system must be designed so that the TPS1HC30-Q1 does not hit thermal shutdown while charging the capacitor.

With the current clamping feature of the TPS1HC30-Q1, capacitors can be charged up at a lower inrush current than other high current limit switches. This lower inrush current means that the capacitor takes a little longer to charge all the way up. The time that it takes to charge up follows the equation below.

Equation 3. ILIM = C × d(VBB – VDS) / dt

However, because the VDS for a typical 3.3A application is much less than the VBB voltage (VDS ≅ 3.3A × 0.03Ω = 100mV, VBB ≅ 13.5V), the equation can be rewritten and approximated as

Equation 4. dt = C × dVBB / ILIM

The following figure pictures charge timing.

TPS1HC30-Q1 Capacitive Charging Timing Figure 7-8 Capacitive Charging Timing

Using this dt calculated based on the current limit, and finding the transient thermal impedance value at half the dt value, the junction temperature rise can be approximated by the Equation 5.

Equation 5. ΔTJ ≅ 2/3 × VBB × ILIM × RθJA(dt/2)

For more information about capacitive charging with high-side switches, see the How to Drive Resistive, Inductive, Capacitive, and Lighting Loads application note. This application note has information about the thermal modeling available along with quick ways to estimate if a high-side switch can charge a capacitor to a given voltage.