TIDUDS9B December   2017  – November 2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Conditions of Use: Assumption
        1. 2.2.1.1 Generic Assumptions
        2. 2.2.1.2 Specific Assumptions
      2. 2.2.2 Diagnostics Coverage
        1. 2.2.2.1 Dual-Channel Monitoring
        2. 2.2.2.2 Checking ISO1211 Functionality With MCU (SIL1)
        3. 2.2.2.3 Checking TPS22919 Functionality With MCU (SIL1)
        4. 2.2.2.4 Checking TPS27S100 Functionality With MCU (SIL1)
        5. 2.2.2.5 Optional Monitoring Using RDY Pin of ISO5452, ISO5852S or UCC21750 Integrated Analog-to-PWM Isolated Sensor
      3. 2.2.3 Drive State
    3. 2.3 Highlighted Products
      1. 2.3.1 ISO1211
      2. 2.3.2 TPS27S100
      3. 2.3.3 TPS22919
      4. 2.3.4 ISO5852S, ISO5452
    4. 2.4 System Design Theory
      1. 2.4.1 Digital Input Receiver for STO
      2. 2.4.2 STO_1 Signal Flow Path for Controlling VCC1
      3. 2.4.3 STO_2 Signal Flow Path
        1. 2.4.3.1 High-Side Switch for Controlling Secondary-Side Supply Voltage of Gate Driver
        2. 2.4.3.2 Powering up Secondary Side: VCC2 of Gate Driver
      4. 2.4.4 Gate Driver Design
      5. 2.4.5 STO_FB Signal Flow Path
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Getting Started Hardware
      1. 3.1.1 PCB Overview
    2. 3.2 Testing and Results
      1. 3.2.1 Logic High and Logic Low STO Thresholds
      2. 3.2.2 Validation of STO1 Signal
        1. 3.2.2.1 Propagation of STO1 to VCC1 of Gate Driver
        2. 3.2.2.2 1-ms STO Pulse Rejection
        3. 3.2.2.3 Diagnostic Pulses From MCU Interface
      3. 3.2.3 Validation of STO2 Signals
        1. 3.2.3.1 Propagation of STO2 to VCC2 of Gate Driver
        2. 3.2.3.2 1-ms Pulse Rejection
        3. 3.2.3.3 Diagnostic Pulses From MCU
        4. 3.2.3.4 Inrush Current Measurement
      4. 3.2.4 3.3-V Voltage Rail From Switcher
      5. 3.2.5 60-V Input Voltage and Reverse Polarity Protection
      6. 3.2.6 Validation of Trip Zone Functionality
  9. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 Layer Plots
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  10. 5Related Documentation
    1. 5.1 Trademarks
  11. 6About the Author
  12. 7Recognition
  13. 8Revision History

3.2.3.4 Inrush Current Measurement

Set the current limit with the TPS27S00 device. As mentioned in Section 2.4.3, the current limit is set to 1 A. The current during the peak is limited to 1 A, as calculated in Equation 8.

Equation 8. GUID-C25FA243-DC1D-4E67-BBA6-A8E702EAB464-low.gif

Calculate the current in the switch during the ON state using Equation 9.

Equation 9. GUID-0BADEAF7-C573-4865-8777-8FBB0A3BCB15-low.gif

This calculated value for IOUT matches well with the value measured by the multimeter (see Figure 3-15 and Figure 3-16).

GUID-F084DB44-2BF7-4147-B370-0A34E4204B20-low.pngFigure 3-15 Inrush Current Measurement From TPS27S100
GUID-120F912F-FF5F-4BDE-81A5-0968184DB361-low.pngFigure 3-16 Zoomed-In Shot of Inrush Current Measurement From TPS27S100

The two peaks that Figure 3-15 and Figure 3-16 show during the transition state corresponds to the current limit due to the input and output capacitance of the TIDA-00199 board. Path 1 and path 2 in Figure 3-17 show the two capacitances charging on the TIDA-00199 board.

Figure 3-17 Charging of Input and Output Capacitors of TIDA-00199