TIDUF61 May   2024

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Highlighted Products
      1. 2.2.1 TLV9002-Q1
      2. 2.2.2 TLV9034-Q1
      3. 2.2.3 TPS7B69-Q1
      4. 2.2.4 SN74HCS08-Q1
      5. 2.2.5 SN74HCS86-Q1
    3. 2.3 System Design Theory
      1. 2.3.1 TIDA-0020069 Operation
        1. 2.3.1.1 Constant Current Source
          1. 2.3.1.1.1 Design Goals
          2. 2.3.1.1.2 Design Description
          3. 2.3.1.1.3 Design Notes
          4. 2.3.1.1.4 Design Steps
        2. 2.3.1.2 Current Sensing
          1. 2.3.1.2.1 Design Goals
          2. 2.3.1.2.2 Design Description
          3. 2.3.1.2.3 Design Steps
        3. 2.3.1.3 Load Connections and Clamps
        4. 2.3.1.4 Modified Window Comparator
        5. 2.3.1.5 Digital Logic Gates
      2. 2.3.2 Status Indication
        1. 2.3.2.1 Normal Operation (Closed Connection) State
        2. 2.3.2.2 Open Connection State
        3. 2.3.2.3 Short-to-Battery State
        4. 2.3.2.4 Short-to-Ground State
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Normal Operation (Closed Connection) Test Results
      2. 3.3.2 Open Connection Test Results
      3. 3.3.3 Short-to-Battery Test Results
      4. 3.3.4 Short-to-Ground Test Results
      5. 3.3.5 Disable (Shutdown) Test Results
  10. 4Design Files
    1. 4.1 Schematics
    2. 4.2 Bill of Materials
    3. 4.3 PCB Layout Recommendations
      1. 4.3.1 Layout Prints
    4. 4.4 Altium Project
    5. 4.5 Gerber Files
    6. 4.6 Assembly Drawings
  11. 5Tools and Software
  12. 6Documentation Support
  13. 7Support Resources
  14. 8Trademarks
  15. 9About the Author

2.3.1.3 Load Connections and Clamps

The TIDA-020069 utilized clamping diodes to prevent overvoltage and undervoltage conditions, as shown in Figure 2-11. The diodes labeled D2, D3, D4, and D5 clamp the HVIL-Send and HVIL-Return voltages to either ground or VCC. In this scenario, VCC is the 5V signal generated by TPS7B69-Q1, not the 12V supply input voltage. These diodes protect the interlock current loop from exceeding 5V or ground in case of a short-to-battery or short-to-ground fault condition. These clamping diodes also protect any downstream devices, like an ADC or microcontroller, that can be connected directly to the HVIL-Send and HVIL-Return pins.

TIDA-020069 Clamping and Load Circuitry Figure 2-11 Clamping and Load Circuitry

Diode D1 directs the interlock current from the TPS7B69-Q1 LDO to the HVIL-Send terminal, through the load resistors, and to the HVIL-Return pin. This creates a unidirectional flow of current that protects the TPS7B69-Q1 LDO. All logic of the different connectors states: normal operation, open connection, short to battery, and short to ground are based on a unidirectional flow of current.

Resistors R1 and R2 are larger-sized 1206 shunt resistors that are used to help prevent overcurrent conditions. The resistors labeled RLOAD1, RLOAD2, RLOAD3, and RLOAD4 represent the resistance of each high-voltage connector within the vehicle that has the HVIL signal.