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

2.3.2.1 Normal Operation (Closed Connection) State

The TIDA-020069 is in normal operation (closed connection) state when all load resistors are connected in series. During this state, the onboard LED marked Normal Operation is turned on, as shown in Figure 3-7 test results image. This state represents a closed and secure connection of all high-voltage connectors in an HVIL system. In a HEV/EV, this is considered normal operation while the vehicle is powered on. In this state, the high-voltage battery is enabled, as the TIDA-020069 is indicating a secure connection of all high-voltage connectors.

Figure 2-15 illustrates the expected behavior of HVIL-Send and HVIL-Return during normal operation. The high-voltage connectors are modeled as resistors connected in series with the TIDA-020069. In this state, current flows though the interlock loop, though each high-voltage connector, and returns to the TIDA-020069.

TIDA-020069 Normal Operation (Closed Connection) State Figure 2-15 Normal Operation (Closed Connection) State

In normal operation, HVIL-Send is expected to be greater than the Upper Threshold voltage level and HVIL-Return is expected to be between the Lower Threshold and Upper Threshold voltage levels. The differential voltage between HVIL-Send and HVIL-Return is:

Equation 9. V D I F = V H V I L - S E N D - V H V I L - R E T U R N = I L O A D × R L O A D

This differential voltage, VDIF, along with an accurate measurement from the current-sense amplifier, VCS-OUTPUT are indicators that the TIDA-020069 is in normal operation.

The TIDA-020069 is designed to allow for flexibility to accommodate various OEM requirements for HVIL systems. Many variables can be adjusted to meet the requirements for each system, including: loop current (ILOAD), loop resistance (RLOAD), and supply voltage. Despite the changes in these variables, the Lower Threshold voltage level needs to be less than HVIL-Return, while the Upper Threshold voltage level needs to be less than HVIL-Return and greater than Lower Threshold during a closed connection for the TIDA-020069 to correctly interpret a normal operation state. The resistor divider ratios selected in Section 2.3.1.4 must be selected to meet these requirements.