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

2.3.1.5 Digital Logic Gates

The TIDA-020069 converts the binary digital signal output generated by the Section 2.3.1.4 circuit to be four state of the HVIL system: Normal Operation, Open Connection, Short to Battery, or Short to Ground. The SN74HCS08-Q1, quad-channel AND gate, and SN74HCS86-Q1, quad-channel XOR gate, translate the two 2-bit binary digital values to output states. These logic gates also control the onboard LEDs to visually indicate each state on the board in real time without the need of external measurement hardware. For even further optimized system integration, these four state values can be translated into a 2-bit binary value, where each combination represents one of the four states. This conversion from the analog HVIL-Send and HVIL-Return signals to binary and then to state values simplifies system-level design by handling state recognition in hardware, rather than software.

The following circuit shows the logic gate configuration used in the TIDA-020069:

TIDA-020069 Digital Logic Gates Figure 2-14 Digital Logic Gates

In this schematic, V1 represents HVIL-Send Logic-Higher, V2 represents HVIL-Send Logic-Lower, V3 represents HVIL-Return Logic-Higher, and V4 represents HVIL-Return Logic-Lower. LED1 represents the Normal Operation LED, LED2 represents the Open Connection LED, LED3 represents the Short to Battery LED, and LED4 represents the Short to Ground LED.

The logic of this circuit was tested and the results are found in Section 3.3. Table 2-5 shows the complete truth table of the design. It is important to note that this is a comprehensive truth table of all theoretical possibilities of this digital logic circuit, but not all input combinations are possible for the TIDA-020069. For example, it is not possible for V1 to equal 0 while V2 equals 1. This is because HVIL-Send Logic-Lower (V2) must be 1 when HVIL-Send Logic-Higher (V1) is 1. The same is true for V3 and V4. Other possibilities are listed in the table that are not generated by the 4 different states, even when shifting where the short to battery or short to load occurs. There is only one status LED indicator on at any given point.

Table 2-5 Digital Logic Gates Truth Table
V1 V2 V3 V4 LED1 LED2 LED3 LED4
0 0 0 0 0 0 0 1
0 0 0 1 0 1 0 0
0 0 1 0 0 0 0 0
0 0 1 1 0 1 0 0
0 1 0 0 0 0 0 0
0 1 0 1 0 1 1 0
0 1 1 0 0 0 0 0
0 1 1 1 0 1 1 0
1 0 0 0 0 1 0 0
1 0 0 1 1 0 0 0
1 0 1 0 1 1 0 0
1 0 1 1 0 0 0 0
1 1 0 0 0 1 0 0
1 1 0 1 1 0 1 0
1 1 1 0 1 1 0 0
1 1 1 1 0 0 1 0