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

2.3.1.4 Modified Window Comparator

The TIDA-020069 converts the analog output voltage of HVIL-Send and HVIL-Return to binary digital values through the use of a modified window comparator circuit. This simplifies overall system design by converting analog values to digital in hardware, without the use of internal ADCs within a microcontroller. The following output pins of the TIDA-020069 all feature the binary digital outputs of the design: HVIL-Send Logic-Higher TP, HVIL-Send Logic-Lower TP, HVIL-Return Logic-Higher TP, and HVIL-Return Logic-Lower TP. The four binary outputs are used as two 2-bit digital representations of analog HVIL-Send and HVIL-Return analog signals.

The schematic in Figure 2-12 features the TLV9034-Q1, configured in a modified window comparator circuit. The TIDA-020069 features two of these circuits, each requiring two comparators, so the quad-channel TLV9034-Q1 was selected. Push-pull output comparators, like the TLV9034-Q1, are required for this circuit. This prevents the need of an output pullup or pulldown resistor for each channel.

The circuit design is based on the Analog Engineer's Circuit: Window Comparator Circuit. Reference this analog circuit design for more details about the circuit, including downloadable simulation models.

TIDA-020069 Modified Window Comparator Circuit Figure 2-12 Modified Window Comparator Circuit

The expected output voltage, VOUT1 and VOUT2 is found in Table 2-3 and Table 2-4 below:

Table 2-3 HVIL-Send Binary Output Logic
PARAMETER HVIL-SEND
LOGIC-LOWER TP		 HVIL-SEND
LOGIC-HIGHER TP
HVIL-Send TP < Lower Threshold 0V 0V
Lower Threshold < HVIL-Send TP < Upper Threshold 5V 0V
HVIL-Send TP > Upper Threshold 5V 5V
Table 2-4 HVIL-Return Binary Output Logic
PARAMETER HVIL-RETURN
LOGIC-LOWER TP		 HVIL-RETURN
LOGIC-HIGHER TP
HVIL-Return TP < Lower Threshold 0V 0V
Lower Threshold < HVIL-Return TP < Upper Threshold 5V 0V
HVIL-Return TP > Upper Threshold 5V 5V

In this design, resistors R1, R2, and R3 are all set to identical values of 10kΩ. This divides the 5V supply voltage, VCC into thirds. This sets the reference voltage of comparator U2 to 1.67V and the reference voltage of comparator U1 to 3.33V. These reference voltages correspond to the Lower Threshold and Upper Threshold of the data in Figure 2-13, respectively. These resistor values were selected to simplify the bill of materials (BOM) by using more similar components. To satisfy the TIDA-020069 State Logic Thresholds, set Upper Threshold lower than HVIL-Send for the normal operation mode. The state logical also requires that HVIL-Return (open connection) < Lower Threshold < HVIL-Return (normal operation).

Figure 2-13 TIDA-020069 State Logic Thresholds