TIDUF04A December   2022  – December 2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1.     8
    2. 1.1 EV Charging Station Challenges
      1. 1.1.1 Efficient Relay and Contactor Drive
      2. 1.1.2 Contact Weld Detection
    3. 1.2 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Isolated AC/DC Power Supply Design
        1. 2.2.1.1  Input Bulk Capacitance and Minimum Bulk Voltage
        2. 2.2.1.2  Transformer Turns-Ratio, Primary Inductance, and Primary Peak Current
        3. 2.2.1.3  Transformer Parameter Calculations: Primary and Secondary RMS Currents
        4. 2.2.1.4  Main Switching Power MOSFET Selection
        5. 2.2.1.5  Rectifying Diode Selection
        6. 2.2.1.6  Output Capacitor Selection
        7. 2.2.1.7  Capacitance on VDD Pin
        8. 2.2.1.8  Open-loop Voltage Regulation Versus Pin Resistor Divider, Line Compensation Resistor
        9. 2.2.1.9  Feedback Elements
        10. 2.2.1.10 Backup Power Supply
        11. 2.2.1.11 Supercapacitor Selection
        12. 2.2.1.12 Supercapacitor Charger Design
      2. 2.2.2 Relay Drive and Weld Detect
    3. 2.3 Highlighted Products
      1. 2.3.1 UCC28742
      2. 2.3.2 DRV8220
      3. 2.3.3 ATL431
      4. 2.3.4 TL431
      5. 2.3.5 TPS55330
      6. 2.3.6 TPS259470
      7. 2.3.7 TL7705A
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Requirements
      1. 3.2.1 Power Supply Test Setup
      2. 3.2.2 Weld Detect Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Isolated AC/DC Power Supply Based on UCC28742
        1. 3.3.1.1 Efficiency and Output Voltage Cross Regulation
        2. 3.3.1.2 Output Voltage Ripple Waveforms
        3. 3.3.1.3 Start, Shutdown, Backup Power, and Transient Response Waveforms
        4. 3.3.1.4 Thermal Performance
      2. 3.3.2 DRV8220-Based Relay Drive
      3. 3.3.3 Isolated Line Voltage Sensing
  10. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 Bill of Materials
    2. 4.2 Documentation Support
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  11. 5About the Author
  12. 6Revision History

1.2 Key System Specifications

Table 1-1 Key System Specifications
PARAMETER NOTES AND CONDITIONS MIN NOM MAX UNIT DETAILS
INPUT CHARACTERISTICS
Input voltage,VIN 85 120, 230 460 VRMS Line voltage
Line frequency, fLINE 47 60, 50 63 Hz
OUTPUT CHARACTERISTICS
Output voltage, VOUT1 Flyback output 1 12 V UCC28742-based AC/DC flyback power stage with 3 outputs
Output current, IOUT1 2.2 A
Output voltage, VOUT2 Flyback output 2 14 V
Output current, IOUT2 0.1 A
Output voltage, VOUT3 Flyback output 3 –14 V
Output current, IOUT3 0.1 A
Total output power, POUT Output power of flyback power stage 28.8 W
POINT OF LOAD AND AUXILIARY SECTION CHARACTERISTICS
TPS7A3901(1)

Dual LDO

 +12 V Nominal current = 100 mA
TPS7A3901(1) –12 V Nominal current = 100 mA
TPS259470(1) eFuse +12 V Overcurrent protection = 4.5 A
TPS563211(1) Sync-Buck +5 V Nominal current = 1.2 A, 1.3 A maximum
TPS563211(1) Sync-Buck +3.3 V Nominal current = 0.8 A, 1.5 A maximum
TPS65130(1) Dual converter (Boost + inverting-Buck/Boost)” active during energy storage release ± 14 V Nominal current = 0.1 A
TPS55330 Non-sync Boost: active during energy storage release +11.5 V Nominal current = 1.8 A
SUPERCAPACITOR BACKUP CHARACTERISTICS
Supercap normal operating voltage 2 × 2.5-μF supercapacitors in series. Charger charges to 7.8 V. Boost UVLO sets min operating voltage to 4.3 V. Supplying 7.5 W for 3 s (after boost) during energy storage release (AC mains failing) +4.3 +7.8 V Peak current = 4.06 A, for 1 s from full rate voltage to half voltage.
TL7705A Voltage supervisor for EoC of 2 × 2.5-μF supercapacitors in series +7.49 V Threshold for End of Charge
Linear charger Charges supercapacitors from 0 V to 7.8 V in 81 s and from 4.3 V to 7.8 V in 36 s +120 mA
(1) On the TIDA-010939.