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

3.3.1.1 Efficiency and Output Voltage Cross Regulation

Total zero-load current power consumption (all outputs active, ultra-capacitor charged):

  • 115 VAC, 60 Hz: 485 mW
  • 230 VAC, 50 Hz: 548 mW

TIDA-010239 Output Power vs Efficiency at 95 V and 115 V AC, 60 Hz; 230 V and 265 V AC, 50 Hz Figure 3-4 Output Power vs Efficiency at 95 V and 115 V AC, 60 Hz; 230 V and 265 V AC, 50 Hz
TIDA-010239 Output Power vs Voltage Regulation Figure 3-5 Output Power vs Voltage Regulation
TIDA-010239 Output Power vs Voltage Regulation Figure 3-6 Output Power vs Voltage Regulation
TIDA-010239 Output Power vs Voltage Regulation Figure 3-7 Output Power vs Voltage Regulation
Table 3-1 Test Data at 95 VAC, 60 Hz AC Input
PIN (W) 12 Vp (V) +12 V (V) –12 V (V) I(12 Vp) (mA) I(+12 V) (mA) I(–12 V) (mA) POUT (W) Efficiency (%)

0.209

12.03

11.96

–11.93

0.00

0.00

0.00

0.00

0.00%

1.782

12.02

11.96

–11.93

104.7

4.98

–4.97

1.38

77.30%

3.225

12.02

11.96

–11.93

200.9

9.97

–9.94

2.65

82.24%

4.759

12.02

11.96

–11.93

302.8

14.95

–14.91

4.00

83.97%

7.821

12.02

11.97

–11.93

501.3

24.94

–24.85

6.62

84.65%

15.745

12.02

11.98

–11.93

1002.0

49.92

–49.71

13.24

84.06%

34.754

12.02

12.00

–11.93

2200.0

100.00

–99.42

28.83

82.95%

Table 3-2 Test Data at 115 VAC, 60 Hz AC Input

PIN (W)

12 Vp (V)

+12 V (V)

–12 V (V)

I(12 Vp) (mA)

I(+12 V) (mA)

I(–12 V) (mA)

POUT (W)

Efficiency (%)

0.216

12.02

11.95

–11.93

0.00

0.00

0.00

0.00

0.00%

1.753

12.02

11.95

–11.93

102.1

4.98

–4.97

1.35

76.78%

3.219

12.02

11.95

–11.93

201.0

9.96

–9.94

2.65

82.45%

4.735

12.02

11.95

–11.93

302.8

14.94

–14.91

4.00

84.39%

7.752

12.02

11.95

–11.94

501.3

24.90

–24.88

6.62

85.40%

15.570

12.02

11.95

–11.95

1002.0

49.79

–49.79

13.23

85.00%

34.213

12.01

11.94

–11.97

2200.0

99.50

–99.75

28.80

84.19%

Table 3-3 Test Data at 230VAC, 50 Hz AC Input

PIN (W)

12 Vp (V)

+12 V (V)

–12 V (V)

I(12 Vp) (mA)

I(+12 V) (mA)

I(–12 V) (mA)

POUT (W)

Efficiency (%)

0.308

12.02

11.96

–11.93

0.00

0.00

0.00

0.00

0.00%

1.888

12.02

11.96

–11.93

102.1

4.98

–4.97

1.35

71.30%

3.337

12.02

11.96

–11.93

201.0

9.97

–9.94

2.65

79.53%

4.824

12.02

11.96

–11.93

302.8

14.95

–14.91

4.00

82.84%

7.748

12.02

11.97

–11.93

501.3

24.94

–24.85

6.62

85.45%

15.304

12.02

11.98

–11.93

1002.0

49.92

–49.71

13.24

86.48%

33.280

12.02

12.00

–11.92

2200.0

100.00

–99.33

28.83

86.62%
Table 3-4 Test Data at 260VAC, 50 Hz AC Input

PIN (W)

12 Vp (V)

+12 V (V)

–12 V (V)

I(12 Vp) (mA)

I(+12 V) (mA)

I(–12 V) (mA)

POUT (W)

Efficiency (%)

0.334

12.02

11.96

–11.93

0.00

0.00

0.00

0.00

0.00%

1.932

12.02

11.96

–11.93

102.1

4.98

–4.97

1.35

69.69%

3.391

12.02

11.93

–11.95

200.9

9.94

–9.96

2.65

78.22%

4.878

12.02

11.93

–11.93

302.8

14.91

–14.91

4.00

81.91%

7.795

12.02

11.94

–11.95

501.3

24.88

–24.90

6.62

84.93%

15.312

12.02

11.95

–11.95

1001.9

49.79

–49.79

13.23

86.42%

33.212

12.01

11.97

–11.94

2200.0

99.75

–99.50

28.80

86.73%

Table 3-5 Output Voltage Cross Regulation at 115-V AC, 60-Hz AC Input

I(12 Vp) (mA)

I(+12 V) (mA)

I(–12 V) (mA)

12 Vp (V)

+12 V (V)

–12 V (V)

2000

100

100.00

12.09

11.95

–11.94

5

100

100.0

12.01

10.88

–10.88

2000

100

0.0

12.09

11.92

–11.93

2000

0

100.0

12.09

11.94

–11.95

50

100

100.0

12.10

11.95

–11.95

0

0

100.0

12.10

11.94

–10.76

0

0

0.0

12.10

11.94

–11.91

0

100

0.0

12.10

10.48

–11.88

2000

0

0.0

12.09

11.94

–11.91