SLVT230 November   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Required Equipment
    3. 1.3 Considerations
    4. 1.4 Safety Considerations
    5. 1.5 Dimensions
    6. 1.6 Test Setup
  8. 2Testing and Results
    1. 2.1 Efficiency Graphs
    2. 2.2 Efficiency Data
    3. 2.3 Thermal Images
    4. 2.4 Bode Plots
  9. 3Waveforms
    1. 3.1 Switching
    2. 3.2 Output Voltage Ripple
    3. 3.3 Load Transients
    4. 3.4 Start-Up Sequence
    5. 3.5 Shut-down Sequence
  10. 4Static Regulation
  11. 5Transformer Details
    1. 5.1 Material List
    2. 5.2 Winding Details
    3. 5.3 Schematic
    4. 5.4 Winding Instructions
    5. 5.5 Details about Core, Air Gap and Bobbin
    6. 5.6 Bobbin Mechanical Details
  12.   Trademarks

1.3 Considerations

All tests refer to ambient temperature of 25⁰C, the board placed horizontal on the bench in still air condition

  1. Connect the AC source to J1-1 and J1-2
  2. Connect the electronic load to J2-1 (positive) and J2-2 (negative), which allows testing the converter as standard power supply
  3. Attach a current probe in series to the output to take load transient response behavior
  4. In this report we are also connecting, later during the report, two lead-acid batteries in series, for example two Yuasa NPH5-12 (12V, 5Ah), instead of a standard constant current load.
  5. Set Vout to 24V (by selecting R21 resistor), (nominal voltage is 26.5V by using the resistor described in schematic)
  6. Set Iout to 4A by adjusting R26 to 324Ω (currently populated value, which defines CC set point
  7. Turn on the AC source
  8. During later CV/CC charging tests, please connect the series batteries to the converter, while AC source is on; this way high inrush current flowing from the battery into the output electrolytic capacitors C7, C8 and C9 can be avoided.
  9. To avoid that the battery is charged or discharged too quickly and therefore the voltage is fluctuating, add the electronic load in parallel to the battery. When a certain battery voltage is reached, the electronic load is set to the charging current: this way, the net battery charging current is zero, keeping constant voltage.
  10. Since the converter has current limit set to 4A, without a battery the converter works mainly as a constant voltage power supply, unless the output current is higher than the constant current (CC) set point.
  11. As battery charger, the current limit must be set to a proper value, according to the charging current level suggested in the battery datasheet.
  12. After turn off, discharge the capacitors C1, C2, and C3 by means of an external resistor (warning: HIGH VOLTAGE).