1.1 Powering the Evaluation Board

The evaluation board was evaluated over a measured AC input voltage range of 180 VAC to 265 VAC. For nominal testing, the input voltage was set to 230 VAC.

  1. Connect the DC load to the output terminals.
  2. Set the load to the desired current level.
  3. Connect the AC input source to the input terminals.
  4. For nominal operation, set the AC input to 230 VAC.
  5. For input range validation, adjust the AC input between 180 VAC and 265 VAC.
  6. Monitor the input current, output voltage, and output current during startup.

Under normal operation, the output voltage should be regulated close to 12V DC.

Normal Operation

During normal operation, the firmware continuously regulates the output voltage by adjusting the switching command delivered to the flyback power stage.

The control loop performs the following sequence:

  1. Samples the feedback signals using the ADC.
  2. Compares the measured output voltage to the internal reference.
  3. Calculates the regulation error.
  4. Updates the control variable used by the NCO.
  5. Selects the appropriate operating range.
  6. Updates the NCO output registers.
  7. Drives the isolated pulse interface to control the primary-side switching stage.