TIDT244 July   2021

 

  1. 1Description
  2. 2Test Prerequisites
    1. 2.1 Voltage and Current Requirements
    2. 2.2 Required Equipment
  3. 3Testing and Results
    1. 3.1 Thermal Images
    2. 3.2 Efficiency and Power Dissipation Graph
    3. 3.3 Efficiency and Power Dissipation Data
    4. 3.4 Current Regulation
    5. 3.5 Voltage Regulation
  4. 4Waveforms
    1. 4.1 Start-up
    2. 4.2 Switch Node
    3. 4.3 Output Voltage Ripple
    4. 4.4 Current Loop to Voltage Loop Transition
    5. 4.5 Voltage Loop to Current Loop Transition
    6. 4.6 Bias Voltage Start-up
    7. 4.7 Bias Voltage Switch Nodes
    8. 4.8 Output Current Sense Signal

4.4 Current Loop to Voltage Loop Transition

The following figure shows the transition between the current loop control mode and the voltage loop control mode.

In the beginning state, the board is set to 1 A of output current and 400 V of output voltage. The resistive load is set to 270 Ω. In this state, the load is attempting to draw more current than the 1 A current limit allows. This means that the output voltage is limited to 270 V and the current loop is in control.

In the end state, the board output current setting is changed from 1 A to 2 A. The increased current limit is more than the current draw of the load. This allows the output voltage to rise up to the commanded 400 V and the voltage control loop takes over.

GUID-20210611-CA0I-WFQM-6BVG-RJZPC5PF3WMC-low.pngFigure 4-10 VIN = 400 V, VOUT = 400 V. Resistive Load = 270 Ω (VOUT: 100 V/DIV, IOUT: 1 A/DIV, 40 ms/DIV, BWL = 20 MHz)