Output Post Filters

Use the Output Post Filters form to review the output post filters used in the current design. PI Expert selects the output post filters when optimizing a design and ensures that the output post filters parameters meet the specification. The main output is marked with the M symbol. For each output you can turn using post filter on or off and change the post filter components by accessing the Component Library.

LC Post filters are commonly used to reduce output switching frequency ripple. The values of the LC post filter can influence the closed loop bide plot if not designed properly. To ensure stable operation, verify that the LC post filter resonant frequency is sufficiently higher than the target crossover frequency. For example, for all applications except DPASwitch, the LC resonant frequency should be 8 kHz or higher. For DPASwitch applications this value should be 50 kHz or higher.

Editing Post Filter Components

To edit a post filter components:

  1. Select the output for that you want to edit the post filter and click Change to display the Post Filter Components dialog box. You can also double-click on the output row.

  2. The Post Filter Components dialog box allows you to you to edit the components of the currently selected post filter components. You can also apply or remove the post filter from the output.

  3. Use Post Filter check box controls whether post filter is applied to the output.

  4. Click OK when you are finished. The icon indicates that the custom selected post filter is added to the list. Double-click the icon to open Post Filter Components dialog box to revise the custom settings or restore the default values.

Top