Click on the row of the device you wish to use. The user selected icon 
will appear.
Click OK to exit the PI Device Selection form.
PI Expert will now try to optimize your design using the device you have selected.
During optimization, PI Expert chooses the most suitable device within the selected device family. In some situations you might want to select the device to be used during optimization manually. PI Expert allows you to choose a different device, within the same device family by using the PI Device Selection form or the Device drop down box in the Device Variables section of the Design Results tab. This gives you the ability to choose a larger device to help improve efficiency or have optimization use the devices available to you.
To deliver the desired output power, you need to select an appropriate device. You must select a device that is larger than PI Expert has chosen during optimization for the manual device optimization process to finish successfully. Using an oversized device reduces the conduction losses and can result in increased efficiency.
However, select a device no more than one or two sizes larger than necessary. Selecting devices three or more sizes larger than necessary can result in a situation when the increase in switching losses, due to the larger COSS, can decease overall efficiency. It is also important to remember that larger devices have higher current limits. In PWM control based devices, the current limit must be reduced with an external resistor to reduce the peak flux density (BP) in order to avoid having to use a larger transformer. PI Expert will automatically reduce the current limit (KI) to reduce BP.
To manually optimize the device using the PI Device Selection form:
Click on the row of the device you wish to use. The user selected icon will appear.
Click OK to exit the PI Device Selection form.
PI Expert will now try to optimize your design using the device you have selected.
You can also select the device to use during optimization manually by using the Device drop down box in the Device Variables section of the Design Results form and then optimizing the design.