Overstressed components are a leading cause of field failure in switched mode power supplies. Part of the problem is that such design flaws are not always easy to detect with hardware measurements. A virtual prototype is of most value when detecting design flaws before the first hardware iteration even though most layout parasitics are not known at this time.

Since over 50% of design errors can be detected without first having this layout information, there is considerable value in doing loss and stress analyses where the layout parasitic parameters are either estimated or ignored.

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If devices are being operated close to or over their limits in the more idealized case of the virtual prototype, then that fact needs to be brought to the designer's attention as early as possible in the design process. It is rare that layout parasitics reduce the device losses and stresses predicted by the virtual prototype. And in those cases where parasitics do play an important role in reducing device losses and stresses, then the value of those parasitics become critical elements of the design. Either way, a virtual prototype can play a major role in improving the quality of a design.

Many power supply designers are becoming increasingly skilled at using SIMPLIS to obtain good estimates of power dissipation and voltage and current stresses for the critical devices in the power stage. The improved model extraction capability of SIMetrix/SIMPLIS provides designers with even more powerful capability to optimize SIMPLIS device models for FETs and diodes to reflect the operating conditions of use, including temperature, maximum current and reverse voltage.

Use SIMPLIS to measure:

• PFC Switching Losses
• PFC Core Losses