Power Products in 3 Images or Less 

ISSUE: October 2009 

A User-Configurable Planar Transformer

The Vishay Sfernice PLAC 100 is a user-configurable planar transformer that can be adapted for use in a wide range of switchmode power supply (SMPS) applications, including flyback, forward, push-pull, and half-bridge converters (Fig. 1). The device can be used as either a transformer or as an output choke inductor.

To provide its configurability, the transformer contains 12 individual windings—6 windings with one turn and 6 windings with three turns—which are made accessible to the user through a pc board (Fig. 2). Users can connect these various windings in different combinations to achieve different turns ratios and winding configurations.

To make the transformer more flexible, it is offered with different cores that provide different values of AL (inductance factor). It also comes with either through-hole or surface-mount interconnects. In all, there are 12 models of the PLAC 100, six models are surface-mount and six are through hole, with AL values of 100, 160, 250, 400, or 630 nH for the gapped core. An ungapped core is also offered. The PLAC 100 operates over a frequency range of 50 kHz to 400 kHz, while handling up to 220 W. Operating temperature ranges from -55°C to +125°C.

To support use of the PLAC 100, the transformer is supplied with software that allows users to calculate the optimum AL, turns ratio and winding configurations for their applications. Users enter the power supply type and the level of input voltage, output voltage, power, and switching frequency in their application. The software then determines which PLAC 100 model, turns ratio and winding configuration will provide optimum performance. The software is provided as part of a design kit that comes with samples of the 12 PLAC 100 models. (Fig. 3)

Samples and production quantities of the transformer are available now. Minimum order quantity pricing starts at $80. An application note is available at and a data sheet is available at

Fig 1. Vishay’s PLAC 100 is a user-configurable, 220-W planar transformer that can be adapted to a variety of SMPS designs.

Fig 2. The PLAC 100 planar transformer contains 12 individual windings that users may configure to suit their power supply application.

Fig. 3. The PLAC 100 design kit provides transformer configuration software and the different transformer models, which offer different values of AL in both surface-mount and through-hole packages.


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