Resonant transformer/inductor saves space and eases PCB layouts in LLC applications

Vishay Intertechnology, Inc has released a new resonant transformer for inductor-inductor-capacitor (LLC) applications that provide the transformer and an integrated inductor in a single package. Created to save PCB space whilst simplifying layouts and lowering component mounting needs, the 5.5kW Vishay Custom Magnetics MRTI5R5EZ supplies fully tunable magnetising and leakage inductance with a minimal parasitic variation.

The device is the first transformer of its type to utilise a second middle transformer leg to complete the resonant inductor portion of the circuit. Other implementations need an extra magnetic core to deliver the same performance. This unique construction saves space and simplifies designs by eradicating the requirement for interconnects or jumpers from the resonant inductor to the transformer's winding.

The device will be used in onboard chargers and half- and full-bridge resonant power supply transformers in industrial controls, solar inverters, and defence, avionics, and construction equipment. As well as providing a customisable turns ratio for these applications, the transformer's losses can be transferred from the core to the coil as required to provide the best performance and heat dissipation, while its minimal parasitic variation optimises capacitor selection.

The device offers operating frequencies from 100kHz to 350kHz, rated power from 4kW to 6kW with 400V to 800V input voltage, and rated current to 28A. The isolation voltage rating for the device is 2500V. The transformer comprises a bracket for cold plate mounting with raised bosses, with flush-mount options available. M4 ring terminals are standard for the transformer, with customisable lead lengths and terminal types offered, and the device may be provided with a thermal gap pad on the mounting surface.