Pulse Electronics Corp. has launched a series of low-loss, flat coil surface mount planar transformers to deliver high efficiency power to applications with tight height constraints. This technology uses a copper fill factor that is twice that of a PCB so the direct current resistance (DCR) of the primary winding is reduced by 50 percent and the power rating is increased by 20 percent to deliver up to 500 watts of power capability. Replacing the traditional multilayer PCB winding with a flat coil winding reduces the price by approximately 20 percent.
Pulse’s new standard series of planar transformers measure 21.6 by 23.4 by 8.6 mm up to 26.7 by 29.5 by 11.9 mm and are a pin-compatible replacement to existing Pulse multilayer PCB-based planar transformers. By eliminating the cost and time to fabricate PCBs for new winding arrangements, this transformer has the additional advantages of flexibility and speed to prototype for custom variations. Applications include low profile/high efficiency bus converters for distributed power architecture, datacom system cards, industrial controls and robotics.
“Traditional multilayer PCB windings with up to eight consecutive winding layers give rise to high leakage inductance, producing unacceptably high voltage spikes and snubber circuit losses,” said Gerard Healy, field application engineer, Pulse Electronics Power Division. “Replacing the multilayer PCB with a reduced number of flat coil winding layers connected in series provides immediate benefits by reducing the AC proximity effect on copper losses. In addition, more winding segments and selective coupling between simultaneously conducting windings can be implemented to reduce the leakage inductance. This improved interleaving capability has been demonstrated to increase the PSU efficiency on high power systems by 2 percent.”
Planar magnetics have been primarily implemented as a high power (>100 W) low profile (< 12.5 mm) solution for medium to low voltage conversions, such as the intermediate bus converter in a distributed power architecture. In recent years, the move to discrete DC/DC power modules with embedded designs has fueled strong growth in planar opportunities. “Pulse is delivering more cost-effective and higher performance solutions in response to this,” said Healy. Pulse Electronics’ new planar series consists of the PH08xx and the PH09xx platforms, which are pin compatible with Pulse’s legacy PA08xx and PA09xx series, but with lower DCR. For further technical information, the white paper “Flat Coil Planar Transformers” is available at here.
Pulse’s planar transformers are RoHS compliant and meet standard EIA481 requirements. They are available in tape-and-reel packaging. Lead time is eight weeks. The price ranges from $3.00 to $4.50 in quantities of 50,000 pieces. Pricing varies according to order configuration and destination. Contact Pulse directly or visit the website.