New IC controller tech eases power supply design

Electronic News, August 12, 1996 by Mehmet Nalbant

The IC has a maximum supply voltage rating of 40V along with a patent-pending soft-start scheme, which virtually eliminates overshoot, regardless of load. Fully integrated protection features, such as dual-mode, short-circuit protection, are also unique to the LX1571. For instantaneous shorts, the IC transitions into a hiccup mode. This hiccup mode greatly reduces the power dissipation of the application.

In summary, recent advancements in IC technology have yielded design solutions which can significantly reduce the size, cost and complexity of multiple-output power supplies while, at the same time, greatly improving the maximum operating frequency limit, efficiency and overall robustness of these power supplies. The compact LX1571 controller IC not only reduces cost and board-space requirements of these power supplies, but, by replacing the core used in mag-amp designs with a low-on-resistance MOSFET, permits the use of switching frequencies above 100kHz. In addition, because the MOSFET turns on before the AC input, the use of this IC provides 100 percent energy transfer. The complexity of doing these designs can be further reduced through the use of a pre-assembled and tested evaluation board, which houses the LX1571 integrated circuit and demonstrates its long list of protection features.

Mehmet Nalbant is senior systems engineer for Linfinity Microelectronics, Inc. (714) 372-8390.