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Smallest 80V buck regulator

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article image LM5007 -- 90% efficiency.

NATIONAL Semiconductor, represented by Arrow Electronics , has announced the industry's smallest high-voltage buck bias switching regulator to satisfy housekeeping or bias power needs in next-generation communication, automotive, -48V distributed and battery-powered systems.

"Our new solution will displace a more expensive, less efficient transformer coupled flyback regulator that is currently being used by many designers to produce bias power," said Paul Greenland, marketing director of National Semiconductor's power management group.

"National Semiconductor's LM5007 effectively eliminates cost and increases efficiency, adopting a simple inductor filter and a couple of external components.

“Customers will benefit because the LM5007 offers more than 90 percent efficiency at a fraction of the cost and space consumed by today's isolated bias supply solutions."

National's LM5007 is a buck bias regulator which steps down a high-voltage (up to 75V) primary-side power supply and produces a low voltage (10V typical) bias supply for secondary-side control devices.

Fully integrated with all functions needed for a high-voltage power supply, the device contains an 80V N-Channel power MOSFET rated at 0.7A peak that can be switched at high frequencies (up to 500kHz), allowing the use of a small output filter to complete a highly efficient cost-effective bias supply solution that sources up to 0.5A continuous load current in minimal printed circuit board (PCB) space.

The control scheme deployed in the LM5007 eliminates the need for loop compensation while offering a very fast transient response using an ON-time that is inversely proportional to the input line voltage (Vin).

This produces a relatively constant and easily filtered switching frequency. An intelligent current limit is implemented with a forced OFF-time, which is inversely proportional to Vout, ensuring short circuit protection with minimal foldback.

Integrating a 0.7A peak, 80V power MOSFET, the LM5007 serves an array of telecommunication, automotive and industrial power supply applications.

It provides an inexpensive bias supply that is easily implemented with the addition of a small inductor filter, greatly reducing component count and PCB space.

Also integrated in the LM5007 is a high voltage start-up bias regulator that operates from 9V to 75V plus over-temperature shutdown and an intelligent current limit OFF-time timer.

The LM5007 is offered in either an MSOP-8 package or a small, thermally enhanced 8-pin LLP chip-scale package.

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