Power controller has split personality

The LM5115 is the industry's first controller that can be used as either a secondary side post regulator (SSPR) or as a stand-alone buck regulator.

The LM5115 is the industry's first controller that can be used as either a secondary side post regulator (SSPR) or as a stand-alone buck regulator.

When paired with National's LM5025 primary-side regulator, the LM5115 SSPR enables designers to develop synchronised, efficient multiple-output DC/DC power supplies.

Used in the stand-alone configuration, the LM5115 operates as a high-voltage (75V) synchronous buck controller.

Applications for the LM5115 include multi-output DC/DC power modules and wide-input-range DC/DC power sources for industrial and consumer electronic products.

"The flexible LM5115 is the industry's first secondary side post regulator that also operates in a free-run mode as a high-voltage buck regulator", said Paul Greenland, Director of Product Marketing for National Semiconductor's Power Management group.

"This unique versatility makes the LM5115 the only solution for customers who want the option of using a controller as a stand-alone high-voltage buck regulator or pairing it with a primary-side regulator such as the LM5025".

The LM5115 has the following features and benefits: operates from AC or DC input up to 75 V peak; synchronises to the main channel DC/DC convertor; optional free-run mode for stand-alone operation from DC input; voltage-mode pulsewidth modulation with input voltage feed-forward; boot-strapped high-side and low-side MOSFET drivers sink 2.5 A peak; precision reference provides accurate 0.75 V feedback threshold; output voltage adjustable from 0.75 to 12V; error amplifier with wide 4MHz bandwidth; current sense amplifier limits forward and reverse inductor current; and programmable soft-start for controlled turn-on.

National's LM5115 is available in a tiny, thermally enhanced 16-lead LLP package and is priced at $1.50 each in 1000-unit quantities.

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