Thursday 24 April 2008
PowerWise buck regulators
Hernan Alcerreca
National Semiconductor has released two step-down switching regulators that suit handheld devices and automotive power adapters. The LM34917A and LM34919, members of National’s PowerWise energy-efficient product family, are the industry’s smallest non-synchronous buck regulators to feature a supply voltage rating up to 50V, 1.25A continuous output current, intelligent current limiting and over-voltage protection.
The LM34917A and LM34919 feature programmable switching frequency of up to 2MHz. The products integrate MOSFET switches to reduce system component count, and a high switching frequency enables use of ultra-small inductors and capacitors for very small solution size.
The LM34917A and LM34919 use a constant on-time (COT) control scheme, which requires no-loop compensation. The regulators are well-suited for use in applications that require high-input voltage regulations such as MP3 players using Firewire connectivity (IEEE1394) as well as MP3 players or auxiliary power adapters with direct connection to a 12V (universal) automotive power outlet, where transient protection requirements can exceed 40V.
The LM34917A and LM34919 feature peak efficiency equal to or greater than 90%.
Arrow Electronics
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