Electronic Design

High-Frequency Buck Regulators Fit In Ultra-Small Packaging

National Semiconductor has added three new parts to its high-power-density regulator product line. The LM2830, LM2831, and LM2832 are the first members in a new family of monolithic pulse-width modulation (PWM) converters offering high power density resulting from a high level of integration, high-frequency operation, and ultra-small packaging.

The regulators are monolithic, high-frequency step-down dc-dc converters that provide all the active functions necessary for local dc-dc conversion. All three regulators have few external components. Their high-frequency operation is made possible by innovative control circuitry, which enables on-times as low as 15 ns.

The LM2831, housed in an SOT23-5 package, provides a 1.5-A output current while operating at 1.6 MHz or 3 MHz. It is also available in a 6-lead LLP package.

The 2-A LM2832 comes in a 6-lead LLP package, and is available at 550-kHz, 1.6-MHz, and 3-MHz switching frequencies. It is also available in an 8-pin MSOP.

The 1-A LM2830 is available with 1.6-MHz and 3-MHz switching frequencies. It’s housed in SOT23-5 or 6-lead LLP packages.

This range of output currents, switching frequencies, and packaging options gives designers flexibility in choosing a regulator for conversion from a 3.3-V to 5-V bus to output voltages as low as 0.6 V. The parts meet point-of-load power requirements in set-top boxes, xDSL cable modems, broadband communications, network cards, computing peripherals, and hard disk drives.

The regulators' switching frequencies are set internally at 550 kHz, 1.6 MHz or 3 MHz, which allows designers to use small surface mount inductors and chip capacitors while achieving efficiencies above 90%. External shutdown is included, with a stand-by current of 30 nA. The regulators also utilize current-mode control and internal compensation to provide high-performance regulation over a wide range of operating conditions. Additional features include internal soft-start circuitry to reduce in-rush current, pulse-by-pulse current limit, thermal shutdown, and output over-voltage protection.

Pricing starts at $1.25 in 1000-unit quantities for the LM2830 at a 1.6-MHz switching frequency. The 1.6-MHz and 3-MHz switching frequencies are available now, and the 550-kHz option will be available later this summer, as will the MSOP-8 version of the LM2832.

National Semiconductor Corp.
http://power.national.com

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