National Semiconductor Introduces New Family of Buck Regulators

National Semiconductor Corp. expanded its high power-density regulator offerings with the introduction of the LM2830, LM2831 and LM2832. The first products in this new family of monolithic pulse-width modulation (PWM) converters offer top power density due to their high level of integration, high-frequency operation and ultra-small packaging.

The LM2831, in a tiny SOT23-5, offers top power density by providing a 1.5A output current while operating at 1.6 MHz or 3 MHz. It is also available in a 6-lead LLP® package. The 2A LM2832, in a 6-lead LLP package, also offers top power density and is available at 550 KHz, 1.6 MHz and 3 MHz switching frequencies. It is also available in a 8-pin MSOP. The 1A LM2830 is available with 1.6 MHz and 3 MHz switching frequency options in SOT23-5 and 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 to 5V bus to output voltages as low as 0.6V. This is well-suited for point-of-load power requirements in set-top boxes, xDSL cable modems, broadband communications, network cards, computing peripherals and hard disk drives.

National's LM2830, LM2831 and LM2832 regulators are monolithic, high-frequency, PWM step-down dc-dc converters. They provide all the active functions necessary for local dc-dc conversion, with fast transient load response and accurate regulation in the smallest possible board area. All three regulators have few external components, making them easy to design with, especially for designers with limited power management expertise. The products' high-frequency operation is made possible by their innovative control circuitry, which enables on-times as low as 15 ns.

The regulators' switching frequencies are set internally at 550 kHz, 1.6 MHz or 3 MHz, which allows designers to use extremely small surface mount inductors and chip capacitors while achieving efficiencies above 90%, even with the highest frequency option. External shutdown is included, with an ultra-low 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. Prices for these regulators start at $1.25 in 1,000-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.