Micrel LDOs target 3.3V processors

Electronic News, April 4, 1994 by Katie Hottinger

SAN JOSE, CALIF.--Micrel Semiconductor is expected to release today a family of low drop out regulators (LDOs) it says will make up the bulk of its future business and spark second-sourcing in the industry. Micrel hopes its new family of LDOs will put the company in the vanguard of what intelligent power products director Martin Vander Kooi called "the revolution going on in LDOs."

Mr. Vander Kooi said the recent explosion in battery-operated applications has brought about increased demamd for LDOs, which transform the 5V charges coming from a battery application's converter into the 3.3V charge necessary for Pentium and Alpha-based systems.

Mr. Vander Kooi said the new releases come on as many as 100 different combinations of current, voltage, features and packaging options and whose current outputs range from 400 milliamps to 7.5 amps in 3.3V, 5V and 12V versions and put Micrel beyond its nearest competition.

Linear Technology Corp. (LTC) has had a group of LDOs since 1986, ranging in output currents from 150 milliamps to 12V. A Linear Technology spokesperson said the company's 10 LDO regulators range from 0.5V drop out at 700 milliamps to 1.5V drop out at 7.5 amps. National Semiconductor also is in the LDO business. What sets Micrel's releases apart, Mr. Vander Kooi said, is the company's guaranteed LDO range of 0.45 to 0.6V.

"It's a major change," Mr. Vander Kooi said. "What those low values mean is number one, you get longer listening time because everything holds up on your telephone. Or you can design your supply such that there's a very small difference between what comes out of the switching regulator with its associated noise, goes through the low drop out regulator and comes out with all the noise cleaned up. And that's efficiency. That means less heat and longer battery life.

"I don't consider LTC a competitior because their LDO voltage is nearly three times ours. In the high-current range, we're all by ourselves. In the low-current range, we're very efficient, we have technical advantages."

Technical characteristics in the devices' architecture, Mr. Vander Kooi said, lend added safety benefits.

"These LDOs have safety features for the automotive industry that none of the other high-current regulators have," Mr. Vander Kooi said. "Most of the other regulators are NPN regulators, referring to the type of transistors used. Ours are PNP, the opposite technology. These PNP regulators have a natural reverse-battery capability to -20V. If you start up your car and flip the wrong terminal, you don't blow away all the electronics."

Mr. Vander Kooi said customers have reacted favorably to the LDOs before their release and Micrel has had to pace its production in its on-site fab to assure availability of orders within three months.

By year-end, Mr. Vander Kooi said, the LDOs will make up the bulk of Micrel's business and contribute to the company's projected doubling in sales for 1994 over last year's figures. "It will be a major part of our business," Mr. Vander Kooi said. "It's one of the things that's fueling our growth."

Such projections will inevitably lead to second-sourcing, licensed and otherwise. "It's the sincerest form of flattery," Mr. Vander Kooi said. "We'll have to wait and see if they violate our patents."

The new products include medium current LDOs MIC2920A, 37A and 40A featuring respective output currents of 400, 650 and 1250 milliamps; and high-current LDOs MIC29150, 300, 500 and 750 featuring outputs of 1.5, 3, 5 and 7.5 amps. Both the medium and high current LDOs in 3.3, 5 and 12V fixed and adjustable versions.

In 100-piece quantities, the medium-current MIC2920A-3.3BS in an SOT-223 package is priced at $1.14, the MIC2937A-3.3BT in a TO-220 package is priced at $1.55, and the MIC2940A-3.3BT in a TO-220 package is priced at $1.65.

For high-current versions, in 100-unit quantities, the three-pin TO-220 and TO-263 MIC29150, MIC29300 and MIC29500 are priced at $1.93, $2.64 and $4.50 respectively.