Looking back over the last five decades, one can realize the tremendous progress our power-supply industry has made. Efficiencies nearly touching the magic 100% limit are the norm, and digital power is making inroads into many of the new designs. Driving this progress are the customers who require better, smaller and more efficient power supplies, and the creative innovators, buried deep in their companies’ laboratories, inventing the and designing the new products.
But who are these innovators? What has happened to them? Where are they today?
To list them all would take too much space, so I will attempt to jog my memory and talk about the innovators I have had the privilege of knowing or meeting.
In the early seventies, Lambda, where Sol Gindoff was one of the principal engineers, introduced a line of standardized linear power supplies. These power supplies were marketed by Merrill Simon, Lambda’s vice president of marketing, in a series of mass-marketed, two-page glossy newspaper ads that pictured Merrill with a cigar in his mouth and the power supply in his hand.
Then, the market began to demand products that could operate on both domestic and higher international voltages. Dick Weise, at the time an engineer with Powertec, recognized this need, but found that Powertec was unwilling to add dual-voltage windings to its power supplies. In response, Weise left Powertec to establish Power-One, which would build power supplies with domestic and foreign voltage ranges.
Around the same time, Walt Hirschberg at AC/DC was developing a new line of standard, form and fit linear power supplies not only to meet the dual-voltage standards, but also the stricter isolation requirements.
With the ability to use power supplies from any one of these and many smaller companies, the competition for power-supply customers became fierce. To compete in the market and because it was unable to purchase TO3 transistors from RCA, Lambda, under the guidance of Merrill Simon, started its own fabrication in Corpus Christi, Texas, to build state-of-the-art Darlington transistors.
By the late 1970s, switching power supplies quickly started to replace inefficient linears. In 1967, Robert Okada of RO Associates had designed the first commercial 20-kHz, 50-W switching power supply. Prior to this, switching power supplies were custom-designed products developed mainly for military and aerospace applications.
In the mid-1970s, switching power supplies made further headway, thanks to efforts by Bob Boschert at Boschert Inc., to power some of the early daisy wheel and band printers. Boschert developed a switching power supply, aptly named “The Meatloaf,” that bolted on the back of the Diablo band printer. Within a few years, Cherokee, under the guidance of Pat Patel, and Power-One, under the engineering direction of Steve Goldman, followed with similar form-factor midpower designs of multiple-output power supplies.
Raising the stakes, other companies developed higher-power switching power supplies in the 1-kW to 2-kW ranges, housed in the 5-in. x 8-in. x 11-in. “shoe-box” format. Pioneer Magnetics, under the leadership of Allen Rosenstein, was one of the early developers of that format, and the holder of the original patent for the power factor correction (PFC) circuit.
In the early 1980s, the need for multiple outputs drove several companies to design high-power supplies with more outputs. Initially, Wally Hersom at LH added internal circuit boards to provide the additional voltages. Phil Koetsch at Powertec developed a multiple-output power supply that used a custom-wound transformer and matching standard output-voltage modules. Jag Chopra at Jetta Power and Wally Hersom, then at his own company HC Power, improved the shoe-box power supply by cramming more power into that format.
In 1978, Power-One, under the guidance of Steve Goldman, introduced the first truly modular power-supply series with up to 12 output voltages and more than a million voltage combinations.
Patrizio Vinciarelli, founder of Vicor and the inventor of zero-current switching, took the market by surprise in 1984 when introducing his technology as a “family,” unheard of at that time, of high-density dc-dc patented format modules.
Soon after, Lucent introduced its own internally developed isolated dc-dc series in various full-, half- and quarter-“brick” formats that quickly set the present industry-standard format and pin-out for isolated dc-dc converters. IPD, later purchased by Power-One, introduced a series of isolated dc-dc devices, followed by Marty Schlecht of SynQor, which introduced dc-dc converters with higher-efficiency synchronous rectification in the late 1990s.
All of these developments led to changes in power system architectures and the introduction of digital control. I’ll discuss those more recent developments and some of the individuals behind them in next month’s online column. In the meantime, feel free to share your comments or questions with me at [email protected].