TelCom Semiconductor, Inc. announced a new series of highly integrated, monolithic, very high voltage, off-line switching regulator circuits, the TC33370 through TC33374. The device series includes multiple on-chip functions, which allow implementation of off-line power converters using fewer external components, and reducing the overall cost and complexity of converter designs. The high integration level of the new TelCom high-voltage off-line switching regulators simplifies power converter designs and enhances functionality.

Designed using a very high voltage SmartMOS process, the switching regulators can operate from a rectified 85 to 276 VAC universal line source. Because the units operate at 100 KHz they function with low power loss and allow use of a smaller transformer - which reduces weight and improves efficiency for new designs. This function allows for economical replacement of bulky 50/60 Hz transformer designs.

"The very high voltage control and power management IC market is a targeted high growth area for TelCom. Our introduction of the exciting new TC33370 family demonstrates our commitment to producing a constant stream of new product offerings for new markets and customers," said Tom Grune, Vice President of Worldwide Sales at TelCom.

This new regulator series, TC33370 through TC33374, incorporates both a BiCMOS controller and a high-voltage and low-voltage transistors on the same chip, which is used to drive the primary side of a transformer in flyback mode applications. TelCom uses a 5-lead version of the TO-220 plastic package, which provides a fifth lead to add functionality other similar units lack. The TC33370 series has an integrated programmable state controller that allows implementation of four On/Off control methods of the converter. These include: Primary Side Manual Toggle On/Off, Secondary Side Microcontroller Toggle On/Off, Primary Side Toggle Request with Secondary Side, and Programmable On or Off State upon Application of AC Power. Furthermore, the On/Off feature is ideally suited for the Instantly Available PC Initiative. It provides a simple and economical method for obtaining low standby power in printers, fax machines, VCRs, DVDs and other consumer and industrial applications.

The graceful shutdown feature allows the TelCom design to interface with a microcontroller to shut it down to a low power mode when not in use. Power supplies incorporating this product can be designed to meet the new Energy Star protocol and the Blue Angel standard.

The TC33370 series consists of 5 devices - TC33370 to TC33374. For low power applications such as scanners or small inkjet printers, the TC33370 delivers up to 20W from universal (85-265 VAC) input. For higher power applications, the TC33374 delivers up to 90W from universal input or 150W with a fixed AC input of 100V, 115V, or 230V.

With access to processes that were not available to the company when it operated its own plant, we should expect to see TelCom go off in directions that take advantage of its designers' talents and knowledge more and more. These parts allow for a really high level of integration in line-driven power supplies with the use of much smaller transformers than conventional systems. The range of the parts' power offerings will cover the vast majority of consumer and office products using transformer supplies. The reduction in supply capacity with universal inputs allowed for in the design is understandable but unfortunate.

I like the ability to use one of the four different on/off control systems, which will allow for much "greener" products to be produced across the consumer and office spectrum; I would bet that the most popular control will be the secondary side microcontroller toggle which will allow for almost instant power when demanded. I also like the elimination of an external startup resistor with the on-board startup circuit, and the on-board power switch. The power range may be a little low for a lot of industrial applications, however, and one would hope that the company is looking for a solution for the 250-W level. If it manages to design such a product the company has the ability to "own" the market. With the supply/fabrication relationship with Motorola the company should also have the inside track to make contact with some of the extremely good power supply designers at Motorola who have some tricks of their own to bring to the table.