Controller eliminates electrolytics for long life

A novel offline power supply controller IC will allow designers to create ultrasmall power supplies that can operate continuously at high temperatures to drive a wide range of LED applications.

The HV9906 offline power supply controller IC is the second in Supertex's new family of FlexSwitch controller ICs.

It enables designers to create ultrasmall power supplies that can operate continuously at high temperatures to drive a wide variety of LED applications that include traffic and street lights, emergency lights and exit signs, automotive head/tail lights, counter and decorative lighting, LED backlights for laptops and instrumentation, as well as other applications such as battery chargers, industrial sensors and programmable logic controllers (PLC) for embedded systems and controls.

The HV9906 FlexSwitch uses Supertex's proprietary integrator lock loop (IL2) technology, an all-new scheme for power supply control.

The IC requires a minimum of external components and works directly from inputs of 9 to 400V DC.

It eliminates the need for compensation components in many applications and can close the loop with a discontinuous waveform (eg pulsed LED waveform), thereby saving filter components and has extremely low noise susceptibility.

The HV9906 is ideally suited to emerging single switch PFC/PWM topologies and multiconvertors that have been shown to have significant cost and size benefits in wide conversion range applications as well as standard topologies.

It is optimised for applications from less than 1 up to 150W.

In certain applications, HV9906 allows designers to eliminate all electrolytic capacitors from their power supply designs and allows transformers to be replaced with low cost, off-the-shelf inductors, thereby increasing reliability and dramatically reducing size over competitive solutions.

Other features include soft start that eliminates the need for inrush control components like thermistors, high frequency operation to reduce magnetic size, a rugged gate driver to drive standard power mosfets and a frequency dither to help meet EMI requirements in certain fixed frequency applications.

"New LED technologies are significantly more efficient and provide much longer life than incandescent lamps, however unlike incandescents that produce radiated heat, they produce large quantities of conducted heat making their operating environments too hot for typical solutions", stated David Schie, Vice President of Supertex.

"HV9906 enables power supplies with the tightly controlled pulsed waveforms that LEDs need for long life in these hot environments.

It's ideal for the design of extremely small form factors where complete solutions can fit easily into mini-lamp applications such as in buttons for vending machines and elevators, replacement LED lamps that install into incandescent lamp sockets, track lighting and for backlighting laptop computers.

The same power supply can also work from AC input or a DC battery while providing LED dimming without any component changes".

Samples of HV9906 are available now from stock in 8-pin plastic DIP or SOIC packages.

Lead-time for production quantities is 6 to 8 weeks ARO, priced at $1.76 each in 10K quantities.

Also available now, the HV9906DB2 demo board is capable of driving LED strings.

(This was Electronicstalk's Top Story on 31 July 2002).

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