White LED driver has built-in soft-start

The HV9903 is a fixed-frequency DC/DC boost convertor IC designed to drive up to six white LEDs with constant current at efficiencies over 85%.

The HV9903 is a fixed-frequency DC/DC boost convertor IC designed to drive up to six white LEDs with constant current at efficiencies over 85%.

It is ideal for applications such as colour LCD backlighting in cellphones, smart phones, PDAs, pocket PCs, organisers, digital cameras, MP3 players and other handheld devices.

HV9903 is a white LED driver that features a built-in soft-start implementation for minimising inrush current to only 30% over steady-state current.

This prevents any false reset problem of the microprocessor due to inrush current and reduces the number of external parts required compared with existing drivers as well as saving valuable PCB space.

With 85% or higher efficiencies and built-in open LED overvoltage protection, the HV9903 will save battery power and improves system reliability.

Additionally, the HV9903 has a split-supply capability offering a wide operating range of 1.8 to 12.5V for greater design flexibility, plus an input supply voltage range into the device of 2.6 to 4.6V.

Its integrated internal oscillator with a 1.2MHz fixed switching frequency allows the use of a very small inductor and a minimum number of passive components to minimise PCB space requirements needed in portable and handheld applications.

Furthermore, a constant current regulation feature assures constant and uniform LED brightness.

However, the LED current can be adjusted from 5 to 40mA by an external resistor.

The amount of current though the LEDs can also be adjusted via DC voltage or a pulsewidth-modulated signal.

HV9903 also features 500nA maximum quiescent current that will save battery power during idle periods.

An open LED indicator diagnostic feature within the device alerts the host system of any LED failure, which in turn disables the driver.

This same feature allows the driver to be easily re-enabled.

"Demand for high-content colour displays in handsets and PDAs continues to grow, but their size keeps on getting smaller.

LED driver manufacturers must integrate more functionality and use less PCB space.

HV9903 has accomplished exactly that.

It is a valuable compliment to our EL backlighting solutions portfolio.

Now our customers have a complete offering of backlighting solutions from us.

They can use our EL drivers for backlighting their monochrome displays or keypads and the HV9903 for their colour displays", says Brian Hedayati, Director of Marketing at Supertex.

"We've done our design homework, added more integration and more features, especially the higher efficiency, built-in soft-start and open LED protection which are exactly what customers are asking for".

Unit price for the HV9903K6 in a tiny, space saving 6-lead, 3 x 3mm MLP package is US $0.99 in 1000-piece quantities.

Samples are available from stock.

Lead-time for production quantities is 4 to 5 weeks ARO.

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