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Optoelectronics/Displays??

LED drivers offer 80% efficiency

Posted: 11 Jul 2005 ?? ?Print Version ?Bookmark and Share

Keywords:vishay intertechnology? led driver? sip12401? boost controller? sip12501?

Deliver up to 80% efficienciesThe two new white LED drivers from Vishay Intertechnology Inc. promise to deliver efficiencies of up to 80 percent during operation in compact handheld and battery-operated electronics.

According to the company, the SiP12401 boost controller and SiP12501 boost converter are optimized to provide efficient, controlled brightness such as white LED backlighting for LCD displays in portable electronics.

The SiP12401 IC uses double-cell NiMH or Alkaline and Li-ion batteries to drive white LEDs connected in series for uniformly bright backlighting without the need for ballast resistors. It supports an input voltage range of 1.8V to 5V.

Designed to drive white LEDs connected in parallel, the SiP12501 is for single- or double-cell NiMH or Alkaline battery packs. An internal low-threshold power MOSFET allows the device to start up with a low battery voltage of 0.65V. This product also accepts input voltages from 0.65V to 3.3V and regulates an output current up to 60mA from a 0.9V input. Vishay added that the performance of this converter is enhanced through thermal shutdown protection and anti-ringing control that minimizes EMI.

Both the SiP12401 boost controller and SiP12501 feature a voltage-mode PWM design with internal frequency compensation to help reduce overall component count and enable design of smaller, lighter end products. For prolonged battery life, operation in PWM mode with 600kHz switching yields high typical efficiency of 80 percent (SiP12401) and 75 percent (SiP12501). The LED current may be adjusted externally for analog control over intensity, and logic-controlled shutdown is provided with 1?A of standby current.

Available in a Pb-free, 6-pin PowerPAK MLP33 package, the two LED drivers are rated for operation over the industrial temperature range of -40C to 85C. Samples and production quantities of these devices are already available, with lead times of six to eight weeks for larger orders.




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