@▷ LED Backlighting Solution with LM3430 and LM3432 Circuit Diagram | Diagram for Schematic

LED Backlighting Solution with LM3430 and LM3432 Circuit Diagram

Since the release of high brightness White LED (HB-WLED) in the middle of 1990′s, tremendous research efforts have been undergoing to improve the emission efficiency, reliability and thermal packaging technologies in order to expand its range of applications. In the last few years, improvements in HB-WLED performance and price structure attracts more potential applications considering this new lighting source technology as an alternative to conventional one. One area of applications, LCD display backlighting, consider this new backlighting method as the ultimate solution to replace the existing Cold Cathode Fluorescent Lamps (CCFL). Backlight LED-driver solutions need to exhibit following characteristics:

• Instead of voltage control, LED-driver need direct LED current control to ensure consistent color and brightness;
• High conversion efficiency under various conditions;
• Support PWM dimming;
• Limit LED’s rail voltage while LEDs open circuited;
• Ability to shutdown individual channel(s) when short or open circuited LED(s) detected;
• Device over temperature detect and shutdown;
• Low profile, small size and ease to use.

The LM3432 is a 6-channel high voltage current regulator which provides a simple solution for LED backlighting applicationsand the LM3430 is a companion device to supply high voltage required to drive serially connected LED strings. The LM3430 and the LM3432 provide a complete solution to most HB-WLED backlighting applications for notebook and PC monitor. In this application note, a typical example for a solution to drive six strings of twelve LEDs in series running at 20mA per string is described in details.– Article quote

LED Backlighting Solution circuit diagram

The topics discussed inside the application note including the introduction, the demonstration board, demonstration board schematic, LED panel connection, evaluation board, dynamic headroom control, LED open and short fault indication, over-temperature monitor and shut down, typical operating waveforms, PCB layout, bill of materials, selecting the switching frequency, selection of power inductor, selection of output capacitor, selection of the power MOSFET, selecting the Boost Schottky Diode, reference documents, and many more.

Source : National Semiconductor Application Notes

Find more details about the LED backlighting solutions from the National Semiconductor by downloading the pdf document from the following source (national.com) :

LED Backlighting Solution with LM3430 and LM3432 Circuit Diagram DOWNLOAD