Boost driver for long LED strings

The long strings of LEDs commonly found in TV and display backlighting, street lights, and parking garage lights require a current driver capable of producing high voltages. This reference design provides such a driver using the MAX16834, and demonstrates how very-high dimming ratios can be obtained.

This is a reference design for a boost LED driver using the MAX16834 for long strings of LEDs. This application is for LED backlighting for large LCD TVs or displays as well as streetlights and parking garage lights.

V_IN: 24VDC ±5% (at 1.22A)
V_LED Config.: 23 LEDs in series (75V) at 350mA.
Dimming: As low as a 3.33µs on-pulse (3000:1 dimming ratio when the dimming frequency = 100Hz).

Note: this design has been built and tested. However, detailed testing has not occurred and there may be nuances that are yet to be discovered.


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Figure 1. The LED driver board.


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Figure 2. Schematic of the LED driver.


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Figure 3. Layout of the LED driver.


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Figure 4. Bill of materials.


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Figure 5. Design spreadsheet. To get the spreadsheet for use in your design, contact your local Maxim sales office.