Boost driver for long LED strings

Thelongstringsof LEDs commonly found in TV and display backlighting, street lights, and parking garage lights require a currentdrivercapable of producing high voltages. This reference design provides such adriverusing the MAX16834, and demonstrates how very-high dimming ratios can be obtained.

This is a reference design for a boost LEDdriverusing the MAX16834 forlongstringsof 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_LEDConfig.: 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.