Direct backlight topologies offer the highest contrast ratio and richest color quality for LCD television. Direct backlight employs a greater number of LEDs and more complex control for zone dimming, allowing for the widest contrast ratio in the market. Direct backlight can be accomplished with white LEDs or RGB LEDs. The RGB LEDs offer color control and white point mixing, a feature not offered with white LEDs. Both types of LEDs can be driven by Microchip LED drivers to offer zone (regional) dimming up to 512 zones (the most zones offered by TV OEMs). LED drivers offer internal current sinks that can sink up to 100 mA per string, eliminating the need for external NFETs. External DC-to-DC supplies are commonly used in direct backlight applications, allowing four to eight LED driver ICs to share a power supply, minimizing component cost and board area. For direct-backlight configurations, an external power supply allows for easy implementation of DC-to-DC boost or SEPIC power supplies to drive 100 mA per string. Microchip LED drivers adaptively control the DC-DC/AC-DC converters that power the LED strings, using Microchip Efficiency Optimizer™ technology, which minimizes power use and maintains LED current accuracy.