LED驅動器提高電池壽命的物聯網便攜式設備

　　便攜式產品制造商正在不斷尋找方法，以減少電力需求，以最大限度地提高電池壽命。隨著對物聯網的運動，以及智能手機，如網絡控制和監測目的的智能設備的普遍使用，需要提高功率效率已變得更加迫切。便攜式設備上的LED背光可以占總有源系統功率的一個重要部分。LED背光驅動器可單獨使用高達40%，使其成為節能工作的首要目標。

　　采用各種技術，以減少背光功率消耗。選擇LED驅動器IC已被優化為低功耗和效率是一個明確的起點。如環境光傳感器和動態背光控制結合調光技術可以作出重要貢獻，節約電池電量。

　　Figure 1： Dynamic backlight control uses dimming to save battery power， such as when using a smartphone in the dark.

　　This article will consider the contribution that can be made through advanced design and the judicious choice of the LED driver. Factors under scrutiny include topology， the characteristics required to support additional power saving techniques， and their impact on efficiency and circuit size.

　　Reference will be made to the Richtek RT9285 boost converter， ideal for operation from a single cell li-ion battery， and from Texas Instruments， the LM3530 current mode boost converter which can drive a single string of up to 11 LEDs and the LM3532 and LM3697 for driving three LED strings.

　　For ultra-low power and wearable devices， low dropout （LDO） regulators with charge pumps， such as the RT9361 from Richtek， are an option， or buck-boost regulators including the RT6150A/B or the ISL9111 from Intersil.