Maxim MAX17129低成本6串白光LED驱动方案

Maxim公司的MAX17129/MAX17149是高效率白光LED（WLED）驱动器，适合中小型LCD屏采用LED作为光源。工作电压3-26V，可驱动六串多个LED串联的LED串，串间电流匹配度在±2%内，支持PWM和混合调光模式，调光比100：1，PWM调光模式的调光频率100Hz到25kHz，LED电流从10mA到45mA可调，具有LED开路和短路保护以及输出过压保护，主要用用在笔记本电脑和平板电脑，显示器，汽车系统和手持终端。本文介绍了MAX17129/MAX17149主要特性，方框图，典型工作电路图以及MAX17129评估板主要特性，电路图，材料清单和PCB布局图。
MAX17129/17149：Low-Cost, 6-String WLED Drivers with Quick-PWM Step-Up  Converters
The MAX17129/MAX17149 are high-efficiency drivers for white LEDs. They are designed for small- to mediumsized LCDs that employ an array of LEDs as the light source. An internal switch step-up controller with Quick- PWMK drives the LED array, which can be configured for up to 6 strings in parallel and either 11 LEDs (MAX17129) or 6 LEDs in series (MAX17149) per string. Each string is terminated with a ballast that achieves Q2% currentregulation accuracy, ensuring even LED brightness and provides an adjustable 10mA to 45mA full-scale LED current. The devices have a wide input voltage range of 6V to 26V. The MAX17129 integrates an LDO to simplify applications that have a single high-voltage supply. The devices also feature a low-input-voltage mode for applications that have a 3V to 5.5V supply voltage.
The devices support both PWM and hybrid dimming mode. In PWM dimming mode, the external PWM signal directly controls the brightness of LEDs. The dimming frequency ranges from 100Hz to 25kHz with 400ns minimum on-time. In hybrid dimming mode, the LED current amplitude can be adjusted to 25% of full-scale LED current to improve system efficiency when brightness is low.
The devices have multiple features to protect the controller from fault conditions. Separate voltage-feedback loops limit the output voltage to safe operation. The open and short-LED detection shuts down the faulty string while keeping other st...