LX1745CPW中文资料LED Drivers数据手册Microchip规格书

描述 Description

The LX1745 is a compact high efficiency step-up boost regulator for driving white or color LEDs in LCD lighting applications while supplying the necessary LCD bias voltages with an additional two integrated boost converters. Designed for maximum efficiency and featuring a pseudo-hysteretic PFM topology (that decreases output voltage ripple), the LX1745 minimizes system cost and condenses layout area making it ideal for PDA, smart-phone, and digital camera applications. While the LCD Bias generation is implemented using an internal N-Channel MOSFET for LCD Bias generation, the LED driver utilizes an external N-Channel MOSFET in order to maintain maximum efficiency along with flexible power requirements.The LX1745’s control circuitry is optimized for portable systems with a shutdown current of less than 1?A. The input voltage range of 1.6V to 6.0 allows for a wide selection of system battery voltages and start-up is guaranteed at a VIN equal to 1.6V with sustained operation as low as 1.1V. The maximum LED drive current is easily programmed using one external current sense resistor in series with the LEDs. In this configuration, LED current provides a feedback signal to the FB pin, maintaining constant current regardless of varying LED forward voltage (VF). Depending on the MOSFET selected, the LX1745 is capable of achieving an LED drive in excess of 1.0W. The LX1745 provides simple dynamic adjustment of the LED drive current (0% to 100% full range dimming) and the LCD Bias output voltages (up to ±15% typ) through separate IC interfaces. Each interface has an internal RC filter allowing designers to make these adjustments via a direct PWM input signal or an analog reference signal. Further, any PWM amplitude is easily accommodated using a single external resistor. The LX1745 is available in the lowprofile 20-Pin TSSOP.  ROHS, PB Free