描述 Description

The LX1992 is a compact high efficiency step-up boost controller for driving white or color LEDs in backlight or frontlight systems and offers designers maximum flexibility with respect to efficiency and cost.The LX1992 features a pseudo-hysteretic pulse frequency modulation topology and uses an external NChannel MOSFET. Further, the LX1992 features control circuitry that is optimized for portable systems (e.g.,quiescent supply current of 80?A (typ) and a shutdown current of less than 1?A). These design enhancements provide for improved performance in battery operated systems applications. The device input voltage range is from 1.6V to 6.0, allowing for a wide selection of system battery voltages and start-up operation is guaranteed at 1.6V input. Programming the output current is readily achieved by 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). Moreover, the LX1992 is capable of achieving output currents in excess of 150mA, depending on the MOSFET selected. The LX1992 has an additional feature for simple dynamic adjustment of the output current (i.e., up to 100% of the maximum programmed current). Designers can make this adjustment via an analog reference signal or a direct PWM generated signal applied to the ADJ pin and any PWM amplitude is easily accommodated with a single external resistor. The LX1992 is available in both the 8-Pin MSOP, and the miniature 8-Pin MLP requiring minimal PCB area.??ROHS, PB Free