双输出升压 - LED驱动器/ LCD偏置 Dual Output Boost ? LED Driver / LCD Bias
The LX1744 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 voltage with an additional integrated boost converter. Designed for maximum efficiency and featuring a pseudo-hysteretic PFM topology that decreases output voltage ripple, the LX1744 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, the LED driver utilizes an external N-Channel MOSFET in order to maintain maximum efficiency along with flexible power requirements. The LX1744’s control circuitry is optimized for portable systems with a shutdown current of less than 1µA. The input voltage range of 1.6V to 6.0V 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 LX1744 is capable of achieving an LED drive in excess of 1.0W. The LX1744 provides simple dynamic adjustment of the LED drive current 0% to 100% full range dimming and the LCD Bias output voltage 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 LX1744 is available in the 14-Pin TSSOP, and the miniature 16-Pin MLP requiring minimal PCB area.
Key Features:
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- > 90% Maximum Efficiency
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- Low Quiescent Supply Current
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- Externally Programmable Peak Inductor Current Limit for Maximum Efficiency Logic Controlled Shutdown
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- < 1µA Shutdown Current
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- Dynamic Output LED Current and LCD Bias Voltage Adjustment via Analog Reference or Direct PWM Input
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- 14-Pin TSSOP or 16-Pin MLPQ Package