Catalyst Semiconductor, Inc. expands its line of high-power LED drivers with the CAT4139 boost converter that provides a switch current up to 750 mA. The boost converter drives LED strings up to 22V, making it suitable for digital photo frames and other backlighting applications where high LED counts (up to 40) are emerging. The driver uses a fixed frequency (1 MHz) switching architecture for low noise applications. A high voltage CMOS output stage allows five LED strings to be biased and regulated from a low voltage input supply, while still delivering efficiency levels of up to 87%. Designers can control LED dimming using a DC voltage, logic signal or pulse width modulation (PWM) signal.