The ISL6422B is a highly integrated voltage regulator andinterface IC, specifically designed for supplying power andcontrol signals from advanced satellite set-top box (STB)modules to the low noise blocks (LNBs) of two antennaports. The device is consists of two independent currentmodeboost PWMs and two low-noise linear regulators alongwith the circuitry required for 22kHz tone generation,modulation and I2C device interface. The device makes thetotal LNB supply design simple, efficient and compact withlow external component count.Two independent current-mode boost converters provide thelinear regulators with input voltages that are set to the finaloutput voltages, plus typically 0.8V to insure minimum powerdissipation across each linear regulator. This maintainsconstant voltage drops across each linear pass elementwhile permitting adequate voltage range for tone injection.