The ISL6422B is a highly integrated voltage regulator and
interface IC, specifically designed for supplying power and
control signals from advanced satellite set-top box (STB)
modules to the low noise blocks (LNBs) of two antenna
ports. The device is consists of two independent currentmode
boost PWMs and two low-noise linear regulators along
with the circuitry required for 22kHz tone generation,
modulation and I2C device interface. The device makes the
total LNB supply design simple, efficient and compact with
low external component count.
Two independent current-mode boost converters provide the
linear regulators with input voltages that are set to the final
output voltages, plus typically 0.8V to insure minimum power
dissipation across each linear regulator. This maintains
constant voltage drops across each linear pass element
while permitting adequate voltage range for tone injection.