The ISL6405 is a highly integrated voltage regulator and interface IC, designed for powering control signals from advanced satellite set-top boxes (STBs) to low noise block two antenna (LNB) module ports. The device is comprised of two independent currentmode boosted PWM and two low noise linear regulators along with 22kHz tone generation with the required circuitry, modulation and I2C device interface. This device enables the total LNB power supply design to be simple, efficient and compact with a low external component count. Two independent current-mode boost converters provide linearity with the input voltage being set to the final regulated output voltage, plus typically to ensure a minimum 1.2V supply dissipation in each linear regulator. This maintains the linear delivery of the constant voltage drop at each element while allowing sufficient voltage range to be injected for the tone. The final regulated output voltage supports two simultaneous dual-tuner antenna ports on both output terminals. The output of each PWM is set to 13V or 18V with independent voltage selection commands (VSEL1, VSEL2) via the I2C bus. Additionally, to compensate for voltage drops in the coaxial cable, the selected voltage may be increased by 1V with the Line Length Compensation (LLC) function. All functions on this IC write 8-bit registers (SR, 8 bits) on the system through the I2C bus control. The same register can be read back, and two bits will report diagnostic status. A separate enable command sent on the I2C bus provides independent standby mode control for each PWM and linear combination, disabling the output into shutdown mode. Each output channel is capable of delivering 750mA continuous current. The overcurrent limit is digitally programmable. The SEL18V pin with QFN package allows 13V to 18V external pin transition, overriding the I2C input.