ISL6421A Single LNB Controller with I2C Interface for Advanced Satellite Set-Top Box Designs ISL6421A Single LNB Controller with I2C Interface for Advanced Satellite Set-Top Box Designs Application Note January 2, 2007 AN1161.2 Introduction The “universal” LNB switches the polarization by looking at the voltage that it receives from the receiver. Communication Satellite Frequency Allocation 12V - Horizontal, 18V - Vertical Communication satellites operate within two fre……