The 3.3V family of Ringing Subscriber Line Interface Circuits (RSLICs) supports analog Plain Old Telephone Service (POTS) in short and medium loop length, wireless and wireline voice over broadband applications. Ideally suited for customer premise equipment, this family of products offers flexibility to designers with high ringing voltage and low power consumption system requirements. The ISL5585 family is capable of operating with 100V ringing battery supply, which translates directly to the amount of ringing voltage supplied to the subscriber. With the high operating voltage, subscriber loop lengths can be extended to 500Ω (i.e., 5,000 feet) and beyond, allowing this family to serve emerging Fiber In The Loop (FITL) markets. Other key features across the product family include 3.3V VCCoperation, low power consumption, ringing using sinusoidal or trapezoidal waveforms, robust auto-detection mechanisms for when subscribers go on or off-hook, and minimal external discrete application components. Integrated test access features are also offered on selected products to support loopback testing as well as line measurement tests. There are ten product offerings of the ISL5585 providing various grades of ringing battery voltage and longitudinal balance.