The SSM4321 is a fully integrated, high efficiency, Class-D audio amplifier with digitized output of output voltage, output current, and the PVDD supply voltage. It is designed to maximize performance for mobile phone applications. The application circuit requires a minimum of external components and operates from a 2.5 V to 5.5 V supply for the amplifier and a 1.42 V to 3.6 V supply for input/output. The SSM4321 is capable of delivering 2.2 W of continuous output power with <1% THD + N driving a 4 Ohms load from a 5.0 V supply with a 0.1 V/I sense resistor. The SSM4321 features a high efficiency, low noise modulation scheme that requires no external LC output filters. The modulation scheme provides high efficiency even at low output power. The SSM4321 operates with 89% efficiency at 1.4 W into 8 ? from a 5.0 V supply with an SNR of >100 dB. The SSM4321 includes circuitry to sense output current, output voltage, and the PVDD supply voltage. Current sense is performed using an external sense resistor that is connected between an output pin and the load. The output current and voltage are sent to ADCs with 16-bit resolution; the PVDD supply voltage is sent to an ADC with 8-bit resolution.