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.
Filterless Class-D amplifier with spread-spectrum ?-? modulation
Digitized output of output voltage, output current, and PVDD supply voltage
72dB signal-to-noise ratio (SNR) on output current sensing and 77 dB SNR on voltage sensing
TDM or multichip I2S slave output interface
Up to 4 chips supported on a single bus
8 kHz to 48 kHz operation
I2S/left justified slave output interface
1 or 2 chips supported on a single bus
8 kHz to 48 kHz operation
PDM output interface operates from 1 MHz to 6.144 MHz
2.2 W into 4 ? load and 1.4 W into 8 ? load at 5.0 V supply with <1% total harmonic distortion plus noise (THD + N)
89% efficiency at 5.0 V, 1.4 W into 8 ? + 0.2? RSENSE speaker >100 dB signal-to-noise ratio (SNR)
High PSRR at 217 Hz: 86 dB
Amplifier supply operation from
2.5 V to 5.5 V
Input/output supply operation from 1.42 V to 3.6 V