Nuvoton Introduces Ultra-Low-Power, Filter-Free 3.1W Class-D Audio Amplifiers

Lowering both power and noise are essential in the fast-moving, highly competitive market for consumer and portable devices,” said Jae-Hong Oh, senior product marketing manager at Nuvoton. “Our engineers, therefore, spearheaded an intensive effort to define a new generation of Class-D amplifiers -- the NAU8223 and NAU8224 -- designed to address the market’s need for power consumption and reduced switching noise, while delivering an array of other experience-enriching features.”



The NAU8223 and NAU8224 stereo Class-D audio amplifiers set a new standard in audio amplifiers by offering an ultra-low quiescent current (2.1mA at 3.7V for two channels) for output power delivered, making the devices ideal for the portable applications where battery life represents a significant differentiating factor. The two new amplifiers’ inputs can be configured in either single-ended or differential mode. Neither the NAU8223 nor NAU8224 amplifiers need an external output filter, as each reduces electromagnetic interference (EMI) through spread-spectrum-oscillator technology and slew-rate control. Moreover, the NAU8223 and NAU8224 provides improved immunity and power supply rejection ratio, or PSRR, of > 85dB at 217Hz, making the devices ideal Class-D audio amplifiers for wireless and AM frequency band applications.



Leap Forward in Efficiency, Power



The Class D topology represents a significant leap forward in both power efficiency and noise minimization in audio devices. Class D amplifiers generate a square wave, making the wave-form binary so that it can be amplified by switching the power devices. The power efficiencies of Class D amplifiers are two-thirds better than those of Class AB devices.



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The Class D NAU8223 and NAU8224 are capable of driving a 4Ω load with up to 3.1W output power, and feature a chip-enable pin for extremely low standby current and fast start-up time of 3.4ms. The NAU8223 has five selectable gain settings, between 0dB and 24dB, which can be controlled by a single gain pin. The NAU8224 features a highly flexible two-wire interface with gain settings from 24dB to -62dB (plus mute).



For more information on the new NAU8223 and NAU8224 Class D amplifiers, along with Nuvoton’s entire line of audio amplifiers – click here.



Availability, Pricing



Both the NAU8223 and NAU8224 are sampling now in a 20-pin QFN package. The NAU8223 is priced at $0.40, the NAU8224 at $0.50 (for quantities of 1,000 or more).