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Filterless Class-D amplifier drives clean audio output

Phoenix, Ariz. — Expanding its audio amplifier portfolio, ON Semiconductor introduced a cost-effective, 2.65-W filterless Class-D audio amplifier designed for portable applications.

From a 5-V supply, the NCP2820 is capable of delivering 2.65 W of continuous average power into a 4Ω bridge-tied load (BTL). Under the same conditions, the output power stage can provide 1.4 W into an 8Ω BTL load with less than 1 percent total harmonic distortion plus noise (THD+N).

For a device in a 1.45mm x 1.45mm, CSP and an input voltage range of 2.5 V to 5.5 V, the NCP2820 drives clean audio output with the highest power in the market, said Andy Williams, ON Semiconductor vice president Power Conversion Products.

The NCP2820 audio amplifier is intended for use in cell phones, digital cameras, portable media players, notebook PCs, LCD monitors and other handheld devices.

The device offers space and cost savings because no output filter is required when using inductive transducers. “With up to 90 percent power efficiency and a very low shutdown current of typically 0.42 μA, this audio amplifier reduces battery drain and drastically lowers the junction temperature,” Williams said.

Utilizing a pulse width modulation (PWM) technique, the NCP2820 processes analog input while keeping output noise and THD low. The “pop and click” noise elimination circuitry ensures that no audible noise will be produced during start-up or shut-down. Consequently, the device can be turned to shutdown mode during the long idle times to reduce power consumption. Due to its low 42 μV noise floor, using an A-weighted filter guarantees clean audio output regardless of the load sensitivity, Williams said.

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The NCP2820 is offered in a 1.45mm x 1.45mm, 9-pin flip-chip CSP and is priced at 68 cents each in 1,000-unit quantities. A lead-free NCP2820 is also available. Click here for the NCP2820 data sheet.

On Semiconductor , 1-602-244-6600, www.Onsemi.com.

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