The LM48824 PowerWise stereo headphone amplifier from National Semiconductor draws only 0.9 mA (typical) of quiescent current to double the audio playback time of smart phones, full-featured mobile phones, and portable music players. Its Class G architecture significantly increases audio playback time with its adaptive power-supply approach, which enables low supply rails and thereby doubles the power efficiency compared to typical Class AB headphone amplifiers, according to the company. Additionally, its output noise created by ground mismatches is improved through common-mode sensing that corrects for differences between the amplifier ground and the headphone return terminal.

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The amplifier comes in an ultra-small, 16-bump, 1.7- by 1.7- by 0.4-mm pitch microSMD package. It features National’s ground-referenced architecture, which saves space and minimizes system cost by eliminating the need for bulky and expensive dc blocking capacitors. The LM48824 also includes a 32-step, I2C-compatible volume control with mute and delivers 37 mW per channel into a 16-Ω load with less than 1% total harmonic distortion plus noise (THD+N) and 3.6 V. Its 105-dB power-supply rejection ratio at 217 Hz enables it to operate in noisy environments without additional power-supply conditioning. Its high-output impedance mode allows its outputs to be driven by an external source without degrading the signal.

Available now, the LM48824 costs $1.06 each in 1000-unit quantities. Samples and an evaluation board are available as well.

National Semiconductor