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National Semiconductor Introduces First Stereo Analog Subsystem for Mobile Handsets with Class G Headphone Amp and Loudspeaker Protection

SANTA CLARA, Calif. Feb. 23, 2011 / / — stereo analog subsystem LM49251

stereo analog subsystem

Key Technical Features – LM49251 Stereo Analog Subsystem

Offered in a 30-bump micro SMD package, the LM49251 provides enhanced Emission Suppression (E2S) and a Class D amplifier featuring a patented, ultra-low EMI pulse-width modulation (PWM) architecture that significantly reduces RF emissions while preserving audio quality. The LM49251’s Class G headphone architecture significantly increases audio playback time with its adaptive power supply approach, enabling very low supply rails and nearly doubling the power-efficiency compared to typical Class AB headphone amplifiers.

The LM49251’s no-clip ALC feature prevents distortion as battery voltages drop, allowing small signals to be amplified at high gains while preventing clipping of high-level signals. Its multiple inputs provide configurability for addressing different system requirements, and the LM49251’s mode selection, shutdown and volume are controlled through an I2C compatible interface. The IC’s click-and-pop suppression eliminates audible transients on power up and during shutdown.

National also introduced the LM49153 mono audio subsystem, which includes the same features as the LM49251, while integrating noise gate functionality onto the Class D amplifier. The noise gate feature prevents noise from being amplified when the volume is turned up. The LM49153 is offered in a 25-bump, 2.30 mm by 2.42 mm, micro SMD package.

Pricing and Availability

$1.60 $1.50

About National Semiconductor

Santa Clara, Calif. $1.42 billion

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SOURCE National Semiconductor Corp.

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