LM49150

The LM49150 is a fully integrated audio subsystem designed for portable handheld applications such as cellular phones. Part of National's Power Wise® product family, the LM49150 consumes very low power in the various modes of operation and still providing great audio performance. The LM49150 combines a 1.25W mono E 2S (Enhanced Emission Suppression) class D amplifier, 135mW Class AB earpiece amplifier, 42mW/channel stereo ground reference headphone amplifiers, volume control, and mixing circuitry into a single device.

The filterless class D amplifier delivers 1.25W into an 8Ω load with <1% THD+N with a 5V supply. The E 2S class D amplifier features a patented, ultra low EMI PWM architecture that significantly reduces RF emissions while preserving audio quality. The 42mW/channel headphone drivers feature National's ground referenced architecture that creates a ground-referenced output from a single supply, eliminating the need for bulky and expensive DC-blocking capacitors, saving space and minimizing cost.

The LM49150 features a fully differential mono input, and two single-ended stereo inputs. The three inputs can be mixed/multiplexed to either the speaker or headphone amplifiers. Each input channel has an independent, 32-step digital volume control. The headphone output stage features an additional, 8-step gain control, while the speaker output stage has a selectable 6dB or 12dB gain. The mixer, volume control and device mode select are controlled through an I 2C compatible serial interface.

The LM49150's superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM49150 is available in a ultra-small 20-bump micro SMD package (2.225mm X 2.644mm).

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