The LM49250 is a fully integrated audio subsystem designed for stereo cell phone
applications. The LM49250 combines a 2.4W/Ch stereo class D speaker amplifiers with a 45mW/Ch
stereo ground referenced headphone amplifier, a class AB earpiece amplifier, TI 3D enhancement,
volume control, and an input mixer into a single device. The filterless class D amplifiers deliver
1.2W/Ch into an 8Ω load with <1% THD+N from a 5V supply.
The LM49250 features a new circuit technology that utilizes a charge pump to generate a
negative supply voltage. This allows the headphone outputs to be biased about ground, thereby
eliminating the output-coupling capacitors.
For improved noise immunity, the LM49250 features fully differential left, right and mono
inputs. The three inputs can be mixed/multiplexed to any output combination of the loudspeaker,
headphone or earpiece amplifiers. The left and right differential inputs can be used as separate
single-ended inputs, mixing multiple stereo audio sources. The mixer, volume control, and device
mode select are controlled through an I2C compatible interface.
Output short circuit and thermal overload protection prevent the device from being
damaged during fault conditions. Superior click and pop suppression eliminates audible transients
on power-up/down and during shutdown.
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