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National Semiconductor Corporation has announced two BoomerÂ® audio amplifiers for mobile phones and portable electronics. These two amplifiers feature an unprecedented level of integration that ensures crisp, crisp sound and a very compact package. The audio subsystem of the LM4845 features an audio amplifier, volume control system, mixer, 8 output modes, power management control system, 3D sound enhancement system and I2C compatible control system. All circuits are integrated into one chip. In addition to the 3D setting function for speakers and headphones, the 2.1W stereo speakers and headphone amplifiers of the LM4888 also have the advantage of ultra-low shutdown current, which helps save power and extend battery life.
National's LM4845 audio subsystem includes a mono amplifier and a stereo headphone amplifier. The mono amplifier can supply 500mW of output power from a 3.3V supply and input it into a mono 8W bridge load with a total harmonic distortion and noise of only 1%. The stereo headphone amplifier can be powered continuously with 3.3V. Provides an average of 25mW per channel and inputs it into a stereo 32W load with only 1% total harmonic distortion and noise. The LM4845 stereo headphone amplifier can be reconfigured to support single-ended or output capacitor-free operation. This amplifier features 32-step digital volume control and 8 different output modes. Digital volume control, 3D sound enhancement, and all output modes can be set via a two-wire I2C or 3-wire SPI-compatible interface, making channel routing design and channel mixing more flexible. The amplifier chip has three input channels: two for the stereo channel, which is responsible for inputting stereo audio signals, and the other for mono, which is responsible for mono input. This chip in a surface mount package delivers high-quality power. With a mode that does not require an output capacitor, it requires only seven external components. If you are operating in single-ended mode, you only need two more components. In addition, the LM4845's shutdown current is extremely low, with a typical shutdown current of 0.1Î¼A.
The LM4888 is a dual-channel bridged audio power amplifier that can deliver 2.1W of output power from a 5 volt supply and input it to a 4W load. It also provides 2.4W of output power and then inputs it into a 3W load. , and the total harmonic distortion and noise will not exceed 1.0%. The 3D enhanced mode is one of the user-specific feature options that can be used to enhance stereo output. The LM4888 chip also features two independent headphone enable inputs, each with a different logic level threshold. Both headphone start inputs can each activate single-ended headphone mode and turn off bridged load output mode. The headphone sense input function is designed for normal stereo headphone jacks. The remaining input headphone logic can accept normal logic level thresholds. The LM4888 chip integrates a dual-bridged speaker amplifier and stereo headphone amplifier into a single chip, helping to streamline the design of the audio system. Both the LM4845 and LM4888 models feature low power shutdown mode and thermal shutdown protection. In addition, the two chips also have special circuits that can suppress "switching/switching" noise when the system is started.
The LM4845 is available in a 25-pad micro SMD package for $2.50 each, while the LM4888 is available in a 25-pin LLPÂ® package for $1.50 each. Both chips are priced at 1,000 units. A large number of stocks.