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National Semiconductor's (NS) high-fidelity LMETM audio amplifier series adds two new products. These new 200V mono audio power amplifier input grades not only have lower distortion rates than competing products, but also shorten the system design cycle for designers. These highly integrated single-chip amplifier input stages can greatly accelerate the market speed of high-end consumer electronics and professional audio products, and can be widely used in recording studio active monitors and subwoofers, audio/video receivers. Commercial sound enhancement systems, non-original car audio systems, professional-grade mixers, distributed audio and guitar amplifiers. In addition, these two products are also suitable for many different industrial systems, such as high voltage electronics with extremely low distortion.Another feature of the LME49811 and LME49830 chips is that the output power can be flexibly adjusted. The system design engineer can set the output power based on the required supply voltage and the number of output chips. In other words, even with the same basic circuit design, the two products set the output stage to meet different output power and high current drive requirements, and ensure that the amplifier can output up to 1kW of power. Take the complete power amplifier design as an example. With the LME49811 chip, total harmonic distortion and noise can be reduced to 0.00035%. With the LME49830 chip, the distortion rate can be as low as 0.0006%.
The LME49811 and LME49830 chips are fully functional, and the necessary circuitry for the high-end, high-performance power amplifier input stage is available. With these two chips, high-power audio amplifiers can save more than 25 discrete components, which not only helps to reduce the board, but also saves design time. In addition, systems using these two chips can support more channels and have higher power density. System designers can not only use these two chips to "tune" the overall sound of the amplifier, but also free up more time to design a more unique output stage and power supply system.
Audio system design engineers can easily increase the system's power output by using National Semiconductor's two power amplifier input stages. Technically this is the new standard in the industry, because even before the engineers still need to use discrete components to achieve such high power and excellent performance.
The LME49811 is a mono version of the LM4702 stereo driver featuring Darlington or bipolar power transistors that drive the amplifier's output stage. The LM4702 driver chip is National's first power amplifier input stage, especially for high-performance audio systems. The LME49811 chip can drive the output stage and input single-ended output power above 500W into the 8-Ohm load. The chip's slew rate is as high as 40V/us, the output drive current is up to 9mA, and the output voltage noise is only 100uV. In addition, the LME49811 is also capable of operating over a wide voltage range of +/-20V to +/-100V with a power supply rejection ratio (PSRR) of up to 115dB.
The LME49830 chip can drive a variety of different MOSFETs, including a class of MOSFETs with standard and low threshold voltages. The chip can drive the output stage and input single-ended output power up to 500W into the 8-Ohm load. The LME49830's output current is up to 60mA, giving system designers ample room to select the most suitable output stage configuration, helping to increase system design flexibility. In addition, the chip's slew rate is as high as 40V/us, the power supply rejection ratio (PSRR) is as high as 115dB, the output voltage noise is only 41uV, and it is suitable for a wide voltage range of +/-20V to +/-100V.
Both the LME49811 and LME49830 chips feature thermal shutdown protection and are manufactured using National's proprietary and patented VIP3 process technology. This high-voltage, high-performance complementary bipolar process technology uses vertically integrated NPN and PNP transistors to increase the peak-to-peak swing of the output voltage, making it ideal for high-end, high-voltage audio systems.
The LME49811 and LME49830 are available in a 15-pin TO-247 package and are also available in 1,000-unit quantities for $3.33 each in volume.
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