National Semiconductor Launches 200V Power Amplifier Input Stages

Santa Clara, CA - National Semiconductor Corporation recently extended its high-fidelity LME audio amplifier family with the introduction of a pair of 200V mono audio power amplifier input stages that deliver low distortion performance and reduce design time. These highly-integrated, single-chip devices accelerate the design of high-end consumer and professional audio applications that span powered studio monitors and subwoofers, audio/visual (AV) receivers, commercial sound reinforcement, automotive after-market audio, professional mixers, distributed audio and guitar amplifiers. They also address a wide range of industrial applications where high-voltage and low-distortion are required.

The LME49811 and LME49830 offer scalable output power based on supply voltage and output device count. With these devices, designers can use the same base circuit design to create multiple power-level solutions up to 1 kW amplifiers, just by scaling the output stage devices to accommodate for more power dissipation and current drive. When implemented in a complete power amplifier design, the LME49811's total harmonic distortion plus noise (THD+N) is a remarkably low 0.00035 percent, while the LME49830's THD+N is 0.0006 percent.

The LME49811 and LME49830 contain all the essential circuitry required for a high-quality, high-performance power amplifier input stage. They save board space and design time by replacing more than 25 discrete components (many of which must be hand selected and matched by the audio system designer) in high- power audio amplifiers. This enables designs with more channels and more power per square-inch of chassis space. These devices also provide designers more time to differentiate their output stage and power supply design, as well as "tune" the amplifier's overall sound.

National's power amplifier input stages have achieved a new benchmark in integrated circuitry by enabling audio designers to easily create high-power systems, where previously only discrete designs could achieve this level of power and performance.

Key Technical Features -- 200V Power Amplifier Input Stages

The LME49811 drives Darlington or bipolar power transistors in an amplifier's output stage. It is a mono version of the LM4702 stereo driver, National's first power amplifier input stage for the high-performance audio market. The LME49811 is capable of driving an output stage to deliver in excess of 500W single-ended into an 8-Ohm load. The device can easily attain slew rates of 40V/us, while providing 9 mA output drive current and 100 microvolts output voltage noise. The LME49811 also provides a wide operating voltage range of plus or minus 20V to plus or minus 100V, and its power supply rejection ratio (PSRR) is 115 dB.

The LME49830 is optimized to drive a wide range of MOSFETs with standard and low threshold voltages. It can drive an output stage in excess of 500W single-ended into an 8-Ohm load. The device's 60 mA output current capability increases design flexibility when selecting output stage configurations. The LME49830 provides slew rates of 40V/us, PSRR of 115 dB, output voltage noise of 41 microvolts and a wide operating voltage range of plus or minus 20V to plus or minus 100V.

The LME49811 and LME49830 are both protected by a thermal shutdown feature. National engineers developed these devices using the company's proprietary VIP3 process technology. The high-voltage, high-performance, complementary bipolar technology, with vertically integrated NPN and PNP transistors, enables larger peak-to-peak output voltage swings that are well-suited for high-voltage requirements in high-end audio applications.

SOURCE: National Semiconductor Corporation