200-volt stereo driver IC serves high-end audio

Santa Clara, Calif.&#8212National touts its LM4702, for high-power, high-end consumer applications, as the industry's first 200-volt stereo driver IC.

Using a proprietary bipolar technology with vertically integrated NPN and PNP devices, which can handle larger peak-to-peak output voltage swings than traditional designs, the LM4702 is suited to driving discrete transistors or Darlington pairs that can deliver from 25 to more than 300 watts per channel. The driver is available in three grades. The LM4702C, rated for operation at &plusmn20 to as high as &plusmn75 VDC, targets high-volume applications such as stereo systems and audio/visual (AV) receivers. The LM4702B (&plusmn20 to &plusmn100 VDC) has tighter specifications for high-end audio, guitar amplifiers, professional audio amplifiers and speakers. For ultra high-end consumer and professional audio, the LM4702A is fully specified, with all limits tested and guaranteed over voltage (&plusmn20 to &plusmn100 VDC) and temperature. It is offered in a military 883-compliant, gold-plated TO-3 package. All versions include thermal protection that kicks in when the die temperature exceeds +150&degC, and a no-click, no-pop mute function.

An amplifier reference design (AN-1490) using the LM4702 (click here) provides a total harmonic distortion plus noise (THD+N) of 0.0006 percent into an 8-ohm load. The amp's output power is scaled by simply adjusting the supply voltage and selecting the appropriate power stage transistors. For higher current and power levels, the output transistors can be configured in parallel without changing the basic LM4702 driver circuit. These drivers can be simply applied to multi-channel surround-sound applications as well.

Click here for additional information and samples. Available now in a 15-lead TO-220 package, the LM4702C is priced at $4.50 each in 1k quantities. The LM4702B is $24.95 each in 100-unit quantities. The LM4702A is $150 in 25-unit quantities and will be available by January.

National Semiconductor , 1-408-721-5000,

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