Geneva, January 22, 2004 – STMicroelectronics is shipping a new single-chip audio power amplifier that delivers 200W, the highest power available from an integrated commercial device. Called STA5150, the new amplifier combines the patented BASH high-efficiency technology licensed from Indigo Manufacturing with ST's proprietary Bipolar-CMOS-DMOS (BCD) process technology.
Merging the benefits of class AB and class D, the BASH technology uses DMOS power transistors operated in class AB mode, reducing the EMI and distortion typical of class D switching amplifiers. To maximize efficiency, by continually adjusting the power supply voltage, depending on the amplitude of the amplified audio signal, a constant voltage drop is achieved across the output transistors, completely independent of the output amplitude. Implementing this technique allows the STA5150 to deliver 200W into a four-ohm load with less than 10% distortion, and with an efficiency three times better than a conventional Class AB.
Each STA5150 device includes a 200W audio power amplifier channel. This amplifier is mainly used in multi-channel multimedia audio systems such as the 5.1 channel surround sound commonly used in A/V receivers. Other BASH-equipped audio power amplifiers available include the 2×100 STA575, 2x70W STA550 and STA530, a quad amplifier fully configurable from 4x50W to 2x50W+ 1x100W. The power amplifiers are used in conjunction with a digital processor, the STABP01, which is the controller for a buck (step-down) converter and implements the BASH supply voltage variation technique, by using a reference feedback signal derived from the power amplifier stage.
STA5150 power amplifiers are assembled in ST's proprietary Flexiwatt plastic package, developed to provide excellent thermal performance, easy assembly and robustness. The products include comprehensive protection features that guard against overload and anomalous supply conditions. By using a BASH specific external circuit topology, it's possible to provide an intended reduction of the power supply voltage, sensing the power stage and the external buck converter to achieve a further improvement of the overall systems' protection scheme.
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