Product Brief
Class-D audio amplifier exhibits power density of 3.2-W/mm-square
Paul Buckley1/24/2012 8:56 PM EST
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RICK.HILLE
The datasheet offers little insight into the Smart Protection. Maybe I'm ...
agk
The smart current protection embedded into this chip seems to produce clean ...
STMicroelectronics has introduced a high-performance, analog class-D audio amplifier that is claiming best-in-class power density. The achievement will allow equipment manufacturers to combine superior audio quality with a small form factor in next-generation home and professional sound systems and active-speaker applications.
To maximize the speaker output power, sound-system manufacturers require high-efficiency amplifiers capable of driving speakers at low impedances of 2 or 3 ohms, which creates a challenge by increasing device sizes. ST designers have addressed this problem by managing to pack 320 W of total output power – 160 W on each channel - on an area of 100 mm2, giving ST's newest analog audio class-D amplifier a 20% power-density advantage over existing solutions on the market.
The device's high-current capability not only delivers high output power, but also enables the design of platform solutions where the speaker impedance can be simply changed - from 8 down to 2 ohms - without any power or current limitation.
ST's newest amplifier also integrates a host of features that increase audio quality in the final application, including built-in suppression of pop/click noises, standby and mute functionality, and balanced input for best TDMA (Time Division Multiple Access) noise rejection. The device embeds smart current protection, which recognizes when the speaker requires a peak of current for a specific frequency range and automatically prevents any interruptions in the sound flow.
The TDA7498E (
TDA7498E datasheet) amplifier offers flexible audio-system configuration, in both stereo and mono modes, and also includes the mono parallel feature for driving the subwoofer/woofer channel in 2.1 sound set-ups. The device exhibits a signal-to-noise ratio of 100dB and provides four selectable, fixed-gain settings at 23.8 dB, 29.8 dB, 33.3 dB and 35.8 dB.
ST's TDA7498E dual-BTL (Bridge Tied Load) class-D audio amplifier with a single power supply is sampling now and volume production is scheduled for February 2012, with unit pricing at $6 for volumes in the range of 1,000 pieces.
Visit STMicroelectronics at http://www.st.com.
This article originally appeared on EE Times Europe.
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agk
1/25/2012 8:14 AM EST
The smart current protection embedded into this chip seems to produce clean sound while a music contains large changes in its sound levels at certain frequency ranges.This will reduce inter harmonic distortion and automatically prevents any interruptions in the sound flow.
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RICK.HILLE
1/25/2012 12:05 PM EST
The datasheet offers little insight into the Smart Protection. Maybe I'm missing something but when I read the description, it sounds like the device immediately clamps the current to some unspecified peak value (first threshold) and has the ability to distinguish a dead short (second threshold). The typical way that can be done is by measuring the voltage that develops across the load during the clamping condition, and if its below a certain level, declare a shorted condition. While this is all happening, of course, a horrible distortion is introduced due to the first threshold clamping.
There is nothing in the information ST posted for the device that reveals the mechanism described in the article, which has a time element to it when they speak of specific frequency range. If it is time based, such as SOA protection (see National Semi's SPIKE mechanism), it would be reasonable to expect that the thresholds are "time at level" determinations. This approach would hold off limiting the occasional large audio peak and only react to a sustained series of high current peaks that would threaten the SOA limit.
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