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Single-chip audio subsystem features 3D-sound enhancement circuitry

STMicroelectronics has introduced a single-chip audio subsystem IC to include 3D sound enhancement for improved stereo effects in small equipment, such as notebook PCs, mobile internet devices, gaming consoles or any portable multimedia devices. The TS4982’s 3D sound-enhancement circuitry allows closely spaced speakers to deliver more stereo spatial effects. The 3D effect is adjustable for low, medium or high volume levels, allowing equipment designers to optimise stereo enhancement according to the type and size of product. The level is set using two external pins on the device, and requires no additional circuitry. The device includes a 2 x 2W stereo speaker driver; a 125mW stereo headphone driver; four-step digital volume control; pop-and-click reduction circuitry to attenuate unwanted system noises; and PC-beep pass-through capability. Separate Enable signals for the headphone and speaker drivers allow low power consumption at all times, enabling battery-powered devices to operate for longer.

The device also draws a low current of 10nA in shutdown mode, which minimises the audio subsystem’s effect on battery life when not being used. The device also helps designers save PC-board space through features such as ground-referenced circuitry for the headphone driver. This avoids the need to add DC-blocking capacitors, thereby reducing overall system size and cost. Since DC-blocking capacitors also represent a source of noise, removing these also contributes to higher audio quality. The device’s speaker driver has a BTL (Bridge-Tied Load) output, which produces high audio power as well as high efficiency. The device’s external PC-Beep input allows PC-generated sounds such as power-up self-test codes to be transmitted through the speaker or headphone driver circuitry. In PC-multimedia applications, this allows the user to stay informed of PC status while playing back local or online content.