According to STMicroelectronics (ST), combined audio converter/driver ICs are simplifying the design of set-top boxes and other consumer audio/video products, but ST states that its new TS4657 improves on this by saving additional external components while reducing power consumption and improving sound quality.
ST’s new TS4657 is a single chip combining audio-DAC (digital-to-analog converter) and line-driver functions to feed the audio Line-Out connection of set-top boxes, DVD players, portable multimedia devices, sound cards, or similar equipment. The Line Out provides a direct connection to drive an external home amplifier.
The IC uses an internal power management unit to produce a 2.2Vrms audio-output signal for voltages from 3.0 to 5.5V, eliminating the need for a separate high-voltage power supply to drive the Line-Out output. Similar devices typically require four external capacitors for the charge pumps but ST’s high-frequency design integrates these on-chip, thereby saving board space and bill-of-materials costs. In addition, the ability to generate negative and positive voltages allows the audio signal to be referenced to ground, which saves the need for a decoupling capacitor in the audio-signal line.
The TS4657 also increases flexibility for designers since it can be operated from any supply voltage from 3.0 to 5.5V. Hence design is simplified and engineers can use the same device for a variety of products. The operating current of only 7.4mA, three times smaller than the nearest competing device, leads to improved efficiency. By achieving 93dB dynamic range, 80dB Power Supply Rejection Ratio (at 217Hz), and 81dB THD+N at 0dBFS, this device also helps maximize the audio performance of equipment connected to the Line-Out.
The TS4657 is in production now, available in the 4 x 4mm QFN20 package and priced at $0.91 in quantities of 1000 units.