According to Juniper Research, Voice over Internet Protocol (VoIP) will account for over 12% of all telephony revenues by 2009 as it evolves from a replacement service for the public switch telephone network to a new converged service for home and business users. In November, Japan's NTT DoCoMo introduced 3G cell phones with VoIP 802.11b as well as W-CDMA capabilities. It won't be long before wireless PDAs with Wi-Fi VoIP capabilities pop up.
To support these applications, Wolfson Microelectronics plc introduced its WM8510 VoIP mono codec. The WM8510 includes a driver for a speaker or headset, two separate microphone inputs (handset and speakerphone), and two dedicated analog audio outputs with volume control. Advanced sigma-delta converters are used along with digital decimation and interpolation filters to provide high-quality audio at sample rates from 8 to 48 ksamples/s. A standard audio interface supports a number of audio data formats, including m-law and a-law, PCM, I2S, and DSP Mode. The codec can perform in master or slave modes, too.
Its operation ranges from 2.5 to 3.6 V, though the digital core can dip down to 1.62 V to save power. The speaker and mono outputs use a separate supply of up to 5 V, which enables increased output power if required. Different sections of the chip also can be powered down under software control via the selectable two- or three-wire control interface.
Housed in a 28-pin SSOP, it costs $1.25 in lots of 10,000.
Wolfson Microelectronics plcwww.wolfsonmicro.com 