ADI circuit powers 3Com modems

ADI circuit powers 3Com modems
NORWOOD, Mass. — Analog Devices Inc. calls the "Winmodem" AD1806 chip, introduced last week, the most integrated modem part it's ever built. The single-chip data pump builds PCI-based controller-less modems for data, fax and voice transmission. Built to 3Com Corp.'s specifications, it is expected to account for more than 40 percent of the modems 3Com sells this year.

ADI said it believes the AD1806 is the first single-chip V.90 56-kbits/second modem to include a PCI interface, POTS line and handset codecs, a 16-bit DSP and memory. The device also includes a separate D/A converter and low-power amplifier to drive the modem monitor speaker, said Maury Wood, modem product line manager for ADI, based here.

The DSP core in the modem chip is a 34-Mips version of the ADSP2181, said Wood. The ADSP2181 is a communications device known for its large 80 kbytes of on-chip memory, configured as 16k of 24-bit words of program RAM, and 16k of 16-bit words of data RAM.

By incorporating the data converters on the same chip with the DSP and memory, ADI believes its Winmodem offers higher levels of integration than V.90 products from competitors Lucent Technologies and Conexant (formerly Rockwell Semiconductor). Most significant, perhaps, is that the AD1806 single-chip modem displaces some of the DSPs supplied up to now by Texas Instruments.

"There is no question that TI has considerable strength in DSP, and that 3Com will continue to buy a lot of DSPs from them," said Wood. The TI modem chip includes hardware communications port controllers, which lend themselves to outboard modem applications, but not the phone line and handset codecs.

"The main advantage of integrating the codecs," said Wood, "is that it allows 3Com to reduce its costs by lowering its bill of materials." Price pressures are pushing modem makers toward "controller-less" designs, and 90 percent of PCI modems will likely use software flow control, he said.

Manufacturers like 3Com are also forced to bundle their after-market modem cards with software enticements for consumers. The low cost of the AD1806 is enabling 3Com to bundle a "Discovery Pack" of Microsoft applications software with the modem card, said Wood. A Christmas retail promotion pack will likely include Microsoft Money, Encarta and "The Age of Empires" for less than $99.

A number of PC makers are taking delivery of 3Com modems that use the ADI chip, Wood said, but he would not "name names."

The AD1806 supports the latest PC industry power-management standards, including Intel's Instantly Available PC, and Microsoft's ACPI/OnNow. These standards call for PCs — even desktops — to slip into a sleep mode when they are not used, and to be awakened by the modem taking an incoming phone call. In such applications, the PCI modem card will use a 3.3-V line as a "keep alive" voltage, but immediately switch to 5-V lines as the system comes awake. The single-chip modem supports "D3cold" (wakeup on ring), said Wood, though that feature is not exclusive to the ADI chip.