Introduction
Overview
The Conexant AccessRunner ADSL-USB Modem Device Set combines an “always-on” high speed Asymmetric Digital Subscriber Line (ADSL) connection to the telephone line, and Universal Serial Bus (USB) connection to a host PC into a single cost-effective solution. Conexant’s AccessRunner ADSL modem device set is compliant with the full-rate ANSI T1.413 Issue 2 and ITU G.dmt (G.992.1) ADSL standards, and with the splitterless ITU G.lite (G.992.2) specification. This rate-adaptive solution is designed for Customer Premise Equipment and supports downstream data rates of up to 8 Mbps and upstream data rates of up to 1 Mbps.
The device set takes advantage of the processing power available with today’s computers by eliminating the need for a separate ATM Segmentation and Reassembly (SAR) device, resulting in a cost-effective solution suitable for both full rate and G.lite applications. Additionally, host-based software provides support for current industry standards for PPP over ATM (RFC 2364) and bridged Ethernet over ATM (RFC 1483) for Windows 98 and Windows 2000.
The USB specification version 1.1 is supported and is the preferred standard method to connect peripherals to PCs.
During periods of no data transmission, the Conexant ADSL DMT data pump performs idle cell insertion and deletion thus unloading this task from the host PC.
The device set consists of four devices (see Figure 1-1 and Figure 1-2):

• USB Interface Controller (UIC), part no. P5200, in a 176-pin TQFP
• ADSL DMT Data Pump (ADDP), part no. CX11627, in a 176-pin TQFP
• Analog Front End (AFE), part no. CX20431, in a 32-pin TQFP
• Line Driver (LD), part no. CX20441, in a 32-pin TQFP

FEATUREs
• Complete ADSL-USB solution
• Compliant with ADSL standards
  − Full-rate ANSI T1.413 Issue 2 and ITU G.dmt (G.992.1) standards
  − Splitterless ITU G.lite (G.992.2) specification
• DMT modulation and demodulation
• Full-rate adaptive modem
   − Maximum downstream rate of 8 Mbps
   − Maximum upstream rate of 1 Mbps
• Supports splitterless ADSL implementation
• WAN mode support: PPP over ATM (RFC 2364)
• LAN mode support: bridged Ethernet over ATM (RFC 1483)
• Tone detection for low power mode
• USB host interface
   − Compliant with USB Specification, Revision 1.1
   − USB full speed (12 Mbps)
   − Suspend/Resume
   − Vendor specific descriptors
   − Bus powered USB device
• ATM SAR performed in software driver

APPLICATIONs
• ADSL Customer Premise Equipment
• ADSL USB modems for desktop PCs
• ADSL USB modems for notebook PCs