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CX20431-21

AccessRunner™ ADSL-USB Modem Device Set

Conexant Systems 

AccessRunner ADSL-USB Modem Device Set Data Sheet

1. Introduction

1.1 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

ADSL (Asymmetric Digital Subscriber Line) is a transmission technology used to carry user data over a single twisted pair line

between the Central Office and the Customer Premises. The downstream (Central Office to Customer Premises) direction

typically supports a much higher data rate than the upstream or return (Customer Premises to Central Office) channel. This

asymmetric nature lends itself to applications like remote LAN access, Internet access, and video delivery. The downstream

data rates can go up to 8 Mbps. The upstream data rates can go up to 1 Mbps. Actual data rates depend on the transceiver

implementation, loop length, impairments, and transmitted power.

The Conexant ADSL-USB Modem Device Set is based upon a scalable architecture. This architecture enables the device set

to support splitterless G.lite as well as splittered and splitterless full-rate ADSL. G.lite enables telephone companies to deploy

consumer-oriented, “always on” 1.5 Mbps Internet access services without the need for splitter equipment, micro-filters, or

wiring changes at the customer premises.

1.2 Applications

• ADSL Customer Premise Equipment

• ADSL USB modems for desktop PCs

• ADSL USB modems for notebook PCs

Host-Based

ADSL

Drivers

USB

Interface

P5200

USB Interface

Controller

(UIC)

176-Pin TQFP

CX11627

ADSL DMT

Data Pump

(ADDP)

176-Pin TQFP

CX20431

Analog Front End

(AFE)

32-Pin TQFP

CX20441

Line Driver

(LD)

32-Pin TQFP

TIP

RING

TELEPHONE LINE

100427B

Device Set

Figure 1-1. AccessRunner ADSL-USB Modem Device Set Simplified Hardware Interface

Conexant

100428_F1-1_SID

1-1

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