CX11627

These devices contain circuitry to protect the inputs against damage due to high static voltages. However, it is advised that normal precautions be taken to avoid application of any voltage higher than maximum rated voltage.

An unterminated input can acquire unpredictable voltages through coupling with stray capacitance and internal cross talk. Both power dissipation and device noise immunity degrades. Therefore, all inputs should be connected to an appropriate supply voltage.

Input signals should never exceed the voltage range from 0.5V or more negative than GND to 0.5V or more positive than VDD. This prevents forward biasing the input protection diodes and possibly entering a latch up mode due to high current transients.

The Conexant AccessRunner™ ADSL-USB Modem Device Set CX11627 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 iCX11627 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.

CX11627 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.