Broadband Modems
Cable Modems
CX24951 Distinguishing Features
A-TDMA and S-CDMA DOCSIS
2.0 upstream modulation
High level of integration
(Single monolithic IC)
Dual software programmable
network processing engines
500 MIPS of processing power
Less than 550mW typical
power dissipation
Embedded IEEE 802.3 MAC with MII
12Mb USB 1.1 communications
transceiver
Support for DOCSIS/EuroDOCSIS 2.0/
1.1/1.0, DVB and proprietary standards
CableHome and PacketCable
compliant
High density, 17mm x 17mm
BGA package
Conexant's next generation cable modem solution
offers a DOCSIS 2.0-based single-chip modem while
providing dual software programmable network
processing engines
Conexant's broadband communications portfolio includes a comprehensive
suite of semiconductor solutions that enable the digital home and information
network. The InfoSurgeTM family of products, supporting broadband cable
modem applications, presents the industry with yet another example of
Conexant's ability to exceed the needs of a growing market segment.
The CX24951, Conexant's DOCSIS 2.0-based single-chip cable modem
solution, provides backwards compatibility with the DOCSIS 1.1 and the
DOCSIS 1.0 standards. The world's fastest, lowest power and smallest cable
modem solution, the CX24951, offers 500 MIPS of processing power while
consuming just 550mW in a 17mm x 17mm BGA package.
The CX24951 fully supports the new upstream physical-layer modulation
technologies A-TDMA (Advanced Time Division Multiple Access) and S-CDMA
(Synchronous Code Division Multiple Access) as specified in DOCSIS 2.0
standard. These new modulation techniques significantly increase upstream
cable bandwidth for data transmissions (up to 30Mbps) without requiring
any physical rebuilding of cable networks.
The CX24951's 500 MIPS and software programmable dual processor architecture
with on-chip memory for cable MAC and application layer processing makes
it ideally suited for CableHomeTM and PacketCableTM applications.
Dual Programmable Network Processors
The CX24951 utilizes the proven software programmable dual processor
architecture of its predecessor, the CX24943, and further boosts its
performance by increasing the instruction memory size to 128K bytes.
The CX24951 is pin compatible with the CX24943.
The dual network processing engine architecture offers real-time-critical
packet management processing and superior performance. The software
programmability of this architecture accommodates application specific
requirements, worldwide standards, and manufacturers' unique value
added features for maximum flexibility.
Part Number CX24951
Description Single-Chip Cable Modem
Single-Chip Cable Modem Solution
DOCSIS
TM
2.0-Based
CX24951
Broadband Modems
Cable Modems
The dual processor architecture of the CX24951 allows it to be
used in CableHome applications, without needing an additional
network processor for the firewall and routing features required
by the CableHome standard. The firewall and routing algorithms
required by CableHome take less than 10 percent of the 500 MIPS
processing power of the CX24951, leaving plenty of processing
power left for developing custom networking applications.
The integrated MII port and the PCMCIA functionality of the
integrated host port allow the CX24951 to provide a seamless
interface to an array of networking peripherals such as wireless
LANs (802.11a/b), HomePlug transceivers, HPNA solutions, and
multi-port Ethernet Switches.
The CX24951 also supports PacketCable applications by
interfacing to Conexant's voice DSP products to execute voice
processing algorithms.
Highly Integrated
The CX24951 supports a number of interfaces including a USB 1.1
communications transceiver, an IEEE 802.3 10/100 Ethernet Media
Access Controller (MAC) with a Media Independent Interface (MII)
for access to home networking standards. Examples are HPNA
2.0, HomePlug 1.0 and a host interface which supports seamless
connectivity to any PCMCIA compliance device such as IEEE
802.11a and IEEE 802.11b wireless transceivers. The CX24951
supports integrated and stand alone cable modems, home
networking gateway products, IP (Internet Protocol) telephony
products, and digital set-top boxes.
The CX24951 was developed using leading-edge process and
packaging technologies. This helps drive down the size of the
monolithic IC, package and power, while allowing clock rates
to increase. The CX24951 dissipates less than 550mW of power
setting a new standard for the industry.
The CX24951, through its high level of integration, enables
manufacturers to develop a complete cable modem with a
minimal number of additional components as shown in the
CX24951-based cable modem block diagram.
CX24951-based Cable Modem Block Diagram
10/100
Ethernet
PHY
SDRAM
Interface
CX24951
Host
Interface
GPIO
MII
USB
Conexant
HPNA 2.0
PHY
Conexant
HomePlug
PHY
Conexant
Voice DSP
RJ-45
RJ-11
RJ-11
RJ-11
Antenna
Powerline
Type B
Socket
2 MB
Flash
4 MB
SDRAM
LED Indicators
Power
Supply
1.3v
3.3v
5.0v
802.11a/b
MAC/PHY
ADC
DAC
Control
Tuner
Cable
Increased Performance
Conexant's seventh-generation physical-layer downstream
receiver includes a 10-bit A/D that accepts a direct IF signal
(at 44 or 36 MHz) and a QPSK/16/32/64/128/256 QAM
demodulator with Annex A, B and C forward error correction.
The CX24951 also contains an 11-bit D/A converter, which can
accommodate 65 MHz of upstream bandwidth for EuroDOCSIS
and DVB applications, and a QPSK/8/16/32/64/128 QAM burst
upstream modulator. Conexant's proven PHY technology exceeds
all DOCSIS/EuroDOCSIS 2.0/1.1/1.0 requirements for low BER
in noise-filled environments.
The CX24951 is the fastest solution in the industry with
integrated dual software programmable network processing
engines on board. Its unique packet management, unified
memory architecture, and advanced system buses, maximize
performance by allowing segmentation of real-time-critical
DOCSIS/EuroDOCSIS 2.0/1.1/1.0 functions from non
real-time-critical application processes. The CX24951
processor performance and unique architecture enables
DOCSIS/EuroDOCSIS 2.0/1.1/1.0 and other software applications,
including VPN firewall for added security and routing for
cable home or VoIP for PacketCable.
The CX24951 also incorporates a PHS (Payload Header
Suppression requirement introduced in DOCSIS 1.1) engine
in hardware. Implementation of PHS in hardware further boosts
the performance of the CX24951 by relieving the internal CPU
from performing repeated filtering operations.
CX24951 Features
Flexible Platform
Cable modem manufacturers have to devote a significant
amount of resources to bring new certifiable solutions to
market. The unique architecture of the CX24951 provides a
number of advantages for cable modem manufacturers and
cable operators alike. The software programmability of the dual
network processing engine allows manufacturers to customize
the CX24951 for application specific requirements, both at
the cable MAC and software applications layer.
The software programmability of the CX24951 allows one base
platform to support numerous products, including PacketCable,
CableHome and set-top box products as shown in the CX24951-
based cable modem block diagram. In addition, the architectural
similarities between the CX24951 and its predecessor, the
CX24943, allows for maximum reuse of certified code.
The CX24951 provides the ability to adapt to a multitude of
standards by downloading different software into the embedded
dual network processing engine, including DOCSIS/EuroDOCSIS
2.0/1.1/1.0, DVB and proprietary standards. Finally, cable operators
can download complex feature enhancements above and beyond
simple code upgrades to field-deployed solutions, minimizing truck
rolls and equipment obsolescence.
Complete Hardware and Software Solution
To reduce the resources and development time required to bring
CX24951-based cable modem solutions to market, Conexant
provides complete certifiable DOCSlS/EuroDOCSIS 2.0/1.1/1.0
cable modem reference designs which incorporate all of the
hardware and software needed for DOCSIS certification.
Cable modem reference designs include Conexant software that
is compliant to DOCSIS/EuroDOCSIS 2.0/1.1/1.0 and include the
USB drivers that meet Microsoft's Windows Hardware Quality Lab
(WHQL) requirements. Additional software enhancements that are
above and beyond standards-based requirements are also included
in this complete software offering.
CX24951 Single-Chip
Cable Modem IC Block Diagram
Peripheral
I/O
Memory
DMA
Interrupt
Controllers
Applications
Network
Processor
USB
Host
Interface
Cable PHY
Downstream
Cable PHY
Upstream
S-CDMA
A-TDMA
A
D
C
D
A
C
Cable MAC
Network
Processor
MII
2002, Conexant Systems, Inc. All Rights Reserved. Conexant and the Conexant
logo are registered trademarks of Conexant Systems, Inc. All other trademarks
are owned by their respective owners. Although Conexant strives for accuracy
in all its publications, this material may contain errors or omissions and is
subject to change without notice.
THIS MATERIAL IS PROVIDED AS IS AND WITHOUT
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NON-INFRINGEMENT.
Conexant shall not be liable for any
special, indirect, incidental or consequential damages as a result of its use.
Broadband Modems
Cable Modems
02-0671
CX24951 Features
Cable PHY Downstream
10-bit A/D
Direct IF sampling at 44 and 36 MHz
QPSK/16/32/64/128/256 QAM demodulator
Programmable equalization
Annex A, B and C FEC
Cable PHY Upstream
11-bit D/A
A-TDMA
S-CDMA with Turbo Trellis coding
QPSK/8/16/32/64/128 QAM burst modulator
Programmable pre-equalization
DMA Interrupt Controller
20 asynchronous channels
Memory to memory moves: aligned/unaligned
Source/destination mode for simple data transfer
Circular/linked buffer support for inbound/outbound data
Peripheral I/O
32 GPIO
JTAG boundary scan
UART
Cable MAC Network Processor
Software Programmable
- DOCSIS 2.0/1.1/1.0 compliant
- EuroDOCSIS 2.0/1.1/1.0 compliant
- DVB compliant
- Fixed wireless compliant
- Proprietary standards
Two PHS engines
Internal 64KB data memory
Internal 128KB Instruction memory
Three 56-bit DES/CRC engines
PID, SID, DA/SA, MAC, IP and LLC filtering
Application Network Processor
ARM940T microcontroller
Up to 225 MHz operation
4KB instruction and 4KB data cache
Embedded ICE and debug extensions
HCS 16- and 32-bit CRC single-cycle engines
MII
IEEE 802.3 MAC layer
Networking technologies
- 10/100 Ethernet
- Conexant HPNA 2.0
- Conexant HomePlug 1.0
Host Interface
Master mode
- 16-bit data
- 8-chip selects
Supports Flash, IP telephony, PCMCIA
- IEEE 802.11a or IEEE 802.11b
- 16/32-bit Slave mode (external host and test)
USB 1.1
Integrated 12 Mb transceiver
Communications peripheral device
Memory
Internal 8K x 32 SRAM
External SDRAM Interface
- 16-bit interface
- Supports both 4MB and 8MB technologies
Phase-Locked Loops (4)
TDM clock and frame sync generator
Transmit clock generator
Supplied 25MHz Ethernet reference clock
Internal USB clock
Miscellaneous Functions
Watchdog timer
Four additional timers
Interrupt controller
Package and Power
228 PBGA (17mm x 17mm)
All I/O at 3.3V
Power supply: 3.3V and 1.3V
<550 mW (typical)
Reference Designs
DOCSIS 2.0/1.1/1.0
EuroDOCSIS 2.0/1.1/1.0
PCI
Product Applications
(DOCSIS/EuroDOCSIS 2.0/1.1/1.0, DVB, Proprietary)
Cable Modems with Ethernet
Cable Modems with USB
Cable Modems with IP Telephony
PCI Cable Modem Card Internal (CMCI)
Cable Modem with Home Networking
PCMCIA Cable Modem
Digital Set-Top Box with Cable Modem
CPE Controlled Cable Modem (CCCM)
www.conexant.com
General Information:
U.S. and Canada: (800) 854-8099
International: (949) 483-6996
Headquarters Newport Beach
4311 Jamboree Rd, P.O. Box C
Newport Beach, CA 92660-3095
Order# 102113A
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