1FEATURES

2• 3.168 Gbits/sec Bandwidth with 66 MHz Clock

• 5.376 Gbits/sec Bandwidth with 112 MHz Clock

• 65 - 112 MHz Input Clock Support

• LVDS SER/DES Reduces Cable and Connector

Size

• Pre-Emphasis Reduces Cable Loading Effects

• Optional DC Balance Encoding Reduces ISI

Distortion

• Cable Deskew of +/−1 LVDS Data Bit Time (up

to 80 MHz Clock Rate)

• 5V Tolerant TxIN and Control Input Pins

• Flow Through Pinout for Easy PCB Design

• +3.3V Supply Voltage

• Transmitter Rejects Cycle-to-Cycle Jitter

• Conforms to ANSI/TIA/EIA-644-1995 LVDS

Standard

DESCRIPTION

The DS90CR481 transmitter converts 48 bits of

CMOS/TTL data into eight LVDS (Low Voltage

Differential Signaling) data streams. A phase-locked

transmit clock is transmitted in parallel with the data prestreams

over a ninth LVDS link. Every cycle of the eyetransmit

clock 48 bits of input data are sampled and

transmitted. The DS90CR482 receiver converts the

LVDS data streams back into 48 bits of

LVCMOS/TTL data. At a transmit clock frequency of

112MHz, 48 bits of TTL data are transmitted at a rate

of 672Mbps per LVDS data channel. Using a 112MHz

clock, the data throughput is 5.38Gbit/s

(672Mbytes/s). At a transmit clock frequency of

112MHz, 48 bits of TTL data are transmitted at a rate

of 672Mbps per LVDS data channel. Using a 66MHz

clock, the data throughput is 3.168Gbit/s

(396Mbytes/s).

The multiplexing of data lines provides a substantial

cable reduction. Long distance parallel single-ended

buses typically require a ground wire per active signal

(and have very limited noise rejection capability).

Thus, for a 48-bit wide data and one clock, up to 98

conductors are required. With this Channel Link chipset as few as 19 conductors (8 data pairs, 1 clock

pair and a minimum of one ground) are needed. This

provides an 80% reduction in cable width, which

provides a system cost savings, reduces connector

physical size and cost, and reduces shielding

requirements due to the cables' smaller form factor.

The 48 CMOS/TTL inputs can support a variety of

signal combinations. For example, 6 8-bit words or 5

9-bit (byte + parity) and 3 controls.

The DS90CR481/DS90CR482 chipset is improved over prior generations of Channel Link devices and

offers higher bandwidth support and longer cable

drive with three areas of enhancement. To increase

bandwidth, the maximum clock rate is increased to

112 MHz and 8 serialized LVDS outputs are

provided. Cable drive is enhanced with a user

selectable pre-emphasis feature that provides

additional output current during transitions to

counteract cable loading effects. Optional DC

balancing on a cycle-to-cycle basis, is also provided

to reduce ISI (Inter-Symbol Interference). With prestreams

emphasis and DC balancing, a low distortion eyetransmit

pattern is provided at the receiver end of the cable. A

cable deskew capability has been added to deskew

long cables of pair-to-pair skew of up to +/−1 LVDS

data bit time (up to 80 MHz Clock Rate). These three

enhancements allow cables 5+ meters in length to be

driven.

The chipset is an ideal means to solve EMI and cable

size problems associated with wide, high speed TTL

interfaces.