Applications Information

Supply Bypassing

ceramic 0.01µF capacitor as close to the device as

possible.

Differential Traces

Input and output trace characteristics affect the perfor-

mance of the MAX9155. Use controlled-impedance dif-

ferential traces. Ensure that noise couples as common

mode by running the traces within a differential pair

close together.

Maintain the distance within a differential pair to avoid

discontinuities in differential impedance. Avoid 90°

turns and minimize the number of vias to further prevent

impedance discontinuities.

Cables and Connectors

The LVDS standards define signal levels for intercon-

nect with a differential characteristic impedance and

termination of 100

Ω. Interconnects with a characteristic

impedance and termination of 90

Ω to 132Ω impedance

are allowed, but produce different signal levels (see

Termination).

Use cables and connectors that have matched differen-

tial impedance to minimize impedance discontinuities.

Avoid the use of unbalanced cables, such as ribbon or

coaxial cable. Balanced cables, such as twisted pair,

offer superior signal quality and tend to generate less

EMI due to canceling effects. Balanced cables tend to

pick up noise as common mode, which is rejected by

the LVDS receiver.

Termination

For point-to-point links, the termination resistor should

be located at the LVDS receiver input and match the

differential characteristic impedance of the transmis-

sion line.

For a multidrop bus driven at one end, terminate at the

other end of the bus with a resistor that matches the

loaded differential characteristic impedance of the bus.

For a multidrop bus driven from a point other than the

end, terminate each end of the bus with a resistor that

matches the loaded differential characteristic imped-

ance of the bus. When terminating at both ends, or for a

large number of drops, a bus LVDS (BLVDS) driver is

needed to drive the bus to LVDS signal levels. The

MAX9155 is not intended to drive double-terminated

multidrop buses to LVDS levels.

The differential output voltage level depends upon the

differential characteristic impedance of the interconnect

and the value of the termination resistance. The

MAX9155 is guaranteed to produce LVDS output levels

into 100

Ω. With the typical 3.6mA output current, the

MAX9155 produces an output voltage of 360mV when

driving a 100

Ω transmission line terminated with a

100

Ω termination resistor (3.6mA x 100Ω = 360mV). For

typical output levels with different loads, see the

Differential Output Voltage vs. Load Resistor typical

operating curve.

Chip Information

TRANSISTOR COUNT: 401

PROCESS: CMOS

Low-Jitter, Low-Noise LVDS

Repeater in an SC70 Package

6

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