Datasheet

MAX4950
Quad PCI Express Equalizer/Redriver
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Applications Information
Figure 2 shows a typical application with two
MAX4950s, both residing on the main board, with input
and output equalization set individually for optimal per-
formance. The receive equalizer is set to receive a
degraded signal coming from a remote board through
two sets of connectors, and a midplane stripline trans-
mission. The output of the Rx section has little or no out-
put equalization. The Tx section takes a high-quality
signal, and provides boost to the output (deemphasis).
Layout
Circuit-board layout and design can significantly affect
the performance of the MAX4950. Use good high-fre-
quency design techniques, including minimizing
ground inductance and using controlled-impedance
transmission lines on data signals. Power-supply
decoupling should also be placed as close to V
CC
as
possible. Always connect V
CC
to a power plane. It is
recommended to run receive and transmit on different
layers to minimize crosstalk.
Exposed-Pad Package
The exposed-pad, 42-pin TQFN package incorporates
features that provide a very low thermal-resistance path
for heat removal from the IC. The exposed pad on the
MAX4950 must be soldered to the circuit-board ground
plane for proper thermal performance. For more infor-
mation on exposed-pad packages, refer to Maxim
Application Note HFAN-08.1: Thermal Considerations of
QFN and Other Exposed-Paddle Packages .
Power-Supply Sequencing
Caution: Do not exceed the absolute maximum rat-
ings because stresses beyond the listed ratings
may cause permanent damage to the device.
Proper power-supply sequencing is recommended for
all devices. Always apply GND then V
CC
before apply-
ing signals, especially if the signal is not current limited.
Chip Information
PROCESS: BiCMOS
EN P_SAV O_AMP
QUIESCENT POWER
SUPPLY CURRENT
(typ) (mA)
QUIESCENT POWER
SUPPLY CURRENT
(max) (mA)
QUIESCENT POWER
DISSIPATION
(3.3V, typ) (mW)
QUIESCENT POWER
DISSIPATION
(3.6V, max) (mW)
0 0 0 100 125 330 450
0 0 1 80 100 264 360
0 1 0 100 125 330 450
0 1 1 80 100 264 360
1 0 0 262 328 865 1181
1 0 1 242 303 799 1091
1 1 0 214 268 706 965
1 1 1 194 243 640 875
Table 5. Power-Save Mode Quiescent Power Dissipation
4 DIFFERENTIAL PAIRS
Rx
Tx
MIDPLANE
REMOTE BOARD
4 DIFFERENTIAL PAIRS
CONNECTORS
MAX4950
PCIe
Tx
Rx
MAIN BOARD
PCIe
MAX4950
Figure 2. Typical Application Diagram