MAX3981 Maxim Integrated Products, MAX3981 Datasheet - Page 7

• Manufacturer Part Number: MAX3981
• Description: XAUI Quad Cable Equalizer
• Manufacturer: Maxim Integrated Products

Figure 2. CML Input Buffer
tion of the signal detect (SDET) function. For constant
operation, connect the EN signal directly to V
Signal activity is detected on channel 1 only (IN1±).
When the peak-to-peak differential voltage at IN1± is
less than 30mVp-p, the TTL output SDET goes low.
When the peak-to-peak differential voltage becomes
greater than 100mVp-p, SDET is asserted high. SDET
can be used to automatically force the equalizer into
standby mode by connecting SDET directly to the EN
input. When not used, SDET should not be connected.
The signal-detect function continues to operate while
the part is in standby mode. While connected to the EN
pin, the signal detect can “wake up” the part and
resume normal operation.
Circuit board layout and design can significantly affect
the MAX3981 performance. Use good high-frequency
design techniques, including minimizing ground induc-
tances and vias and using controlled-impedance trans-
mission lines for the high-frequency data signals.
Signals should be routed differentially to reduce EMI
susceptibility and crosstalk. Power-supply decoupling
capacitors should be placed as close as possible to
the V
STRUCTURES
IN+
IN-
ESD
CC
pins.
Signal Detect with Standby Mode
_______________________________________________________________________________________
50Ω
3.125Gbps XAUI Quad Cable Equalizer
V
CC
Layout Considerations
1.2kΩ
200µA
50Ω
CC
.
Figure 3. CML Output Buffer
*Note: Exposed pad must be soldered to supply ground.
TOP VIEW
IN1+
GND
IN2+
GND
IN3+
IN1-
IN2-
IN3-
V
V
V
DATA
CC
CC
CC
10
11
1
2
3
4
5
6
7
8
9
50Ω
Q1
V
CC
Q2
MAX3981
50Ω
QFN*
Pin Configuration
STRUCTURES
33
32
31
30
29
28
27
26
25
24
23
ESD
OUT2+
OUT2-
V
GND
OUT3+
OUT3-
V
GND
OUT4+
OUT4-
V
OUT+
OUT-
CC
CC
CC
7