LU82551QM Intel, LU82551QM Datasheet - Page 119

• Manufacturer Part Number: LU82551QM
• Manufacturer: Intel

Specifications of LU82551QM

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 3V
• Operating Supply Voltage (max): 3.6V
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 196
• Lead Free Status / RoHS Status: Compliant

Datasheet
Figure 34. Reference Schematic Layout (Sheet 1 of 2)
82551QM
S
P
E
A
E
C
L
T
D
L I
L
L
RDP
RDN
TDP
TDN
E
E
E
D
D
D
C13
C14
E13
E14
C11
A12
B11
TD+ 16
Keep all termination resistors as
close to the 82551 as possible.
TD- 15
RD+
RDC
RD- 2
1
3
TDC 14
MDI Mode Only
1:1
2
TRANSMIT
RECEIVE
L
E
D
1
This capacitor is normally not installed; however a placement can be provided.
It might need to be placed based on the results of FCC conformance testing. If it
is required, values in the pico fared range can be used. Large capacitance values
installed in this location can have a negative effect on long cable performance. So care
must be taken in selecting the values used.
8-22 pF
4
7 .
TXCT
75 Ohms
u
0.1 uF
F
1
3
0 3
4
7 .
u
F
2
5
7
6
1500pF
2kV
RX+
RX-
10 TX+
11 TX-
CT
2
0
Place decoupling capacitors as close to the 82551 as possible. If component placements
are used on the bottom side of the board, then place decoupling under the 82551IT.
1 .
u
F
L
E
D
3
0
0 3
Keep trace length from magnetics to RJ-45 connector under one inch.
1 .
1
3
u
V
F
S
Create termination plane in PCB. This plane
acts as a path for low-frequency noise that
might be coupled to unused pins. The plane
should not have any direct connection.
B
The 82551IT can drive three
LEDs with the cathode of
each device connected to
the 82551IT as shown with
the SPEEDLED or a two LED
configuration can be used,
as shown. In the two LED
configuration the link and the
activity functions share an
indicator. In this scheme the
LINK LED would flash LOW
each time activity is detected.
0
RD+
TD+
1 .
RD-
TD-
Termplane
Use plane for
this signal to
make a board
capacitor.
u
Termplane
F
15
16
1
2
0
1 .
u
F
3
MDI-X Mode Only
V
0
S
1 .
B
u
Networking Silicon — 82551QM
F
TRANSMIT
Optional capacitor
to help with EFT
conformance.
RECEIVE
0
1:1
1:1
1 .
u
pF
F
0
1 .
u
F
0.1 uF
0
1 .
CGND = Chassis ground
Use plane for this signal
u
F
6
11
10
7
0.1 uF
RX+
RX-
TX+
TX-
0
1 .
u
F
0
1 .
u
F
uF
113