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R3 R3
V
CC
I
CC
5 Meters
of CAT-5
R1 R1
V
EE
R2
V
CC
I
CC
R3 = 240 Ω
R1 = 50 Ω
R2 = 50 Ω
V
B
V
B
LVDSLV/PECL
DEVICE POWER AND GROUNDING
SN65LVDS348 , SN65LVDT348
SN65LVDS352 , SN65LVDT352
SLLS523E – FEBRUARY 2002 – REVISED MAY 2004
APPLICATION INFORMATION (continued)
Figure 17. LVPECL or PECL to Remote Wide Common-Mode LVDS Receiver
The SN65LVDS352 device provides separate power and ground pins for the analog input section and the two
digital output sections. All of the power pins and all of the ground pins of the device must be tied together at
some point in the system. Figure 18 shows one recommended scheme for power and ground to the device. This
point will be determined by the power and grounding distribution design, which can greatly affect system
performance.
Key points to remember when routing power and grounds in your system are:
• The grounding system must provide a low impedance path back to the power source.
• The signal return must be close to the signal path.
• Ground noise occurs due to ground loops and common-mode noise pick-up.
• Closely spaced power and ground planes reduce inductance and increase capacitance.
A good rule to remember when doing your power distribution and board layout is that the current always flows in
the lowest impedance path. At dc the lowest resistance is the lowest impedance, but at high frequencies the
lowest impedance is the lowest inductance path.
16
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