Datasheet

OUT+
OUT-
DS25BR100
IN+
IN-
50:50:
V
CC
CML3.3V or CML2.5V
100: Differential T-Line
OUT+
OUT-
DS25BR100
IN+
IN-
100: Differential T-Line
LVDS
DS25BR100
www.ti.com SNLS217F –MARCH 2007–REVISED APRIL 2013
Test Channel Loss Characteristics
The test channel was fabricated with Polyclad PCL-FR-370-Laminate/PCL-FRP-370 Prepreg materials (Dielectric
constant of 3.7 and Loss Tangent of 0.02). The edge coupled differential striplines have the following geometries:
Trace Width (W) = 5 mils, Gap (S) = 5 mils, Height (B) = 16 mils.
Test Channel Length Insertion Loss (dB)
(inches)
500 MHz 750 MHz 1000 MHz 1250 MHz 1500 MHz 1560 MHz
A 10 -1.2 -1.7 -2.0 -2.4 -2.7 -2.8
B 20 -2.6 -3.5 -4.1 -4.8 -5.5 -5.6
C 30 -4.3 -5.7 -7.0 -8.2 -9.4 -9.7
D 15 -1.6 -2.2 -2.7 -3.2 -3.7 -3.8
E 30 -3.4 -4.5 -5.6 -6.6 -7.7 -7.9
F 60 -7.8 -10.3 -12.4 -14.5 -16.6 -17.0
Device Operation
INPUT INTERFACING
The DS25BR100/101 accepts differential signals and allows simple AC or DC coupling. With a wide common
mode range, the DS25BR100/101 can be DC-coupled with all common differential drivers (i.e. LVPECL, LVDS,
CML). The following three figures illustrate typical DC-coupled interface to common differential drivers.
The DS25BR100 inputs are internally terminated with a 100Ω resistor for optimal device performance, reduced
component count, and minimum board space. External input terminations on the DS25BR101 need to be placed
as close as possible to the device inputs to achieve equivalent AC performance. It is recommended to use SMT
resistors sized 0402 or smaller and to keep the mounting distance to the DS25BR101 pins under 200 mils.
When using the DS25BR101 in a limited multi-drop topology, any transmission line stubs should be kept very
short to minimize any negative effects on signal quality. A single termination resistor or resistor network that
matches the differential line impedance should be used. If DS25BR101 input pairs from two separate devices are
to be connected to a single differential output, it is recommended to mount the DS25BR101 devices directly
opposite of each other. One on top of the PCB and the other directly under the first on the bottom of the PCB
keeps the distance between inputs equal to the PCB thickness.
Figure 19. Typical LVDS Driver DC-Coupled Interface to DS25BR100 Input
Figure 20. Typical CML Driver DC-Coupled Interface to DS25BR100 Input
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Product Folder Links: DS25BR100