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DS10BR150

Torsten Aurich
Prodigy 190 points
Other Parts Discussed in Thread: DS10BR150

Hi,

for a new project i want to use your DS10BR150 LVDS Buffer/Repeater.
I have a question regarding termination of this product.
In the data sheet on page 1 i can found the sentence:
"The differential inputs and outputs are internally terminated with
a 100Ω resistor to lower device input and output return losses, reduce
component count and further minimize board space."
In block diagramm on page 2 i can found the symbols for this resistors on
input and output too.
If i have a look on the user manual of the DS10BR150 evaluation kit,
i can found in the schematics (page 6) an extra 100Ohm termination
resistor (R1) on the input of the DS10BR150.

So my questions are:

1. Is this a double termination or does the circuit DS10BR150 not have
an internal 100Ohm terminator? How can i unstand it?
2. If the DS10BR150 have a internal termination resistor on the input,
is this internal termination resistor (100Ohm) biased, so that i can use ac-coupling
on the input of the DS10BR150?

Kind Regard

Torsten

  • 0
    TI__Mastermind 43795 points

    Hi Torsten,

    1. Is this a double termination or does the circuit DS10BR150 not have 
    an internal 100 Ohm terminator?

    Answer:  The DS10BR150 has an internal termination resistor with a typical value of 100 Ohms.  The DS10BR150EVM has a position for an external termination as well.  This resistor is not populated on the board.  The SMT component location provides for a good differential probe test point.

    2. If the DS10BR150 have a internal termination resistor on the input,
    is this internal termination resistor (100 Ohm) biased, so that i can use ac-coupling
    on the input of the DS10BR150?

    Answer:  The internal termination resistor is not biased.  LVDS signals are biased by the transmitter to a 1.2V common mode.  With an AC coupled interface I have been successful without any bias on the DS10BR150 input in low noise applications.  Another approach would be to use a simple resistor divider to reset the input common mode to ~ 1.2V.

    Regards,

    Lee