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Output Format Selection
22
SNAU235 – May 2018
Copyright © 2018, Texas Instruments Incorporated
Reference PRO
B.2
Output Format Selection
The OE pin is used to enable or disable the output.
The OS pin is used to bias internal drivers and change the output format.
Table 9. Reference PRO Output Format Selection
OE
OS
OUTPUT FORMAT
GND
Don't Care
Disabled
Vdd
GND
LVPECL
Vdd
NC
LVDS
Vdd
Vdd
HCSL
It is imperative to match the output termination passive components as shown in
(1)
50-
Ω
to V
CC
– 2-V termination is required on receiver.
(2)
100-
Ω
differential termination (R31) is provided onboard. Removing this termination is possible if the differential termination is
available on the receiver.
Table 10. Output Termination Configuration
OUTPUT FORMAT
COUPLING
COMPONENT
VALUE
LVPECL
AC (Default
configuration)
R15, R28
0
Ω
R26, R29
150
Ω
C24, C25
0.01 µF
R27, R30, R31
DNP
DC
(1)
R15, R28, C24, C25
0
Ω
R26, R27, R29, R30, R31
DNP
LVDS
(2)
AC
R25, R27, R28, R30
0
Ω
R31
100
Ω
C24, C25
0.01 µF
R26, R29
DNP
DC
R25, R27, R28, R30, C24, C25
0
Ω
R31
100
Ω
R26, R29
DNP
HCSL
AC
R25, R28
0
Ω
R26, R29
50
Ω
C24, C25
0.01 µF
R27, R30, R31
DNP
DC
R25, R28, C24, C25
0
Ω
R26, R29
50
Ω
R27, R30, R31
DNP
Figure 25. Output Termination Schematic