DS92LV0421_15 Datasheet, PDF (25/48 Pages) Texas Instruments – 10 - 75 MHz Channel Link II Serializer/Deserializer with LVDS Parallel Interface

DS92LV0421, DS92LV0422
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Ser — Integrated Signal Conditioning Features
SNLS325C – MAY 2010 – REVISED APRIL 2013
Ser — VOD Select (VODSEL)
The DS92LV0421 differential output voltage may be increased by setting the VODSEL pin High. When VODSEL
is Low, the DC VOD is at the standard (default) level. When VODSEL is High, the DC VOD is increased in level.
The increased VOD is useful in extremely high noise environments and also on extra long cable length
applications. When using de-emphasis it is recommended to set VODSEL = H to avoid excessive signal
attenuation especially with the larger de-emphasis settings. This feature may be controlled by the external pin or
by register.
Table 3. Ser — Differential Output Voltage
Input
VODSEL
H
L
VOD
mV
±420
±280
Effect
VOD
mVp-p
840
560
Ser — De-Emphasis (De-Emph)
The De-Emph pin controls the amount of de-emphasis beginning one full bit time after a logic transition that the
device drives. This is useful to counteract loading effects of long or lossy cables. This pin should be left open for
standard switching currents (no de-emphasis) or if controlled by register. De-emphasis is selected by connecting
a resistor on this pin to ground, with R value between 0.5 kΩ to 1 MΩ, or by register setting. When using De-
Emphasis it is recommended to set VODSEL = H.
Table 4. De-Emphasis Resistor Value
Resistor Value (kΩ)
Open
0.6
1.0
2.0
5.0
De-Emphasis Setting
Disabled
- 12 dB
- 9 dB
- 6 dB
- 3 dB
0.00
-2.00
VDD = 1.8V,
T_A = 25^oC
-4.00
-6.00
-8.00
-10.00
-12.00
-14.00
1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06
R VALUE - LOG SCALE (:)
Figure 26. De-Emph vs. R value
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