Datasheet

1.0E+02
R VALUE - LOG SCALE (:)
-14.00
-12.00
-10.00
-8.00
-6.00
-4.00
-2.00
0.00
DE-EMPH (dB)
VDD = 1.8V,
T
A
= 25
o
C
1.0E+03 1.0E+04 1.0E+05 1.0E+06
DS92LV2411, DS92LV2412
www.ti.com SNLS302C –MAY 2010–REVISED APRIL 2013
Ser — Spread Spectrum Compatibility
The Ser CLKIN is capable of tracking spread spectrum clocking (SSC) from a host source. The CLKIN will
accept spread spectrum tracking up to 35 kHz modulation and ±0.5, ±1 or ±2% deviations (center spread). The
maximum conditions for the CLKIN input are: a modulation frequency of 35 kHz and amplitude deviations of ±2%
(4% total).
Integrated Signal Conditioning Features — Ser
Ser — VOD Select (VODSEL)
The Ser differential output voltage may be increased by setting the VODSEL pin High. When VODSEL is Low,
the VOD is at the standard (default) level. When VODSEL is High, the 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. Differential Output Voltage
Input Effect
VOD VOD
VODSEL
mV mVp-p
H ±420 840
L ±280 560
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
Ser 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) De-Emphasis Setting
Open Disabled
0.6 - 12 dB
1.0 - 9 dB
2.0 - 6 dB
5.0 - 3 dB
Figure 24. De-Emph vs. R value
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