DS90UR905Q-Q1 Datasheet, PDF (26/58 Pages) Texas Instruments – 5- to 65-MHz, 24-bit Color FPD-Link II Serializer and Deserializer

DS90UR905Q-Q1, DS90UR906Q-Q1
SNLS313H – SEPTEMBER 2009 – REVISED JULY 2015
www.ti.com
Feature Description (continued)
8.3.3.2 Signal Quality Enhancers
8.3.3.2.1 Serializer VOD Select (VODSEL)
The serializer 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 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 1. Differential Output Voltage
INPUT
VODSEL
H
L
VOD (mV)
±420
±280
EFFECT
VOD (mVp-p)
840
560
8.3.3.2.2 Serializer 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
serializer 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, TI recommends to set VODSEL = H.
RESISTOR VALUE (KΩ)
Open
0.6
1.0
2.0
5.0
Table 2. De-Emphasis Resistor Value
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 25. De-Emph vs. R value
8.3.3.3 Power-Saving Features
8.3.3.3.1 Serializer Power-down Feature (PDB)
The serializer has a PDB input pin to ENABLE or POWER DOWN the device. This pin is controlled by the host
and is used to save power, disabling the link when the display is not needed. In the power-down mode, the high-
speed driver outputs are both pulled to VDD and present a 0-V VOD state.
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