Low Voltage Differential Signaling - Panasonic TC-26LX20 Technical Manual

Low Voltage Differential Signaling

The method used to transfer the video information from the Main circuit board to th e
LCD drive circuit is called Low Voltage Differential Signaling (LVDS). LVDS devices
typically consume less power than other signaling systems such as TTL. LVDS devic es
use a constant current driver. Therefore, power consumption is independent of
frequency. The LVDS interface voltage is much less than TTL, approximately 2V. The
voltage swing is typically 350mV with a n offset of 1.25V. Integrated circuits based on
L VDS technology distribute signals with low-jitter, while creating little noise.
In this application, three 8-bit streams of data are converted from parallel to serial and
interleaved. The interleave process makes the data less susceptible to noise. The peak-
to-peak v oltage level is reduced as well. The lower voltage level reduces the power
c onsumption and the generated noise from data transmission. Another benefit of the
LVDS standard is minimal concern for cable length. The data rates for LVDS are 110
Mbps for a 1-meter distance, dropping to 90 Mbps over a 10-meter distance.
Figure 27
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