2-14
Workstation 5 Field Service Guide
Workstation 5 System Board Technical Descriptions
TFT LCD and Backlight Interface
LCD Interface (REF: ABRD88 - Sheets 5, 16 and 27)
Figure 2-6 displays a block diagram of the Workstation 5 LCD and Backlight
Interfaces.
LX800 Pixel Data outputs
DRGB[23:2]
are fed to U29, a THC63LVDM83R
LVDS Transmitter. This device contains four seven-bit parallel-load serial-out
shift registers coupled to low voltage differential signalling (LVDS) line
drivers. Its primary function is to convert the 28-bits of Low Voltage TTL level
pixel, control and clock data from the LX800 TFT Controller into four data
streams and a single clock stream. The output of U29 drives LCD connector
J8.
The primary reasons for converting the TTL/CMOS level video signals to the
LVDS format are reduced noise and cable pin count. The LVDS compatible
signals are converted back into Low Voltage TTL/CMOS voltage levels within
the LCD Panel.
LCD Panel power sequencing is provided by the
VDDEN_VIPSYNC
output of
the LX800 TFT controller. This signal drives a switch consisting of Q9 and
Q10.
VDDEN_VIPSYNC
does not go active until all system voltages and
busses have become stable and the processor is executing instructions.
Figure 2-6: WS5 System Board TFT LCD and Backlight Interface
