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ViewSonic
:
Service Manual
April 1999 - Version 1.0
VG150
THEORY OF CIRCUIT OPERATION
Input Mode Detection Data
Symbol | Width bits)| Address [Description
SSS
Calibration mode
2
123H [1:0] | This is to select different operation modes of
internal
phase
calibration.
The
selection
criterion is as follow:
0:when input video signal has overshot,
it results in longest calibration time
4:when input video signal has median
overshot, it results in long calibration
time
2:when input video signal has normal
overshot, it results in normal calibration
time (recommended)
3:when input video signal has no overshot,
it results in shortest calibration time
Res0O threshold
10
124H-125H | Upper bound of the line number for 640x350
mode, and lower bound for 640x400
Res1 threshold
10
126H
Upper bound of the line number for 640x400
mode, and lower bound for 720x400
Res2 threshold
10
128H-129H | Upper bound of the line number for 720x400
mode, and lower bound for 640x480
Res3 threshold
10
42AH-12BH | Upper bound of the line number for 640x480
mode, and iower bound for 800x600
Res4 threshold
10
42CH-12DH | Upper bound of the line number for 800x600
mode, and lower bound for 1024x768
Res5 threshold
10
{2EH-12FH | Upper bound of the line number for 1024x768
mode, and lower bound for 1280x1024
Res6 threshold
10
130H-131H
| Upper
bound
of
the
line
number
for
1280x1024
mode.
If the input has more line
than this threshold, it is considered
INVALID
mode
Mode.640x350
2
132H[1:0]
| The polarity of input synchronization signals
Sync Polarity
Bit 0 is for VSYNC and bit 1 is for HSYNC
Mode 640x400
2
132H[3:2] | The polarity of input synchronization signals
Sync Polarity
Bit 0 is for VSYNC and bit 1 is for HSYNC
Mode 720x400
2
132H[5:4]
| The polarity of input synchronization signals
Sync Polarity
Bit 0 is for VSYNC and bit 1 is for HSYNC
Mode 640x480
2
132H[7:6]
| The polarity of input synchronization signals
Sync Polarity
Bit 0 is for VSYNC and bit 1 is for HSYNC
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