ViewSonic VP150M Service Manual - Page 35

Service, Manual, ViewSonic, THEORY, CIRCUIT, OPERATION

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Service Manual VP150m THEORY OF CIRCUIT OPERATION ViewSonic September 2000 - Version 1.0 Input Mode Detection & Auto Calibration Block Supported input modes AM101-1 can handle up to 14 different input modes. For AM101-1, an input mode is defined by its horizontal resolution with its vertical resolution. The input modes with the same horizontal and vertical resolution but with different frame rates are still considered as one single input mode. In the default EEPROM setup, AM101-1 accepts the following seven input video modes: 1. 640 x 350 2. 640 x 400 3. 720 x 400 4. 640 x 480 (VGA) 5. 800 x 600 (SVGA) 6. 832 x 624 (MAC) 7. 1024 x 768 (XGA) Users can easily change the definitions of the acceptable input modes by adjusting the values in the appropriate EEPROM entries. There is no frame rate restriction on the input modes. However, since the output signal is synchronized with the input signal at the same refresh rate, the input refresh rate has to be within the acceptable range of the LCD panel. The user-defined video modes can be defined by storing appropriate timing information in the EEPROM. Input mode detection and frequency detection The AM101-1 can automatically detect the mode of the input signal without any user adjustment or driver running on the PC host or external CPU. This block automatically detects polarity of input synchronization, the sizes of back porch, valid data window, the synchronization pulse width in both vertical and horizontal directions. The size information is then used not only to decide the input resolution, to generate the frequency divider for the input PLL, to lock the PLL output clock with HSYNC, but also to automatically scale the image to full screen and to synchronize the output signal with the input signal. Page 34 Confidential - Do Not Copy

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Service
Manual
VP150m
ViewSonic
September
2000
-
Version
1.0
THEORY
OF
CIRCUIT
OPERATION
Input
Mode
Detection
&
Auto
Calibration
Block
Supported
input
modes
AM101-1
can
handle
up
to
14
different
input
modes.
For
AM101-1,
an
input
mode
is
defined
by
its
horizontal
resolution
with
its
vertical
resolution.
The
input
modes
with
the
same
horizontal
and
vertical
resolution
but
with
different
frame
rates
are
still
considered
as
one
single
input
mode.
In
the
default
EEPROM
setup,
AM101-1
accepts
the
following
seven
input
video
modes:
1.
640
x
350
2.
640
x
400
3.
720
x
400
4.
640
x
480
(VGA)
5.
800
x
600
(SVGA)
6.
832
x
624
(MAC)
7.
1024
x
768
(XGA)
Users
can
easily
change
the
definitions
of
the
acceptable
input
modes
by
adjusting
the
values
in
the
appropriate
EEPROM
entries.
There
is
no
frame rate
restriction
on
the input
modes.
However,
since
the
output
signal
is
synchronized
with
the
input
signal
at
the
same
refresh
rate,
the
input
refresh
rate
has
to
be
within
the
acceptable
range
of
the
LCD
panel.
The
user
-defined
video
modes
can
be
defined
by
storing
appropriate
timing
information
in
the
EEPROM.
Input
mode
detection
and
frequency
detection
The
AM101-1
can
automatically
detect
the
mode
of
the
input
signal
without
any
user
adjustment
or
driver
running
on
the
PC
host
or
external
CPU.
This
block
automatically
detects
polarity
of
input
synchronization,
the
sizes
of
back
porch,
valid
data
window,
the
synchronization
pulse
width
in
both
vertical
and
horizontal
directions.
The
size
information
is
then
used
not
only
to
decide
the
input
resolution,
to
generate
the
frequency
divider
for
the
input
PLL,
to
lock
the
PLL
output
clock
with
HSYNC,
but
also
to
automatically
scale
the
image
to
full
screen
and
to
synchronize
the
output
signal
with
the
input
signal.
Page
34
Confidential
—
Do
Not
Copy