Rev. 1.0, 02/00, page 786 of 1141
(b) Using the Csync Schmitt Circuit
The Hsync component is processed in the same way as described in (a), but the Vsync
component is processed differently; the Csync/Hsync terminal is left open and the
separated Vsync component is input through the Csync Schmitt circuit to the digital V
separation counter. Figure 27.16 shows this method.
CVin2
Csync
a
1
1
0
0
b
a
b
Hsync
Vsync
VLPF
Vsync/VLPF
Csync/Hsync
Hsync
Vsync
External
SW3
Internal
SW5
Internal
SW6
External
SW2
External
SW1
Reference
voltage switch
Register
control
I/O switch
I/O
switch
Polarity
switch
Polarity
switch
Digital H
separation
counter
Digital V
separation
counter
DLPFON
Csync polarity
Schmitt circuit
Vsync polarity
Schmitt circuit
External circuit
Inside LSI
Csync
separation
comparator
External
SW4
CVin2
–
+
CCMPSL
CCMPV0, 1
SYNCT
VSEL
SEPV
SEPH
Sync tip
clamp
Figure 27.16 Sync Source Selection When Using the CVin2 Signal and
the Csync Schmitt Circuit
Source
Signal
Vsync
Detection
External
SW1
External
SW2
External
SW3
External
SW4
CCMPSL
(Internal
SW5)
VSEL
(Internal
SW6)
Csync/
Hsync
Terminal
I/O
CVin2
input
Csync
Schmitt
Off
Off
Open
Fixed to
0 or 1
0
1
Output