la7688b Sanyo Semiconductor Corporation, la7688b Datasheet - Page 15

• Manufacturer Part Number: la7688b
• Description: Pal/ntsc Color Television-use Single-chip Lsi
• Manufacturer: Sanyo Semiconductor Corporation

Continued from preceding page.
Maximum RGB
output
APC pull-in range
Tint center
Tint variable range
Demodulation
output ratio
Demodulation
angle
Parameter
EBMAXn
Dfscn+
Dfscn-
TCEN
dPTIN
R/Bn
G/Bn
∠ RBn
∠ GBn
Symbol
O-33
O-27A
O-33
O-33
O-33
O-35
O-33
O-34
O-33
O-35
O-33
O-35
point
Test
(1)
Y-OFF
chroma
50%
(1)
fsc
frequency
variable
(1)
Y-OFF
(1)
Y-OFF
(2)
(2)
(2)
(2)
signal
Input
Adjust the SG so that the B output
assumes a horizontal waveform and
measure the Vp-p value of the B output's
signal component.
BRIGHT : 5V
Vary the subcarrier frequency to measure
the pull-in frequency and calculate the
difference from fsc.
Make the relative phase of the SG's
chroma and burst normal.
Adjust the relative phase of the SG's
chroma and burst so that the B output
assumes an oblique linear waveform.
That phase amount adjusted relative to
the normal mode is TCEN.
Adjust the relative phase of the SG's
chroma and burst so that the B output
assumes a horizontal waveform.
(Tint VR : 2.5V) Set the tint VR at 5V and
adjust the relative phase of the SG's
chroma and burst so that the B-Y output
assumes a horizontal waveform ; that
phase amount is + ∆ T.
In the same manner, set the tint VR at 0V
and obtain - ∆ T.
Adjust the relative phase of the SG's
chroma and burst so that the B output is
maximized and adjust the color VR so
that the B output becomes 2Vp-p.
And then adjust the relative phase of the
SG's chroma and burst so that the R
output is maximized and measure the R
output's Vp-p. Calculate the ratio to
2Vp-p. (R/B)
In the same manner, calculate the
demodulation output ratio between the G
output at TP33 and the B output. (G/B)
Adjust the relative phase of the SG's
chroma and burst so that the B output
becomes 0 at the demodulation output
ratio R/B's color position. And then adjust
the relative phase of the SG's chroma
and burat so that the R output becomes
0 ; that phase amount is ∠ RBn.
In the same manner as above, measure
the G output and B output's demodulation
angle ∠ GBn.
LA7688B
Test method
COLOR VR
Adjust
Adjust
Adjust
Adjust
2.5V
2.5V
2.5V
5V
CONTRAST
4V
4V
4V
4V
4V
4V
4V
4V
No.0077-15/20
TINT VR
3V
3V
3V
1V
3V
5V
3V
3V
3V
3V
↑
↓