la7688b Sanyo Semiconductor Corporation, la7688b Datasheet - Page 8

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

[VIF block]
RF AGC voltage max
RF AGC voltage min
Input sensitivity
AGC range
Maximum allowable input
No-signal video output
voltage
Sync signal tip voltage
Video output amplitude
Black noise threshold
voltage
Black noise clamp voltage
Video S/N
1.07MHz beat level
Parameter
V 50 H
V 50 L
V I
GR
V I max
V 8
V 8 TIP
VO 8
VBTH
VBCL
S/N
I1.07
Symbol
TPO-50
TPO-50
TPO-8
+100k
TPO-8
TPO-8
TPO-8
TPO-8
TPO-8
TPO-8
TPO-8
TPO-8
TPO-8
point
Test
SG1,
fp = 38.9MHz cw,
85dBµ
Same as above
SIG1
fp = 38.9MHz
fm = 400Hz
AM = 40%
mod
Same as above
SG1
fp = 38.9MHz,
fm = 15kHz,
AM = 78% mod
No-signal
SG1,
fp = 38.9MHz
cw, 80dBµ
SIG
fp = 38.9MHz,
fm = 15kHz,
AM = 78% MOD
80dBµ
SG1
fp = 38.9MHz
fm = 400Hz
AM 78% MOD
Same as above
SG1,
fp = 38.9MHz
cw, 80dBµ
SG1,
fp = 38.9MHz,
cw, 80dBµ
SG3,
fc = 4.43MHz,
cw, 70dBµ
SG4,
fs = 5.5MHz,
cw, 70dBµ
symbol
Input
LA7688B
Measure the level at TP0-50 using a
DC digital voltmeter.
Same as above
Monitor the level at TP0-8 using an
oscilloscope with a resistor of 100kΩ
connected to TP0-8.
Measure the VIF input level at which
the 400Hz demodulation signal level
becomes 0.8Vp-p.
Monitor the level at TP0-8 using an
oscilloscope and measure the VIF input
level at which the 400Hz demodulation
signal level becomes 0.8Vp-p. Assign
the measured value to V I .
GR = 20log (V I ’/V I ) [dB]
Increase the VIF input relative to the
output level at TO0-8 when the VIF
input is 80dBµ and measure the VIF
input level at which the output level
increases by 1dB.
Measure the level at TO0-8 using a DC
digital voltmeter.
Same as above
Monitor the level at TP0-8 using an
oscilloscope and measure the p-p
value of the 15kHz demodulation
waveform.
Connect an oscilloscope to TP0-8 and
input a sweep signal to the VIF input.
Apply voltage to TPZ-46 externally and
adjust it as shown below.
Measure the level at clamp voltage of
shown above.
Using an RMS voltmeter, measure a
noise voltage generated at TO0-8
through a band-pass filter of 10kHz to
5MHz.
S/N = 20log (1.43 (Vp-p) /noise voltage
(Vrms) ) [dB]
Mix the SG1 signal, SG3 signal, and
SG4 signal and input the mixed signal
to VIF IN. (The level at VIF IN must be
as shown left.)
Connect an oscilloscope and a
spectrum analyzer to TP0-8 and
adjust the external voltage at TPZ-46
so that the lower end of the
demodulation waveformbecomes 3V.
Measure the differential component
between 4.43MHz and 1.07MHz using
the spectrum analyzer.
Clamp level
VBTH
Test method
Continued on next page.
VR center
VR center
VR center
VR center
VR center
VR center
VR center
VR center
VR center
VR center
TPO-2
7.8V
Applied voltage (V)
0
No.0077-8/20
Variable
Variable
Variable
TPZ-46
Open
Open
Open
Open
Open
Open
Open
7.8V
7.8V