Multimedia ICs
NTSC color TV signal encoder
BA7230LS
The BA7230LS comprises an RGB signal matrix circuit, balanced modulator circuit (rectangular 2-phase modula-
tion), oscillator circuit (VCXO) for a 3.58MHz subcarrier synchronized with video input burst signals, luminosity and
color difference signal mixing circuit, and a high speed switch for selecting composite signals of video input and RGB
input. RGB signals, synch signals, BFP (burst flag pulses), PCP (pedestal clamp pulses) are input, and an NTSC
composite signal is output.
•
Applications
Televisions (Teletext-capable), captain systems, video cameras, personal computers
•
Featuressuperimposition of video images (VIDEO IN)
1) Allows
and computer images (RGB IN).
2) During superimposition, the subcarrier locked onto
the video input burst signal RGB is modulated with
the RGB signals by the APC circuit, preventing
unnatural color disturbance due to switching.
3) Both the RGB and video input signals are pedestal-
clamped, maintaining a natural image even during
fluctuation in luminosity.
4) Using a half down pulse, the video signal can be
reduced by 5dB to darken the background and
make the superimposed RGB image easier to see.
5) Carrier leak is suppressible to less than 70mV
P-P
(V
OUT
= 2V
P-P
) without adjustment.
6) Can be adapted for analog RGB input.
7) Compact 24-pin SZIP package minimizes external
components.
•
Block diagram
BA7230LS
VIDEO OUT
1
2
SYNC IN
Y IN
R-Y IN
3
+
+
4
B-Y IN
BURST LEVEL
ADJUSTMENT
V
B
5
6
V
C
V
A
7
MOD
MOD
8
9
VCXO
10
BFP IN
APC PHASE
11
ADJUSTMENT
AR
13
PD
12
PD
14
AG
AB
15
MATRIX
B-Y OUT
17
B-Y
GND
19
HD
PCP IN
21
22
HDP IN
20
VIDEO IN
16
Y OUT
R-Y
18
R-Y OUT
Y
S
P IN
23
V
CC
24
V
CC
1
Multimedia ICs
BA7230LS
CC
•
Electrical characteristics (unless otherwise noted, Ta = 25°C, V
Parameter
Quiescent current
Video output level
Half down level change
DC offset
Crosstalk
ER-EY output level
EB-EY output level
YOUT output level
Ys switching delay time
SYNC output level
Burst output level
Composite output level
R-Y modulation gain
B-Y modulation gain
(R-Y) / (B-Y) modulation gain differential
(R-Y) / (B-Y) orthogonal phase shift
(R - Y) ·Burst orthogonal phase shift
Carrier leak
APC capture range
Carrier phase range
Video frequency characteristic
Video output DG
Video output DP
Input impedance (SY, BF, PC, HD)
Input impedance (Ys)
Threshold level (SY, BF, PC, HD)
Threshold level (Ys)
Symbol
I
Q
V
OV
G
VH
V
OF
CT
V
R-Y
V
B-Y
V
Y
T
D
V
OS
V
OB
V
OY
G
R-Y
G
B-Y
G
R-B
∆R
∆B
L
SC
f
CAP
φ
SC
f
V
DG
DP
Z
T
Z
TY
V
T
V
TY
Min.
—
1.7
–3
—
—
0.3
0.2
1.0
—
0.4
0.25
1.7
9
9
—
–6
–6
—
±
100
±
30
4.5
—
—
8
3
0.9
0.5
Typ.
38
2.2
–5
50
– 46
0.42
0.31
1.4
60
0.65
0.46
2.2
11
11
—
—
—
30
—
±
45
6
±
3.5
±
2.5
15
7.5
2.0
1.1
Max.
54
2.6
–7
160
– 40
0.55
0.42
1.8
—
0.9
0.8
2.6
13
13
2
6
6
70
—
—
—
—
—
—
—
2.8
1.8
= 5.0V)
Conditions
—
VIDEO IN = 1V
P-P
—
VIDEO IN = 1V
P-P
VIDEO IN = 1V
P-P
V
R
= 0.7V
P-P
V
B
= 0.7V
P-P
V
R
= V
G
= V
B
= 0.7V
P-P
—
—
R
E
= 1.8kΩ
Y
IN
= 0.7V
P-P
R - Y
IN
= 0.3V
P-P
B - Y
IN
= 0.2V
P-P
Difference between above gains
—
—
V
OUT
= 2V
P-P
Burst = 0.1V
P-P
, 2.8µS
Superimposition
– 3dB when f = 100kHz
VIDEO IN = 1V
P-P
VIDEO IN = 1V
P-P
—
—
—
—
Unit
mA
V
P-P
dB
mV
P-P
dB
V
P-P
V
P-P
V
P-P
ns
V
P-P
V
P-P
V
P-P
dB
dB
dB
deg
deg
mV
P-P
Hz
deg
MHz
%
deg
kΩ
kΩ
V
V
3
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