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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.

Televisions (Teletext-capable), captain systems, video cameras, personal computers

1) Allows superimposition of video images (VIDEO IN)

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.

6) Can be adapted for analog RGB input.

7) Compact 24-pin SZIP package minimizes external

components.

1

VIDEO OUT

3

Y IN

5

R-Y IN

7

9

APC PHASE

ADJUSTMENT

11

13

AR

15

AB

17

B-Y OUT

19

GND

21

PCP IN

23

2

SYNC IN

BA7230LS

4

B-Y IN

6

PD

8

10

BURST LEVEL

ADJUSTMENT

12

BFP IN

B - Y

R - Y

+

HD

MATRIX

PD

VCXO

MOD

MOD

+