The BA7230LS comprises an RGB signal matrix circuit, balanced modulator circuit (rectangular 2-phase modulation), 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.

Features
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.
5) Carrier leak is suppressible to less than 70mVP-P (VOUT = 2VP-P) without adjustment.
6) Can be adapted for analog RGB input.
7) Compact 24-pin SZIP package minimizes external components.

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