BA7230LS

Overview

The BA7230LS is an NTSC color TV signal encoder manufactured by Rohm. It integrates an RGB signal matrix circuit, balanced modulator circuit, VCXO oscillator 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. The device accepts RGB signals, sync signals, BFP (burst flag pulses), and PCP (pedestal clamp pulses) as inputs to output an NTSC composite signal.

Feature Summary

• Enables superimposition of video images and computer images while preventing unnatural color disturbance during switching via APC circuit modulation.
• Maintains natural image quality during luminosity fluctuations through pedestal clamping of both RGB and video input signals.
• Allows background darkening using a half-down pulse to enhance the visibility of superimposed RGB images.
• Suppresses carrier leak to less than 70mV P-P without adjustment and supports analog RGB input adaptation.

Applications

• Televisions (Teletext-capable)
• Captain systems
• Video cameras
• Personal computers

Procurement Notes

Verify that the component matches the specified 24-pin SZIP package configuration. Confirm compatibility with NTSC standards and required operating voltage ranges between 4.5V and 5.5V. Ensure proper grounding of unused input pins with low impedance or capacitors to prevent noise susceptibility.

Selection Notes

Select this encoder when integrating RGB and video sources requiring seamless superimposition in NTSC systems. Consider its compact packaging and minimal external component requirements. Evaluate its capability to maintain signal integrity during switching operations and its suitability for applications demanding precise color burst synchronization.

Part Context

This component belongs to Rohm's multimedia ICs category, specifically designed for NTSC color TV signal encoding. It serves as a specialized solution for combining different video sources into a single composite output, addressing needs in consumer electronics where picture-in-picture or overlay functionalities are essential.

Replacement Considerations

BA7232

FAQ

How does the BA7230LS handle color disturbance during switching?

It uses an APC circuit to modulate the subcarrier locked onto the video input burst signal with RGB signals, preventing unnatural color disturbance due to switching.

What is the function of the half-down pulse?

The half-down pulse reduces the video signal by approximately 5dB to darken the background, making the superimposed RGB image easier to see.