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  • TI Thinks Resolved

TVP7002: TVP7002 input signal issue

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Part Number: TVP7002

Are there some special requirments for the input signal of TVP7002 VSYNC?

1. What's the function of the 1nF capacitor?  But I found that the rising edge of VSYNC will be better when I added this 1nF capacitor espeically for complicated application environment.

2. Besides, for the Componet marked as 5V/3.3V,is it a level shifter or just a 5V or 3.3V buffer? I tested the VGA signal but the VSYNC is usually 5V.

  • The Schmitt triggers are there to do both voltage level conversion and help clean up the sync inputs.

    The 300R/1nF components form a low pass filter, again, to help ensure the TVP seems a stable sync input.

    The VESA standard says the sync signals should be 5V but the TVP input signal level requirement is 3.3V. In theory you could just voltage divide the sync inputs, but using Schmitt triggers helps provide a consistent signal and helps protect against over vltages that might occir.

    The rising edge at the input to the level shifter should end up being slower with the capacitor, but also more stable leading to the input to the TVP being more stable and having fewer glitches.

    BR,

    Steve

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