TVP5154A

MT12

Other Parts Discussed in Thread: TVP5154A

Hello,

I am configuring a PCB with a TVP5154A. I have a bitec card with the same chip that is working perfectly. My pcb is configured the same in i2c. It mostly show a black screen out. If I place a card with text or stand at a certain angle in front of the camera I can see it on the screen but as I move it away It gets grainy, crazy colors, and then blacks out. I have followed the data sheet's example for my schematic. The black screen has some thin slanted lines that move around.

Thanks,

Mike

over 11 years ago

0 Steve Clynes over 11 years ago

TI__Mastermind 43875 points

Mike,

Could you possibly get an oscilloscope capture of the analog input signal on each side of the input coupling capacitor please?

Can you also please let me see your schematic for the TVP input?

BR,

Steve

0 MT12 over 11 years ago in reply to Steve Clynes

Prodigy 120 points

Steve,

I am running only 2 channels.

The camera works fine with the TVP5154A on the Bitec card I am using.

Thanks

0 MT12 over 11 years ago in reply to MT12

Prodigy 120 points

Here are two scope pictures. One is a single waveform view the other is a "live" view. The dark blue is connector side of the cap, light blue is on the chip side. The purple is on the connector side of the resistor.

0 Steve Clynes over 11 years ago in reply to MT12

TI__Mastermind 43875 points

OK, it looks like you have a source issue. The signal being fee to the connector is completely destroyed.

As a comparison can you do the same experiment with the working system too for comparison?

As a test can you remove the coupling capacitor and repeat the captures (obviously the TVP input will not be correct, but still interesting to see).

Here is what is should look like...

waveform

(http://www.doom9.org/index.html?/capture/analogue_video.html)

Can you check that the resistor values are correct. It looks like the resistors might be too small.

Without the camera connected measure the DC resistance across the input connector. It should be 75 ohms.

BR,

Steve

0 MT12 over 11 years ago in reply to Steve Clynes

Prodigy 120 points

Thanks Steve,

We took the cap off and it looked the same. It turns out there was a connector issue. Now everything is working fine. Thanks for you help.

0 Steve Clynes over 11 years ago in reply to MT12

TI__Mastermind 43875 points

Glad everything is good for you now.

BR,

Steve

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TVP5154A