AD8134 Help Required

Hello everyone,

 

I require to convert RGsB (Gs means "Sync on Green") signals of a Single Ended video stream into Differential output.

I researched and found AD8134 to be suitable for the job. I developed an evaluation board on the resources available on Analog Site, and I looked at following discussion to create a board for AD8134 (I used the designs for AD8142 (same as AD8134) in the answer of AnnaFeB ):

 

https://ez.analog.com/message/211413#211413

 

 

However, in my card i kept the option to give a "negative 5" volt supply. In my case, i have no use for Vsync, Hsync and Sync Level pins (atleast that is what i think, since my Sync signal is on GREEN line), so there fore i have left these three signals "DISCONNECTED"

 

My issue is that once i start the board, power it up at "Positive and Negative 5 volts", and give no input, i get strange results on my outputs. the Red outputs, show no value, the green outputs show "negative 1 volt", while the blue output shows "Positive one volt". When i give an Input signal of "+1 volt" at all 3 positive inputs ( the negative inputs are grounded), i receive following outputs:

 

    1) R+ and R- show nothing

    2) G+= -1, G- = -2

    3) B+= +2, B-= +1

 

I do not think this working correctly, does this have something to do with the three signals i left unconnected?  please help..

Parents
  • 1. I already had a 38.3 ohm resistor connected.

    2. And yes, the answer was in the HSYNC and VSYNC, and SYNC lines. I had left them open, but the datasheet says that they are referenced to the "VS -" pin, and since i was using a "-5 volts" VS-, i had to connected those three lines to -5. Thanks alot, all issues are fixed now!!

Reply
  • 1. I already had a 38.3 ohm resistor connected.

    2. And yes, the answer was in the HSYNC and VSYNC, and SYNC lines. I had left them open, but the datasheet says that they are referenced to the "VS -" pin, and since i was using a "-5 volts" VS-, i had to connected those three lines to -5. Thanks alot, all issues are fixed now!!

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