AM3715: CVIDEO1_RSET pin configuration

Zane Tarumoto

Part Number: AM3715

So in this application we have cvideo1_vfb and Cvideo1_out tied together with a 2700 ohm resistor but the output is not connected to any composite connector. Normally we have cvideo1_rset tied to ground through a 4700 ohm resistor. So the set-up is ready for a s-video dc coupled high fs swing OR composite, DC coupled high FS swing but the output is not tied to a composite connector. On some of our units Rset did not get populated due to an error and what we are trying to figure out is if Rset is floating and video cvideo1_Vfb and cvideo1_out are looped together is there going to be any problems?

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

Please see the Caution note on page 1605 of the AM37x TRM Rev. R:

0 Zane Tarumoto over 8 years ago in reply to Biser Gatchev-XID

Prodigy 50 points

Thanks for the quick turn around. The original designer for our circuit is no longer with us so we cannot ask him why he configured the processor to composite if they did not ever plan on using it. When I was looking through the user manual I did come across this section about configuration and we may end up changing to this here shortly. The problem is that the board that has this set-up, but has the resistor on Rset accidentally removed is going through some qualified testing. What we are trying to figure out is would this cause a major problem with the processor were the unit could fail more often or a situation where it would fail less? And what are, if any, the major side effects of not having the resistor at Rset if the set-up is currently set to composite?

0 Zane Tarumoto over 8 years ago in reply to Zane Tarumoto

Prodigy 50 points

is there someone or can call me to help resolve this issue?

0 Biser Gatchev-XID over 8 years ago in reply to Zane Tarumoto

TI__Guru**** 393215 points

I have asked the factory team to comment. Feedback will be posted here.

0 QJ Wang over 8 years ago in reply to Biser Gatchev-XID

TI__Guru**** 201456 points

High swing DC coupling is the default mode. We recommend to tie the the signals to GND or leave them NC if the TV outputs are not used. If the Rset is not populated, there is no reference current for the DAC1. Since the output current at the output of the DAC is a function of the reference current, so there will be no output current from the DAC (if External current reference is used).

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AM3715: CVIDEO1_RSET pin configuration