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Re: ADV7401 video drifting. Rising GND reference?

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Kevin,

 

  I'm in Central Apps and was previously in the precision op amp group, so the only thing I know about

the video parts is most of the part numbers start with ADV.....<g>  So I can't comment on TEST0/1.

 

--  page 120 of the manual says "No Support for external Hs/VS inputs..."????

 

-- Page 332 Yes, digital inputs are designed for 3.3V, so pull up or pull down w/ R1023 et al is good.

 

--  Page 333 Probably not related to your problem, but Crystal should be parallel resonant, fundamental mode

not third overtone.  Also, you need to check on what the stated load capacitance is, and make sure the 47pF

caps are right or might have to change.

 

For test 5, you said "...change the input filter...."  where is this??  labels for L/C/R?

 

Test 8 leads me to believe that your PAL generator is bad??  Not standard PAL??

 

Test 12.  Time to grasp at straws....  What is mfgr and type of caps for you and for the eval board,

specifically C1036-C1038??   Caps can be leaky.   A 100nF cap can vary in capacitance depending

on the applied voltage, temperature, etc.   Is the voltage at pin 54 one volt pk-pk up to one point six volts?

 

Can you read the ISD and IFSD registers continuously as it fades?

 

Harry

 



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