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ADV7180 LLC frequency for PAL and NTSC

Question asked by nikhil on Dec 2, 2013
Latest reply on Dec 2, 2013 by GuenterL

Hi,

 

As given in datasheet of ADV7180 the LLC frequency remains 27MHz nominally and varies up or down based on video line length. if we calculate the frequency of byte transfer for PAL and NTSC standard there is a difference.

for PAL (in 4:2:2 format) -

625*2*864*25 = 27MHz

but for NTSC (in 4:2:2 format) -

525*2*858*29.97 = 26.999973MHz

 

so for NTSC does this clock actually works on 26.999973MHz or at 27MHz only and the difference is taken under allowed ppm error on video clock (30ppm) ?

 

Thanks and regards,

Nikhil

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