ADV7802 - Output clock jitter and possible coasting

Question

Hi, 
 When using the ADV7802 with a 1080i source, it was noticed that there is a large amount of jitter, after the VBI region of the video. This jitter is affecting sensitive backend device. 
 This noise does not appear to be board/or noise coupling.

ADIApproved · Accepted Answer

The ADV7802 contains coast features which allow it to coast/free-run in the event of missing sync or non-standard input. 
 The coast feature is automatically enabled , however manual controls are available. 
 CP Map 
 0xCC[3] - COAST_MAN_EN 
 This control overrides the automatic values and uses. 
 This bit changes the coasting mode into a manual mode and also changes the coasting so that it coasts on all lines. Auto mode is only coasting on active video. 
 0xCC[2] – COAST_MAN allows you to use manual controls. 
 0xCC[5:4] – Coast lock 
 2'b00 = 15 lines 
 2'b01 = 31 lines 
 2'b10 = 63 lines 
 2'b11 =127 lines 
 In the question above, the PLL needs to reacquire after active video is recieved, ehich is leading to jitter. 
 Rgds, 
 Ray

EZAdministrator · Answer

This question has been closed by the EZ team and is assumed answered.

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ADV7802 - Output clock jitter and possible coasting