ADV7403

Hi,

  Please refer this thread (+) ADV7441 HS_IN and VS_IN, are these digital or analog inputs? - Q&A - Video - EngineerZone Here expert given some suggestion about SYN_LOTRIG register usage.

Note: HS_IN and CS_IN are digital inputs.  SYN_LOTRIG register allows you to change the threshold levels used for these digital inputs.  Normally these syncs are 3.3V signals with the threshold set to ~1.5V.  Some designs may use logic levels down to 1.0V with the threshold set to ~0.6V.

The zener and series resistor provide ESD protection.  Normally the zener is the needs to be the same voltage as the DVDDIO level.  Any small signal <400mW device should suffice.  Something similiar to MMSZ5226BS.  Alternately you can use something like an On Semiconductor CM1213A, diode bridge arrangement.  Any good digital ESD protection design will work well for these low frequency digital signals.

Thanks,

Poornima