Is the external DDR memory for ADV7842 optional? In other wors, if I don't connect a DDR momery to ADV7842, ADV7842 still work? I don't need any 3D Comb or Frame Synchronizer.
The ADV7842 uses external SDRAM memory for 3-D comb and/or frame synchronizer operations. If you are not using this functionality, then external SDRAM memory is not required.
How do I connect DDR SDRAM signals. Left is N.C.
Do I still need to provide power for VDD_SDRAM?
you can't leave the signals floating,
if you connect them directly to ground ,then there might be a problem during power up (large current will flow through these pins), so its better to connect those pins to ground through 4.7K resistors.
and for Powering VDD_SDRAM , as you already using 3.3V so you can connect
3.3V to VDD_SDRAM using a 0E or small (100E) resistance.
Please refer to Table 100 (Recommended Configuration of Unused Pins) in the ADV7842 Hardware User Guide. It documents what should be done with various pins associated with SDRAM.
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