I've designed the ADV7280 typical schematic with 1.8V on all power lines.
But, there is no signals on XTAL or any output after switch power.
I've tried to reset it manually (RSTn pin) and also - no effect.
Is it needs for some initialization sequence through I2C to start clock?
XTALN is an input-- the part requires a 28.636 crystal to operate. Is it not oscillating?
Yes, it is not oscillating. And it has 0V potential on XTALP (no short circuit to GND)
It looks like "sleep mode". And the same occurs in second sample pcb.
I used the crystal TXC 7A-28.63636MAAJ-T
Have you checked:
1) Power/Ground on the crystal is somehow not right.
2) The capacitive loading on XTALP and XTALN is not correct for the crystal.
Nothing on the part will work properly without the clock.
Thank you for answer
But, as far as I understand, if the problem is capacitive load, then some DC voltage level ~1V must be at the XTALP output. In fact, I have 0V on it in both boards.
This means that the problem is power. I've checked the 1.8V on pins 2,3,13,16,21, and GND on pad and pins 1,4.
My mind is broken.
the 28.63636MHz crystal connected to the ADV7280 will not oscillate until the ADV7280 has been programmed.
See this engineering zone post for more information:
There is also a test method that can be used to test that the XTAL is not damaged.
Digital Video Products Group
Analog Devices Inc.