Hi King,
Sorry for the delayed response on this. There are couple of things about this address issue.
ur customer say when they floating the address Rtop/Rbottom resistor, device is not found,
This could be happening because of wrong datasheet description for SADR0 pin. We will fix this in our update to datasheet. Datasheet shows that that floating this pin will set it to mid level but that's actually not true after investigating it. SADR0 pin default is pulled down or set to L when the the R627 and R598 is floating.
So you should be looking for D8 and D9 addresses for that case. This could tell why you are not able to see the device.
when they pop the 1K ohm Rtop/Rbottom resistor, they found the address is 6D.
When its populated, then you are biasing it externally so correct level is set but I do see one issue which is address. It should be DB/ DA instead of D6 / DA. I see that in their design note as well. CDCDB400 device doesn't have that. I don't know why this address was chosen, maybe you could help me understand it.
If they are reading D6 from our device then we could look at the power sequence of core device supply 'P3V3_9ZX_VDD/-3' and 'P3V3'. Since they are separate supplies as seen from schematic this could potentially cause this address issue. We need to make sure that 'P3V3_9ZX_VDD/-3' is established before the 'P3V3'. We can also check the ramp rate for both supplies and see if its too slow for core supply. PWRGD pin is also a good option to check if supply is established.
Best,
Asim
