Hello we made 80 sets of trial PCB for video suitcher.The PCB has 4ch analog video inputs using a couple of AD9984A. However some of the PCB shows abnorminal operation on I2C operation. A micro-controller read/write data from/to AD9984A through same I2C line. To make different I2C address for the AD9984As, we put external 10k ohm pull-up resistor ( to Vdd ) on VSOUT/A0 line of one AD9984A. And we don't put any pull-up nor pull-down resistor on VSOUT/A0 line of another AD9984A. Now we try to put external pull-down resistor ( to GND ) on the VSOUT/A0 line of another AD9984A. So I need advise as followings;
(1) Is it appropriate measure to put pull-down resistor on VSOUT/A0 line of another AD9984A to make " A0 = 0" address ?
(2) If (1) is appropriate, how much resistor should we put ? 1k ohm, 10k ohm or other ohm ?
(3) When does AD9984A read data on VSOUT/A0 for setting I2C address ? After Vdd power-up or later ? We want to know precise timing !