AD9649-80 analog input range

Hello,

I have 2 boards with AD9649-80 out of 5 same boards that the input analog range is smaller : 1.2 Vptp instead of 2 Vptp. I used a DC analog input to check this.

I use  the 1V internal reference  and also measured the Vref pin which is  0.990 V.

I use the power up defaults definition of the AD9649-80, not using SPI. 

The power up sequence is DRVDD first and it is 3.3V. 

the CSB pin is connected to the 1.8V AVDD (by mistake)  while the DRVDD is 3.3v, but the data sheet says Vih is 1.2v till DRVDD+0.3 but this data is for DRVDD=1.8  so I don't sure what is the Vih, but I reduced the DRVDD to 2.5V by connecting a serial diode and still have the same problem. 

May be the power up sequence is important in order to got the defaults? is any register definition that affect the range?

Can you help please ? 

Regards,

Yaacov.