My customer has an issues to terminate the TX output. He pulled the Tx output to 1.3 (like figure 49 in datasheet), but the voltage he is measuring is 1.78V). What happen? Does the Tx drive here?
I assume that Figure 49 you are referring to is in the UG-570 User Guide?
If this is a truly unused output you do not have to do everything shown in Figure 49. It is sufficient to make a direct connection to 1.3V supply from the two sides of the Tx output.
I suspect that the outputs got connected to VDD_INTERFACE (which is set to 1.8V typically).
It would be helpful if you could provide a schematic of that section.
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