The TX of the ADN4605 comes disabled on reset according to Table 13.
Are the P and N pins still pulled up to VTTO ?
When the ADN4605 output is disabled (value 0x00 in Tx Drive Control Registers, addresses 0xB0-0xBA) the output current source is disabled (see diagram below), but the termination resistors stay connected and pull the output nodes to VTTO. This is the default after reset.
When the ADN4605 output is squelched (value 0x01 in Tx Drive Control Registers, addresses 0xB0-0xBA) the output current source remains enabled with value set by output level (OLEV) and pre-emphasis (PE) settings, while the voltages VP and VN are set to be equal (VP=VN). This forces the outputs OP and ON to be at the output common mode voltage for the given OLEV and PE setting.
Please let me know if you have any further questions.
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