Hello,
I have assembled a board with a TCA9534 and when I power it with 2.85V the part pulls the supply down to 0.95V. I can confirm that the TCA9534 is the issue because it gets warm to the touch and no other parts are connected to the 2.85V rail. The datasheet does not specify anything about floating pins and I currently have the INT and one of the port pins floating - could that be the issue?