When power (from 0 V) is applied to V_CC, an internal power-on reset holds the PCA9536 in a reset condition until V_CC has reached V_POR. At that time, the reset condition is released and the PCA9536 registers and I²C/SMBus state machine initialize to their default states. After that, V_CC must be lowered to below 0.2 V and then back up to the operating voltage for a power-reset cycle.

Refer to the Section 10.1 section.