SCPS133K December 2005 – December 2024 PCA9557
PRODUCTION DATA
When power (from 0 V) is applied to VCC, an internal power-on reset holds the PCA9557 in a reset condition until VCC has reached VPOR. At that time, the reset condition is released, and the PCA9557 registers and I2C/SMBus state machine initialize to their default states. After that, VCC must be lowered to below 0.2 V and back up to the operating voltage for a power-reset cycle. The RESET input can be asserted to reset the system, while keeping the VCC at its operating level.
See the Power-On Reset Errata section.