The PCA9557D is an 8-bit parallel Input/output Expander for SMBus and I2C-bus applications. The PCA9557 consists of an 8-bit input port register, 8-bit output port register and an I2C-bus/SMBus interface. It has low current consumption and a high-impedance open-drain output pin, IO0. The system master can enable the PCA9557's I/O as either input or output by writing to the configuration register. The system master can also invert the expander inputs by writing to the active HIGH polarity inversion register. Finally, the system master can reset the expander in the event of a time-out by asserting a LOW in the reset input. The power-on reset puts the registers in their default state and initializes the I2C-bus/SMBus state machine. The RESET pin causes the same reset/initialization to occur without de-powering the part.
Input/output configuration register
Active high polarity inversion register
Internal power-ON reset
Noise filter on SCL/SDA input
Active low reset input
3 Address pins allowing up to 8 devices on the I2C-bus/SMBus
High-impedance open-drain on IO0
No glitch on power-up
Power-up with all channels configured as inputs
Low standby current consumption
Latch-up testing is done to JEDEC standard JESD78 which exceeds 100mA
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