DESCRIPTION
The PCA9557 is a silicon CMOS circuit which provides parallel input/output expansion for SMBus and I2C applications. The PCA9557 consists of an 8-bit input port register, 8-bit output port register, and an I2C/SMBus interface. It has low current consumption and a high impedance open drain output pin, I/O0. The system master can enable the PCA9557’s I/O as either input or output by writing to the configuration register.

FEATURES
• Lower voltage, higher performance migration path for the PCA9556
• 8 general purpose input/output expander/collector
• Input/output configuration register
• Active HIGH polarity inversion register
• I2C and SMBus interface logic
• Internal power-on reset
• Noise filter on SCL/SDA inputs
• Active LOW reset input
• 3 address pins allowing up to 8 devices on the I2C/SMBus
• High impedance open drain on I/O0
• No glitch on power-up
• Power-up with all channels configured as inputs
• Low standby current
• Operating power supply voltage range of 2.3 V to 5.5 V
• 5 V tolerant inputs/outputs
• 0 to 400 kHz clock frequency
• ESD protection exceeds 2000 V HBM per JESD22-A114, 200 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
• Latch-up testing is done to JESDEC Standard JESD78 which exceeds 100 mA
• Package offer: SO 16, TSSOP 16