8-bit I2C and SMBus I/O Port
The CAT9554 and CAT9554A are CMOS devices that provide 8−bit
parallel input/output port expansion for I2C and SMBus compatible
applications. These I/O expanders provide a simple solution in
applications where additional I/Os are needed: sensors, power
switches, LEDs, pushbuttons, and fans.
The CAT9554/9554A consist of an input port register, an output port
register, a configuration register, a polarity inversion register and an
I2C/SMBus−compatible serial interface.
Any of the eight I/Os can be configured as an input or output by
writing to the configuration register. The system master can invert the
CAT9554/9554A input data by writing to the active−high polarity
The CAT9554/9554A features an active low interrupt output which
indicates to the system master that an input state has changed.
The device’s extended addressing capability allows up to 8 devices
to share the same bus. The CAT9554A is identical to the CAT9554
except the fixed part of the I2C slave address is different. This allows
up to 16 of devices (eight CAT9554 and eight CAT9554A) to be
connected on the same bus.
• 400 kHz I2C Bus Compatible (Note 1)
• 2.3 V to 5.5 V Operation
• Low Stand−by Current
• 5 V Tolerant I/Os
• 8 I/O Pins that Default to Inputs at Power−up
• High Drive Capability
• Individual I/O Configuration
• Polarity Inversion Register
• Active Low Interrupt Output
• Internal Power−on Reset
• No Glitch on Power−up
• Noise Filter on SDA/SCL Inputs
• Cascadable up to 8 Devices
• Industrial Temperature Range
• 16−lead SOIC and TSSOP, and 16−pad TQFN (4 x 4 mm) Packages
• These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
• White Goods (dishwashers, washing machines)
• Handheld Devices (cell phones, PDAs, digital cameras)
• Data Communications (routers, hubs and servers)
1. All I/Os are set to inputs at RESET.
SOIC (W), TSSOP (Y)
TQFN 4 x 4 mm (HV4)
See detailed ordering and shipping information in the package
dimensions section on page 14 of this data sheet.
© Semiconductor Components Industries, LLC, 2011
June, 2011 − Rev. 6
Publication Order Number: