CAT9554WI-G

Overview

The CAT9554WI-G is an 8-bit I2C and SMBus compatible I/O port expander manufactured by onsemi. It provides parallel input/output expansion for applications requiring additional I/O lines. The device operates within a supply voltage range of 2.3 V to 5.5 V and supports clock frequencies up to 400 kHz. It features eight configurable I/O pins that default to inputs at power-up, an active low interrupt output, and individual polarity inversion capabilities. The component is housed in a 16-lead SOIC package (suffix W) with industrial temperature rating (-40°C to +85°C).

Feature Summary

• I2C/SMBus compatible serial interface with extended addressing allowing multiple devices on one bus.
• Configurable I/O ports with push-pull output drivers and weak pull-up resistors when configured as inputs.
• Active low interrupt output signaling state changes on input pins.
• Internal power-on reset ensures known initial state without glitches.

Applications

• White goods such as dishwashers and washing machines.
• Handheld devices including cell phones, PDAs, and digital cameras.
• Data communications equipment like routers, hubs, and servers.

Procurement Notes

Verify the specific ordering suffix to confirm package type and lead finish. The 'W' suffix indicates a SOIC-16 package, while 'Y' denotes TSSOP and 'HV4' indicates TQFN. The 'G' suffix specifies NiPdAu lead finish. Confirm tape and reel quantities if 'T2' is included in the part number. Ensure the base model matches the required slave address configuration, as CAT9554 and CAT9554A have different fixed address bits.

Selection Notes

Select the CAT9554WI-G when an 8-bit I/O expander with I2C interface is required in a SOIC-16 package. Verify that the system voltage falls within the 2.3 V to 5.5 V operating range. Consider the CAT9554A variant if a different fixed slave address prefix is needed to avoid conflicts on the bus. Ensure the application does not exceed the maximum DC current limits per pin or total package dissipation.

Part Context

This component belongs to the CAT9554 family of CMOS I/O expanders. It is functionally identical to the CAT9554A except for the fixed portion of the I2C slave address. The family supports various packages including SOIC, TSSOP, and TQFN. The device is designed for general-purpose GPIO expansion in embedded systems where bus lines are limited.

Replacement Considerations

The CAT9554AWI-G is a direct functional substitute with a different fixed I2C slave address prefix. Other variants in the same package include CAT9554YI-G (TSSOP) and CAT9554HV4I-G (TQFN). Cross-referencing with other manufacturers' I2C expanders requires verification of register maps and electrical characteristics.

FAQ

What is the difference between CAT9554 and CAT9554A?

The primary difference is the fixed portion of the I2C slave address. CAT9554 uses binary 0100, while CAT9554A uses 0111. This allows up to 16 devices from both families to coexist on the same bus.

How many devices can be connected on a single I2C bus?

Up to eight CAT9554 devices or eight CAT9554A devices can share the same bus using the A0, A1, and A2 address pins. Combining both families allows a maximum of 16 devices.

What happens to the I/O pins at power-up?

All I/O pins default to input mode with a weak pull-up resistor to VCC. An internal power-on reset ensures no glitches occur during initialization.