PCA9555N,112

I/o Expanders Overview

The PCA9555N,112 is a 24-pin CMOS device providing 16-bit General Purpose parallel Input/Output (GPIO) expansion for I²C-bus and SMBus applications. It operates within a supply voltage range of 2.3 V to 5.5 V and supports clock frequencies from 0 Hz to 400 kHz. The device features five registers: two input port registers, two output port registers, two polarity inversion registers, and two configuration registers. All I/O pins default to inputs at reset. The fixed I²C address is determined by hardware pins A0, A1, and A2, allowing up to eight devices on the same bus.

I/o Expanders Feature Summary

• Provides 16 individually configurable I/O pins with independent input or output selection via configuration registers.
• Features an open-drain interrupt output that activates when any input state differs from its corresponding input port register state.
• Includes polarity inversion registers to invert read register data for active HIGH or active LOW operation flexibility.
• Incorporates noise filters on SCL and SDA inputs and internal power-on reset to prevent glitches during startup.

I/o Expanders Applications

• ACPI power switches
• Sensors and push buttons
• LED drivers
• Fan control systems

I/o Expanders Procurement Notes

Verify the ordering suffix '112' against official NXP documentation to confirm specific packaging details such as reel orientation or tape dimensions. Ensure the DIP24 package variant matches the required board layout constraints. Cross-reference the part number with the manufacturer's current product status to confirm availability and lifecycle stage before finalizing procurement plans.

I/o Expanders Selection Notes

Select this component when existing microcontroller GPIO resources are insufficient for the application requirements. The PCA9555 allows up to eight units to share a single I²C bus through hardware address pins A0, A1, and A2. Ensure the system logic levels are compatible with the 5 V tolerant I/Os and verify that the required drive current does not exceed the specified limits per pin and per octal group.

I/o Expanders Part Context

The PCA9555 enhances the NXP Semiconductors family of I²C-bus I/O expanders by offering higher drive capability, lower supply current, and smaller packaging options compared to predecessors like the PCF8575. Although pin-to-pin and I²C-bus address compatible with the PCF8575, software changes are required due to the enhanced features. It serves as a direct replacement for legacy expanders in designs needing improved performance and flexibility.

I/o Expanders Replacement Considerations

The PCA9555 is pin-to-pin and I²C-bus address compatible with the PCF8575. However, software modifications are necessary due to functional enhancements. Verify compatibility with other family members like the PCA9554, which shares the same fixed I²C-bus address base.