PCA8574D,512

I/o Expanders Overview

The PCA8574D,512 is an NXP remote 8-bit I/O expander for the I2C-bus with interrupt output. It operates between 2.3 V and 5.5 V with a typical standby current of 4.5 µA. The device features eight quasi-bidirectional ports (P0–P7) that default to inputs at power-up, each equipped with a weak internal pull-up. Latched outputs provide up to 25 mA sink capability per pin and 200 mA total package sink capability. It supports Fast-mode I2C communication at 400 kHz and includes three hardware address pins to allow up to eight devices on a single bus.

I/o Expanders Feature Summary

• Provides general-purpose remote I/O expansion via the two-wire bidirectional I2C-bus interface
• Features latched outputs with high-current drive capability suitable for directly driving LEDs
• Includes an active LOW open-drain interrupt output to notify microcontrollers of input state changes
• Supports eight programmable slave addresses using three dedicated hardware address pins

I/o Expanders Applications

• LED signs and displays
• Servers and industrial control systems
• Key pads and PLCs
• Medical equipment and instrumentation
• Cellular telephones and mobile devices

I/o Expanders Procurement Notes

Verify the specific ordering suffix '512' against the manufacturer's official documentation to confirm standard marking and tube dry pack packing methods. Ensure the SO16 plastic small outline package variant matches the required board layout dimensions. Cross-reference the part number with the latest datasheet revision to confirm compatibility with existing system designs.

I/o Expanders Selection Notes

Select this component when an 8-bit I/O expander with interrupt functionality is required for I2C-based systems. The PCA8574D serves as a drop-in replacement for the PCF8574T/3. Consider the PCA8574AD if a different fixed portion of the slave address is needed to avoid conflicts with other devices on the same bus.

I/o Expanders Part Context

This device belongs to the PCA8574 family of remote I/O expanders designed for I2C-bus applications. It is functionally identical to the PCA8574A, differing only in the fixed portion of the slave address. This allows both variants to coexist on the same bus, supporting up to 16 devices simultaneously. The D suffix indicates the SO16 package version.

I/o Expanders Replacement Considerations

The PCA8574D is documented as a drop-in replacement for the PCF8574T/3. For migration paths offering higher speeds or additional features, newer models such as the PCA9674 or PCA9670 are available.