PCF8574AT/3,518

I/o Expanders Overview

The PCF8574AT/3,518 is an 8-bit I/O expander for the two-wire bidirectional I2C-bus. It operates between 2.5 V and 6 V with a typical standby current of 2.5 µA. The device provides eight quasi-bidirectional ports (P0–P7) that default to inputs at power-up via a weak internal pull-up. It features a 100 kHz I2C interface, three hardware address inputs allowing up to eight devices on one bus, and an active LOW open-drain interrupt output. The SOIC-16 package supports an operating temperature range from -40 °C to +85 °C.

I/o Expanders Feature Summary

• I2C-bus to parallel port expander
• Active LOW open-drain interrupt output
• Eight programmable slave addresses using three address pins
• Latch-up testing exceeds 100 mA per JEDEC standard JESD78

I/o Expanders Applications

• LED signs and displays
• Servers
• Key pads
• Industrial control
• Medical equipment

I/o Expanders Procurement Notes

Verify the specific ordering suffix matches the required reel packaging configuration. Confirm the component type corresponds to the fixed slave address portion defined in the datasheet. Ensure the package variant aligns with the specified board layout dimensions before finalizing procurement orders.

I/o Expanders Selection Notes

Select this component when expanding GPIO resources via a standard I2C interface is required. The device is suitable for applications needing remote input monitoring or LED driving within the specified voltage range. Consider the interrupt capability for event-driven microcontroller interactions without continuous polling overhead.

I/o Expanders Part Context

This part belongs to the PCF8574 family of remote 8-bit I/O expanders. It shares functional similarities with the PCF8574A but utilizes a different fixed portion of the slave address. This distinction allows both variants to coexist on the same I2C bus, supporting up to 16 total devices.

I/o Expanders Replacement Considerations

The PCA9674 serves as a migration path offering higher speed and increased address capacity. For designs requiring hardware reset functionality instead of interrupts, the PCA9670 is a compatible alternative.