PCA8574TS,118

I/o Expanders Overview

The PCA8574TS,118 is an 8-bit remote I/O expander for the I2C-bus with interrupt, manufactured by NXP. It operates within a supply voltage range of 2.3 V to 5.5 V and supports Fast-mode I2C communication at up to 400 kHz. The device features eight quasi-bidirectional ports that default to inputs upon power-up, utilizing a weak internal pull-up current source of 100 µA. Latched outputs provide a high current sink capability of 25 mA per pin, with a total package sink limit of 200 mA. An active LOW open-drain interrupt output signals input state changes. The component is housed in an SSOP20 plastic shrink small outline package (SOT266-1) and functions across an ambient temperature range of -40 °C to +85 °C.

I/o Expanders Feature Summary

• Provides general-purpose remote I/O expansion via a two-wire bidirectional I2C-bus interface.
• Features latched outputs with high current sink capability suitable for directly driving LEDs.
• Includes an active LOW open-drain interrupt output to notify microcontrollers of input state changes without polling.
• Supports eight programmable slave addresses using three hardware address pins.

I/o Expanders Applications

• LED signs and displays
• Industrial control systems
• Key pads
• Medical equipment
• PLCs

I/o Expanders Procurement Notes

Verify the specific ordering suffix

I/o Expanders Selection Notes

Select this component when an 8-bit I/O expander with interrupt functionality is required on an I2C bus. Ensure the system voltage falls between 2.3 V and 5.5 V. Consider the SSOP20 package dimensions if space is constrained. Use the PCA8574 variant for standard addressing or PCA8574A if address conflict avoidance with other devices is necessary.

I/o Expanders Part Context

The PCA8574 series serves as a drop-in replacement for the PCF8574/74A family, offering improved performance characteristics such as higher I2C bus speeds and greater drive currents. While functionally similar to the PCF8574T/3, the PCA8574TS,118 utilizes an SSOP20 package instead of SOIC-16. It belongs to the broader category of remote I/O expanders designed to extend microcontroller capabilities over serial buses.

I/o Expanders Replacement Considerations

The datasheet identifies the PCA8574D as a drop-in replacement for the PCF8574T/3. For migration to newer packages, the PCA9674, PCA9670, and PCA9672 are listed as more capable alternatives supporting higher frequencies and additional features like hardware reset.

I/o Expanders FAQ

How does the PCA8574 handle input states after power-on?

Upon power-on reset, all I/O ports are initialized as inputs with a weak internal pull-up current source of 100 µA to VDD. This ensures the ports read as HIGH unless pulled LOW by an external signal.

What is the maximum current sink capability of the device?

Each individual port pin has a guaranteed minimum sinking current of 25 mA. The total package sink capability is limited to 200 mA due to internal busing constraints.

Can multiple PCA8574 devices be used on the same I2C bus?

Yes, up to eight PCA8574 devices can be connected to the same I2C bus by configuring the three hardware address pins (A0, A1, A2). Additionally, eight PCA8574A devices can coexist on the same bus, allowing for a total of 16 expanders.