PCF8574APW

I/o Expanders Overview

The PCF8574APW is an 8-bit I/O expander for the I2C bus, manufactured by Texas Instruments. It operates within a supply voltage range of 2.5 V to 6 V and supports a maximum clock frequency of 100 kHz. The device features eight quasi-bidirectional ports (P0–P7) with latched outputs capable of driving LEDs directly. It includes an open-drain interrupt output (INT) that signals port state changes without continuous bus polling. The component is housed in a TSSOP-20 package and functions across an operating temperature range of -40°C to +85°C.

I/o Expanders Feature Summary

• Provides remote I/O expansion via a two-wire bidirectional I2C interface
• Features an open-drain interrupt output for efficient status monitoring
• Includes latched outputs with high-current drive capability for direct LED activation

I/o Expanders Applications

• Telecom shelters: filter units
• Servers
• Routers (telecom switching equipment)
• Personal computers
• Products with GPIO-Limited Processors

I/o Expanders Procurement Notes

Verify the specific ordering suffix against the manufacturer's current orderable addendum to confirm the TSSOP-20 package configuration. Ensure compatibility with system voltage levels and I2C bus timing requirements before integration. Confirm RoHS compliance status through official documentation.

I/o Expanders Selection Notes

Select this component when expanding microcontroller GPIO capabilities using the I2C protocol. It is suitable for applications requiring low standby current consumption and direct LED driving. Verify that the required number of address pins allows for the necessary device density on the bus.

I/o Expanders Part Context

This part belongs to the PCF8574A series of remote I/O expanders. It shares functional characteristics with other variants in the family but differs in physical packaging. The 'PW' suffix specifically denotes the Thin Shrink Small Outline Package (TSSOP) form factor.

I/o Expanders Replacement Considerations

PCF8574NE4

I/o Expanders FAQ

How is the interrupt signal reset?

The interrupt circuit resets when data on the port generating the interrupt is changed back to its original setting or when data is read from or written to that specific port.

What is the default state of the I/Os at power-on?

At power-on, the I/Os are high, activating only a current source to VCC until configured otherwise.

Can the I/Os be used as inputs without a direction control signal?

Yes, each quasi-bidirectional I/O can be independently assigned as an input or output without using a data-direction control signal.