PCF8574AT/3,518

• 8-Bit Remote I/O Expander with 8 I/O Channels
• I2C Interface at Up to 100k Hz
• 2.5V to 6V Supply range, 40µA Nominal Supply Current
• 25mA Output Current per Device Rating
• 16-Pin SO package, 2.65mm height, Tape and Reel
• -40°C to 85°C Operating range, Lead Free and RoHS Compliant

The PCF8574AT/3,518 is an NXP Semiconductors remote 8-bit I/O expander that adds general-purpose inputs and outputs to a system over an I2C bus. It provides 8 I/O channels with 25mA output current, operates from a 2.5V to 6V supply drawing a nominal 40µA, and runs at up to 100k Hz on the I2C interface. The PCF8574AT/3,518 is supplied in a 16-pin SO package on tape and reel and is rated for -40°C to 85°C.

An I/O expander converts two I2C bus wires into a block of general-purpose input and output pins, which is the standard way to add discrete signals to a design when the host microcontroller has run out of pins or when I/O must sit physically far from the processor. The 25mA output current is enough to drive indicator LEDs, small relays through a driver, or logic-level control lines directly. Multiple devices can share the same two-wire bus at different addresses, so pin count scales without additional routing. It is used widely in industrial control panels, keypad and display boards, instrumentation, consumer appliances and any design where a compact processor is expanded late in development.