Product Overview

PCF8574T/3,518 is an I2C-bus 8-bit remote I/O expander from NXP Semiconductors, featuring an SO16 package (16-pin small outline package with 7.5mm body width), part of the PCF8574 series. It extends microcontroller I/O interfaces via the I2C-bus, supporting a 2.5V to 6V wide voltage range and integrating 8 quasi-bidirectional I/O ports. Suitable for LED displays, keypads, industrial control, and other scenarios requiring I/O expansion.

Key Features

• I2C-Bus Expansion：Supports 100kHz standard I2C-bus protocol, communicating with the host controller via SCL (serial clock) and SDA (serial data) lines. A single chip expands 8 I/Os, simplifying circuit design.
• Quasi-Bidirectional I/Os：8 I/O ports can be independently configured as input or output, defaulting to input at power-up with a 100μA weak pull-up current source. No direction control register is needed, enabling easy operation.
• Flexible Addressing：3 hardware address pins (A0, A1, A2) support 8 slave addresses. Up to 8 PCF8574s can be connected on one I2C-bus, extendable to 16 with PCF8574A, totaling 128 I/Os.
• Interrupt Output：Active-LOW open-drain interrupt output (INT) triggers when input states change, reducing host polling and improving system efficiency.
• Low Power & Reliability：Typical quiescent current of 2.5μA, ideal for battery-powered devices; ESD protection exceeds 2000V (HBM), operating temperature -40°C to +85°C for harsh environments.

Technical Specifications

Typical Applications

• In LED displays, PCF8574T/3,518 receives commands from the host controller via I2C to control 8 LEDs. Cascading multiple chips expands to more LEDs, reducing host I/O usage and simplifying wiring. Its low power consumption suits outdoor displays requiring long-term operation.
• In industrial control panels, it expands to multiple key inputs and indicator outputs. The INT pin feeds back key status in real time, eliminating continuous host polling and improving response speed. The wide temperature range ensures stability in high-temperature factory environments.

Why Choose PCF8574T/3,518？

• Simplified I/O Expansion：Expands 8 I/Os with one chip, reducing host pin usage, ideal for microcontrollers with limited pins (e.g., 8-bit MCUs).
• Low Power Consumption：2.5μA typical quiescent current extends battery life, suitable for portable instruments.
• Scalable Cascading：Supports multi-device bus connection, expanding to 128 I/Os for large systems.
• High Reliability：Industrial temperature range and ESD protection adapt to complex electromagnetic environments, lowering failure rates.
• Easy Integration：No external direction registers, with simple read/write operations. Compatible with mainstream I2C controllers, reducing development costs.

SUNTOP COMPANY INTRODUCTION

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