NXP Semiconductors PCA8574N,112

Overview

PCA8574N,112 from NXP Semiconductors is an 8-bit quasi-bidirectional I/O expander for I²C-bus (SCL/SDA), operating from 2.3 V to 5.5 V with 400 kHz Fast-mode support. It features eight latched I/O ports (P0–P7), active LOW open-drain interrupt (INT), three hardware address pins (A0–A2), and 25 mA per-pin sink capability-enabling direct LED drive in embedded control panels and industrial HMI systems.

For engineers reviewing the PCA8574N,112 datasheet, PCA8574N,112 pinout, PCA8574N,112 application, or PCA8574N,112 equivalent, this device serves as a low-power remote GPIO extension solution where interrupt-driven input monitoring and high-current sinking outputs are required without direction registers or external pull-ups.

Technical Context

The PCA8574N,112 implements a single-register quasi-bidirectional I/O architecture: each port defaults to input at power-on with a 100 µA internal weak pull-up, and writes of '1' or '0' configure it as input or output without dedicated direction control. Its interrupt logic asserts INT (active LOW) on any input state change relative to the input register, eliminating polling overhead.

It uses standard I²C Fast-mode timing (400 kHz), supports up to eight devices per bus via A0–A2 address selection, and integrates Power-On Reset (POR) that initializes all I/Os as inputs. The SO16 package variant (PCA8574N,112) shares identical electrical behavior with PCA8574D but differs only in top-side marking and packing method.

Key Specifications

Pinout & Package

PCA8574N,112 is supplied in SO16 (plastic small outline, 16-lead, 7.5 mm body width) per SOT162-1. Pin functions align with PCA8574D, confirmed by NXP's official pin configuration diagram (Figure 3).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C I/O expander applications.

Compared with PCA8574N,112, PCA8574D,512 offers identical performance in tube packaging for evaluation, while PCA8574APW,112 provides address-space separation and space savings via TSSOP16 - enabling higher-density I/O expansion without bus contention.

Availability

PCA8574N,112 is available at Aetrix Electronics and suitable for industrial HMI panels, LED signage control, medical device front panels, server rack monitoring, and embedded sensor interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for PCA8574N,112 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface and mixed-signal ICs.

The PCA8574 series belongs to NXP's I²C peripheral portfolio, designed specifically to extend microcontroller GPIO count in space- and power-constrained embedded systems using standardized two-wire communication.

FAQ

What is the I²C address range supported by PCA8574N,112?

The PCA8574N,112 uses the PCA8574 address map: fixed prefix 0b0100, with A2–A0 selecting the lower three bits, yielding seven-bit addresses 0x40 through 0x47. This allows eight PCA8574N,112 devices on one I²C bus. The PCA8574N,112 does not support the PCA8574A range (0x70–0x7F).

Can PCA8574N,112 drive LEDs directly without external components?

Yes - PCA8574N,112 provides 25 mA sink current per I/O pin (P0–P7) at VDD = 4.5 V, sufficient to drive standard LEDs directly when connected anode-to-VDD with appropriate current-limiting resistors. Total package sink is limited to 200 mA, so simultaneous activation of multiple LEDs must stay within this bound.

How does the interrupt (INT) pin of PCA8574N,112 behave during power-up?

At power-on, PCA8574N,112's internal POR initializes all I/Os as inputs with 100 µA weak pull-ups. If any P0–P7 pin is externally pulled LOW, the mismatch between physical state and register value triggers INT assertion (LOW) immediately after reset release - enabling immediate fault or status detection.

Is PCA8574N,112 compatible with 3.3 V microcontrollers?

Yes - PCA8574N,112 operates from 2.3 V to 5.5 V and supports I²C Fast-mode (400 kHz) at 3.3 V. Its I/Os are 5.5 V tolerant when VDD ≤ 5.5 V, allowing safe interfacing with 3.3 V controllers even if pull-ups are tied to 5 V, provided SDA/SCL voltages remain within absolute maximum ratings.

What is the function of the A0, A1, and A2 pins on PCA8574N,112?

A0, A1, and A2 are hardware address inputs that set the three LSBs of the 7-bit I²C slave address. Each must be externally tied HIGH or LOW (no internal pull-ups) to select one of eight possible addresses (0x40–0x47). This enables multiple PCA8574N,112 devices to coexist on the same I²C bus without address conflict.