NXP Semiconductors PCA8574PW,112

Overview

PCA8574PW,112 from NXP Semiconductors is an 8-bit quasi-bidirectional I/O expander for I²C-bus (Fast-mode, 400 kHz), operating from 2.3 V to 5.5 V with 25 mA per-pin sink capability, active-low open-drain interrupt output (INT), and eight hardware-programmable slave addresses via A0–A2. It enables remote GPIO expansion in space-constrained industrial control and LED display systems.

For engineers reviewing the PCA8574PW,112 datasheet, PCA8574PW,112 pinout, PCA8574PW,112 application, or PCA8574PW,112 equivalent, this device delivers low-quiescent-current (4.5 µA typical) I/O expansion with latch-up immunity (>100 mA), ESD protection (>2 kV HBM), and TSSOP16 packaging suitable for high-density PCB layouts requiring minimal board area and reliable interrupt-driven input monitoring.

Technical Context

The PCA8574PW,112 implements a single-register quasi-bidirectional I/O architecture: each of P0–P7 functions as input or output without direction register overhead, initialized at power-on as inputs with 100 µA weak pull-up to VDD. Its interrupt logic asserts INT (active LOW) on any input state change versus register value, eliminating polling.

I²C communication uses Fast-mode timing (400 kHz max), with slave address determined by A0–A2 pins and fixed prefix (0x40–0x47 for PCA8574 variant). The device supports up to 8 units per bus (via A0–A2), enabling scalable I/O expansion - e.g., 128 total I/Os when combined with PCA8574A devices sharing same bus.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1): 4.4 mm body width, 0.65 mm pitch, surface-mount, RoHS-compliant. Pin 1 marked with dot; pin 1 = A0.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C-based remote I/O expansion applications.

Compared with PCA8574D,512, PCA8574PW,112 offers superior board-area efficiency and thermal performance in compact designs; compared with PCA8574APW,112, it provides complementary addressing for bus scalability - neither is pin-compatible replacement but both share identical register-level firmware compatibility.

Availability

PCA8574PW,112 is available at Aetrix Electronics and suitable for industrial control, LED signage, and medical device applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for PCA8574PW,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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with core expertise in interface, power management, and microcontroller technologies.

The PCA8574 family was designed specifically to simplify I²C-based GPIO expansion in resource-constrained embedded systems - delivering low-power, interrupt-aware remote I/O with minimal firmware overhead and robust industrial-grade reliability.

FAQ

What is the I²C slave address range for PCA8574PW,112?

The PCA8574PW,112 uses the PCA8574 variant address prefix (0x40–0x47 in 7-bit format). With A0–A2 pins set to specific HIGH/LOW states, the device responds to one of eight addresses: 0x40 (A2=A1=A0=0) through 0x47 (A2=A1=A0=1). This differs from PCA8574A (0x70–0x7F), allowing both variants to coexist on the same I²C bus. PCA8574PW,112 does not support dynamic address reconfiguration - address is fixed at power-on based on hardware pin states.

Can PCA8574PW,112 drive LEDs directly without external components?

Yes, PCA8574PW,112 can directly drive LEDs in common-anode configurations: each P0–P7 pin sinks up to 25 mA at VDD = 4.5 V, sufficient for standard indicator LEDs. A current-limiting resistor must be placed in series with each LED anode (connected to VDD) to set forward current. For higher brightness or multiple LEDs per pin, verify total package sink current stays ≤200 mA. PCA8574PW,112's 100 µA weak pull-up ensures safe HIGH state when configured as input.

How does the interrupt (INT) pin function on PCA8574PW,112?

The INT pin on PCA8574PW,112 is an active LOW open-drain output that asserts when any input state on P0–P7 differs from its corresponding bit in the input register - indicating a change since last read. It resets to HIGH after the host reads the input register or writes any value to the port. No external debouncing is required for switch inputs, as INT triggers on edge transitions. PCA8574PW,112's INT requires an external pull-up resistor (typically 4.7 kΩ to VDD) to operate correctly.

What is the power-on behavior of PCA8574PW,112 I/O pins?

At power-on, PCA8574PW,112's internal Power-On Reset (POR) initializes all P0–P7 pins as inputs with a 100 µA weak current source pulling toward VDD. This ensures a known HIGH-impedance, fail-safe state before host firmware configures the port directions. Writing '1' to a port bit maintains input mode; writing '0' activates the strong sink transistor for output LOW. The POR threshold (VPOR) is internally calibrated and requires VDD to stabilize above ~1.5 V before release.

Is PCA8574PW,112 compatible with 3.3 V microcontrollers?

Yes, PCA8574PW,112 operates across 2.3 V to 5.5 V, making it fully compatible with 3.3 V systems. Its I²C interface is voltage-tolerant: SDA and SCL pins accept input voltages up to 5.5 V regardless of VDD, and the 100 µA pull-up current source scales with VDD. When VDD = 3.3 V, output sink current remains ≥20 mA per pin (per datasheet), sufficient for most 3.3 V logic-level LED and switch applications. PCA8574PW,112 requires no level shifters for 3.3 V I²C buses.