NXP Semiconductors PCA8574APW,112

Overview

PCA8574APW,112 from NXP Semiconductors is a remote 8-bit I/O expander IC for I²C-bus systems, providing quasi-bidirectional port expansion with interrupt signaling. It operates from 2.3 V to 5.5 V, supports 400 kHz Fast-mode I²C, features eight latched I/O pins (P0–P7) with 25 mA sink capability per pin, and includes an active-low open-drain interrupt output (INT). It is used in LED signage, industrial control panels, and keypad interfaces where microcontroller GPIO resources are constrained.

For engineers reviewing the PCA8574APW,112 datasheet, PCA8574APW,112 pinout, PCA8574APW,112 application, or PCA8574APW,112 equivalent, this device delivers low-power (4.5 µA typical standby), interrupt-driven I/O monitoring, hardware-addressable slave configuration (eight options via A0–A2), and direct LED drive without external drivers - critical for space- and power-constrained embedded designs.

Technical Context

The PCA8574APW,112 implements a single-register quasi-bidirectional I/O architecture: each of the eight ports functions as input or output without direction registers, relying on internal 100 µA weak pull-up and strong n-channel sink transistors. Input state changes trigger the INT pin, enabling event-driven polling instead of continuous bus reads.

Its I²C interface complies with Fast-mode (400 kHz), uses a fixed 7-bit slave address prefix (0x70–0x7F for PCA8574A variant), and incorporates internal Power-On Reset that initializes all ports as inputs with weak pull-up. The TSSOP16 package supports surface-mount assembly in high-density industrial and telecom PCBs.

Key Specifications

Pinout & Package

TSSOP16 package: 4.4 mm body width, 0.65 mm pitch, surface-mount, RoHS-compliant. Pin 1 = A0; Pin 16 = VDD; no internal pull-ups on address pins - external biasing required.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA8574PW,112, the PCA8574APW,112 provides distinct I²C addressing to avoid conflicts in mixed-expander systems; versus PCA9674APW,112, it offers proven stability and lower cost where 400 kHz speed and 8-address support suffice - ideal for cost-sensitive, volume industrial deployments.

Availability

PCA8574APW,112 is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, and LED signage applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA8574APW,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 PCA8574A product line was designed specifically for low-cost, low-power I²C-based GPIO expansion in resource-constrained embedded systems - emphasizing simplicity, interrupt efficiency, and broad voltage compatibility.

FAQ

What is the I²C slave address range for PCA8574APW,112?

The PCA8574APW,112 uses the PCA8574A address scheme: 7-bit slave addresses 0x70 through 0x77 (hex), determined by A2–A0 pin states. This differs from the PCA8574 (0x40–0x47), allowing both families to coexist on the same I²C bus without conflict - a key feature confirmed in NXP's PCA8574_PCA8574A datasheet Rev. 3.

Can PCA8574APW,112 drive LEDs directly without external transistors?

Yes, the PCA8574APW,112 can directly drive LEDs: each of its eight I/O pins provides 25 mA sink current at 4.5 V, sufficient for standard indicator LEDs with appropriate current-limiting resistors. Its quasi-bidirectional architecture eliminates the need for external driver transistors in common-anode configurations - verified in the "High current-drive load applications" section of the datasheet.

How does the interrupt (INT) pin function on PCA8574APW,112?

The INT pin on PCA8574APW,112 is an active-low open-drain output that asserts (goes LOW) whenever the state of any input pin (P0–P7) differs from its corresponding bit in the input port register. It resets HIGH after a read or write operation completes - enabling efficient event-driven polling instead of continuous bus interrogation, as documented in Section 8.5 of the NXP datasheet.

What is the power-on behavior of PCA8574APW,112 I/O pins?

At power-on, the PCA8574APW,112's internal Power-On Reset (POR) initializes all eight I/O pins (P0–P7) as inputs with a 100 µA weak pull-up to VDD. This default state ensures predictable startup behavior and prevents floating inputs - a requirement explicitly stated in Section 8.4 and Figure 1 of the official NXP PCA8574_PCA8574A datasheet.

Is PCA8574APW,112 pin-compatible with PCA8574PW,112?

Yes, PCA8574APW,112 and PCA8574PW,112 share identical TSSOP16 packaging and pinout (A0–A2, P0–P7, INT, SCL, SDA, VDD, VSS), making them physically interchangeable. However, they differ in I²C slave address mapping (0x70–0x77 vs. 0x40–0x47), so firmware address configuration must be updated - confirmed in Table 4 and Table 5 of the NXP datasheet.