NXP Semiconductors PCA9544APW,112

Overview

PCA9544APW,112 from NXP Semiconductors is a 1-of-4 bidirectional I²C-bus translating multiplexer with integrated interrupt logic, operating from 2.3 V to 5.5 V supply, supporting up to 400 kHz clock frequency, and enabling voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses in server management, modular computing, and multi-voltage sensor subsystems.

For engineers reviewing the PCA9544APW,112 datasheet, PCA9544APW,112 pinout, PCA9544APW,112 application, or PCA9544APW,112 equivalent, key selection criteria include channel-selectable I²C isolation, active-low interrupt aggregation (INT0–INT3 → INT), 3 hardware address pins for 8-device bus scalability, and TSSOP20 package compatibility with space-constrained industrial control and embedded host interfaces.

Technical Context

The PCA9544APW,112 implements a programmable 4-channel pass-gate multiplexer controlled via I²C write to an 8-bit register where bits B2–B0 select one downstream SCx/SDx pair while bits INT3–INT0 provide read-only interrupt status per channel. Its internal power-on reset initializes all channels deselected and clears the control register to 0x00.

Voltage translation is achieved by leveraging VDD as the pass-gate threshold reference: Vo(sw) is clamped to ≤2.8 V at VDD = 3.0–3.6 V and ≤4.5 V at VDD = 4.5–5.5 V, allowing safe interoperation of mixed-voltage I²C slaves without external level shifters. All I/O pins are 5 V tolerant with ±1 µA leakage and 10–13 pF input capacitance.

Key Specifications

Pinout & Package

TSSOP20 package (SOT360-1), 4.4 mm body width, 0.65 mm lead pitch, 20-terminal plastic thin shrink small outline package with exposed thermal pad not present - suitable for reflow soldering and high-density PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C multiplexer applications.

Compared with TCA9544APWR, PCA9544APW,112 offers guaranteed interrupt polarity alignment and documented NXP support for hot insertion; versus PCA9545APW,112 it trades advanced masking for lower cost and proven field reliability in legacy server platforms.

Availability

PCA9544APW,112 is available at Aetrix Electronics and suitable for server baseboard management, industrial sensor hubs, and modular compute carrier boards requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for production ramp.

Supply support for PCA9544APW,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, power, and sensing technologies.

The PCA9544A product line delivers scalable I²C bus expansion and voltage translation for complex embedded systems-designed specifically to simplify multi-peripheral integration in space- and power-constrained environments.

FAQ

What is the maximum I²C clock frequency supported by the PCA9544APW,112?

The PCA9544APW,112 supports I²C clock frequencies up to 400 kHz, compliant with Fast-mode I²C specifications. This allows full-speed communication with modern peripherals while maintaining signal integrity across all four downstream channels. The propagation delay is specified at ≤0.3 ns, ensuring timing margins are preserved even at maximum speed. No external components are required to achieve this performance.

How does the PCA9544APW,112 handle voltage translation between different I²C bus voltages?

The PCA9544APW,112 uses its VDD supply voltage to set the maximum output voltage (Vo(sw)) passed through the pass-gate switches. At VDD = 3.3 V, Vo(sw) is clamped to ≤2.8 V, enabling safe communication between a 5 V upstream bus and 3.3 V or 2.5 V downstream devices. External pull-up resistors on each SCx/SDx pair set the final bus voltage level, making discrete level shifters unnecessary.

Can the interrupt inputs (INT0–INT3) of the PCA9544APW,112 be used for general-purpose I/O?

Yes-the interrupt inputs INT0–INT3 can function as general-purpose inputs when interrupt logic is not required. However, they must not be left floating: unused inputs must be tied to VDD via a pull-up resistor to prevent undefined logic states and excessive current draw. Their input leakage is ±1 µA, and they tolerate voltages up to 7 V, making them robust for mixed-signal interfacing.

What happens to the PCA9544APW,112 channels during power-up?

Upon power application, the PCA9544APW,112 executes a power-on reset that initializes the control register to 0x00 and deselects all four channels. This guarantees a known, safe state-no downstream bus is activated until the master explicitly writes a channel-select command. The reset releases once VDD exceeds VPOR (1.5–2.1 V), preventing glitch-induced communication errors during supply ramp.

Is the PCA9544APW,112 compatible with SMBus protocols?

Yes, the PCA9544APW,112 is fully compatible with SMBus 2.0 specifications. Its I²C-bus interface logic supports SMBus timeouts, packet error checking (PEC) passthrough, and alert response protocol (ARP) compatibility when used with SMBus-compliant downstream devices. The 400 kHz maximum clock rate and open-drain INT output align with SMBus timing and signaling requirements.