NXP Semiconductors PCA9544ABS,118

Overview

The PCA9544ABS,118 from NXP Semiconductors is a 1-of-4 bidirectional I²C-bus translating multiplexer in HVQFN20 package, enabling voltage-level translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses. It features four independent downstream I²C channels (SC0/SD0–SC3/SD3), active-low interrupt inputs per channel, and a shared open-drain INT output. It is used in server baseboard management controllers (BMC) to isolate and route I²C traffic to multiple sensor clusters.

For engineers reviewing the PCA9544ABS,118 datasheet, PCA9544ABS,118 pinout, PCA9544ABS,118 application, or PCA9544ABS,118 equivalent, key selection criteria include its 400 kHz Fast-mode I²C support, 5 V-tolerant I/O, low Ron (≤11 Ω at 3.3 V), integrated interrupt aggregation logic, and thermal-enhanced HVQFN20 package for high-density board layouts.

Technical Context

The PCA9544ABS,118 implements a digitally controlled analog switch matrix with pass-gate architecture, where VDD directly limits the maximum translated voltage on downstream buses. Its control register (8-bit, read/write) uses B2–B0 bits to select one of four channels, while INT3–INT0 bits (read-only) reflect real-time interrupt status across all channels - enabling interrupt-driven channel arbitration without polling.

It integrates hardware power-on reset (POR) that initializes all registers to zero and deselects all channels, ensuring glitch-free startup. The device supports hot insertion and operates across −40 °C to +85 °C with supply voltage range 2.3 V to 5.5 V, making it suitable for mixed-voltage industrial and telecom backplane systems requiring robust bus isolation.

Key Specifications

Pinout & Package

HVQFN20 package: 5 mm × 5 mm × 0.85 mm body, thermally enhanced exposed pad (connected to VSS), 20-pin no-lead quad flat construction optimized for high thermal dissipation and PCB space efficiency in dense server and networking applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9544A and PCA9548A, the PCA9544ABS,118 delivers optimal balance of channel count, speed (400 kHz), low Ron (5–11 Ω), and thermal efficiency (32 °C/W) - making it the preferred choice for space-constrained, high-speed, mixed-voltage I²C routing in servers and industrial controllers.

Availability

The PCA9544ABS,118 is available at Aetrix Electronics and suitable for server BMC architectures, industrial PLC I/O expansion, and telecom line card monitoring requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9544ABS,118 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 power management ICs.

The PCA9544A family was designed specifically to solve I²C bus congestion and voltage-domain interoperability challenges in complex embedded systems - delivering scalable, interrupt-aware multiplexing with minimal external components.

FAQ

What is the maximum I²C clock frequency supported by the PCA9544ABS,118?

The PCA9544ABS,118 supports up to 400 kHz Fast-mode I²C operation, verified across its full operating voltage range (2.3 V to 5.5 V) and temperature range (−40 °C to +85 °C). This enables high-throughput communication with sensors and peripherals without compromising timing margins, and is explicitly specified in Table 10 of the NXP datasheet Rev. 5.

How does the PCA9544ABS,118 handle voltage translation between different I²C buses?

The PCA9544ABS,118 uses its VDD supply voltage to clamp the maximum translated voltage on downstream SCx/SDx lines - for example, setting VDD = 3.3 V allows safe interfacing between a 5 V upstream bus and 3.3 V or 1.8 V downstream peripherals. External pull-up resistors on each channel set the final bus voltage level, and all I/O pins are 5 V tolerant regardless of VDD.

Can the interrupt inputs (INT0–INT3) of the PCA9544ABS,118 be used for purposes other than interrupt signaling?

Yes - if interrupt functionality is not required, the INT0–INT3 pins may be used as general-purpose digital inputs. However, they must not be left floating: unused inputs must be pulled to VDD via a resistor (typically 10 kΩ) to ensure defined logic levels and prevent noise-induced false triggers in the PCA9544ABS,118 control register.

What is the role of the exposed thermal pad on the HVQFN20 package of the PCA9544ABS,118?

The exposed center pad of the PCA9544ABS,118 HVQFN20 package is electrically and thermally connected to VSS. It must be soldered to a matching PCB thermal pad with thermal vias to achieve the specified R_th(j-a) of 32 °C/W. Omitting this connection degrades thermal performance and risks exceeding the 125 °C maximum junction temperature under sustained load.

Does the PCA9544ABS,118 require external pull-up resistors on its I²C lines?

Yes - external pull-up resistors are required on all I²C lines: upstream SCL/SDA and each downstream SCx/SDx pair. Resistor values depend on bus capacitance and target speed (e.g., 2.2 kΩ for 400 kHz with ≤400 pF load). No internal pull-ups exist on address pins (A0–A2) or interrupt inputs (INT0–INT3), which also require external biasing if used.