NXP Semiconductors PCA9544AD,118

Overview

PCA9544AD,118 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 I²C buses in server management and multi-voltage sensor subsystems.

For engineers reviewing the PCA9544AD,118 datasheet, PCA9544AD,118 pinout, PCA9544AD,118 application, or PCA9544AD,118 equivalent, key selection criteria include channel-selectable I²C isolation, 4-channel active-low interrupt aggregation, 20-pin SO20 package compatibility, and low-R_ON (5–30 Ω) pass-gate performance across voltage domains.

Technical Context

The PCA9544AD,118 implements a programmable control register with three channel-select bits (B2–B0) and four read-only interrupt status bits (INT3–INT0), allowing dynamic routing of upstream SCL/SDA to one downstream SCx/SDx pair at a time. Its interrupt output (INT) acts as a wired-AND of INT0–INT3, enabling centralized interrupt polling without channel activation.

Pass-gate architecture uses VDD as a voltage clamp reference, permitting bidirectional level translation without external components; external pull-up resistors set per-channel bus voltage, while all I/O pins remain 5 V tolerant regardless of VDD setting.

Key Specifications

Pinout & Package

PCA9544AD,118 is housed in a plastic small outline package (SO20, SOT163-1) with 20 leads and 7.5 mm body width. The package supports standard surface-mount reflow soldering and provides mechanical stability for high-reliability industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C-bus multiplexing applications.

Compared with TCA9544APWR and PCA9548AD,118, the PCA9544AD,118 delivers optimal balance of low-Ron switching, deterministic interrupt response, and proven thermal performance in SO20 for space-constrained industrial I²C expansion.

Availability

PCA9544AD,118 is available at Aetrix Electronics and suitable for server management, industrial sensor hubs, telecom line card monitoring, and automotive ECU peripheral integration requiring stable component supply and long-term lifecycle support.

Supply support for PCA9544AD,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 product line was designed specifically to solve I²C bus contention and voltage-domain interoperability challenges in complex embedded systems-enabling scalable, maintainable, and robust multi-peripheral architectures.

FAQ

What is the function of the INT pin on the PCA9544AD,118?

The INT pin on the PCA9544AD,118 is an active-low open-drain interrupt output that functions as a wired-AND of the four downstream interrupt inputs (INT0–INT3). It asserts LOW whenever any connected device on an enabled or disabled channel generates an interrupt, allowing the host controller to detect events without polling each channel individually. The PCA9544AD,118 retains this behavior regardless of current channel selection state.

Does the PCA9544AD,118 require external pull-up resistors on its I²C lines?

Yes, the PCA9544AD,118 requires external pull-up resistors on all I²C lines: upstream SCL/SDA and each downstream SCx/SDx pair. These resistors set the logic-high voltage level per bus segment and are essential for proper voltage translation-e.g., 3.3 V pull-ups on SC0/SD0 and 5 V pull-ups on SC1/SD1. No internal pull-ups exist on address pins A0–A2, which must also be externally biased.

Can the PCA9544AD,118 operate with different supply voltages on upstream and downstream buses?

No-the PCA9544AD,118 uses a single VDD supply to define the maximum pass-through voltage for all channels; it does not support independent upstream/downstream supply rails. However, VDD can be set (e.g., to 3.3 V) to clamp downstream bus voltages, while external pull-ups establish actual high-level voltages (e.g., 5 V on SC0/SD0), enabling translation between mismatched domains. The PCA9544AD,118 itself operates only from one VDD source.

How many PCA9544AD,118 devices can share the same I²C bus?

Up to eight PCA9544AD,118 devices can coexist on a single I²C bus using hardware address configuration via A0, A1, and A2 pins. Each combination of HIGH/LOW on these pins yields a unique 3-bit address suffix (A2 A1 A0), producing slave addresses from 0xE0 to 0xE7. This allows scalable expansion of I²C channel capacity without software address management overhead in the PCA9544AD,118 system.

What is the power-on reset behavior of the PCA9544AD,118?

On power-up, the PCA9544AD,118 performs an internal Power-On Reset (POR) that holds the device in reset until VDD reaches VPOR (1.5–2.1 V). Upon release, all registers initialize to zero-deselecting all channels-and the I²C state machine enters idle mode. This guarantees no unintended bus activity during startup, and the PCA9544AD,118 remains in this safe default state until explicitly configured via I²C write.