Texas Instruments PCA9544AGQNR

Overview

PCA9544AGQNR from Texas Instruments is a low-voltage 4-channel I²C/SMBus multiplexer with interrupt logic, enabling bidirectional voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V buses. It features four active-low interrupt inputs (INT3–INT0), one active-low interrupt output (INT), and supports up to eight devices on the same I²C bus via three address pins (A2–A0). It operates from 2.3 V to 5.5 V and handles clock frequencies up to 400 kHz - used in server backplanes to resolve I²C slave address conflicts among identical temperature sensors.

For engineers reviewing the PCA9544AGQNR datasheet, PCA9544AGQNR pinout, PCA9544AGQNR application, or PCA9544AGQNR equivalent, this page delivers verified electrical specs, validated channel selection timing, confirmed interrupt propagation delays (tiv = 4 µs), package-specific thermal resistance (RθJA = 62.7 °C/W for RGY), and real-world use cases in telecom switching equipment and factory automation systems.

Technical Context

The PCA9544AGQNR implements a single 8-bit control register where bits B0–B2 select one of four downstream I²C channels (SCn/SDn), while bits INT3–INT0 reflect real-time interrupt status per channel. Its interrupt logic performs a wired-AND function: INT asserts low if any INTn input is low, with tiv = 4 µs and tir = 2 µs propagation delay under 100-pF load.

Each channel uses low-RON pass-gate switches (4–45 Ω depending on VCC) that allow voltage translation by isolating pull-up references - VDPUM for master bus and VDPU0–VDPU3 for each slave channel. Power-on reset (VPORR = 1.5 V typ., VPORF = 1.0 V typ.) initializes all channels deselected and resets the I²C state machine without glitch.

Key Specifications

Pinout & Package

VQFN-20 (RGY) package, 4.50 mm × 3.50 mm, thermally enhanced with exposed pad; pin-compatible with DGV/DW/PW variants but optimized for space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9544A and PCA9548A, the PCA9544AGQNR offers optimal balance of channel count, thermal performance (RθJA = 62.7 °C/W), and proven field reliability in high-density server applications - making it the preferred choice for fixed 4-channel, space-constrained deployments requiring robust hot-insertion support.

Availability

PCA9544AGQNR is available at Aetrix Electronics and suitable for server backplane management, telecom router control planes, and factory automation I/O modules requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9544AGQNR 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

Texas Instruments is a global semiconductor leader focused on analog and embedded processing technologies, with decades of expertise in I²C infrastructure and power-efficient interface solutions.

The PCA9544AGQNR belongs to TI's I²C multiplexer product line, designed specifically to resolve slave address conflicts and enable voltage-level translation in resource-constrained embedded systems - targeting servers, networking gear, and industrial controllers.

FAQ

What is the primary function of the PCA9544AGQNR in an I²C system?

The PCA9544AGQNR acts as a 4-channel bidirectional I²C multiplexer that routes a single upstream master SCL/SDA pair to one of four isolated downstream slave buses. It resolves I²C slave address conflicts and enables voltage-level translation between different logic families - for example, allowing a 3.3-V microcontroller to communicate with both 1.8-V and 5-V peripherals without external level shifters. Its core function is channel isolation and interrupt aggregation.

Does the PCA9544AGQNR support hot insertion, and how is this implemented?

Yes, the PCA9544AGQNR supports hot insertion per its datasheet specification. This is achieved through 5.5-V tolerant I/O pins, no-glitch power-up behavior, and robust ESD protection (±2000 V HBM). During hot plug-in, the internal power-on reset circuit holds the device in reset until VCC stabilizes above VPORR (1.5 V typ.), ensuring all channels remain deselected and preventing bus contention. The low standby current (≤2 µA) further minimizes inrush effects.

How does the interrupt logic work in the PCA9544AGQNR?

The PCA9544AGQNR features four active-low interrupt inputs (INT0–INT3), one per downstream channel, and a single active-low interrupt output (INT) that functions as a wired-AND of all four inputs. When any INTn pin is pulled low by a connected slave device, the INT output asserts low within 4 µs (tiv). The interrupt status is also readable in the upper nibble of the 8-bit control register. This design reduces master GPIO usage while preserving per-channel fault visibility.

Can the PCA9544AGQNR translate between 1.8-V and 5-V I²C buses, and what design considerations apply?

Yes, the PCA9544AGQNR supports voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V I²C buses. Translation is achieved by using separate pull-up resistors on each SDA/SCL line referenced to their respective domain voltages (VDPUM for master, VDPU0–VDPU3 for slaves). The VCC pin sets the maximum pass-through voltage. Critical design considerations include matching pull-up resistor values to bus capacitance and ensuring no floating address pins (A0–A2 must be hard-wired to VCC or GND).

What package type is used for the PCA9544AGQNR, and why is it suitable for high-density layouts?

The PCA9544AGQNR uses the VQFN-20 (RGY) package: 4.50 mm × 3.50 mm with an exposed thermal pad. Its compact footprint and low profile (0.8 mm height) make it ideal for space-constrained applications like server DIMM modules and telecom line cards. The RGY variant offers superior thermal performance (RθJA = 62.7 °C/W) versus larger packages, enabling higher channel density without derating - critical for thermally demanding embedded systems.