Texas Instruments PCA9544ADW

Overview

PCA9544ADW 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 PCA9544ADW datasheet, PCA9544ADW pinout, PCA9544ADW application, or PCA9544ADW equivalent, this page delivers verified pin functions, real-world voltage-translation use cases, confirmed interrupt timing (tiv = 4 µs, tir = 2 µs), validated thermal metrics for SOIC (DW) package (RθJA = 58 °C/W), and two field-tested alternative parts with documented functional trade-offs.

Technical Context

The PCA9544ADW implements a single 8-bit control register where bits B2–B0 select one of four downstream I²C channels (SCn/SDn), while bits INT3–INT0 reflect real-time interrupt status from each channel. Its interrupt logic performs a wired-AND function: INT asserts low if any INTn input is low.

Channel switching is synchronized to I²C stop conditions to prevent bus glitches; power-on reset initializes all channels deselected and clears the state machine. The pass-gate architecture uses VCC as a voltage clamp, enabling true bidirectional level translation without external logic - e.g., 3.3-V master communicates with 5-V slaves by pulling SC0/SD0 to 5 V and SCL/SDA to 3.3 V.

Key Specifications

Pinout & Package

PCA9544ADW is packaged in SOIC (DW) - 20-pin, 12.8 mm × 7.50 mm body - with gull-wing leads and standard JEDEC MO-026AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9544ADW, TCA9544A offers superior ESD immunity and lower quiescent current for extended battery-powered operation, while PCA9548A trades off lower RON and smaller footprint for channel count scalability - making PCA9544ADW optimal for space-constrained 4-channel applications where cost and thermal performance are prioritized.

Availability

PCA9544ADW is available at Aetrix Electronics and suitable for server backplane management, telecom router chassis design, and factory automation PLC I/O modules requiring stable component supply across multi-year production cycles.

Supply support for PCA9544ADW 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and communications markets.

The PCA9544ADW belongs to TI's I²C infrastructure portfolio, engineered specifically to resolve bus contention and voltage-domain mismatches in dense, multi-peripheral embedded systems - targeting high-reliability applications where deterministic interrupt handling and glitch-free power-up are mandatory.

FAQ

What is the maximum I²C clock frequency supported by the PCA9544ADW?

The PCA9544ADW supports I²C clock frequencies up to 400 kHz, meeting Fast-Mode specification requirements. This is confirmed in Section 6.6 of the official datasheet, which specifies t_sch = 0.6 µs minimum high time and t_scl = 1.3 µs minimum low time at 400 kHz. The PCA9544ADW maintains full signal integrity within these timing windows across its entire 2.3 V–5.5 V operating range - ensuring compatibility with both Standard-Mode (100 kHz) and Fast-Mode masters without external timing adjustments.

Does the PCA9544ADW require external pull-up resistors on all I²C lines?

Yes, the PCA9544ADW requires external pull-up resistors on all I²C lines: SDA, SCL, SD0–SD3, SC0–SC3, INT, and INT0–INT3. Per Section 5.1 of the datasheet, each line must connect to its respective voltage domain (VDPUM for upstream, VDPUx for downstream channels) via a pull-up resistor. The PCA9544ADW contains no internal pull-ups - omission causes bus failure due to undefined logic levels and violates I²C open-drain protocol requirements.

How does the PCA9544ADW handle power-on reset and bus recovery?

The PCA9544ADW incorporates an internal power-on reset (POR) circuit that holds the I²C state machine in reset until VCC rises above VPORR (1.5 V typical). Upon release, all channels are deselected and the control register resets to 0x00. If a downstream I²C bus locks low, cycling VCC triggers POR - restoring communication without requiring master firmware intervention. This behavior is explicitly defined in Sections 3, 8.1, and 8.4.1 of the datasheet and is fundamental to the PCA9544ADW's role in fault-tolerant systems.

Can the PCA9544ADW translate between 1.8-V and 5-V I²C buses simultaneously?

Yes, the PCA9544ADW can translate between 1.8-V and 5-V I²C buses simultaneously. Its pass-gate architecture uses VCC as a voltage clamp: upstream SDA/SCL are pulled to 1.8 V, while SD0/SC0 are pulled to 5 V. The datasheet confirms this in Section 3 ("Allows voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V Buses") and Figure 8-1 of the application diagram. Critical design requirement: pull-up resistors must match their respective domain voltages - mismatch causes logic threshold violations.

What is the function of the INT pin on the PCA9544ADW?

INT is an active-low interrupt output that functions as a wired-AND of the four downstream interrupt inputs (INT0–INT3). When any INTn input is asserted low, INT pulls low - signaling the master processor that at least one downstream device requires attention. As specified in Section 5.1 and Figure 5-1, INT must be pulled up to VDPUM (master-side supply) and has a typical sink current of 7 mA at VOL = 0.4 V. This aggregation eliminates the need for additional GPIO pins or discrete logic gates in multi-sensor systems.