Texas Instruments PCA9544ADWR

Overview

PCA9544ADWR from Texas Instruments is a low-voltage 4-channel I²C and SMBus multiplexer with integrated interrupt logic, designed to resolve slave address conflicts by enabling time-division access to four downstream I²C buses. It supports bidirectional voltage-level translation across 1.8-V, 2.5-V, 3.3-V, and 5-V domains, operates from 2.3 V to 5.5 V, and delivers <10 Ω typical switch-on resistance at 3.3 V. It is used in server backplanes to isolate temperature sensor clusters sharing identical I²C addresses.

For engineers reviewing the PCA9544ADWR datasheet, PCA9544ADWR pinout, PCA9544ADWR application, or PCA9544ADWR equivalent, this page provides verified functional specifications, validated channel-select timing, confirmed interrupt propagation delay (≤4 μs), package-specific thermal metrics for TVSOP-20, and real-world design meaning for each key parameter - all directly traceable to TI's SCPS146G revision March 2021 production data sheet.

Technical Context

The PCA9544ADWR implements a single-control-register architecture where three LSBs select one of four downstream SCL/SDA channels while four MSBs reflect real-time active-low interrupt status from INT3–INT0 inputs. Its pass-gate structure uses VCC as a voltage-limiting reference, enabling true bidirectional level translation without external level shifters.

Interrupt logic performs a wired-AND function: the active-low INT output asserts only when ≥1 downstream INTn input is asserted, with 1-μs pulse rejection filtering and ≤4-μs valid propagation delay. Power-on reset initializes all channels deselected and clears the I²C state machine, ensuring deterministic startup even after bus lockup.

Key Specifications

Pinout & Package

PCA9544ADWR is packaged in a 20-pin TVSOP (DGV) with 0.5-mm pitch, 5.00 mm × 4.40 mm body size, and exposed thermal pad for enhanced heat dissipation in dense server PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9544APWR, PCA9544ADWR offers lower cost and sufficient performance for commercial-temperature server and networking gear, while PCA9548ADWR trades off efficiency and size for scalability - making PCA9544ADWR the optimal balance of density, thermal performance, and I²C timing fidelity in space-constrained 4-channel designs.

Availability

PCA9544ADWR is available at Aetrix Electronics and suitable for server backplanes, telecom switching equipment, and factory automation systems requiring stable component supply, long-lifecycle support, and guaranteed traceability for industrial deployments.

Supply support for PCA9544ADWR 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 company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets since 1930.

The PCA9544A product line was developed to solve I²C address collision in high-density electronic systems, targeting server, networking, and industrial control applications where multiple identical slave devices must share a single controller bus.

FAQ

What is the maximum clock frequency supported by the PCA9544ADWR?

The PCA9544ADWR supports I²C Standard-Mode up to 100 kHz and Fast-Mode up to 400 kHz, as specified in Section 6.6 of the TI SCPS146G datasheet. Its internal switch propagation delay (≤0.3 ns) and bus capacitance tolerance (≤400 pF) ensure reliable operation at 400 kHz across all four channels without timing violations. This makes PCA9544ADWR suitable for high-throughput sensor aggregation in modern server platforms.

Does the PCA9544ADWR require external pull-up resistors on all I²C lines?

Yes, the PCA9544ADWR requires external pull-up resistors on all SDA/SCL lines - both upstream (SDA, SCL) and downstream (SD0–SD3, SC0–SC3). Each channel's pull-up voltage (VDPU0–VDPU3) is independent and set by its respective resistor network, enabling voltage translation. The PCA9544ADWR itself contains no internal pull-ups, as confirmed in Section 8.6.1.1 of the datasheet. This design gives full control over rise time and noise immunity per bus segment.

How does the interrupt logic work on the PCA9544ADWR?

The PCA9544ADWR 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 input is asserted, INT goes low within ≤4 μs (tiv), and remains low until all asserted inputs are de-asserted. This behavior is hardware-implemented and requires no register polling, as detailed in Sections 3, 5, and 6.7 of the SCPS146G datasheet.

Can the PCA9544ADWR be used for voltage-level translation between 1.8-V and 5-V I²C buses?

Yes, the PCA9544ADWR supports bidirectional voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V I²C buses. Its pass-gate architecture uses VCC as the maximum pass-through voltage reference, and external pull-up resistors on each channel set the local bus voltage. For example, with VCC = 3.3 V, a 1.8-V slave on SD0/SC0 can communicate with a 5-V master on SDA/SCL - verified in Sections 1, 3, and 8.1 of the TI datasheet.

What happens to the PCA9544ADWR channels during power-up?

On power-up, the PCA9544ADWR executes a hardware power-on reset (POR) that initializes all internal registers to zero and deselects all four channels. This ensures no downstream bus is inadvertently enabled before firmware configuration, preventing bus contention or false START conditions. The POR threshold is 1.5 V (typ), and the device remains in reset until VCC exceeds VPORR, as defined in Section 6.5 and 8.4.1 of the SCPS146G datasheet.