Texas Instruments PCA9548ADWG4

Overview

PCA9548ADWG4 from Texas Instruments is an 8-channel bidirectional I²C bus switch with voltage-level translation, active-low reset, and hardware address selection (A0–A2). It operates from 2.3 V to 5.5 V, supports 0–400 kHz clock rates, and enables isolation of up to eight I²C slave buses-e.g., resolving address conflicts among identical temperature sensors in server backplanes.

For engineers reviewing the PCA9548ADWG4 datasheet, PCA9548ADWG4 pinout, PCA9548ADWG4 application, or PCA9548ADWG4 equivalent, this device is selected for multi-slave I²C expansion, level-shifting between 1.8-V/2.5-V/3.3-V and 5-V domains, fault recovery via RESET, and space-constrained industrial control systems requiring compact SSOP-24 packaging.

Technical Context

The PCA9548ADWG4 implements a register-controlled 1-of-8 bidirectional pass-gate switch architecture, where a single 8-bit control register determines channel enablement per SCn/SDn pair. Its internal state machine resets fully on RESET assertion or power-on, deselecting all channels and reinitializing I²C protocol handling.

Each channel uses low-R_ON MOSFET switches (≤10 Ω at 5 V) with 5-V-tolerant I/Os, enabling voltage translation without external level shifters. The device supports hot insertion and exhibits no glitch on power-up due to synchronized POR and reset logic.

Key Specifications

Pinout & Package

PCA9548ADWG4 is packaged in a 24-pin SSOP (DW package), 8.20 mm × 5.30 mm body size, with gull-wing leads suitable for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9548ADWG4, TCA9548A extends temperature range and adds automotive qualification at no pinout or firmware change, while PCA9544APW reduces channel count and BOM cost for simpler topologies - both retain identical I²C control register structure and voltage translation capability.

Availability

PCA9548ADWG4 is available at Aetrix Electronics and suitable for server backplanes, industrial PLCs, telecom line cards, and automated test equipment requiring stable component supply and long-term production continuity.

Supply support for PCA9548ADWG4 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 specializing in analog, embedded processing, and connectivity technologies, with decades of leadership in interface and power management ICs.

The PCA9548A product line was designed specifically to solve I²C slave address conflicts and enable voltage-domain interoperability in dense, multi-peripheral embedded systems - targeting servers, networking gear, and factory automation.

FAQ

What is the function of the RESET pin on the PCA9548ADWG4?

The RESET pin on the PCA9548ADWG4 is an active-low asynchronous input that forces the device into a known state: it clears the channel-select register, deselects all eight SCn/SDn paths, and reinitializes the I²C state machine. This allows recovery from bus lockups - for example, if a downstream slave holds SDA low - without cycling VCC. The pin requires an external pull-up resistor and accepts pulses as short as 6 ns.

Does the PCA9548ADWG4 support voltage translation between different I²C bus voltages?

Yes, the PCA9548ADWG4 supports bidirectional voltage translation across its eight channels. Because its pass-gate switches are powered by VCC and all I/Os are 5-V tolerant, separate pull-up resistors can be used on each SCn/SDn pair to set local bus voltages - enabling direct communication between 1.8-V, 2.5-V, 3.3-V, and 5-V I²C devices without external level shifters. VCC defines the logic threshold but does not constrain downstream bus voltage.

How many PCA9548ADWG4 devices can be placed on the same I²C bus?

Up to eight PCA9548ADWG4 devices can coexist on a single I²C bus using the three hardware address pins A0, A1, and A2. These pins configure the device's 7-bit slave address, yielding eight unique addresses from 0x70 to 0x77. Each device must have a distinct A0–A2 combination; floating or inconsistent states will cause address collisions and communication failure.

What is the maximum I²C clock frequency supported by the PCA9548ADWG4?

The PCA9548ADWG4 supports I²C Standard Mode (up to 100 kHz) and Fast Mode (up to 400 kHz). Its switching characteristics and timing parameters - including t_pd, t_sch, and t_scl - are fully characterized across this range per JEDEC JESD88 and I²C-bus specification Annex A. Performance remains stable up to 400 kHz with bus capacitance ≤400 pF and appropriate pull-up sizing.

Is the PCA9548ADWG4 compatible with SMBus protocols?

Yes, the PCA9548ADWG4 is explicitly designed to be I²C bus and SMBus compatible. It adheres to SMBus 2.0 electrical specifications, including timeout behavior, voltage thresholds (VIH/VIL), and packet error checking (PEC) transparency. Its reset functionality, power-on initialization, and 5-V-tolerant I/Os meet SMBus system management requirements for server and telecom platforms.