Texas Instruments PCA9548ADW

Overview

PCA9548ADW 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 up to 400 kHz clock frequency, and enables resolution of I²C slave address conflicts in multi-sensor server and telecom systems.

For engineers reviewing the PCA9548ADW datasheet, PCA9548ADW pinout, PCA9548ADW application, or PCA9548ADW equivalent, this device serves as a critical I²C channel selector for systems requiring isolated downstream buses, hot-insertion support, and mixed-voltage communication between 1.8-V, 2.5-V, 3.3-V, and 5-V peripherals.

Technical Context

The PCA9548ADW implements eight independent bidirectional pass-gate switches controlled via a single 8-bit I²C register, where each bit enables one SCn/SDn channel. Its internal state machine resets on power-up or RESET assertion, deselecting all channels and initializing I²C logic.

Switch architecture uses low-ON-resistance MOSFETs (RON ≤ 10 Ω at 5 V), enabling voltage translation without level shifters. All I/O pins are 5-V tolerant, and external pull-up resistors set bus voltage per channel - allowing 1.8-V sensors to communicate with a 5-V master via separate SDn/SCn pairs.

Key Specifications

Pinout & Package

PCA9548ADW is supplied in a 24-pin SOIC (DW) package measuring 15.40 mm × 7.50 mm, with gull-wing leads and standard JEDEC outline.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548A, PCA9548ADW offers identical I²C switching performance at lower cost and standard industrial temperature grade; compared with PCA9546ADW, it doubles channel count while maintaining pin compatibility - enabling scalable design reuse across product tiers.

Availability

PCA9548ADW is available at Aetrix Electronics and suitable for server management, telecom routing, and factory automation applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for PCA9548ADW 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 delivering analog and embedded processing solutions, with leadership in interface, power management, and signal chain technologies.

The PCA9548ADW belongs to TI's I²C switch and multiplexer product line, designed specifically to resolve slave address conflicts and enable voltage-translation-aware bus expansion in resource-constrained embedded systems.

FAQ

What is the primary function of the PCA9548ADW in an I²C system?

The PCA9548ADW functions as an 8-channel bidirectional I²C bus switch that routes a single upstream master SCL/SDA pair to any combination of eight isolated downstream I²C buses. It resolves slave address conflicts by enabling time-multiplexed access to identically addressed peripherals - for example, eight identical temperature sensors - without requiring firmware changes or additional address lines. This capability is implemented via an internal 8-bit control register accessible over the same I²C bus.

Does the PCA9548ADW support voltage-level translation between different I²C bus voltages?

Yes, the PCA9548ADW supports voltage-level translation by leveraging its pass-gate architecture and 5-V-tolerant I/Os. Each downstream SCn/SDn channel can operate at a different voltage (1.8 V, 2.5 V, 3.3 V, or 5 V) because the VCC pin sets the maximum voltage passed through the switch, while external pull-up resistors on each channel define the local bus voltage. This allows, for instance, a 5-V microcontroller to communicate with 1.8-V sensors on SC0/SD0 and 3.3-V EEPROMs on SC4/SD4 - all using the same PCA9548ADW device.

How does the RESET pin on the PCA9548ADW improve system reliability?

The active-low RESET pin on the PCA9548ADW provides hardware-level recovery from I²C bus lockups - such as when a downstream slave holds SDA low indefinitely. Asserting RESET for ≥6 ns forces the device to clear its channel-selection register, deselect all eight switches, and reinitialize its I²C state machine, restoring upstream bus functionality without powering down the system. This feature is especially valuable in unattended infrastructure equipment like servers and routers, where software-initiated resets may be unavailable during firmware hangs.

Can multiple PCA9548ADW devices share the same I²C bus? If so, how is addressing managed?

Yes, up to eight PCA9548ADW devices can coexist on a single I²C bus using the three hardware address pins A0, A1, and A2. These pins are strapped to VCC or GND to configure a unique 3-bit address offset, resulting in slave addresses ranging from 0x70 to 0x77 (7-bit format). Each device responds only to its assigned address, allowing independent control of channel selection across all units. This scalability supports complex systems requiring hierarchical I²C expansion - for example, one PCA9548ADW managing sensors per blade, another managing power rails per shelf.

What package type is used for the PCA9548ADW, and what are its key mechanical characteristics?

The PCA9548ADW is packaged in a 24-pin SOIC (DW) outline measuring 15.40 mm × 7.50 mm with standard gull-wing leads. It conforms to JEDEC MS-013AC, features a 1.27-mm lead pitch, and is RoHS-compliant and lead-free. The DW package offers robust thermal performance (RθJA = 73.2°C/W) and is optimized for wave soldering and automated optical inspection in high-volume manufacturing. Its larger footprint compared to TSSOP or VQFN variants provides superior mechanical stability in vibration-prone industrial environments.