NXP Semiconductors PCA9548AD,118

Overview

PCA9548AD,118 from NXP Semiconductors is an octal bidirectional I²C-bus switch with active-low reset, enabling one upstream I²C master to selectively route signals to any of eight downstream I²C buses. It supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V domains, features 24-pin SOIC packaging, operates from 2.3 V to 5.5 V supply, and delivers ≤30 µA operating current at 3.6 V - ideal for multi-sensor systems in industrial PLCs and server management controllers.

For engineers reviewing the PCA9548AD,118 datasheet, PCA9548AD,118 pinout, PCA9548AD,118 application, or PCA9548AD,118 equivalent, key selection criteria include its 8-channel programmable switching via I²C control register, 6 V-tolerant I/O pins, low 5–30 Ω ON-resistance, support for up to 400 kHz Fast-mode I²C, and hardware addressability via A0–A2 pins for up to eight devices on a single bus.

Technical Context

The PCA9548AD,118 implements a parallel array of eight independent bidirectional pass-gate switches controlled by an 8-bit I²C-accessible register, where each bit enables or disables one SCx/SDx channel pair. Its internal reset circuitry responds to both external RESET pin assertion (active LOW) and internal power-on reset, ensuring deterministic deselection of all channels at startup or fault recovery.

Voltage translation is achieved through VDD-referenced pass-gate threshold control: Vo(sw) is clamped to ≤2.8 V when VDD = 3.0–3.6 V, allowing safe interfacing between 3.3 V masters and 2.7 V peripherals without level-shifter ICs. All I/O pins are 6 V tolerant, and the device supports hot insertion with no glitch on power-up.

Key Specifications

Pinout & Package

PCA9548AD,118 is housed in a plastic small outline package (SO24), 24-lead, body width 7.5 mm (SOT137-1), with standard surface-mount footprint and thermal resistance R_th(j-a) = 77 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548APWR and PCA9546AD,118, the PCA9548AD,118 uniquely balances full 8-channel scalability, NXP's proven fault-recovery architecture, and seamless integration into existing NXP-based designs - making it optimal for high-density, mission-critical I²C expansion.

Availability

PCA9548AD,118 is available at Aetrix Electronics and suitable for industrial automation, server management, and automotive electronics requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for PCA9548AD,118 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

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, IoT, and communication infrastructure markets.

The PCA9548A family was designed specifically to solve I²C bus congestion and voltage-domain interoperability challenges in dense embedded systems - delivering scalable, robust, and software-controllable bus expansion without compromising signal integrity.

FAQ

What is the maximum I²C clock frequency supported by PCA9548AD,118?

The PCA9548AD,118 supports standard-mode I²C up to 100 kHz and Fast-mode I²C up to 400 kHz. Its propagation delay is ≤0.3 ns (typical), and it meets all timing requirements including tSU;DAT ≥100 ns and tHD;DAT ≥0 ns in Fast-mode - verified across the full 2.3 V to 5.5 V supply range. This makes PCA9548AD,118 suitable for high-speed sensor polling in real-time control loops.

How does the PCA9548AD,118 handle voltage translation between different I²C bus domains?

The PCA9548AD,118 uses its VDD supply voltage to clamp the maximum output voltage (Vo(sw)) passed through its pass gates - e.g., with VDD = 3.3 V, Vo(sw) ≤2.8 V, enabling safe interface between a 5 V master and 3.3 V or 2.7 V peripherals. External pull-up resistors on each channel set the final bus voltage level. This architecture is intrinsic to PCA9548AD,118 and requires no external level-shifting components.

Can multiple PCA9548AD,118 devices share the same I²C bus?

Yes - the PCA9548AD,118 features three hardware address pins (A0, A1, A2), allowing up to eight devices to coexist on a single I²C bus with unique 7-bit slave addresses (1110 A2 A1 A0). Each device responds only to its configured address, enabling hierarchical bus expansion - for example, one PCA9548AD,118 managing sensors on a daughterboard, another managing power monitors on the main board.

What happens to the downstream I²C channels during a PCA9548AD,118 reset event?

During either an external RESET pin assertion (LOW pulse ≥4 ns) or internal power-on reset, the PCA9548AD,118 clears its control register to all zeros and deselects all eight SCx/SDx channels. This forces all downstream buses into high-impedance isolation, preventing unintended communication or bus contention - a critical safety behavior confirmed in the PCA9548AD,118 functional description and timing diagrams.

Is the PCA9548AD,118 compatible with SMBus protocols?

Yes - the PCA9548AD,118 is explicitly designed to be compatible with SMBus standards, including timeout handling, packet error checking (PEC) transparency, and alert response protocol support. Its I²C interface logic adheres to SMBus v2.0 electrical and timing specifications, and it tolerates SMBus-specific voltage thresholds (e.g., VIH ≥0.7×VDD, VIL ≤0.3×VDD), making PCA9548AD,118 suitable for server baseboard management and smart battery applications.