NXP Semiconductors PCA9548AD,112

Overview

PCA9548AD,112 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 - used in multi-sensor server management and modular embedded systems requiring bus isolation.

For engineers reviewing the PCA9548AD,112 datasheet, PCA9548AD,112 pinout, PCA9548AD,112 application, or PCA9548AD,112 equivalent, this page provides verified technical context, SO24 package pin mapping, real-world I²C channel selection behavior, voltage translation design constraints, and validated alternatives for bus expansion in industrial control, telecom chassis, and PCIe-based compute modules.

Technical Context

The PCA9548AD,112 implements eight independent bidirectional pass-gate switches controlled by an 8-bit I²C-accessible register. Each SCx/SDx channel is enabled/disabled via individual bit writes, with no automatic arbitration - multiple channels may be active simultaneously if bus capacitance remains ≤400 pF per line. The internal state machine resets on START/STOP boundaries to prevent false transitions during channel activation.

Its reset circuit responds to a low pulse ≥4 ns on the dedicated RESET pin, forcing all channels off and clearing the control register. The VDD-referenced pass-gate architecture enables voltage level translation: Vo(sw) is clamped to ≤2.8 V when VDD = 3.0–3.6 V, allowing safe interconnection of 3.3 V masters with 2.7 V peripherals without external level shifters.

Key Specifications

Pinout & Package

PCA9548AD,112 uses the SO24 (SOT137-1) package: plastic small outline, 24 leads, 7.5 mm body width, 1.0 mm max height, with standard gull-wing lead form and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548A and PCA9546AD, PCA9548AD,112 offers the broadest channel count in SO24 packaging, fastest reset response, and longest field-proven deployment history in high-availability systems - making it optimal for scalable, fault-tolerant I²C architectures.

Availability

PCA9548AD,112 is available at Aetrix Electronics and suitable for server baseboard management, industrial PLC I/O expansion, telecom chassis monitoring, and PCIe add-in card sensor hub applications requiring stable component supply across extended product lifecycles.

Supply support for PCA9548AD,112 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 focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface and power management ICs.

The PCA9548A family was designed specifically to solve I²C bus contention and voltage domain isolation challenges in dense, multi-peripheral embedded systems - targeting server, networking, and programmable logic platforms.

FAQ

What is the maximum I²C clock frequency supported by PCA9548AD,112?

The PCA9548AD,112 supports I²C clock frequencies up to 400 kHz, compliant with Fast-mode I²C specifications. It does not support Fast-mode Plus (1 MHz). Timing parameters such as tLOW, tHIGH, and tSU;DAT are guaranteed across the full 2.3 V to 5.5 V supply range, with propagation delay ≤0.3 ns per channel under typical load conditions.

How does PCA9548AD,112 handle voltage translation between different I²C bus domains?

The PCA9548AD,112 uses its VDD supply voltage to clamp the maximum output voltage (Vo(sw)) passed through its pass gates. For example, with VDD = 3.3 V, Vo(sw) is limited to ≤2.8 V, enabling safe communication between a 3.3 V master and 2.5 V or 1.8 V peripherals - no external level shifters required. Pull-up resistors on each downstream bus set the final logic-high voltage.

Can multiple channels of PCA9548AD,112 be enabled simultaneously?

Yes, the PCA9548AD,112 allows any combination of its eight channels to be enabled simultaneously via the 8-bit control register. However, total bus capacitance across all active channels must remain ≤400 pF to maintain I²C timing compliance at 400 kHz. Enabling too many channels risks violating tR/tF rise/fall time specs and causing ACK timeouts.

What is the purpose of the RESET pin on PCA9548AD,112?

RESET is an active-low asynchronous input that forces the PCA9548AD,112 to clear its control register and disable all eight channels, recovering from downstream I²C bus lockups (e.g., a stuck LOW condition on SCx/SDx). It requires a minimum pulse width of 4 ns and must be pulled up to VDD externally - unlike power-on reset, it operates independently of VDD sequencing.

Is PCA9548AD,112 compatible with SMBus protocols?

Yes, the PCA9548AD,112 is fully compatible with SMBus 2.0 specifications, including timeout, alert response, and packet error checking (PEC) pass-through. Its I²C interface logic meets SMBus electrical requirements, and its reset functionality aligns with SMBus host alert recovery sequences - making it suitable for server management controllers and intelligent platform management interface (IPMI) implementations.