NXP Semiconductors PCA9546APW,112

Overview

PCA9546APW,112 from NXP Semiconductors is a quad-channel bidirectional I²C-bus switch with active-low reset, enabling selective routing of SCL/SDA signals to four downstream buses. It supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V domains, features low ON-resistance (5–30 Ω), operates from 2.3 V to 5.5 V, and delivers 0 Hz to 400 kHz clock support - ideal for multi-voltage sensor hub or peripheral expansion in embedded control systems.

For engineers reviewing the PCA9546APW,112 datasheet, PCA9546APW,112 pinout, PCA9546APW,112 application, or PCA9546APW,112 equivalent, key selection criteria include I²C channel isolation capability, reset-driven bus fault recovery, voltage-level translation without external level shifters, and compatibility with SMBus standards across industrial temperature range (−40 °C to +85 °C).

Technical Context

The PCA9546APW,112 implements four independent pass-gate switches controlled via an 8-bit I²C-compatible control register, where bits B0–B3 directly enable/disable SCx/SDx channels. Its internal power-on reset (POR) and external active-low RESET input independently initialize the control register to all-zero state, deselecting all channels and clearing the I²C-bus state machine.

Voltage translation is achieved through VDD-referenced pass-gate threshold control: Vo(sw) is clamped by VDD, allowing upstream 5 V buses to safely interface with downstream 1.8–3.3 V peripherals when VDD is set to the lowest target bus voltage. All I/O pins are 5 V tolerant, and no glitch occurs at power-up due to synchronized POR timing.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, 16-pin surface-mount plastic thin shrink small outline package with gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9546APWR and PCA9544APW,112, the PCA9546APW,112 uniquely combines hardware reset-driven bus recovery, tighter reset timing, and POR synchronization - making it optimal for mission-critical industrial and automotive I²C infrastructure where deterministic fault containment is required.

Availability

PCA9546APW,112 is available at Aetrix Electronics and suitable for server baseboard management, industrial sensor hubs, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for PCA9546APW,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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with deep expertise in interface, power, and sensing technologies.

The PCA9546A product line was designed specifically to solve I²C bus congestion and voltage-domain interoperability challenges in resource-constrained embedded systems - delivering scalable, pin-compatible switching with integrated fault recovery.

FAQ

What is the primary function of the PCA9546APW,112 in an I²C system?

The PCA9546APW,112 functions as a quad-channel bidirectional I²C-bus switch that routes a single upstream SCL/SDA pair to any combination of four isolated downstream I²C buses. It enables dynamic channel selection via I²C write to its control register, supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V domains using VDD as a clamp reference, and provides active-low RESET for bus fault recovery - all within a TSSOP16 package. This makes PCA9546APW,112 essential for expanding I²C connectivity while maintaining signal integrity and system robustness.

How does the PCA9546APW,112 handle voltage level translation between different I²C buses?

The PCA9546APW,112 uses its VDD supply voltage to limit the maximum output voltage (Vo(sw)) passed through its pass-gate switches. When VDD is set to the lowest target bus voltage (e.g., 3.3 V), Vo(sw) is clamped to ≤2.8 V, allowing safe communication between a 5 V upstream master and 3.3 V or lower downstream peripherals. External pull-up resistors on each SCx/SDx pair set the final bus voltage level, and all I/O pins are 5 V tolerant. This eliminates external level shifters - a core design value of PCA9546APW,112 in mixed-voltage systems.

Can the PCA9546APW,112 be used without connecting the RESET pin?

Yes, the PCA9546APW,112 can operate without an external RESET signal, as it includes an internal Power-On Reset (POR) that initializes the control register to deselect all channels upon power-up. However, omitting the RESET connection removes the ability to recover from downstream bus lockups (e.g., stuck LOW conditions) without cycling VDD. The RESET pin must be pulled HIGH via an external resistor; leaving it floating is not recommended. For robust field operation, connecting RESET is strongly advised - a key reliability feature distinguishing PCA9546APW,112 from non-reset variants like PCA9544APW,112.

What is the maximum capacitive load supported on each I²C channel of the PCA9546APW,112?

The PCA9546APW,112 supports a maximum bus capacitance of 400 pF per channel (SCx/SDx), as specified in its dynamic characteristics table. This aligns with standard I²C Fast-mode requirements and allows reliable operation with typical peripheral counts (e.g., 10–15 devices per segment). Exceeding 400 pF may violate timing margins for tR/tF, tHD;DAT, and tSU;DAT, especially at 400 kHz. Designers should account for PCB trace capacitance, device input capacitance (e.g., 12–13 pF per pin), and pull-up network effects when sizing total load - a critical constraint verified in PCA9546APW,112's characterization across voltage and temperature ranges.

Is the PCA9546APW,112 pin-compatible with other members of the PCA954xA family?

Yes, the PCA9546APW,112 is pin-compatible with other TSSOP16 variants in the PCA954xA family, including PCA9544APW,112 (4-channel, no RESET) and PCA9548APW,112 (8-channel, with RESET). All share identical pinout, supply range, I²C address structure (A0–A2), and voltage translation behavior. The only functional differences lie in channel count and presence/absence of RESET - meaning PCB layout can be reused across these variants for flexible scalability. This pin-compatibility is explicitly confirmed in NXP's ordering information and package drawings for SOT403-1, reinforcing PCA9546APW,112's role in modular I²C infrastructure design.