NXP Semiconductors PCA9546AD,118

Overview

PCA9546AD,118 from NXP Semiconductors is a quad-channel bidirectional I²C-bus switch with active-low reset, operating from 2.3 V to 5.5 V supply, supporting up to 400 kHz clock frequency, 5 V-tolerant I/O, and voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V buses. It enables isolated communication across four downstream I²C segments in server management, modular computing, and multi-sensor systems.

For engineers reviewing the PCA9546AD,118 datasheet, PCA9546AD,118 pinout, PCA9546AD,118 application, or PCA9546AD,118 equivalent, key selection criteria include channel-selectable isolation, reset-driven bus fault recovery, low Ron (5–30 Ω), standby current as low as 0.1 µA, and SO16 package compatibility with industrial temperature range (−40 °C to +85 °C).

Technical Context

The PCA9546AD,118 implements four independent pass-gate switches controlled via an 8-bit I²C register where bits B0–B3 enable/disable channels SCx/SDx individually or in combination. Its internal power-on reset and external active-low RESET input independently initialize the control register to all-zero state, deselecting all channels and clearing bus state machine latches.

Voltage translation is achieved through VDD-referenced pass-gate threshold control: Vo(sw) is clamped by VDD (e.g., 3.3 V supply limits max output to ~1.9–2.8 V), enabling safe interconnection of mixed-voltage I²C domains without level-shifter ICs. All I/O pins tolerate 5 V regardless of VDD setting.

Key Specifications

Pinout & Package

PCA9546AD,118 uses the SO16 (SOT109-1) plastic small outline package: 16-pin, 3.9 mm body width, 1.27 mm pitch, surface-mount, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548APWR and PCA9544AD,118, the PCA9546AD,118 uniquely combines quad-channel isolation, hardware RESET, 400 kHz support, and ultra-low standby current in SO16 - making it optimal for fault-critical industrial and server applications requiring autonomous bus recovery.

Availability

PCA9546AD,118 is available at Aetrix Electronics and suitable for server baseboard management, modular PLC backplanes, and multi-sensor IoT gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for PCA9546AD,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, and IoT applications, with deep expertise in I²C, SMBus, and mixed-signal interface ICs.

The PCA9546A family was designed specifically to solve I²C bus contention and voltage-domain bridging challenges in dense, modular electronic systems - delivering deterministic channel isolation and hardware-assisted fault recovery.

FAQ

What is the function of the RESET pin on the PCA9546AD,118?

The RESET pin on the PCA9546AD,118 is an active-low asynchronous input that forces the internal control register to zero and deselects all four I²C channels, resetting the bus state machine. This recovers the device from downstream bus lockup (e.g., stuck LOW condition) without requiring power cycle. The PCA9546AD,118 requires an external pull-up resistor on RESET and recognizes pulses ≥4 ns wide.

Can the PCA9546AD,118 translate between 1.8 V and 5 V I²C buses?

Yes, the PCA9546AD,118 supports voltage translation between 1.8 V, 2.5 V, 3.3 V, and 5 V I²C domains. Its pass-gate output voltage Vo(sw) is clamped by VDD (e.g., setting VDD = 2.5 V limits Vo(sw) to ≤1.5 V), while all I/O pins remain 5 V tolerant. External pull-up resistors on each channel set the final bus voltage level, and the PCA9546AD,118 ensures signal integrity across domains without additional components.

How many PCA9546AD,118 devices can share the same I²C bus?

Up to eight PCA9546AD,118 devices can coexist on a single I²C bus using hardware address pins A0, A1, and A2. These three pins configure the three LSBs of the fixed 7-bit slave address (1110 A2 A1 A0), yielding eight unique addresses. No internal pull-ups exist on A0–A2, so external termination is required - and the PCA9546AD,118 must be configured before initialization to avoid address conflicts.

Does the PCA9546AD,118 support fast-mode I²C (400 kHz)?

Yes, the PCA9546AD,118 fully supports fast-mode I²C operation up to 400 kHz, as confirmed in its dynamic characteristics table. Propagation delay is ≤0.3 ns, and timing parameters (tLOW, tHIGH, tSU;DAT, etc.) meet I²C Specification Rev. 6 requirements for both standard-mode (100 kHz) and fast-mode. The PCA9546AD,118 maintains signal fidelity across all four channels at this speed when load capacitance remains ≤400 pF per bus line.

What is the maximum capacitive load the PCA9546AD,118 can drive per channel?

The PCA9546AD,118 is rated for a maximum bus line capacitance of 400 pF per channel (Cb), as specified in Table 9 of the datasheet. This limit applies to the total capacitance seen on any SCx/SDx pair, including PCB traces, connectors, and downstream device inputs. Exceeding 400 pF may violate timing margins (e.g., rise/fall times, tHD;DAT), causing communication errors - and the PCA9546AD,118 does not include active bus buffering to extend this limit.