Texas Instruments PCA9546APWRE4

Overview

PCA9546APWRE4 from Texas Instruments is a low-voltage 4-channel bidirectional I²C and SMBus switch with active-low reset, used to resolve slave address conflicts and enable voltage-level translation between 1.8-V, 2.5-V, 3.3-V, and 5-V buses. It supports up to 400-kHz clock frequency, features 5.5-V tolerant inputs, and operates from 2.3 V to 5.5 V.

For engineers reviewing the PCA9546APWRE4 datasheet, PCA9546APWRE4 pinout, PCA9546APWRE4 application, or PCA9546APWRE4 equivalent, this page delivers verified functional role, channel selection logic, reset behavior, voltage translation capability, and real-world use in multi-sensor and high-density I²C systems.

Technical Context

The PCA9546APWRE4 implements four independent bidirectional pass-gate switches controlled via an 8-bit I²C register, where B0–B3 bits directly enable/disable channels 0–3. Its internal state machine resets on power-up or active-low RESET assertion, deselecting all channels and clearing bus contention.

Each SCn/SDn channel supports independent pull-up voltages (VDPU0–VDPU3), enabling true voltage translation without level shifters. The device uses no internal pull-ups on A0–A2 address pins and requires external resistors on SDA/SCL and all SD/SC lines to define bus voltage levels per channel.

Key Specifications

Pinout & Package

TSSOP-16 package (5.00 mm × 4.40 mm), lead-free and RoHS-compliant. Pin mapping validated per TI SCPS148G datasheet Rev G (May 2016).

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCA9544APW, PCA9546APWRE4 provides deterministic bus recovery via RESET; compared with TCA9548APWR, it offers smaller footprint and lower cost for ≤4-channel systems while retaining full register compatibility.

Availability

PCA9546APWRE4 is available at Aetrix Electronics and suitable for server management, industrial sensor hubs, telecom router backplanes, and embedded test equipment requiring stable component supply and long-term industrial lifecycle support.

Supply support for PCA9546APWRE4 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The PCA9546A belongs to TI's I²C infrastructure portfolio, designed specifically to solve bus congestion, slave address conflict, and mixed-voltage interoperability in high-density embedded systems.

FAQ

What is the primary function of the PCA9546APWRE4 in an I²C system?

The PCA9546APWRE4 functions as a 4-channel bidirectional I²C bus switch that isolates and selects downstream slave devices to resolve address conflicts and enable voltage-level translation. It allows a single I²C master to communicate with up to four groups of slaves-each potentially operating at different voltages-without bus contention. The PCA9546APWRE4 achieves this through programmable channel enable bits in its 8-bit control register and hardware address pins A0–A2.

How does the RESET pin on the PCA9546APWRE4 improve system reliability?

The active-low RESET pin on the PCA9546APWRE4 forces an immediate reset of the internal I²C state machine and deselects all four channels, recovering from stuck-bus conditions where a downstream slave holds SDA or SCL low. This avoids full system power cycling and restores communication within nanoseconds. The PCA9546APWRE4 requires a minimum 6 ns pulse width on RESET and must be pulled up externally; improper voltage sequencing (RESET > VCC) can cause current leakage.

Can the PCA9546APWRE4 translate between 1.8-V and 5-V I²C buses? How is this implemented?

Yes, the PCA9546APWRE4 supports 1.8-V ↔ 5-V translation by leveraging its pass-gate architecture and external pull-up resistors. VCC sets the maximum pass voltage, while each SDn/SCn pair is pulled up to its target slave voltage (e.g., VDPU0 = 1.8 V, VDPU3 = 5 V). The PCA9546APWRE4's 5.5-V tolerant I/Os and low RON ensure signal integrity across voltage domains. No additional level-shifting components are needed when VCC ≥ highest slave voltage.

What are the hardware address options for the PCA9546APWRE4, and how are they configured?

The PCA9546APWRE4 uses three hardware address pins-A0, A1, and A2-to configure one of eight possible I²C slave addresses (0x70 to 0x77). Each pin must be hard-wired to either VCC (logic high) or GND (logic low); floating connections are not permitted. These pins are sampled at power-up and remain static during operation. The PCA9546APWRE4 does not include internal pull-ups on A0–A2, so external termination is mandatory for deterministic addressing.

Does the PCA9546APWRE4 support Fast Mode I²C (400 kHz), and what timing constraints apply?

Yes, the PCA9546APWRE4 fully supports I²C Fast Mode up to 400 kHz, with validated timing parameters including tSCL (1.3 µs min), tSCH (0.6 µs min), and tSDS (100 ns min). Propagation delay is ≤1 ns (CL = 50 pF), and bus capacitance is limited to 400 pF per channel. To maintain timing compliance, designers must observe recommended rise/fall times (20 + 0.1Cb ns) and ensure total capacitive load-including PCB traces and slave inputs-stays within specification for each selected channel.