NXP Semiconductors PCA9846PWJ

Overview

PCA9846PWJ from NXP Semiconductors is a 4-channel ultra-low voltage I²C-bus switch with active-low reset, supporting Fast-mode Plus (1 MHz) operation and bidirectional voltage translation between 0.8 V, 1.8 V, 2.5 V, and 3.3 V buses. It enables channel-selectable fan-out from one upstream SCL/SDA pair to four downstream SCx/SDx channels, allowing multiple devices with identical I²C addresses to coexist on the same bus. Used in multi-voltage embedded systems requiring bus segmentation and fault recovery.

For engineers reviewing the PCA9846PWJ datasheet, PCA9846PWJ pinout, PCA9846PWJ application, or PCA9846PWJ equivalent, key selection considerations include its dual-supply architecture (VDD1 for input thresholds, VDD2 for core logic), programmable 4-bit control register for channel enable/disable, hardware RESET pin for bus fault recovery, and support for up to 16 devices via A0/A1 address pins.

Technical Context

The PCA9846PWJ implements a quad-channel pass-gate switching architecture controlled entirely via I²C commands - no external logic required. Its control register (B3–B0) directly maps to SC0/SD0 through SC3/SD3 channel enable states, with channel activation deferred until STOP condition detection to prevent false bus transitions.

It features two independent supply domains: VDD1 (0.8 V–3.6 V) sets input threshold levels (VIH = 0.7×VDD1, VIL = 0.3×VDD1) and limits maximum translated output voltage, while VDD2 (1.65 V–3.6 V) powers internal logic and must exceed 1.65 V for guaranteed operation. The device includes both hardware RESET (active LOW) and software reset via General Call address 00h + data byte 06h.

Key Specifications

Pinout & Package

TSSOP16 package (SOT403-1), 4.4 mm body width, lead pitch 0.65 mm, exposed pad not present - suitable for standard surface-mount assembly and reflow processes.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548APWR and PCA9546ADW, the PCA9846PWJ uniquely delivers 0.8 V controller compatibility, dual-supply voltage translation, hardware RESET, and 1 MHz operation - making it the only option for modern ultra-low-power, multi-voltage I²C architectures.

Availability

PCA9846PWJ is available at Aetrix Electronics and suitable for industrial automation, server management, multi-sensor IoT edge nodes, and automotive infotainment subsystems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for PCA9846PWJ 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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The PCA9846PWJ belongs to NXP's I²C infrastructure portfolio, designed specifically to solve voltage-domain interoperability and bus scalability challenges in resource-constrained, multi-rail embedded systems.

FAQ

What is the minimum VDD1 voltage required for PCA9846PWJ to operate with a 0.8 V controller?

The PCA9846PWJ specifies VDD1 = 0.8 V as the absolute minimum supply voltage. At this level, input thresholds are VIH = 0.56 V (0.7×VDD1) and VIL = 0.24 V (0.3×VDD1), ensuring reliable recognition of 0.8 V logic levels. Operation below 0.8 V is not characterized or guaranteed - the PCA9846PWJ must be powered with VDD1 ≥ 0.8 V to interface with 0.8 V controllers.

Can PCA9846PWJ translate from a higher-voltage upstream bus to lower-voltage downstream peripherals?

Yes - the PCA9846PWJ supports bidirectional translation in either direction. When VDD1 is set to a higher voltage (e.g., 3.3 V) and VDD2 ≥ 1.65 V, the device can translate signals from a 3.3 V controller to 1.8 V or 0.8 V peripherals. Input thresholds scale with VDD1, and output voltage is clamped to min(VDD1, VDD2), so proper pull-up placement on each downstream bus remains essential for correct logic levels.

How does the PCA9846PWJ handle simultaneous activation of multiple channels?

The PCA9846PWJ allows any combination of its four channels to be enabled simultaneously via bits B0–B3 in the control register. When multiple channels are active, their SCx/SDx lines are electrically connected to the upstream SCL/SDA - effectively paralleling all selected downstream buses. Designers must verify total bus capacitance stays within I²C specification limits (≤400 pF) and that pull-up resistors on each segment collectively meet LOW-level sink current requirements.

Is the RESET pin on PCA9846PWJ debounced internally, and what is the minimum pulse width required?

The PCA9846PWJ RESET pin has no internal debounce circuitry - external RC filtering or microcontroller-driven debouncing is recommended for noisy environments. The datasheet specifies tw(rst)L as the minimum LOW pulse width required to trigger reset; while not explicitly quantified in the provided excerpt, typical NXP I²C switch reset timing is ≥100 ns. For robust operation, maintain RESET LOW for ≥1 μs to ensure reliable state machine and channel register reset.

Does PCA9846PWJ support hot-plug detection or automatic channel disable on fault?

No - the PCA9846PWJ does not include hot-plug detection circuitry or automatic fault-based channel disable. It relies on external supervision (e.g., host MCU monitoring SCL/SDA line states) to detect bus faults. Recovery is manual: either assert the hardware RESET pin LOW or issue the I²C software reset command (General Call 00h + 06h). Channel selection remains static until explicitly updated via I²C write to the control register.