Diodes Incorporated PI4MSD5V9540BUEX

Overview

PI4MSD5V9540BUEX from Diodes Incorporated is a 1-of-2 bidirectional I²C bus multiplexer with voltage-level translation capability, designed to isolate and route SCL/SDA signals between one upstream master and two downstream slave channels (SC0/SD0 and SC1/SD1). It operates from 1.65V to 5.5V, supports 0–400 kHz I²C Fast Mode, features 5V-tolerant I/O pins, and uses VCC to clamp pass-gate output voltage for interoperability across 1.2V, 1.8V, 2.5V, 3.3V, and 5V buses.

For engineers reviewing the PI4MSD5V9540BUEX datasheet, PI4MSD5V9540BUEX pinout, PI4MSD5V9540BUEX application, or PI4MSD5V9540BUEX equivalent, this device addresses critical I²C bus expansion, mixed-voltage system integration, channel isolation under hot-insertion conditions, and low-power standby operation in resource-constrained embedded systems.

Technical Context

The PI4MSD5V9540BUEX implements a dual-channel analog pass-gate architecture controlled by an I²C-accessible 8-bit control register, where only bits B1–B0 determine channel selection (00 = none, 01 = channel 1, 10 = channel 0). Its power-on reset initializes all registers to zero and deselects both channels, eliminating glitch risk during power-up.

Voltage translation is achieved via VCC-referenced pass transistors: Vpass ≤ VCC ensures downstream bus clamping-e.g., setting VCC = 3.3V limits Vpass to ≤2.7V, enabling safe interfacing of 5V masters with 3.3V/2.7V slaves. Input capacitance is 9–10 pF per I/O, and propagation delay is 0.3 ns under 15 pF load.

Key Specifications

Pinout & Package

PI4MSD5V9540BUEX is packaged in an 8-pin MSOP (U) surface-mount package with 0.65 mm pitch, moisture sensitivity level 1, matte tin-plated leads, and UL 94V-0 flammability rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9548A and PCA9546A, the PI4MSD5V9540BUEX uniquely delivers 2-channel bidirectional voltage translation (1.2V–5V), hot-swap readiness, and 400 kHz Fast Mode support-making it optimal for compact, mixed-voltage, dynamically reconfigurable I²C topologies.

Availability

PI4MSD5V9540BUEX is available at Aetrix Electronics and suitable for multi-sensor data acquisition, industrial PLC bus expansion, hot-swappable FRU interfacing, and embedded debug/test access requiring stable component supply and long-term manufacturability.

Supply support for PI4MSD5V9540BUEX 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, specializing in high-performance, high-reliability components for automotive, industrial, computing, and consumer markets.

The PI4MSD5V9540BUEX belongs to Diodes' Pericom® interface solutions product line, engineered specifically for robust, low-latency I²C signal routing and voltage-domain bridging in space-constrained embedded systems.

FAQ

What is the maximum capacitive load the PI4MSD5V9540BUEX can drive on each downstream channel?

The device supports up to 400 pF total I²C bus capacitance per channel, consistent with standard I²C Fast Mode specifications. This includes contributions from PCB traces, slave devices, and pull-up resistors. The 9–10 pF input capacitance and 3–5 pF I/O capacitance ensure minimal loading impact, allowing full utilization of the 400 kHz bandwidth without signal degradation.

Can the PI4MSD5V9540BUEX translate between 1.2V and 5V I²C buses simultaneously?

Yes-by setting VCC to ≤1.5V (e.g., 1.2V or 1.5V), Vpass is clamped to ≤0.9V or ≤1.3V respectively, enabling safe 1.2V slave communication with a 5V master. External pull-up resistors on each SCx/SDx pair must match their respective bus voltages (e.g., 5V pull-ups on upstream side, 1.2V pull-ups on downstream side), as confirmed in Table 1 of the datasheet.

Does the PI4MSD5V9540BUEX support repeated START conditions during channel switching?

No-channel selection takes effect only after a STOP condition is issued on the I²C bus. The control register accepts new configuration bytes during ongoing transactions, but the hardware switch activates post-STOP to guarantee all SCx/SDx lines settle HIGH before connection, preventing false START/STOP detection or data corruption.

How does the power-on reset behavior affect system initialization sequence?

At power-up, the internal POR holds the device in reset until VCC reaches ≥1.3V (typical), then initializes the control register to 0x00-deselecting both channels and disabling all pass gates. This guarantees zero bus contention during MCU boot. To reinitialize mid-operation, VCC must drop below 0.2V for ≥5 µs, which is typically implemented via dedicated reset circuitry or controlled power sequencing.