Diodes Incorporated PI4MSD5V9544ALEX

Overview

PI4MSD5V9544ALEX from Diodes Incorporated is a 1-of-4 bidirectional I²C/SMBus multiplexer with integrated interrupt logic, designed to isolate and route I²C traffic across four downstream channels (SC0/SD0–SC3/SD3) from a single upstream SCL/SDA bus. It supports voltage translation between 1.2 V, 1.8 V, 2.5 V, 3.3 V, and 5 V domains, operates from 1.65 V to 5.5 V, features 400 kHz Fast Mode I²C compatibility, and includes active-low interrupt aggregation (INT0–INT3 → INT). It is used in server baseboard management controllers (BMCs) to manage multiple temperature sensors or EEPROMs on separate voltage rails.

For engineers reviewing the PI4MSD5V9544ALEX datasheet, PI4MSD5V9544ALEX pinout, PI4MSD5V9544ALEX application, or PI4MSD5V9544ALEX equivalent, key selection criteria include its 4-channel I²C fanout capability, 5 V-tolerant inputs, low Ron (4–70 Ω depending on VCC), power-up default channel deselection, and interrupt status reporting via I²C-readable control register bits D3–D0.

Technical Context

The device implements a programmable 1-of-4 analog switch matrix controlled by an I²C-accessible 8-bit control register, where bits B1–B0 select the active channel (00–11) and bits D3–D0 reflect real-time interrupt status per channel. Its pass-gate architecture uses VCC as a voltage clamp reference, enabling bidirectional level translation without external translators.

Interrupt handling is asynchronous: INTn inputs are sampled independently of channel selection state, and the aggregated open-drain INT output asserts low when any INTn is low. The control register retains interrupt flags until cleared by host read, supporting polled or interrupt-driven fault detection in multi-sensor systems.

Key Specifications

Pinout & Package

PI4MSD5V9544ALEX is housed in a 20-pin TSSOP package (4.4 mm × 6.5 mm, 0.65 mm pitch) with exposed pad for thermal performance. Pin numbering follows standard TSSOP orientation (pin 1 at top-left corner, counterclockwise).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA9544APWR and PCA9544ADW, PI4MSD5V9544ALEX uniquely integrates bidirectional voltage translation and wider supply range (1.65–5.5 V), making it the only option among the three capable of connecting 1.2 V sensors to a 5 V host without external components.

Availability

PI4MSD5V9544ALEX is available at Aetrix Electronics and suitable for server BMCs, industrial PLCs, automotive ADAS modules, and network equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for PI4MSD5V9544ALEX 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 semiconductor company specializing in discrete, analog, and mixed-signal ICs for power management, signal integrity, and connectivity applications.

This device belongs to Diodes' I²C interface and system management product line, engineered specifically for high-reliability, multi-rail embedded systems requiring intelligent bus expansion and fault-aware peripheral management.

FAQ

What is the minimum VCC required for reliable 1.8 V downstream bus operation?

The PI4MSD5V9544ALEX achieves Vpass ≈ 0.9 V at 1.8 V VCC, which is insufficient to pass 1.8 V signals. To support 1.8 V downstream buses, VCC must be set ≥2.3 V (yielding Vpass ≥1.1 V). Per DC Electrical Characteristics, VCC = 2.5 V delivers Vpass ≈1.5 V - adequate for 1.8 V logic high thresholds with margin. Always verify Vpass vs. downstream VIH(min) in final design.

Can INT0–INT3 be used as general-purpose inputs when interrupt functionality is unused?

Yes - the INT0–INT3 pins are CMOS-compatible inputs with ±1 µA leakage and 0.3×VCC/0.7×VCC logic thresholds. When not used for interrupts, they must be externally pulled to VCC via ≥10 kΩ resistors to prevent floating states. No internal pull-ups exist, so unconnected pins risk noise-induced false interrupts or increased power consumption.

How does the device handle simultaneous interrupts on multiple channels?

The INT output is an open-drain AND of INT0–INT3, so it asserts low if any input is low. Simultaneous interrupts are preserved in the control register: bits D3–D0 directly reflect the instantaneous state of INT3–INT0. A host read returns the full 8-bit register, allowing software to decode all asserted channels (e.g., 0b0110 = INT1 and INT2 active) without loss of information.

Is there a hardware reset pin, and how is the device reset after power-up?

No hardware reset pin exists. Reset is fully managed by internal Power-On Reset (POR): when VCC rises above VPOR (1.3–1.5 V), the device initializes registers to 0x00 and deselects all channels. To force a reset outside power cycle, VCC must be lowered to ≤0.2 V for ≥5 µs - a technique usable in firmware-controlled recovery sequences but requiring precise power rail control.