Diodes Incorporated PI4IOE5V9537UEX

Overview

PI4IOE5V9537UEX from Diodes Incorporated (acquired Pericom Semiconductor) is a 4-bit I²C/SMBus GPIO expander with active-low interrupt and reset, 5V-tolerant I/Os, 2.3–5.5 V operation, and MSOP-10 package. It serves as a low-power remote I/O interface for ACPI power switches, push buttons, LEDs, fans, and sensors in embedded control subsystems.

For engineers reviewing the PI4IOE5V9537UEX datasheet, PI4IOE5V9537UEX pinout, PI4IOE5V9537UEX application, or PI4IOE5V9537UEX equivalent, key selection criteria include 5V I/O tolerance, open-drain INT output timing (≤4 µs valid), standby current ≤1 µA at 5.5 V, and support for I²C Fast Mode Plus (1 MHz).

Technical Context

The device implements a register-mapped I²C slave interface with four dedicated I/O pins (IO0–IO3), each configurable as input or output via Configuration Register (Reg 3). Polarity inversion (Reg 2) and input port read-back (Reg 0) enable flexible signal conditioning without external logic.

Its interrupt generation is edge-triggered on input state change and cleared only upon reading the Input Port register - not by INT pin release - ensuring no missed events during bus arbitration. Power-on reset (VPOR = 1.16–1.41 V) and asynchronous active-low RESET pin provide deterministic initialization independent of I²C traffic.

Key Specifications

Pinout & Package

Package: MSOP-10 (3.0 mm × 4.9 mm, 0.5 mm pitch), RoHS-compliant, Pb-free, tape-and-reel (UEX suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TCA6408A and PCA9534A, PI4IOE5V9537UEX delivers targeted 4-bit expansion with lower standby current, hardware polarity inversion, and integrated noise filtering - making it optimal for space-constrained, interrupt-sensitive, and battery-aware designs.

Availability

PI4IOE5V9537UEX is available at Aetrix Electronics and suitable for ACPI power management, LED indicator control, fan tachometer monitoring, and sensor interface applications requiring stable component supply and long-term manufacturability.

Supply support for PI4IOE5V9537UEX 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 acquired Pericom Semiconductor in 2017 and integrates its high-performance interface and timing solutions into its broad analog portfolio.

This device belongs to Diodes' legacy Pericom GPIO expander product line, designed specifically for low-power, interrupt-capable I²C peripheral expansion in space- and power-constrained embedded systems.

FAQ

What is the minimum VCC required for reliable I²C communication?

The PI4IOE5V9537UEX specifies a minimum supply voltage of 2.3 V across all operating conditions. At this voltage, I²C Fast Mode (400 kHz) remains functional with guaranteed VOL ≤ 0.7 V and VIH ≥ 1.8 V for SCL/SDA, enabling interoperability with 2.5 V or 3.3 V masters without level translation.

How does the interrupt pin behave after a state change on an input pin?

The INT pin goes low within 4 µs of an input state change and remains asserted until the Input Port register is read by the master - not upon pin reversion. This latched behavior ensures no interrupt loss during bus contention or delayed servicing, and requires explicit register access to clear.

Can IO pins be used as both inputs and outputs simultaneously on the same device?

Yes - each of IO0–IO3 is individually configurable as input or output via bits in the Configuration Register (Reg 3). For example, IO0 and IO1 can drive LEDs (outputs), while IO2 and IO3 monitor push buttons (inputs), all within one MSOP-10 package without external logic.

Is an external pull-up resistor required on the INT pin?

Yes - the INT pin is open-drain and requires an external pull-up resistor to VCC (typically 4.7 kΩ) to generate a valid high-level signal. The value must balance rise time (per I²C bus capacitance) and current draw; Diodes recommends 2.2–10 kΩ depending on bus speed and load.