Diodes Incorporated PI3B3126WEX

Overview

PI3B3126WEX from Diodes Incorporated is a 3.3V, 4-bit, 2-port bus switch with individual active-HIGH enables, fabricated in sub-micron CMOS. It features four 5Ω analog switches, 0.25ns propagation delay, ultra-low 0.1µA quiescent current, and SOIC-14 packaging-designed for high-speed data routing in notebook I/O expansion and low-power peripheral interconnects.

For engineers reviewing the PI3B3126WEX datasheet, PI3B3126WEX pinout, PI3B3126WEX application, or PI3B3126WEX equivalent, key selection criteria include enable polarity (active-HIGH), on-resistance matching across channels, bus isolation during disable, rail-to-rail input tolerance up to 3.6V, and compatibility with 74xx126 logic footprints.

Technical Context

The PI3B3126 operates as a bidirectional, voltage-transparent analog switch array where each A–B channel connects only when its corresponding BE pin is HIGH. Its CMOS transmission-gate architecture ensures no DC path between ports when disabled and introduces negligible RC delay (<0.25ns time constant with 50pF load).

Unlike level-shifters or buffers, it provides passive signal pass-through with no internal logic state retention or timing control-enabling seamless integration into hot-plug-capable systems and mixed-voltage I/O domains where V_IN may exceed V_CC (up to +3.6V).

Key Specifications

Pinout & Package

PI3B3126WEX is housed in a 14-pin SOIC (W) package (150mil width), with exposed pad omitted and standard JEDEC MS-012AC outline. Pin 1 is marked by notch or dot; pin numbering follows counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PI3B3126WEX, the LEX variant offers identical functionality in a smaller TSSOP package for density-sensitive layouts, while the SN74CBT3126PW trades ultra-low quiescent current for broader vendor availability-making WEX optimal for power-constrained notebooks and LEX for compact industrial controllers.

Availability

PI3B3126WEX is available at Aetrix Electronics and suitable for notebook I/O expansion, SMBus device selection, and LPC bus isolation requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for PI3B3126WEX 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, energy-efficient solutions for consumer, computing, industrial, and automotive markets.

The PI3B series targets high-speed, low-power bus switching applications-specifically engineered to replace legacy 74-series logic with superior analog characteristics, zero propagation delay, and rail-to-rail interoperability.

FAQ

What is the maximum signal voltage that can be passed through PI3B3126WEX?

The PI3B3126WEX supports input voltages from –0.5V to +3.6V on all A/B pins, independent of V_CC. This allows safe operation with 1.8V, 2.5V, or 3.3V logic families-even when V_CC is at nominal 3.3V. Exceeding +3.6V risks damage due to internal clamp diode conduction.

Does PI3B3126WEX require external pull-up resistors on enable pins?

No external pull-ups are required for normal operation, but Diodes recommends a weak pull-up (≥100kΩ) on each BE pin for power-up protection-ensuring all switches remain disabled until firmware asserts valid enable states. This prevents unintended signal coupling during cold boot or brown-out conditions.

Can PI3B3126WEX be used in bidirectional analog signal paths?

Yes-the PI3B3126WEX is fully bidirectional with symmetrical R_ON and capacitance. It passes analog signals such as audio, sensor outputs, or clock references with minimal distortion, provided peak voltage stays within the –0.5V to +3.6V range and current remains below 120mA per channel.

How does PI3B3126WEX differ from PI3B3125WEX?

The PI3B3126WEX uses active-HIGH enables (BE = HIGH → ON), whereas PI3B3125WEX uses active-LOW enables (BE = LOW → ON). All other electrical specs-including R_ON, propagation delay, and package-are identical. The choice depends solely on system-level enable logic polarity and existing PCB layout constraints.