Diodes Incorporated PI3B3257AQEX

Overview

PI3B3257AQEX from Diodes Incorporated is a 3.3 V quad 2:1 multiplexer/demultiplexer with three-state outputs, pinout- and function-compatible with 74F257/74ALS257 logic devices. It features 5 Ω switch on-resistance, 4.8 ns max propagation delay, and 0.1 µA typical quiescent current, enabling low-noise signal routing in notebook and portable embedded systems.

For engineers reviewing the PI3B3257AQEX datasheet, PI3B3257AQEX pinout, PI3B3257AQEX application, or PI3B3257AQEX equivalent, this device serves as a high-speed, low-power bus switch for logic-level signal selection in space-constrained digital interfaces requiring rail-to-rail input tolerance and minimal ground bounce.

Technical Context

The PI3B3257AQEX implements four independent bidirectional analog/digital switches controlled by a shared select (S) and enable (E) input. Each switch exhibits near-zero propagation delay due to its passive FET architecture-delay arises only from RC time constant of 5 Ω R_ON and load capacitance-not active logic stages.

It operates strictly at 3.3 V nominal supply (–0.5 V to +4.6 V absolute max), supports TTL-level control inputs up to +3.6 V regardless of V_CC, and maintains high-impedance outputs when disabled-enabling hot-swap-safe bus sharing without contention.

Key Specifications

Pinout & Package

PI3B3257AQEX is housed in a 16-pin QSOP (150 mil wide), RoHS-compliant, Pb-free package with standard pin pitch and thermal profile suitable for reflow assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 bus switch applications.

Compared with PI3B3257AQEX, the PI3B3257 offers identical performance with enhanced reliability, while PI3CH480 trades pin compatibility for higher speed and lower resistance-making it suitable only for redesigns targeting next-generation bandwidth.

Availability

PI3B3257AQEX is available at Aetrix Electronics and suitable for high-speed notebook bus switching, PCIe lane multiplexing, hot-plug SATA port expansion, and industrial FPGA I/O expansion requiring stable component supply and legacy footprint compatibility.

Supply support for PI3B3257AQEX 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 communications markets.

The PI3B3257A belongs to Diodes' NanoSwitch™ product line, engineered specifically for low-latency, low-power signal routing in portable and space-constrained digital systems where traditional logic-based muxes introduce unacceptable delay or power overhead.

FAQ

Is PI3B3257AQEX pin-compatible with standard 74-series 257 logic devices?

Yes. The PI3B3257AQEX is explicitly designed to be pinout- and function-compatible with 74F257, 74ALS257, and 74AS257 devices. Its 16-pin QSOP footprint matches industry-standard layouts, allowing direct substitution in existing designs without PCB revision-provided V_CC is 3.3 V and signal levels comply with its input voltage range.

What is the maximum data rate supported by PI3B3257AQEX?

The PI3B3257AQEX supports data rates up to 200+ Mbps in practice, based on its 5 Ω R_ON and 7.5 pF Y-output capacitance, yielding a 37.5 ps RC time constant. Measured propagation delay is 0.25 ns (typical), and switching characteristics are validated to 50 pF load-making it suitable for USB 2.0, LPC, and legacy PCIe Gen1 applications.

Can PI3B3257AQEX operate with mixed-voltage control signals?

Yes. Its logic inputs (E and S) accept voltages from –0.5 V to +4.6 V independent of V_CC, enabling direct interfacing with 1.8 V, 2.5 V, or 3.3 V controllers-even when V_CC is 3.3 V. This rail-to-rail input tolerance eliminates level shifters in multi-voltage SoC designs.

Why was PI3B3257AQEX discontinued, and what should designers use instead?

Diodes Incorporated discontinued PI3B3257AQEX in favor of the improved PI3B3257, which retains identical electrical and mechanical specifications but incorporates enhanced ESD protection (HBM 4 kV) and updated process reliability. For new designs, PI3B3257 is the recommended drop-in replacement; PI3CH480 is an alternative only if higher bandwidth and dual-supply operation are required.