Diodes Incorporated PI3B3257ZHDEX

Overview

PI3B3257ZHDEX from Diodes Incorporated is a 3.3 V quad 2:1 multiplexer/demultiplexer with three-state outputs, pinout- and function-compatible with 74F257, 74ALS257, and PI74FCT257T. It features 5 Ω on-resistance, 4.8 ns max propagation delay, and 0.1 µA typical quiescent current, enabling low-noise signal routing in notebook and portable logic systems.

For engineers reviewing the PI3B3257ZHDEX datasheet, PI3B3257ZHDEX pinout, PI3B3257ZHDEX application, or PI3B3257ZHDEX equivalent, key selection criteria include its UQFN-16 (ZHD) package, rail-to-rail logic inputs up to +3.6 V, 50 pF load timing performance, and compatibility with legacy TTL/CMOS bus architectures.

Technical Context

The PI3B3257ZHDEX 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 low R_ON–C_OFF time constant (~0.25 ns for 50 pF), with no added ground bounce noise during switching.

It operates strictly at 3.3 V ±10%, supports logic inputs beyond V_CC (up to +3.6 V), and maintains high-impedance outputs when disabled. The UQFN-16 (ZHD) package integrates an exposed thermal pad requiring PCB soldering and thermal vias for reliable operation under continuous 120 mA per channel loads.

Key Specifications

Pinout & Package

PI3B3257ZHDEX is housed in a 16-pin UQFN (ZHD) package measuring 3 mm × 3 mm with 0.5 mm pitch and an exposed thermal pad. Pin 1 index is marked via top-side laser marking; GND connects to both pin 12 and the center thermal pad, which must be soldered to PCB ground for electrical stability and thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PI74FCT257TQE and SN74CBT3257PWR, PI3B3257ZHDEX delivers superior low-power performance (0.1 µA vs. ≥1 µA), smallest footprint (UQFN-16), and lowest R_ON, making it optimal for space-constrained, energy-sensitive portable and embedded platforms.

Availability

PI3B3257ZHDEX is available at Aetrix Electronics and suitable for USB switching, notebook display arbitration, PCIe lane sharing, and industrial I/O routing requiring stable component supply across production lifecycles.

Supply support for PI3B3257ZHDEX 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 PI3B3257 belongs to Diodes' NanoSwitch™ bus-switch family, engineered for low-latency, low-power signal routing in portable and space-constrained electronics where board area and battery life are critical constraints.

FAQ

Is PI3B3257ZHDEX compatible with 5 V logic inputs?

No - its logic inputs tolerate up to +3.6 V regardless of V_CC, but it is not rated for 5 V operation. Applying 5 V to any pin exceeds the absolute maximum rating of –0.5 V to +4.6 V and risks permanent damage. For 5 V systems, use PI74FCT257TQE instead.

What is the role of the exposed thermal pad on the ZHD package?

The exposed pad serves as both an electrical ground connection and primary thermal path. It must be soldered to a dedicated PCB ground plane with ≥4 thermal vias (0.3 mm diameter) to ensure proper device operation, prevent latch-up, and maintain junction temperature below 125°C at 120 mA per channel.

Can PI3B3257ZHDEX be used for analog signal switching?

Yes - its 5 Ω R_ON, 25 pF C_ON, and rail-to-rail input capability support analog signals up to 100 MHz. However, THD and crosstalk are not characterized in the datasheet; for precision analog paths, verify performance with actual signal levels and source/load impedances.

Does PI3B3257ZHDEX require external pull-up or pull-down resistors on control pins?

No - the E and S inputs have internal clamp diodes and specified VIH/VIL thresholds (2.0 V/0.8 V). With clean 3.3 V logic drivers, external biasing is unnecessary. Pull-ups are only needed if driving from open-drain sources or when floating states must be avoided during power-up sequencing.