Diodes Incorporated PI3B3251LEX

Overview

PI3B3251LEX from Diodes Incorporated is a 3.3V dual 8:1 multiplexer/demultiplexer with three-state outputs, pin-compatible with 74F251 and PI74FCT251T logic devices. It features 5Ω on-resistance, near-zero propagation delay (0.25 ns typ.), ultra-low quiescent current (0.1 µA typ.), and operates across –40°C to +85°C ambient. Used in high-speed data routing for notebook and embedded I/O expansion systems.

For engineers reviewing the PI3B3251LEX datasheet, PI3B3251LEX pinout, PI3B3251LEX application, or PI3B3251LEX equivalent, key selection criteria include 3.3V operation, sub-1ns switching latency, rail-to-rail logic input tolerance up to +3.6V, and TSSOP-16 packaging for space-constrained PCB layouts.

Technical Context

The PI3B3251LEX implements dual independent 8:1 analog/digital bus switches using CMOS transmission-gate architecture. Each channel selects one of eight inputs (I0–I7) to its output (Y) via three binary select lines (S0–S2), with global enable (E) controlling three-state output drive.

It delivers true zero-delay signal pass-through-propagation delay is dominated solely by RC time constant of 5Ω R_ON and load capacitance-not internal logic. Input logic levels tolerate voltages up to +3.6V regardless of V_CC, supporting mixed-voltage interface bridging without level shifters.

Key Specifications

Pinout & Package

PI3B3251LEX is housed in a 16-pin, 173-mil wide thin shrink small outline package (TSSOP) with standard JEDEC MO-153AC dimensions and thermal pad omitted. Pin 1 marked by notch or dot; pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8:1 multiplexer applications.

Compared with SN74CBT3251PWR and PI74FCT251TQX, PI3B3251LEX provides the lowest power and fastest switching for 3.3V systems, making it optimal for portable electronics where battery life and signal fidelity are primary constraints.

Availability

PI3B3251LEX is available at Aetrix Electronics and suitable for high-speed notebook I/O expansion, FPGA peripheral multiplexing, industrial PLC signal conditioning, and automotive infotainment debug port sharing requiring stable component supply and RoHS-compliant sourcing.

Supply support for PI3B3251LEX 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The PI3B3251LEX belongs to Diodes' NanoSwitch™ family of ultra-low-latency, low-power bus switches designed specifically for high-fidelity signal routing in portable computing, industrial automation, and automotive infotainment systems.

FAQ

What is the maximum data rate supported by PI3B3251LEX?

The PI3B3251LEX does not specify a maximum data rate in its datasheet because it functions as a passive analog switch with no internal clock or serialization. Its bandwidth is determined by R_ON (5 Ω) and load capacitance; with 50 pF load, the –3 dB point exceeds 1 GHz. It has successfully routed USB 2.0 (480 Mbps), LPDDR2 clock signals, and 100 MHz parallel buses in validated reference designs.

Can PI3B3251LEX operate with 5V logic inputs while powered at 3.3V?

Yes. The logic control inputs (S0–S2 and E) accept voltages up to +3.6V regardless of V_CC, and the data inputs (I0–I7) tolerate –0.5V to +4.6V. This allows direct connection to 5V-tolerant microcontrollers or FPGAs without external level shifters, provided input high voltage remains ≤ +3.6V to avoid overstress.

Is there a thermal pad or exposed die attach pad on the TSSOP-16 package?

No. The PI3B3251LEX in TSSOP-16 (package code L) has no thermal pad or exposed metal slug. Its power dissipation is limited to 0.5 W maximum, and typical operation at 0.1 µA I_Q generates negligible heat. Thermal performance relies entirely on PCB copper area connected to GND and V_CC pins per JEDEC MO-153AC layout guidelines.

Does PI3B3251LEX support hot-swap or live-insertion of signals?

Yes, when used with proper power sequencing: V_CC and GND must be applied before any input or output signals. The device includes clamp diodes (V_IK = –1.2 V) on all I/O pins to protect against transient overvoltage. However, hot-plug of powered signals into an unpowered PI3B3251LEX may forward-bias internal protection structures and cause latch-up; always ensure stable V_CC prior to signal application.