Diodes Incorporated PI3B3125LEX

Overview

PI3B3125LEX from Diodes Incorporated is a 3.3V, 4-bit, 2-port bus switch with individual active-low enables, fabricated in advanced sub-micron CMOS. It features four 5Ω analog switches, near-zero propagation delay (0.25ns), ultra-low quiescent current (0.1µA typical), and operates across –40°C to +85°C. It is used in notebook I/O signal routing where low power, fast switching, and minimal signal distortion are critical.

For engineers reviewing the PI3B3125LEX datasheet, PI3B3125LEX pinout, PI3B3125LEX application, or PI3B3125LEX equivalent, key selection criteria include its active-low enable logic, 5Ω on-resistance, 14-pin TSSOP package, 3.3V-only operation, and compatibility with 74XX125/126 pinouts for drop-in replacement in legacy designs.

Technical Context

The PI3B3125LEX implements four independent bidirectional analog switches, each controlled by a dedicated active-low Bus Enable (BE) input. When enabled, the A–B path conducts with no added propagation delay beyond RC time constant (~0.25ns for 50pF load), preserving signal integrity in high-speed digital buses.

It uses rail-to-rail logic inputs tolerant up to +3.6V regardless of VCC, supports hot-plug sequencing (VCC/GND applied before signals), and draws only 0.1µA quiescent current-enabling always-on I/O isolation in battery-sensitive portable systems.

Key Specifications

Pinout & Package

PI3B3125LEX is housed in a 14-pin, 173mil-wide TSSOP (Package Code L), RoHS-compliant and halogen-free. Pin pitch is 0.65mm; body width is 4.4mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit bus switch applications.

Compared with PI3B3125WEX, the PI3B3125LEX offers superior thermal performance in compact layouts; versus SN74CBT3125CPWR, it delivers 50× lower quiescent current and 12× faster enable response-critical for battery runtime and real-time I/O arbitration.

Availability

PI3B3125LEX is available at Aetrix Electronics and suitable for notebook I/O routing, embedded controller interface isolation, hot-pluggable module detection, and low-power sensor hub multiplexing requiring stable component supply across long-life portable product cycles.

Supply support for PI3B3125LEX 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 logic switching applications-designed specifically for portable electronics where signal fidelity, power efficiency, and small-footprint packaging are essential design constraints.

FAQ

Is PI3B3125LEX compatible with 5V logic systems?

No. PI3B3125LEX is strictly a 3.3V-only device: VCC must be 3.3V ±10%, and while its control inputs tolerate up to +3.6V, they are not 5V-tolerant. Driving BE pins above 3.6V risks latch-up or damage. For 5V systems, consider TI's SN74CBT3125 or ON Semiconductor's NLAS3125, both rated for 5V operation.

What is the maximum capacitive load this switch can drive reliably?

The PI3B3125LEX is characterized with CL = 50pF in switching tests, and its 5Ω RON forms an RC time constant of ~0.25ns with that load. It remains functional up to 100pF, but rise/fall times degrade linearly beyond 50pF. For loads >75pF, verify signal integrity via IBIS simulation or bench measurement using actual PCB trace capacitance.

Does PI3B3125LEX require external pull-up resistors on BE pins?

Yes. The datasheet specifies a pull-up resistor is required on each BE pin for power-up protection to ensure all switches default to high-impedance (disabled) state at startup. A 10kΩ pull-up to VCC is recommended; values between 4.7kΩ and 100kΩ maintain reliable logic levels while minimizing current draw.

Can PI3B3125LEX be used for analog signal switching, such as audio or sensor signals?

Yes-within limits. Its 5Ω RON and 8pF off-capacitance support low-distortion switching of DC-coupled analog signals up to ~10MHz (e.g., I²C, SMBus, GPIO, or low-bandwidth sensor outputs). However, it lacks rail-to-rail analog swing capability: signal voltage must stay within GND to VCC (0–3.3V). For AC-coupled or wider-range analog use, a dedicated analog switch like DG417 or ADG714 is preferred.