Diodes Incorporated PI5C3125QEX

Overview

PI5C3125QEX from Pericom Semiconductor is a 4-bit bus switch IC with four independent active-low enable-controlled 5Ω analog switches in a 16-pin QSOP package, operating at 5V ±10%, supporting bidirectional signal routing without propagation delay or ground bounce, and used in notebook I/O isolation and memory address/data bus gating.

For engineers reviewing the PI5C3125QEX datasheet, PI5C3125QEX pinout, PI5C3125QEX application, or PI5C3125QEX equivalent, key selection criteria include on-resistance (5Ω typ), quiescent current (0.1µA typ), individual enable control per channel, and 50pF load-compatible switching speed (0.25ns propagation delay).

Technical Context

This device implements four independent transmission-gate-style CMOS bus switches, each controlled by a dedicated active-low BE pin. Each switch provides direct low-impedance conduction (Ron = 5Ω typ) between A and B terminals when enabled, and high-impedance isolation (Iozh ≤ ±1µA) when disabled.

The architecture eliminates added propagation delay beyond RC time constant of Ron and load capacitance, supports TTL/CMOS logic levels (VIH = 2.0V min, VIL = 0.8V max), and maintains rail-to-rail analog signal pass-through capability up to ±0.5V beyond supply rails.

Key Specifications

Pinout & Package

Package: 16-pin QSOP (150-mil wide), Pb-free & Green compliant, body dimensions 3.99mm × 4.80mm × 1.35mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3125DBQR and PI5C3257LEX, PI5C3125QEX provides dedicated active-low enable per channel in compact QSOP, making it optimal for discrete bus segment control where polarity alignment and board space are critical.

Availability

PI5C3125QEX is available at Aetrix Electronics and suitable for laptop memory bus isolation, PCIe lane sharing, notebook I/O expansion, and legacy peripheral interface gating requiring stable component supply and long-term lifecycle support.

Supply support for PI5C3125QEX 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

Pericom Semiconductor (now part of Diodes Incorporated) specialized in high-speed interface and signal-integrity solutions for computing, communications, and consumer electronics.

The PI5Cxx bus switch product line was engineered for low-latency, low-power bidirectional signal routing in portable and embedded systems with strict thermal and space constraints.

FAQ

What is the maximum allowable voltage on A/B pins relative to VCC and GND?

A/B pins tolerate –0.5V to +7.0V relative to GND, and can safely handle signals up to 0.5V beyond VCC or below GND. This rail-to-rail analog capability supports hot-swap and level-shifting use cases without external clamping diodes.

Can PI5C3125QEX operate with 3.3V logic levels?

No - the device is specified only for 5V ±10% VCC operation. Input thresholds (VIH = 2.0V min, VIL = 0.8V max) and Ron performance are characterized at 5V; using 3.3V supply violates absolute maximum ratings and degrades switch resistance and timing.

Are the NC pins (pins 9 and 11) internally connected or should they be grounded?

Pins 9 and 11 are no-connect terminals with no internal connection. They must remain unconnected per datasheet guidance; grounding or routing them risks parasitic coupling or mechanical stress-induced failure in the QSOP package.

Does PI5C3125QEX require external pull-up resistors on BE pins?

Yes - a pull-up resistor is recommended on each BE pin for power-up protection, ensuring all switches remain disabled (high-Z) until firmware asserts active-low enables. Typical value is 10kΩ to VCC, per datasheet Note 2 in Truth Table section.