Diodes Incorporated PI5C3125Q

Overview

PI5C3125Q from Pericom Semiconductor is a 4-bit bus switch IC with four individually controlled 5Ω analog switches, active-low enable inputs, and industry-standard 74XX125 pinout. It provides near-zero propagation delay (<0.25 ns), ultra-low quiescent current (0.1 µA typical), and operates over –40°C to +85°C for notebook and low-power system interconnect applications.

For engineers reviewing the PI5C3125Q datasheet, PI5C3125Q pinout, PI5C3125Q application, or PI5C3125Q equivalent, key selection criteria include individual BE pin control logic, 5Ω on-resistance at 5V, high-impedance isolation during disable, and QSOP-16 packaging compatibility with legacy 74-series layouts.

Technical Context

The PI5C3125Q implements four independent bidirectional analog switches, each controlled by a dedicated active-low Bus Enable (BE) input. Each switch connects A_n to B_n with no added propagation delay beyond RC time constant (5Ω × 50pF ≈ 0.25 ns), and presents high-impedance (Hi-Z) output when disabled.

It uses CMOS transmission-gate architecture with rail-to-rail analog signal handling (–0.5 V to +7.0 V), supports TTL-compatible control inputs (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), and features integrated clamp diodes (V_IK = –0.7 V) for ESD protection on all I/O pins.

Key Specifications

Pinout & Package

PI5C3125Q is housed in a 16-pin QSOP (150-mil wide) package with exposed leadframe, RoHS-compliant and Pb-free (E suffix). Pin pitch is 0.025" (0.635 mm), body width 0.157", and total footprint compatible with standard 74XX125 PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3125PW and 74LVC1G3157GW, the PI5C3125Q uniquely combines industrial temperature rating, 0.1 µA quiescent current, and native 4-bit parallel control in a single QSOP-16 package - making it optimal for space-constrained, low-power, and thermally demanding embedded designs.

Availability

PI5C3125Q is available at Aetrix Electronics and suitable for memory expansion interfaces, hot-swappable peripheral ports, notebook system power gating, and legacy ISA/LPC bus multiplexing requiring stable component supply across industrial temperature ranges and long-lifecycle programs.

Supply support for PI5C3125Q 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 was a fabless analog and mixed-signal IC company headquartered in San Jose, CA, specializing in high-speed interface, timing, and signal-integrity solutions before its acquisition by Diodes Incorporated in 2016.

The PI5C3125Q belongs to Pericom's 5C-series low-voltage bus switch family, designed specifically for low-power, low-noise, and high-density interconnect in portable computing and industrial control systems.

FAQ

What is the maximum capacitive load the PI5C3125Q can drive while maintaining signal integrity?

The PI5C3125Q is characterized for 50 pF load capacitance with <0.25 ns propagation delay. Its 5Ω R_ON and 6 pF C_OFF ensure minimal distortion up to 100 pF in most PCB layouts. Driving loads >100 pF may increase rise/fall times due to RC time constant but does not affect logic-level validity or switch reliability.

Can the PI5C3125Q be used with 3.3V logic while powered from 5V?

Yes - the PI5C3125Q supports mixed-voltage operation: V_CC = 5V, while A/B pins tolerate –0.5 V to +7.0 V. Input thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) are compatible with 3.3V LVTTL outputs, and the 5Ω R_ON introduces negligible voltage drop on 3.3V signals.

Is there a recommended pull-up resistor value for the BE pins?

A 10 kΩ pull-up resistor to V_CC is recommended per BE pin to ensure defined HIGH state at power-up and prevent unintended switch activation. This value balances noise immunity against current draw and ensures reliable TTL-level recognition without overloading driving sources.

Does the PI5C3125Q require external bypass capacitors?

Yes - a 0.1 µF ceramic capacitor placed within 5 mm of V_CC (Pin 16) and GND (Pin 8) is required to suppress high-frequency switching noise and stabilize internal bias. Additional bulk capacitance (e.g., 4.7 µF tantalum) is recommended near the power entry point for multi-switch systems.