Renesas QS3861PAG

Overview

QS3861PAG from Renesas Electronics (formerly IDT) is a high-speed CMOS 10-bit bus switch with flow-through pinout, designed for bidirectional signal routing in TTL-compatible systems. It features 5 Ω ON resistance, zero propagation delay, and industrial temperature operation (–40°C to +85°C), enabling hot-swap-capable bus isolation in server backplanes.

For engineers reviewing the QS3861PAG datasheet, QS3861PAG pinout, QS3861PAG application, or QS3861PAG equivalent, key selection criteria include guaranteed 5 Ω R_ON, undershoot clamp diodes on all I/Os, flow-through layout for PCB trace optimization, and dual QSOP/TSSOP package availability.

Technical Context

The QS3861PAG implements ten independent N-channel FET switches with no inherent body diode to V_CC, eliminating unwanted current paths during voltage translation. Its control logic uses a single Bus Enable (BE) input to simultaneously connect or isolate A0–A9 ↔ B0–B9 pairs.

Switching behavior is characterized by t_PZL/t_PLZ turn-on/turn-off delays of 1.5–6.5 ns and 1.5–5.5 ns respectively, with no added propagation delay beyond RC time constant (≤0.25 ns at C_L = 50 pF). All I/O pins include undershoot clamp diodes for robust ESD protection.

Key Specifications

Pinout & Package

QS3861PAG is available in 24-pin QSOP (PAG suffix) with flow-through pinout optimized for minimal PCB trace length and signal integrity. Pin 1 = GND; Pin 24 = BE; A0–A9 and B0–B9 are arranged in mirrored order across the package for straight-through routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3384APWR and PI3CHD3245LEX, the QS3861PAG delivers superior signal fidelity via its 5 Ω R_ON, flow-through routing, and comprehensive undershoot protection - critical for hot-swap and high-reliability industrial backplanes.

Availability

QS3861PAG is available at Aetrix Electronics and suitable for hot-swappable backplanes, voltage translation interfaces, and low-power system sleep mode implementations requiring stable component supply across extended temperature ranges.

Supply support for QS3861PAG 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

Renesas Electronics Corporation is a global semiconductor leader delivering microcontrollers, analog, power, and connectivity solutions for automotive, industrial, infrastructure, and IoT applications.

The QS3861PAG belongs to Renesas' QuickSwitch® bus switch product line, engineered specifically for high-fidelity, low-latency signal routing in mission-critical industrial and telecom systems.

FAQ

What is the maximum operating voltage for QS3861PAG?

The QS3861PAG supports DC supply and signal voltages from –0.5 V to +7 V on all terminals except V_CC, which operates at 5 V ±5%. This wide range allows safe interfacing between 3.3 V and 5 V systems and provides margin against transient overshoot. The absolute maximum rating ensures robustness during hot-swap events without external clamping circuitry.

Does QS3861PAG support bidirectional signal flow?

Yes, QS3861PAG supports fully bidirectional signal flow between A0–A9 and B0–B9 pins. Each of the ten channels uses an enhanced N-channel FET with no intrinsic body diode, enabling symmetrical conduction regardless of signal direction. This makes QS3861PAG ideal for data buses, clock distribution, and shared control lines where signal polarity or direction may vary dynamically.

What package type does QS3861PAG use?

QS3861PAG uses a 24-pin Quarter Size Outline Package (QSOP) with green RoHS-compliant finish. Its flow-through pinout places A0–A9 on one side and corresponding B0–B9 on the opposite side in mirrored order, enabling straight PCB trace routing with minimal stubs or vias. Pin 1 is GND and Pin 24 is the Bus Enable (BE) input.

How does the QS3861PAG handle ground bounce?

The QS3861PAG eliminates ground bounce through architecture-level design: its switch FETs lack parasitic source-body diodes, and internal layout minimizes shared ground paths during switching. Combined with zero added propagation delay, this ensures that simultaneous switching of multiple channels does not induce noise on the GND plane - a critical advantage in dense backplane and high-speed interface designs using QS3861PAG.

Is QS3861PAG suitable for hot-swap applications?

Yes, QS3861PAG is explicitly designed for hot-swap applications. Its undershoot clamp diodes protect all A/B/BE pins against –3 V transients, and its 5 Ω R_ON ensures minimal voltage drop during live insertion. The device operates across –40°C to +85°C and supports immediate connection/disconnection without sequencing - making QS3861PAG a proven solution in telecom line cards and modular server architectures.