Renesas QS3861PAG8

Overview

QS3861PAG8 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 digital systems. It features 5Ω ON resistance, zero propagation delay, undershoot clamp diodes on all I/O and control pins, and operates across –40°C to +85°C for industrial hot-swap and voltage translation applications.

For engineers reviewing the QS3861PAG8 datasheet, QS3861PAG8 pinout, QS3861PAG8 application, or QS3861PAG8 equivalent, key selection criteria include its 5Ω bidirectional switch resistance, flow-through pinout for PCB trace optimization, ±1μA off-state leakage, 0.25ns typical propagation delay contribution, and support for 5V-to-3.3V level shifting without external components.

Technical Context

The QS3861PAG8 implements ten independent N-channel FET switches with no inherent body diode to V_CC, enabling true bidirectional signal pass-through without forward voltage drop or latch-up risk. Its BE (Bus Enable) control input directly gates all ten channels simultaneously, with turn-on/turn-off delays of 1.5–6.5ns.

Designed for minimal signal integrity impact, it delivers 5pF typical input capacitance per channel (switch OFF), 7pF max, and supports DC switching voltages from –0.5V to +7V on all terminals except V_CC. The device draws only 0.2μA quiescent supply current and adds negligible RC delay-less than 0.25ns at 50pF load-making it suitable for high-speed clock and data bus isolation.

Key Specifications

Pinout & Package

QS3861PAG8 is packaged in a 24-pin QSOP (Quarter Size Outline Package), green RoHS-compliant, with 0.65mm lead pitch and flow-through pinout optimized for straight PCB trace routing between Bus A and Bus B.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBTD3384CPWR and 74LVC1G3157GW,125, the QS3861PAG8 uniquely combines integrated undershoot clamps, flow-through pinout, and guaranteed 5Ω R_ON in a single 24-pin QSOP-enabling simpler, more robust hot-swap and level-shifting implementations without external protection or layout compromises.

Availability

QS3861PAG8 is available at Aetrix Electronics and suitable for industrial backplane interfaces, voltage-level translating data buses, low-power clock gating, and capacitive load isolation requiring stable component supply and long-term manufacturability.

Supply support for QS3861PAG8 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 QS3861PAG8 belongs to Renesas' legacy QuickSwitch® bus switch family-designed specifically for high-fidelity, low-latency signal routing in mixed-voltage, hot-pluggable digital systems.

FAQ

What is the maximum allowable voltage on the A and B pins of the QS3861PAG8?

The QS3861PAG8 supports a DC input voltage range of –0.5V to +7V on all A and B pins, independent of V_CC. This rating applies across the full industrial temperature range and enables safe operation during hot-swap events and mixed-voltage interfacing. The device includes undershoot clamp diodes rated for –3V pulses (≤20ns), further protecting against transient overvoltage conditions.

Does the QS3861PAG8 require external pull-up or pull-down resistors on the BE pin?

No, the QS3861PAG8 does not require external biasing on the BE pin. Its control input has ±1μA max leakage current and is TTL-compatible, with VIH ≥2V and VIL ≤0.8V. A direct logic-level drive (e.g., from an MCU GPIO or FPGA output) is sufficient. External resistors are unnecessary unless system-level noise immunity requirements dictate weak pull-up/pull-down for default state assurance.

Can the QS3861PAG8 be used for 3.3V-to-5V level translation?

Yes, the QS3861PAG8 supports bidirectional level translation between 3.3V and 5V domains. With V_CC = 5V and –0.5V to +7V tolerance on A/B pins, it passes 3.3V signals from a low-voltage side to a 5V side without degradation. The 5Ω ON resistance ensures minimal voltage drop, and the absence of a body diode prevents reverse conduction-making it suitable for both 5V→3.3V and 3.3V→5V translation in the same configuration.

What is the thermal performance of the QS3861PAG8 in continuous operation?

The QS3861PAG8 has a maximum power dissipation of 0.5W and a storage temperature range of –65°C to +150°C. Under typical operation (10 channels ON, 5V supply, 120mA total output current), junction temperature rise remains minimal due to low R_ON and quiescent current (≤3μA). No heatsink is required in standard PCB layouts with ≥2 oz copper and moderate airflow, as confirmed by thermal characterization across –40°C to +85°C ambient.

Is the QS3861PAG8 pin-compatible with other QuickSwitch® devices like QS3862 or QS3863?

No, the QS3861PAG8 is not pin-compatible with QS3862 or QS3863. While all belong to the QuickSwitch® family, QS3862 is a 12-bit variant in 28-pin packages, and QS3863 is an 8-bit version in 20-pin packages. The QS3861PAG8 uses a unique 24-pin QSOP flow-through pinout (A0–A9, B0–B9, BE, V_CC, GND, NC) with no shared pin mapping. Direct substitution requires PCB redesign.