Renesas QS3125QG8

Overview

QS3125QG8 from Renesas Electronics is a high-speed CMOS quadruple bus switch with individual active-low enables, designed for zero-propagation-delay signal routing in industrial-grade systems (–40°C to +85°C). It features 5 Ω typical ON resistance at 5 V, <0.25 ns propagation delay contribution, and undershoot clamp diodes on all I/O and control pins. Used for hot-swapping, voltage translation (5 V ↔ 3.3 V), and clock gating in embedded data paths.

For engineers reviewing the QS3125QG8 datasheet, QS3125QG8 pinout, QS3125QG8 application, or QS3125QG8 equivalent, key selection criteria include individual enable control per channel, sub-1 ns turn-on/turn-off timing, low capacitance (5–7 pF per channel), industrial temperature operation, and QSOP-16 package compatibility with legacy 74'125 logic footprints.

Technical Context

The QS3125QG8 implements four independent N-channel FET switches with no inherent body diode to V_CC, enabling bidirectional analog/digital signal routing without DC path constraints. Each channel has dedicated active-low OE input, supporting asynchronous isolation of data buses or clock domains.

It operates with 5 V ±5% supply, supports DC input voltages from –0.5 V to +7 V, and delivers pass voltage ≥3.7 V at full load - critical for level-shifting integrity. Switching is characterized by t_PZL/t_PLZ ≤6.5/5.5 ns and dynamic ICCD of 0.25 mA/MHz, confirming minimal system-level power impact during high-frequency toggling.

Key Specifications

Pinout & Package

QS3125QG8 is packaged in a 16-pin Quarter Size Outline Package (QSOP, PCG16), 0.150" wide body, 0.025" pitch, with exposed pad not present. Pin 1 is marked via notch or dot; NC pins are unconnected and must remain floating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT3125PW and 74LVC1G3157GW, the QS3125QG8 uniquely combines industrial temperature rating, integrated undershoot protection on all pins, and true 5 Ω R_ON in a single quad-channel QSOP-16 package - making it optimal for ruggedized hot-swap and mixed-voltage infrastructure.

Availability

QS3125QG8 is available at Aetrix Electronics and suitable for hot-swapping systems, voltage translation interfaces, and clock-gated embedded controllers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for QS3125QG8 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, and IoT applications.

The QS3125QG8 belongs to Renesas' QuickSwitch® bus switch product line, engineered specifically for zero-delay, low-noise signal routing in high-reliability industrial and computing infrastructure.

FAQ

What is the operating temperature range of the QS3125QG8?

The QS3125QG8 is characterized for industrial operation from –40°C to +85°C. This range is fully specified in its DC electrical characteristics, switching parameters, and absolute maximum ratings. All guaranteed performance metrics - including R_ON, t_PZL, and V_IL/V_IH - apply across this full span without derating. The QS3125QG8 does not support extended or military temperature grades.

Does the QS3125QG8 support bidirectional signal flow?

Yes, the QS3125QG8 supports true bidirectional analog/digital signal routing between each A and Y terminal pair. Its N-channel FET structure has no intrinsic body diode to V_CC, eliminating DC path constraints. Signals can propagate equally well from A to Y or Y to A, provided voltage levels remain within the –0.5 V to +7 V absolute maximum range on both sides. This makes QS3125QG8 suitable for data bus isolation and video switching.

What package type is used for the QS3125QG8?

The QS3125QG8 uses a 16-pin Quarter Size Outline Package (QSOP) with package code PCG16. It measures 0.150" wide with 0.025" lead pitch and conforms to JEDEC MS-012 standards. The "QG" suffix in QS3125QG8 explicitly denotes this QSOP variant; alternate SOIC versions (e.g., QS3125S1G8) use DCG14 packaging and are not footprint-compatible.

How does the QS3125QG8 handle undershoot transients?

The QS3125QG8 integrates undershoot clamp diodes on all switch (A/Y) and control (OE) inputs. These diodes conduct when pin voltage falls below GND by more than ~0.5 V, limiting negative excursions and protecting internal circuitry. This feature is explicitly documented in the Features section and Absolute Maximum Ratings table, and is critical for hot-swap reliability where cable disconnection can induce large negative spikes on data lines.

Is the QS3125QG8 pin-compatible with standard logic devices?

Yes, the QS3125QG8 is pin-compatible with the 74'125 function, as confirmed in its official datasheet Features section. Its pin configuration matches the quad buffer layout - including identical placement of V_CC, GND, and channel I/O pairs - allowing direct substitution in existing PCBs designed for that logic family. However, unlike 74'125, QS3125QG8 provides zero propagation delay and no ground bounce, delivering superior signal integrity.