Renesas QS3VH125QG

Overview

QS3VH125QG from Renesas Electronics (formerly IDT) is a quad, active-low, high-bandwidth bus switch with N-channel FET architecture, 4 Ω typical ON resistance, rail-to-rail 0–5 V switching, and 500 MHz bandwidth. It operates from 2.3 V to 3.6 V V_CC, supports hot-swapping in live backplanes, and delivers <250 ps propagation delay in bidirectional data paths.

For engineers reviewing the QS3VH125QG datasheet, QS3VH125QG pinout, QS3VH125QG application, or QS3VH125QG equivalent, key selection criteria include its 5 V-tolerant I/Os in both ON/OFF states, isolation under power-off conditions, LVTTL-compatible control inputs, and flat R_ON over voltage/temperature - critical for Ethernet LAN switching and analog signal routing.

Technical Context

The QS3VH125QG implements four independent, actively controlled transmission gates using enhancement-mode N-channel MOSFETs without parasitic body diodes to V_CC, enabling true 5 V tolerance and zero DC path to supply or ground. Each channel features undershoot clamp diodes on A, Y, and OE pins.

Its control logic is active-low (1OE–4OE), with guaranteed VIH/VIL thresholds across 2.3–3.6 V V_CC, and it exhibits near-zero ground bounce due to symmetric bidirectional conduction and absence of internal charge pumps or level shifters.

Key Specifications

Pinout & Package

QS3VH125QG is packaged in a 16-pin QSOP (QG) with 0.15 inch body width and standard JEDEC MO-137AC footprint. Pin 1 is NC; Pin 2 is V_CC; Pins 3–6 and 9–12 are control (1OE–4OE) and data terminals (1A–4A, 1Y–4Y); Pin 16 is GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74CBT16212DGGR and PI3CH400QE, the QS3VH125QG offers superior hot-swap resilience via integrated undershoot clamps and zero-V_CC isolation, tighter R_ON matching, and lower ICCQ - making it optimal for industrial Ethernet and sensor multiplexing where signal fidelity and reliability are non-negotiable.

Availability

QS3VH125QG is available at Aetrix Electronics and suitable for hot-swappable backplane interfaces, Fast Ethernet LAN switching, analog sensor multiplexing, and solid-state relay replacement requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for QS3VH125QG 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 QS3VH125QG belongs to Renesas' legacy QuickSwitch® bus switch family, designed specifically for high-fidelity, low-latency signal routing in communications infrastructure and industrial control systems requiring 5 V tolerance and hot-swap capability.

FAQ

What is the maximum signal voltage the QS3VH125QG can pass when V_CC = 0 V?

The QS3VH125QG supports rail-to-rail switching from 0 V to 5 V regardless of V_CC state. When V_CC = 0 V, it maintains 5 V tolerance on all A, Y, and OE pins due to its N-channel FET architecture with no parasitic diode to V_CC. This allows safe hot-insertion into live 5 V backplanes without risk of latch-up or damage - a core design feature confirmed in the Absolute Maximum Ratings table (V_TERM(3) = –0.5 V to +5.5 V).

Does the QS3VH125QG require external clamping diodes for ESD protection?

No. The QS3VH125QG integrates undershoot clamp diodes on all switch (1A–4A, 1Y–4Y) and control (1OE–4OE) inputs, rated for –3 V AC pulses (≤20 ns). These on-die clamps eliminate the need for external TVS or Schottky diodes in most industrial and telecom applications, reducing BOM count and PCB area - a key advantage documented in the Features section and Absolute Maximum Ratings.

What is the typical ON resistance variation across the operating temperature range for QS3VH125QG?

The QS3VH125QG exhibits flat R_ON characteristics over –40°C to +85°C, with typical values ranging from 4 Ω to 6 Ω depending on V_CC and input voltage. At V_CC = 3.3 V and V_IN = 2.4 V, R_ON is 5 Ω (typ), and the datasheet explicitly states "Flat R_ON characteristics over operating range" as a defined feature - critical for maintaining consistent gain and THD in analog multiplexing applications.

Can the QS3VH125QG be used to switch differential signals like USB or LVDS?

No. The QS3VH125QG is a single-ended bus switch optimized for TTL/CMOS logic and analog signals up to 500 MHz, but it lacks matched pair routing, common-mode rejection, or differential impedance control. Its 4 pF OFF capacitance and 4 Ω R_ON are specified per pin, not per differential pair. For USB or LVDS, dedicated differential switches (e.g., PI3L100 or SN65LVDSx series) are required - the QS3VH125QG datasheet does not claim or characterize differential operation.

Is the QS3VH125QG pin-compatible with other members of the QS3VHxxx family?

Yes. The QS3VH125QG shares identical pinout, package (16-pin QSOP), and functional block diagram with other QS3VHxxx quad switches (e.g., QS3VH16240, QS3VH244), differing only in control logic (active-low OE vs active-high) and channel count. All use the same 1A–4A/1Y–4Y/1OE–4OE assignment and NC/V_CC/GND placement - enabling drop-in substitution within the family when logic polarity matches system requirements.