Renesas QS3VH125S1G

Overview

QS3VH125S1G from Renesas Electronics (formerly IDT) is a quad, active-low, high-bandwidth bus switch IC 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 Ethernet LAN switches, and provides 5 V-tolerant I/Os with isolation under power-off conditions.

For engineers reviewing the QS3VH125S1G datasheet, QS3VH125S1G pinout, QS3VH125S1G application, or QS3VH125S1G equivalent, key selection criteria include bidirectional near-zero-delay data flow, LVTTL-compatible control inputs, undershoot clamp diodes, low 4 pF I/O capacitance, and industrial temperature range (–40°C to +85°C) operation.

Technical Context

The QS3VH125S1G implements four independent, active-low-controlled N-channel FET switches with no parasitic diode to V_CC, enabling true isolation and 5 V tolerance in both ON and OFF states. Its architecture eliminates DC paths to V_CC or GND and supports rail-to-rail analog/digital signal routing without ground bounce.

Each channel features matched R_ON (typ. 4 Ω at V_CC = 3.3 V), flat R_ON vs. input voltage, and propagation delay under 250 ps. Control inputs are LVTTL-compatible with VIH ≥ 2.0 V (V_CC = 2.7–3.6 V) and VIL ≤ 0.8 V, and all switch/control pins include undershoot clamp diodes.

Key Specifications

Pinout & Package

QS3VH125S1G is packaged in 16-pin QSOP (Green, RoHS-compliant). Pinout follows standard QSOP top-view layout with dual-row 0.65 mm pitch.

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 QS3VH125S1G uniquely combines 5 V I/O tolerance in both states, built-in undershoot clamps, and guaranteed power-off isolation-making it the preferred choice for industrial hot-swap and mixed-voltage Ethernet infrastructure.

Availability

QS3VH125S1G is available at Aetrix Electronics and suitable for industrial networking, telecom infrastructure, and embedded test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.

Supply support for QS3VH125S1G 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 enterprise applications.

The QS3VH125S1G belongs to Renesas' legacy IDT QuickSwitch® bus switch family, engineered specifically for high-bandwidth, low-latency signal routing in hot-pluggable and Ethernet infrastructure systems.

FAQ

What is the maximum operating frequency supported by the QS3VH125S1G?

The QS3VH125S1G supports an enable toggle frequency up to 20 MHz at V_CC = 3.3 V, and its analog bandwidth extends to 500 MHz-enabling use in Fast Ethernet (100BASE-TX) and ATM 155 Mbps applications. The device achieves this via low 4 Ω R_ON and 4 pF I/O capacitance, minimizing RC time constants. Propagation delay remains under 250 ps, making the QS3VH125S1G suitable for timing-critical signal routing where latency must be minimized.

Does the QS3VH125S1G support 5 V signals when powered from a 3.3 V supply?

Yes, the QS3VH125S1G supports 5 V-tolerant I/Os in both ON and OFF states when V_CC is 2.3–3.6 V. This is enabled by its N-channel FET architecture with no parasitic diode to V_CC, eliminating DC paths and allowing safe interfacing with 5 V peripherals-even during power-off conditions. This feature is explicitly verified in the Absolute Maximum Ratings table (V_TERM(3) = –0.5 V to +5.5 V) and is a core design requirement for hot-swap applications using the QS3VH125S1G.

What package type does the QS3VH125S1G use, and is it RoHS-compliant?

The QS3VH125S1G uses a 16-pin QSOP (Quarter-Size Outline Package) with green, lead-free, RoHS-compliant construction, indicated by the "S1G" suffix in the ordering code. The package has 0.65 mm pin pitch and is optimized for high-density PCB layouts. Thermal and mechanical data confirm compatibility with standard reflow profiles, and the "G" designation confirms compliance with JEDEC J-STD-020 and EU RoHS Directive 2011/65/EU-critical for industrial and telecom deployments requiring environmental certification.

How does the QS3VH125S1G handle undershoot transients on its I/O pins?

The QS3VH125S1G integrates undershoot clamp diodes on all switch (A/Y) and control (OE) inputs, rated to handle –3 V pulses (≤20 ns). These internal diodes shunt negative transients to GND, protecting downstream logic and eliminating the need for external TVS devices in many applications. This capability is documented in the Absolute Maximum Ratings table and validated in system-level hot-swap testing-making the QS3VH125S1G especially robust in pluggable card interfaces where cable discharge events occur.

Can the QS3VH125S1G replace mechanical relays in low-power signal routing?

Yes, the QS3VH125S1G is explicitly positioned as a solid-state replacement for mechanical relays in low-power analog and digital signal routing. Its 4 Ω R_ON, rail-to-rail 0–5 V switching, bidirectional operation, and absence of contact wear or bounce make it ideal for applications like test instrumentation multiplexing and modular I/O conditioning. Unlike relays, the QS3VH125S1G offers microsecond-scale switching, no audible noise, and infinite cycle life-key advantages confirmed in IDT's application notes on relay replacement using the QS3VH125S1G.