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Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Renesas QS3125S1G8

Name: QS3125S1G8
Brand: Renesas
SKU: QS3125S1G8
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: QS3125S1G8

Manufacturer:: Renesas

Category:: Signal Switches, Multiplexers, Decoders

Package:: 14-SOIC (0.154", 3.90mm Width)

Datasheet:: QS3125S1G8.pdf

Description:: IC BUS SWITCH 1 X 1:1 14SOIC

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Product details

Overview

QS3125S1G8 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. It features 5 Ω typical ON resistance at 5 V, ±1 µA input leakage, and operates across –40°C to +85°C. Used for hot-swapping, voltage translation (5 V ↔ 3.3 V), and clock gating in embedded control and data processing systems.

For engineers reviewing the QS3125S1G8 datasheet, QS3125S1G8 pinout, QS3125S1G8 application, or QS3125S1G8 equivalent, key selection criteria include guaranteed sub-1 ns turn-on/turn-off delay, undershoot clamp diodes on all I/Os, industrial temperature rating, and SOIC-14 package compatibility with legacy 74'125 logic footprints.

Technical Context

The QS3125S1G8 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 enable (1OE–4OE) and supports rail-to-rail voltage translation between 0 V and 7 V on A/Y terminals.

It delivers zero added ground bounce and no propagation delay beyond RC time constant of R_ON × C_LOAD; t_PZL and t_PLZ are specified at 1.5–6.5 ns and 1.5–5.5 ns respectively under 50 pF load. Input clamping diodes protect against –3 V AC undershoot pulses.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	4.5 V to 5.5 V - Supports standard 5 V TTL/CMOS systems with ±5% tolerance
R_ON (Typ.)	5 Ω at V_CC = 5 V, I_ON = 30 mA - Enables low-loss signal switching with <10 mV drop at 20 mA
t_PZL/t_PLZ	1.5–6.5 ns / 1.5–5.5 ns - Ensures fast bus isolation for hot-swap and clock-gating timing margins
I_IN, I_OZ	±1 µA max - Minimizes standby current draw and leakage-induced logic errors in Hi-Z state
V_TERM	–0.5 V to +7 V - Allows safe interfacing with 3.3 V, 5 V, and mixed-voltage domains including undershoot protection
Operating Temp	–40°C to +85°C - Qualified for industrial control, storage, and embedded computing environments

Pinout & Package

QS3125S1G8 is packaged in a 14-pin Small Outline Integrated Circuit (SOIC) with standard DCG14 footprint and 1.27 mm pitch. Pin 1 is marked by notch or dot; pin 8 is GND, pin 9 is V_CC.

Pin/Terminal	Circuit Role	Design Meaning
1OE–4OE	Active-low enable inputs	Each independently controls one switch; LOW enables A↔Y conduction, HIGH forces Hi-Z
1A–4A	Switch input/output terminals	Bidirectional I/O pins; tolerate –0.5 V to +7 V, support analog/video switching
1Y–4Y	Switch input/output terminals	Paired with corresponding A pins; identical electrical characteristics and clamping
GND (Pin 8)	Ground reference	Primary return path for switch current and internal logic; decoupling required near pin
V_CC (Pin 9)	Power supply	5 V nominal supply; powers internal control logic and switch bias; requires local 0.1 µF bypass

Key Features

Feature	Design Value
Zero propagation delay architecture	Eliminates timing skew in critical paths; system-level delay determined solely by driver/load, not switch
Undershoot clamp diodes on all I/Os	Withstands –3 V transient pulses (≤20 ns), protecting downstream logic during hot-plug events
Enhanced N-channel FET with no V_CC diode	Enables true bidirectional analog switching without forward-biased parasitic path to supply rail
Pin-compatible with 74'125 function	Direct drop-in replacement in existing designs using industry-standard quad buffer footprint
Industrial temperature qualification	Guaranteed operation from –40°C to +85°C without derating, suitable for uncontrolled environments

Applications

Hot-Swapping Systems	Voltage Translation
Use Scenario: Insertion/removal of PCIe add-in cards or modular I/O boards while main system remains powered. IC Role / Device Role / Timing Role: Bus switch isolates backplane signals during insertion to prevent glitch propagation and power rail disturbance. Use Value: Undershoot clamps and zero ground bounce ensure no false triggering of connected logic during plug/unplug transients.	Use Scenario: Interfacing 5 V microcontroller GPIOs with 3.3 V ADC or FPGA I/O banks. IC Role / Device Role / Timing Role: Level-shifting bus switch enabling bidirectional data flow without direction control pins or external resistors. Use Value: R_ON ≤ 7 Ω ensures minimal voltage drop (<150 mV at 20 mA), preserving noise margin across voltage domains.
Clock Gating	Bus Isolation in Mass Storage
Use Scenario: Dynamic disabling of clock distribution to inactive peripheral modules (e.g., USB PHY, display controller) to reduce dynamic power. IC Role / Device Role / Timing Role: High-speed switch placed in clock path; enables/disables clock edge delivery with sub-7 ns turn-off delay. Use Value: t_PHZ ≤ 5.5 ns guarantees clean clock stop/start edges, preventing metastability in downstream registers.	Use Scenario: Isolating SATA or parallel ATA data buses between host controller and drive during power sequencing or fault recovery. IC Role / Device Role / Timing Role: Quad switch disconnects bidirectional data lanes to prevent backfeed, leakage, or capacitive loading during idle states. Use Value: 5 pF typical OFF-state capacitance minimizes signal integrity degradation when multiple drives share a common bus.

Hot-Swapping Systems

Voltage Translation

Use Scenario: Insertion/removal of PCIe add-in cards or modular I/O boards while main system remains powered.

IC Role / Device Role / Timing Role: Bus switch isolates backplane signals during insertion to prevent glitch propagation and power rail disturbance.

Use Value: Undershoot clamps and zero ground bounce ensure no false triggering of connected logic during plug/unplug transients.

Use Scenario: Interfacing 5 V microcontroller GPIOs with 3.3 V ADC or FPGA I/O banks.

IC Role / Device Role / Timing Role: Level-shifting bus switch enabling bidirectional data flow without direction control pins or external resistors.

Use Value: R_ON ≤ 7 Ω ensures minimal voltage drop (<150 mV at 20 mA), preserving noise margin across voltage domains.

Clock Gating

Bus Isolation in Mass Storage

Use Scenario: Dynamic disabling of clock distribution to inactive peripheral modules (e.g., USB PHY, display controller) to reduce dynamic power.

IC Role / Device Role / Timing Role: High-speed switch placed in clock path; enables/disables clock edge delivery with sub-7 ns turn-off delay.

Use Value: t_PHZ ≤ 5.5 ns guarantees clean clock stop/start edges, preventing metastability in downstream registers.

Use Scenario: Isolating SATA or parallel ATA data buses between host controller and drive during power sequencing or fault recovery.

IC Role / Device Role / Timing Role: Quad switch disconnects bidirectional data lanes to prevent backfeed, leakage, or capacitive loading during idle states.

Use Value: 5 pF typical OFF-state capacitance minimizes signal integrity degradation when multiple drives share a common bus.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74CBT3125DBR	Same 14-pin SOIC, 5 V only, R_ON = 6 Ω typ., t_OFF = 5.5 ns max - TI's pin-compatible variant with identical timing specs	Qualified per AEC-Q100 Grade 2; preferred for automotive infotainment bus isolation where extended temp is required	Select SN74CBT3125DBR if AEC-Q100 compliance or TI ecosystem alignment is mandatory
74LVC1G3157GW	Single-channel, 6-pin SOT363, R_ON = 10 Ω typ., V_CC = 1.65–5.5 V - Lower integration, wider voltage range, smaller footprint	Suitable for space-constrained single-line isolation (e.g., I²C SCL/SDA), not direct quad replacement	Choose 74LVC1G3157GW only for new designs needing ultra-small size and multi-voltage flexibility over quad functionality

Compared with SN74CBT3125DBR and 74LVC1G3157GW, the QS3125S1G8 offers industrial-qualified quad-channel integration in standard SOIC-14, making it optimal for legacy-compatible board upgrades requiring minimal layout change and guaranteed –40°C to +85°C performance without voltage scaling trade-offs.

Availability

QS3125S1G8 is available at Aetrix Electronics and suitable for hot-swapping systems, voltage translation interfaces, and clock gating circuits requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for QS3125S1G8 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 QS3125S1G8 belongs to Renesas' QuickSwitch® family of high-speed bus switches, engineered specifically for noise-free, zero-delay signal routing in industrial control, data processing, and hot-plug-capable systems.

FAQ

What is the maximum allowable undershoot voltage on QS3125S1G8 I/O pins?

The QS3125S1G8 includes integrated undershoot clamp diodes on all A, Y, and OE pins. Per Absolute Maximum Ratings, it tolerates –3 V AC undershoot (pulse width ≤20 ns) and –0.5 V DC. This protects connected devices during hot-swap events and ensures robustness in noisy industrial environments. The clamping action activates below ~–0.5 V, limiting negative excursion without damaging the QS3125S1G8.

Does QS3125S1G8 support bidirectional analog signal switching?

Yes, QS3125S1G8 supports true bidirectional analog switching due to its enhanced N-channel FET structure with no inherent diode to V_CC. Signals up to 7 V peak-to-peak can pass between A and Y terminals in either direction with minimal distortion. Its 5 Ω typical R_ON and low OFF-capacitance (5–7 pF) make it suitable for video, audio, and sensor signal routing where DC coupling and bandwidth preservation are critical.

Is QS3125S1G8 pin-compatible with standard 74-series logic devices?

Yes, QS3125S1G8 is explicitly designed as a pin-compatible replacement for the 74'125 quad buffer function in SOIC-14 packaging. Pin assignments match: 1OE–4OE correspond to 1G–4G enables, and 1A–4A/1Y–4Y align with input/output positions. No PCB redesign is needed when upgrading from 74LS125 or 74HC125 to QS3125S1G8 for improved speed, lower power, and hot-swap capability.

What is the quiescent supply current of QS3125S1G8 at 85°C?

QS3125S1G8 draws a maximum quiescent supply current (I_CCQ) of 3 µA at V_CC = 5.5 V and ambient temperature up to +85°C. This ultra-low static current enables use in always-on subsystems such as battery-backed real-time clocks or standby monitoring circuits where power conservation is essential. The value is guaranteed across the full industrial temperature range.

Can QS3125S1G8 be used for 3.3 V to 5 V level translation without external components?

Yes, QS3125S1G8 supports passive bidirectional level translation between 3.3 V and 5 V domains without pull-up resistors or direction control. When V_CC = 5 V, the device passes signals from 3.3 V A-side to 5 V Y-side (and vice versa) with R_ON ≤ 7 Ω, resulting in <150 mV drop at 20 mA. Its wide input voltage range (–0.5 V to +7 V) and rail-tolerant I/O eliminate need for external level shifters in mixed-voltage data buses.

QS3125S1G8 Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: -

Package/Case:: 14-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Bus Switch

Circuit:: 1 x 1:1

Independent Circuits:: 4

Current - Output High, Low:: -

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 14-SOIC

QS3125S1G8 FAQ

1.How can I place an order for QS3125S1G8 through Aetrix?

Please submit a Request for Quotation (RFQ) for QS3125S1G8 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for QS3125S1G8 reliable?

The price and inventory of QS3125S1G8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for QS3125S1G8 is usually 5 days.

3.What payment methods are accepted for QS3125S1G8?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for QS3125S1G8 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for QS3125S1G8?

QS3125S1G8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your QS3125S1G8 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for QS3125S1G8?

For technical support, including QS3125S1G8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your QS3125S1G8 requirements.

6.How does Aetrix verify that QS3125S1G8 is sourced from the original manufacturer or authorized distributors?

All QS3125S1G8 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that QS3125S1G8 meets industry standards.

7.What is the process for return or replacement of QS3125S1G8?

All QS3125S1G8 units undergo pre-shipment inspection (PSI). If there is an issue with QS3125S1G8, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The QS3125S1G8 part is unused and in its original packaging.

Return procedure for QS3125S1G8:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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