My Inquiry
My Account
Renesas QS3126QG8
- Part No.:
- QS3126QG8
- Manufacturer:
- Renesas
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
QS3126QG8.pdf
- Description:
- IC BUS SWITCH 1 X 1:1 16QSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,842
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
QS3126QG8 from Renesas Electronics is a high-speed CMOS quadruple bus switch with individual active-high enables, designed for bidirectional signal routing between A and Y buses. It features 5 Ω typical ON resistance at 5 V, zero propagation delay, and undershoot clamp diodes on all inputs. Used in hot-swap interfaces and voltage translation (5 V ↔ 3.3 V) in industrial embedded systems.
For engineers reviewing the QS3126QG8 datasheet, QS3126QG8 pinout, QS3126QG8 application, or QS3126QG8 equivalent, key selection criteria include ON-resistance matching, enable-input logic polarity, bus isolation capability, and QSOP-16 package compatibility with legacy 74'126 footprint designs.
Technical Context
The QS3126QG8 implements four independent N-channel FET switches with no inherent body diode to VCC, enabling true bidirectional signal flow without forward-bias risk. Each channel has a dedicated active-high OE input controlling connection between corresponding A and Y terminals.
It operates across –40°C to +85°C with 5 V ±5% supply, supports DC switch voltages up to ±7 V, and delivers sub-nanosecond turn-on/turn-off delays (tPZL ≤ 6.5 ns, tPLZ ≤ 5.5 ns) under 50 pF load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| ON Resistance (RON) | 5 Ω typical at VCC = 5 V, 30 mA - ensures minimal signal attenuation and voltage drop across enabled paths |
| Propagation Delay | 0.25 ns max - adds negligible timing skew in high-speed data paths |
| Input Voltage Range | –0.5 V to +7 V - supports robust undershoot/overshoot tolerance on control and bus pins |
| Quiescent Current (ICCQ) | 3 µA max - enables ultra-low static power in always-on isolation circuits |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade reliability without derating |
| Switch Capacitance | 5–7 pF (OFF-state) - minimizes loading on upstream drivers and downstream receivers |
| Enable Logic Polarity | Active-HIGH (OE) - simplifies direct interface with microcontroller GPIOs without inverters |
Pinout & Package
QS3126QG8 is packaged in a 16-pin Quarter Size Outline Package (QSOP), code PCG16, with 0.65 mm lead pitch and standard JEDEC MO-137AC footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE–4OE | Control Input | Active-high enable for channels 1–4; each independently gates its A↔Y path |
| 1A–4A | Switch Terminal | Bidirectional bus A-side connection; electrically identical to Y pins |
| 1Y–4Y | Switch Terminal | Bidirectional bus Y-side connection; no internal diode to VCC |
| VCC | Power Supply | +5 V supply rail; all switching and logic referenced to this node |
| GND | Ground Reference | Signal and power return; required for proper clamp diode operation |
| NC (Pins 1, 16) | No Connect | Unbonded pads; must remain unconnected per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Zero-propagation-delay switching | RC-limited delay <0.25 ns at 50 pF - preserves signal integrity in >100 MHz digital buses |
| Undershoot clamp diodes | Integrated on all A, Y, and OE pins - protects against –3 V transient spikes without external components |
| Enhanced N-channel FET architecture | No intrinsic source-to-drain diode - prevents unintended current flow when VA > VY or vice versa |
| Pin compatibility with 74'126 | Same functional mapping and pinout as SN74LVC126A in QSOP-16 - enables drop-in replacement in existing layouts |
| Industrial temperature range | Full functionality from –40°C to +85°C - suitable for factory automation and outdoor edge nodes |
Applications
| Hot-Swappable Backplane Interface | Voltage-Level Translation |
|---|---|
Use Scenario: Inserting/removing line cards in powered telecom chassis without disrupting system operation. IC Role / Device Role / Timing Role: Bus switch isolates card-side signals from backplane during insertion; OE controlled by hot-swap controller. Use Value: Prevents bus contention and ground bounce during plug events; RON <7 Ω maintains signal fidelity at 100 Mbps. | Use Scenario: Interfacing 5 V legacy peripherals with 3.3 V microcontrollers in industrial HMIs. IC Role / Device Role / Timing Role: Bidirectional level shifter for data/control lines (e.g., I²C, SPI, GPIO). Use Value: No direction control needed; pass voltage ≥3.7 V at 5 V VCC ensures reliable 3.3 V logic HIGH recognition. |
| Logic-Controlled Clock Gating | Capacitive Load Isolation |
Use Scenario: Dynamically disabling clock distribution to idle subsystems in programmable logic controllers. IC Role / Device Role / Timing Role: High-speed gate for clock signals; OE driven by power management unit. Use Value: Sub-ns turn-off delay (tPHZ ≤5.5 ns) eliminates clock glitches; low COFF (5 pF) minimizes jitter injection. | Use Scenario: Isolating high-capacitance storage interfaces (e.g., SATA PHY, DDR termination networks) from sensitive analog sections. IC Role / Device Role / Timing Role: Signal path disconnect switch activated during analog measurement cycles. Use Value: OFF-state leakage ≤±1 µA and 7 pF capacitance prevent crosstalk and settling errors in precision ADC front-ends. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switch applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC126APW | 4-channel, 3.3 V only, lower RON (3.5 Ω typ), no undershoot clamps | Requires level-shifting for 5 V systems; unsuitable for hot-swap transients | Prefer for 3.3 V-only designs where cost and lower RON outweigh transient protection needs |
| 74FST3126MTCX | 5 V only, higher speed (tPLH/tPHL <0.2 ns), no industrial temp grade | Limited to 0°C to +70°C; lacks clamp diodes and wide voltage tolerance | Select only for commercial-grade, high-frequency test equipment where ambient stays within 0–70°C |
Compared with SN74LVC126APW and 74FST3126MTCX, the QS3126QG8 uniquely combines 5 V operation, industrial temperature range, integrated undershoot protection, and true bidirectional isolation-making it the sole option for ruggedized hot-swap and mixed-voltage industrial interfaces.
Availability
QS3126QG8 is available at Aetrix Electronics and suitable for hot-swapping, voltage translation, and clock gating applications requiring stable component supply in industrial environments.
Supply support for QS3126QG8 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 markets.
The QS3126QG8 belongs to Renesas' QuickSwitch® family of high-speed bus switches, engineered specifically for noise-free, zero-delay signal routing in industrial control, telecom infrastructure, and embedded computing systems.
FAQ
What is the maximum allowable voltage on QS3126QG8 A and Y pins?
The QS3126QG8 supports DC switch voltages from –0.5 V to +7 V on all A and Y terminals, independent of VCC. This allows safe operation during hot-swap events with transient undershoot down to –3 V (AC pulse ≤20 ns) and overvoltage up to +7 V, provided clamp diodes remain within safe conduction limits. The QS3126QG8 datasheet explicitly guarantees this rating under Absolute Maximum Ratings.
Does QS3126QG8 support bidirectional signal flow without additional circuitry?
Yes, the QS3126QG8 supports true bidirectional signal flow between A and Y terminals due to its enhanced N-channel FET architecture with no inherent body diode to VCC. Signals propagate equally well from A to Y or Y to A when the corresponding OE is asserted. This eliminates need for direction-control logic or external diodes, making QS3126QG8 ideal for I²C, JTAG, and other bidirectional protocols.
Is QS3126QG8 pin-compatible with standard 74-series logic devices?
Yes, the QS3126QG8 is pin-compatible with the 74'126 function in QSOP-16 packaging. Its pin configuration matches SN74LVC126A and 74FST3126 in the same package outline, including identical placement of VCC, GND, and channel I/O pairs. This enables direct PCB-level replacement in legacy designs without layout modification.
What is the typical ON resistance of QS3126QG8 and how does it affect signal integrity?
The QS3126QG8 has a typical ON resistance of 5 Ω at VCC = 5 V and 30 mA drive current. At 50 pF load, this yields an RC time constant of ~0.25 ns - far below typical signal rise times - resulting in negligible added propagation delay or distortion. This low RON ensures minimal voltage drop (<150 mV at 30 mA) and preserves signal amplitude integrity in high-speed digital buses.
Why is QS3126QG8 marked as obsolete and what are the implications for new designs?
QS3126QG8 was declared obsolete per Renesas PLC230010 (effective Nov 30, 2025), with last-time-buy ending July 31, 2024. While Aetrix Electronics maintains limited inventory and supports legacy production, new designs should evaluate Renesas' recommended replacements such as the 74LVC1G3157 or IDT's newer QuickSwitch families. The QS3126QG8 remains fully functional and qualified for industrial use until stock depletion.
QS3126QG8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Renesas
- Series:
- -
- Package/Case:
- 16-SSOP (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:
- 16-QSOP
QS3126QG8 FAQ
1.How can I place an order for QS3126QG8 through Aetrix?
Please submit a Request for Quotation (RFQ) for QS3126QG8 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 QS3126QG8 reliable?
The price and inventory of QS3126QG8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for QS3126QG8 is usually 5 days.
3.What payment methods are accepted for QS3126QG8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for QS3126QG8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for QS3126QG8?
QS3126QG8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your QS3126QG8 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 QS3126QG8?
For technical support, including QS3126QG8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your QS3126QG8 requirements.
6.How does Aetrix verify that QS3126QG8 is sourced from the original manufacturer or authorized distributors?
All QS3126QG8 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 QS3126QG8 meets industry standards.
7.What is the process for return or replacement of QS3126QG8?
All QS3126QG8 units undergo pre-shipment inspection (PSI). If there is an issue with QS3126QG8, 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 QS3126QG8 part is unused and in its original packaging.
Return procedure for QS3126QG8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
QS3126QG8 Tags
-
SN74HC138DR
Texas Instruments
-
TC7SB3157CFU,LF(CT
Toshiba Semiconductor and Storage
-
74CBTLV3257PW,118
Nexperia USA Inc.
-
SN74CBTLV3257PWR
Texas Instruments
-
74CBTLV3257GUX
Nexperia USA Inc.
-
74HC154BQ,118
Nexperia USA Inc.
-
P3S0200GMX
NXP USA Inc.
-
SN74CB3Q3245PWR
Texas Instruments
-
SN74CB3Q3257RGYR
Texas Instruments
-
TCA9543APWR
Texas Instruments
-
TCA9546APWR
Texas Instruments
-
SN74HC138N
Texas Instruments
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
