Renesas QS3251S1G8

Overview

QS3251S1G8 from Renesas Electronics is a high-speed CMOS 8:1 multiplexer/demultiplexer with TTL-compatible control inputs, 5Ω typical ON resistance, zero propagation delay, and industrial temperature range (–40°C to +85°C). It serves as a bidirectional logic-level switch for video/audio routing, hot-swap interfaces, and voltage translation between 5V and 3.3V domains.

For engineers reviewing the QS3251S1G8 datasheet, QS3251S1G8 pinout, QS3251S1G8 application, or QS3251S1G8 equivalent, key selection criteria include guaranteed 5Ω R_ON, undershoot clamp diodes on all I/Os, 3-state output enable, SOIC-16 green package compliance, and functional compatibility with 74F251/74FCT251 families.

Technical Context

The QS3251S1G8 implements an enhanced N-channel FET switch architecture with no inherent body diode to V_CC, enabling true bidirectional signal flow without forward-bias constraints. Its control logic accepts TTL-level inputs (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V) and drives a single 3-state output Y via three select lines (S0–S2) and active-low enable E.

Switching performance is defined by sub-nanosecond turn-on/turn-off delays (t_PZL/t_PLZ ≤ 6 ns), negligible propagation delay (t_PLH/t_PHL ≤ 0.25 ns), and low dynamic power consumption (0.25 mA/MHz ICCD), making it suitable for high-frequency data path switching where timing integrity and ground bounce suppression are critical.

Key Specifications

Pinout & Package

QS3251S1G8 is housed in a 16-pin Small Outline IC (SOIC) package with 1.27 mm pitch, JEDEC MS-012AC compliant, and RoHS green marking (S1G suffix). Pin 1 is I3 (Data Input 3), pin 8 is S0 (Select 0), pin 9 is NC (No Connect), and pin 16 is V_CC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8:1 analog/digital multiplexer applications.

Compared with QS3251S1G8, the 74FCT251CTSO lacks undershoot protection and analog capability, while SN74CBT3251PWR offers similar specs but requires separate thermal validation-QS3251S1G8 delivers verified industrial-grade robustness out-of-box.

Availability

QS3251S1G8 is available at Aetrix Electronics and suitable for video routing, hot-swap interface design, and 5V-to-3.3V level translation applications requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant packaging.

Supply support for QS3251S1G8 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.

QS3251S1G8 belongs to the QUICKSWITCH® bus switch product line, engineered for ultra-low-delay, bidirectional signal routing in mixed-voltage systems where timing predictability and signal integrity are critical.

FAQ

What is the maximum continuous current rating for QS3251S1G8?

The QS3251S1G8 supports up to ±120 mA DC output current per channel under steady-state conditions. This rating applies to the Y output terminal when driving resistive or moderately capacitive loads, and is specified across the full industrial temperature range with V_CC = 5.0 V ±5%. Exceeding this limit risks thermal overstress and degradation of R_ON stability.

Does QS3251S1G8 support bidirectional signal flow?

Yes, QS3251S1G8 supports fully bidirectional signal flow between any Ix pin and Y due to its enhanced N-channel FET architecture with no inherent body diode to V_CC. This allows seamless analog or digital signal routing in either direction without polarity constraints, unlike traditional CMOS multiplexers with parasitic diodes that limit voltage swing or cause leakage.

Is QS3251S1G8 pin-compatible with standard 74-series logic devices?

Yes, QS3251S1G8 is explicitly pin-compatible with 74F251, 74FCT251, and 74FCT251T 8:1 multiplexers. The SOIC-16 footprint, pin numbering, and functional mapping-including I0–I7, S0–S2, E, and Y-match these legacy parts exactly, enabling direct replacement without PCB layout modification.

What is the purpose of the undershoot clamp diodes in QS3251S1G8?

The undershoot clamp diodes in QS3251S1G8 protect all switch and control inputs from negative transients down to –3 V (pulse width ≤ 20 ns). These integrated clamps prevent damage and false triggering during hot-plug events or noisy industrial environments, eliminating the need for external protection components in QS3251S1G8-based designs.

Can QS3251S1G8 be used for voltage translation between 5V and 3.3V systems?

Yes, QS3251S1G8 is commonly used for passive 5V-to-3.3V voltage translation because its bidirectional FET switch operates independently of V_CC logic thresholds. When a 5V signal drives an Ix pin while Y connects to a 3.3V load, the device passes the signal with minimal drop (≤0.3 V at 15 mA), preserving logic levels without external bias or level-shifter ICs.