Semtech Corporation 1N6474US

Overview

1N6474US from Semtech is a transient diverting suppressor (TDS) designed for high-energy EOS protection of 22V-rated power or I/O lines, featuring ±30kV IEC 61000-4-2 ESD immunity, 40A peak pulse current (8/20μs), 27.5–28V clamping voltage at 40A, and ultra-low 20mΩ dynamic resistance. It protects USB PD, USB Type-C VBus, and load switch inputs in industrial and portable electronics.

For engineers reviewing the 1N6474US datasheet, pinout, applications, or equivalent options, this device offers stable clamping across temperature (−40°C to +125°C) and current (24–40A), low 175pF junction capacitance at 22V, and DFN 1.6×1.6mm package compatibility with space-constrained USB and IoT designs.

Technical Context

The 1N6474US uses a surge-rated FET as its primary protection element, activated by a precision trigger circuit that turns on the shunt path when transient voltage exceeds breakdown. Unlike conventional TVS diodes, its clamping voltage remains nearly constant due to decreasing R_DS(on) under surge conditions.

It operates with reverse stand-off voltage of 22V, breakdown voltage of 25–27.9V at 1mA, and maintains <28V clamping up to 40A with 2Ω source impedance using 1.2/50μs voltage + 8/20μs current combination waveform - meeting IEC 61000-4-5 Level 3 (±1kV) for unsymmetrical lines.

Key Specifications

Pinout & Package

1N6474US is housed in a Pb-free, RoHS-compliant DFN 1.6mm × 1.6mm × 0.55mm 6-lead package with exposed thermal pad (not electrically connected). All pins must be soldered for full 40A surge rating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Compared with SMAJ22A and TDS2211P, the 1N6474US delivers identical clamping stability and surge rating as TDS2211P but differs in part numbering and branding; unlike SMAJ22A, it avoids temperature- and current-dependent clamping rise, ensuring consistent protection across operating conditions.

Availability

1N6474US is available at Aetrix Electronics and suitable for USB Type-C power delivery systems, industrial load switch inputs, and IoT edge node power rail protection requiring stable component supply, high-volume traceability, and long-term lifecycle support.

Supply support for 1N6474US 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

Semtech Corporation is a U.S.-based fabless semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, protection, sensing, and connectivity.

The 1N6474US belongs to Semtech's Transient Diverting Suppressor (TDS) product line, engineered to replace conventional TVS diodes with FET-based clamping for stable, temperature-independent surge protection in high-reliability power and interface applications.

FAQ

What is the maximum continuous operating voltage for the 1N6474US?

The 1N6474US has a reverse stand-off voltage (V_RWM) of 22V, meaning it can continuously block up to 22V DC without significant leakage or conduction. This makes it suitable for protecting 20V–22V power rails such as USB PD VBus, industrial 24V systems (derated), and notebook auxiliary supplies. Exceeding 22V risks premature triggering or accelerated aging.

How does the 1N6474US achieve stable clamping voltage across temperature and current?

The 1N6474US uses a precision-triggered surge-rated FET instead of a PN-junction diode. When an overvoltage event occurs, the trigger circuit activates the FET, whose R_DS(on) decreases as current increases - resulting in near-constant clamping voltage (27.5–28V) from 24A to 40A and across −40°C to +125°C. This contrasts sharply with standard TVS diodes, whose clamping rises linearly with both current and temperature.

Can the 1N6474US replace a standard TVS diode like SMAJ22A in an existing design?

The 1N6474US is not a direct drop-in replacement for SMAJ22A due to different package (DFN 1.6×1.6mm vs. DO-214AC), pinout (6-pin dual-terminal vs. 2-pin), and electrical behavior (constant-clamp vs. rising-clamp). While both have 22V V_RWM, the 1N6474US requires PCB layout changes to accommodate its 6-pin configuration and ground/power plane routing. It is best implemented in new designs targeting superior surge performance.

What is the junction capacitance of the 1N6474US and why does it matter?

The 1N6474US exhibits 175pF junction capacitance at 22V and 1MHz. This value is low enough to avoid degrading signal integrity on 22V power rails yet high enough to sustain robust surge energy absorption. In contrast, sub-1pF TVS devices used for high-speed data lines cannot handle 40A surges - making the 1N6474US ideal for power-line protection where bandwidth is not critical but energy handling is.

Is the 1N6474US compliant with industry environmental standards?

Yes, the 1N6474US is Pb-free, halogen-free, and RoHS/WEEE compliant. Its molding compound meets UL 94V-0 flammability rating, and it is qualified for operating temperatures from −40°C to +125°C. These attributes support its use in automotive-adjacent industrial equipment, medical peripherals, and consumer electronics requiring strict material and thermal compliance.