onsemi SA40ARLG

Overview

SA40ARLG from onsemi is a unidirectional MiniMOSORB Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power lines and signal paths. It features a 40 V working peak reverse voltage (VRWM), 500 W peak pulse power rating at 1.0 ms, 64.5 V maximum clamping voltage at 7.8 A peak pulse current, <1 µA reverse leakage at VRWM, and sub-1 ns response time. It is used in industrial power supplies and medical equipment input protection.

For engineers reviewing the SA40ARLG datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC V_MAX, surge current capability under IEC 61000-4-5 waveforms, UL 497B certification for isolated loop circuits, and axial leaded Surmetic package thermal performance under sustained surge conditions.

Technical Context

The SA40ARLG operates as a voltage-clamping device in parallel with sensitive circuitry, entering avalanche breakdown when transient voltage exceeds its breakdown threshold of 44.4–49.3 V at 1 mA test current. Its low zener impedance and fast response ensure effective suppression of ESD (Class 3 HBM >16 kV) and lightning-induced surges.

It is rated for 500 W nonrepetitive peak pulse power per 1.0 ms waveform (Figure 4), with derating to 3.0 W steady-state power at T_L ≤ 25°C and thermal resistance R_JL = 33.3°C/W. The device meets UL 497B requirements for isolated loop circuit protection and is Pb-free in Surmetic axial package Case 59AA.

Key Specifications

Pinout & Package

SA40ARLG is housed in ON Semiconductor's Surmetic axial-leaded plastic package, Case 59AA, with cathode indicated by a polarity band. Leads are solderable per J-STD-020, rated for 260°C for 10 seconds at 1/16 inch from case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ40A and 1.5KE40A, SA40ARLG uniquely combines axial-leaded mechanical robustness, UL 497B certification for safety-critical isolation, and optimized leakage (<1 µA) for precision analog signal paths-making it preferred for medical and telecom infrastructure where regulatory validation and low-error operation are mandatory.

Availability

SA40ARLG is available at Aetrix Electronics and suitable for industrial power supplies, medical equipment front-end protection, and telecom line interface circuits requiring stable component supply, long-lifecycle support, and certified surge immunity.

Supply support for SA40ARLG 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The SA5.0A Series-including SA40ARLG-is part of onsemi's MiniMOSORB TVS portfolio, engineered specifically for high-reliability transient suppression in safety-certified systems such as medical devices, industrial controls, and communications infrastructure.

FAQ

What is the clamping voltage of SA40ARLG at its rated peak pulse current?

The SA40ARLG has a maximum clamping voltage (VC) of 64.5 V at its rated peak pulse current (IPP) of 7.8 A, measured using the 1.0 ms exponential waveform defined in Figure 4 of the datasheet. This value represents the worst-case voltage imposed on protected circuitry during a full-rated surge event and must be compared directly against the absolute maximum voltage ratings of downstream components to ensure safe operation. The SA40ARLG maintains this clamping performance across its full operating temperature range of −55°C to +150°C.

Is SA40ARLG certified for use in safety-isolated circuits?

Yes, SA40ARLG carries UL 497B recognition under File #E210057 for protector classification (QVGQ2), validating its suitability in isolated loop circuits such as those found in medical equipment and telecom interfaces. This certification covers dielectric withstand, endurance conditioning, and strike voltage breakdown testing-going beyond basic flammability compliance. The SA40ARLG shares this UL listing with the full SA5.0A–SA170A series, making it appropriate for applications requiring formal safety agency approval where isolation integrity is critical.

How does the SA40ARLG differ from the SMAJ40A in terms of mounting and thermal performance?

SA40ARLG uses an axial-leaded Surmetic package (Case 59AA) with 33.3°C/W junction-to-lead thermal resistance, enabling direct heat sinking via leads and compatibility with through-hole assembly. In contrast, SMAJ40A uses a surface-mount DO-214AC (SMA) package with higher thermal resistance and reliance on PCB copper for heat dissipation. The SA40ARLG's leaded construction supports higher mechanical reliability in vibration-prone environments and simplifies replacement in field-serviceable equipment-key distinctions confirmed in onsemi's packaging documentation for both parts.

What is the reverse leakage current specification for SA40ARLG at its working voltage?

SA40ARLG specifies a maximum reverse leakage current (IR) of 1 µA at its working peak reverse voltage (VRWM) of 40 V and ambient temperature of 25°C. This ultra-low leakage ensures minimal impact on high-impedance signal paths and precision analog circuits-such as 4–20 mA current loops or sensor front-ends-where even nanoamp-level errors could degrade measurement accuracy. The SA40ARLG maintains leakage below 5 µA up to 85°C, supporting reliable operation in industrial temperature environments.

Does SA40ARLG meet industry-standard ESD immunity requirements?

Yes, SA40ARLG is rated for Class 3 Human Body Model (HBM) ESD immunity with >16 kV withstand capability, per ANSI/ESDA/JEDEC JS-001. This qualifies it for direct placement on user-accessible ports, front-panel connectors, and other ESD-prone interfaces without supplemental protection. Its sub-1 ns response time ensures clamping occurs before ESD energy couples into sensitive ICs, and its low zener impedance provides low-impedance shunt path-both verified in onsemi's characterization data for the SA5.0A Series, including SA40ARLG.