onsemi SA45ARL

Overview

SA45ARL from onsemi is a unidirectional MiniMOSORB Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 45 V working peak reverse voltage (VRWM), 500 W peak pulse power rating at 1.0 ms, clamping voltage of 70.1 V at 7.1 A peak pulse current, <1 µA leakage above 8.5 V, and sub-1 ns response time - deployed in industrial power supplies and medical equipment surge protection.

For engineers reviewing the SA45ARL datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to protected IC's absolute maximum rating, UL 497B certification for isolated loop circuits, and axial leaded Surmetic package compatibility with through-hole reflow or hand-soldering processes.

Technical Context

The SA45ARL operates as a unidirectional Zener-based TVS diode, conducting only during reverse overvoltage events while remaining high-impedance under normal bias. Its clamping action begins at breakdown voltage (VBR = 50–52.7 V @ IT = 1 mA) and sustains energy absorption up to 500 W for 1 ms per IEC 61000-4-5 waveform.

It exhibits low zener impedance, temperature coefficient of ±0.05 %/°C for VBR, and ESD robustness >16 kV HBM. The device is rated for -55°C to +175°C operation, with thermal resistance R_JL = 33.3 °C/W and maximum lead temperature of 260°C for 10 s at 1/16″ from case.

Key Specifications

Pinout & Package

SA45ARL is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode indicated by a polarity band. Leads are tin-plated, solderable, and rated for 260°C for 10 seconds at 1/16″ from case.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SA45ARL, SMAJ45A trades surge margin for footprint reduction, while P6SMB45A matches all key specs but requires PCB redesign for SMT assembly - making SA45ARL optimal for legacy through-hole industrial power modules needing proven axial reliability.

Availability

SA45ARL is available at Aetrix Electronics and suitable for industrial power supplies, medical equipment input stages, and telecom line card surge protection requiring stable component supply, long-term lifecycle support, and UL-certified transient immunity.

Supply support for SA45ARL 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 manufacturer specializing in energy-efficient silicon solutions for automotive, industrial, cloud computing, and IoT applications.

The SA45ARL belongs to the SA5.0A Series MiniMOSORB family, engineered specifically for high-reliability, high-energy transient suppression in harsh industrial and medical environments where UL 497B certification and axial mechanical robustness are mandatory.

FAQ

What is the clamping voltage of SA45ARL and how does it relate to system protection?

The SA45ARL clamps at 70.1 V when subjected to a 7.1 A peak pulse current (1 ms waveform). This value defines the maximum voltage imposed on downstream components during a surge event. To ensure protection, the clamped voltage must remain below the absolute maximum rating of the IC or capacitor being safeguarded - for example, selecting SA45ARL for a 60 V-rated DC-DC controller provides 10.1 V design margin. The SA45ARL achieves this via low dynamic impedance and fast Zener avalanche response.

Is SA45ARL RoHS compliant and what does the "RLG" suffix indicate?

Yes, SA45ARL is RoHS compliant and Pb-Free. The "RLG" suffix denotes an axial-leaded, tape-and-reel packaged version (5000 units per reel) with Pb-Free Surmetic construction. This aligns with JEDEC standard DO-41 outlines and supports lead-free reflow profiles up to 260°C for 10 seconds. The SA45ARL meets EU Directive 2011/65/EU and is documented in onsemi's Pb-Free Packaging Reference Manual SOLDERRM/D.

Does SA45ARL require a heatsink for continuous operation?

No, SA45ARL is not intended for continuous power dissipation. Its 3.0 W steady-state rating applies only at TL ≤ 75°C with 3/8″ lead length; typical use is transient-only clamping. For repetitive surges, derating per Figure 2 of the datasheet is required. The SA45ARL relies on thermal mass of its leads and PCB copper for short-duration energy absorption - no external heatsink is specified or recommended in the official onsemi application guidance for SA45ARL.

How does UL 497B recognition benefit SA45ARL in medical or industrial designs?

UL 497B recognition certifies SA45ARL for use in isolated loop circuits - critical for medical devices with patient-connected circuits and industrial systems using galvanically isolated signal paths. Unlike basic flammability certifications, UL 497B validates performance in Strike Voltage Breakdown, Endurance Conditioning, and Dielectric Withstand tests. This eliminates need for additional third-party testing when using SA45ARL in UL-listed end equipment, accelerating time-to-market for designs requiring SA45ARL-level protection.

Can SA45ARL be used in bidirectional configurations?

No, SA45ARL is strictly unidirectional and must be installed with correct polarity (cathode to protected line, anode to ground). For bidirectional protection, onsemi offers the CA-series counterparts (e.g., SA45A has a bidirectional variant CA45A), but SA45ARL itself lacks symmetrical breakdown characteristics. Using SA45ARL in reverse orientation will not provide forward surge protection and may fail catastrophically under positive transients - always observe the cathode band marking per SA45ARL datasheet Figure 1.