onsemi SA20ARLG

Overview

SA20ARLG from onsemi is a unidirectional 500 W peak power MiniMOSORB Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 20 V working peak reverse voltage (VRWM), 32.4 V maximum clamping voltage at 15.4 A peak pulse current, <1 µA leakage at VRWM, and sub-1 ns response time. It is used in industrial power supplies, medical equipment surge protection, and communication interface line protection.

For engineers reviewing the SA20ARLG datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected circuit's max operating voltage, UL 497B certification for isolated loop protection, axial leaded Surmetic package thermal performance, and ESD robustness (>16 kV HBM).

Technical Context

The SA20ARLG operates as a unidirectional Zener-based TVS diode, conducting only during reverse overvoltage events above its breakdown voltage (22.2–24.5 V). Its low zener impedance and fast response (<1 ns) enable effective suppression of EFT, lightning-induced surges, and inductive switching transients.

It is rated for 500 W nonrepetitive peak pulse power (1 ms), with derating above 25°C ambient per Figure 5, and meets UL 497B for isolated loop circuit protection - a requirement for telecom and industrial safety-critical interfaces.

Key Specifications

Pinout & Package

SA20ARLG uses an axial-leaded Surmetic plastic package (Case 59AA), with cathode indicated by a polarity band. Leads are solderable, corrosion-resistant, and 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 SMAJ20A and P6SMB20A, the SA20ARLG offers tape-and-reel axial delivery for selective through-hole automation, UL 497B certification not shared by SMAJ20A, and a tighter thermal resistance (33.3 °C/W vs. ~45 °C/W for P6SMB20A), enabling more predictable derating in thermally dense industrial enclosures.

Availability

SA20ARLG is available at Aetrix Electronics and suitable for industrial power supplies, medical equipment, and communication interface protection requiring stable component supply and long-term manufacturability.

Supply support for SA20ARLG 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The SA5.0A Series belongs to onsemi's MiniMOSORB TVS portfolio, engineered specifically for high-reliability transient suppression in safety-critical and regulated systems - emphasizing UL recognition, repeatable clamping, and axial-package robustness for industrial longevity.

FAQ

What is the clamping voltage of SA20ARLG at its rated peak pulse current?

The SA20ARLG has a maximum clamping voltage (VC) of 32.4 V when subjected to its rated peak pulse current of 15.4 A (1 ms waveform). This value is measured per Figure 4 in the datasheet and defines the upper voltage limit imposed on protected circuits during surge events. Designers must ensure this clamping level remains below the absolute maximum voltage rating of downstream components. The SA20ARLG achieves this with low dynamic impedance and tight VBR distribution (22.2–24.5 V).

Is SA20ARLG certified for UL 497B, and what does that mean for my design?

Yes, SA20ARLG is UL 497B recognized (File #E210057, QVGQ2 category) for isolated loop circuit protection - a critical requirement for telecom, industrial control, and medical isolation barriers. This certification confirms successful completion of Strike Voltage Breakdown, Endurance Conditioning, Dielectric Withstand, and Discharge tests. Unlike basic flammability-only approvals, UL 497B validates functional protection integrity, reducing compliance risk in your SA20ARLG-based designs.

How does the SA20ARLG differ from the SA20A or SA20AG variants?

The SA20ARLG is the Pb-free, tape-and-reel packaged version of the SA20A, using the same silicon die and electrical specs. "RLG" denotes axial leads, RoHS-compliant finish, and 5000-unit tape-and-reel packaging - optimized for automated through-hole insertion. SA20A is the base part number (often bulk-packed), while SA20AG indicates Pb-free in box packaging. All share identical VRWM (20 V), VBR (22.2–24.5 V), and VC (32.4 V), ensuring direct form-fit-function equivalence.

Can SA20ARLG be used in bidirectional protection configurations?

No - SA20ARLG is strictly unidirectional and must be used with cathode toward the protected line and anode to reference ground. For bidirectional protection (e.g., AC lines or differential buses), two SA20ARLG devices may be connected anode-to-anode, but this configuration requires careful layout to avoid parasitic coupling and does not replace purpose-built bidirectional TVS devices like the CA-series. The datasheet explicitly specifies SA20ARLG as unidirectional; no bidirectional capability is characterized or guaranteed.

What is the maximum steady-state power dissipation for SA20ARLG at 25°C ambient?

At TL ≤ 25°C lead temperature, the SA20ARLG has a steady-state power dissipation (PD) rating of 3.0 W. This value derates linearly at 30 mW/°C above 50°C lead temperature, per Figure 5. Unlike its 500 W peak pulse rating, this 3.0 W limit applies only to continuous DC or low-frequency AC power dissipation - such as leakage current heating under sustained overvoltage. In normal operation below VRWM, leakage is <1 µA, resulting in negligible self-heating.