onsemi SA170ARL

Overview

SA170ARL from onsemi is a unidirectional MiniMOSORB Zener transient voltage suppressor (TVS) designed for high-energy surge clamping in DC power rails and signal lines. It features a 170 V working peak reverse voltage (VRWM), 275 V maximum clamping voltage at 208 A peak pulse current, 500 W peak pulse power (1 ms), <1.0 ns response time, and UL 497B recognition for isolated loop circuit protection.

For engineers reviewing the SA170ARL datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 208 A surges, thermal derating above 75°C lead temperature, compliance with Class 3 ESD (>16 kV HBM), and axial leaded Surmetic package compatibility with through-hole PCB assembly.

Technical Context

The SA170ARL operates as a voltage-clamped shunt protector: it remains high-impedance below 170 V VRWM, then avalanches sharply at 189–209 V breakdown (VBR @ 1 mA), limiting transients to ≤275 V at 208 A. Its low zener impedance and sub-nanosecond response enable effective suppression of EFT/burst and lightning-induced surges.

Thermally, it delivers 3.0 W steady-state dissipation at TL ≤ 75°C with 33.3°C/W junction-to-lead resistance, and supports pulsed operation up to 500 W (1 ms) per Figure 4 waveform-derated linearly above TA = 25°C per Figure 2. UL 497B certification confirms suitability for telecom and industrial isolated loop protection.

Key Specifications

Pinout & Package

SA170ARL is housed in ON Semiconductor's Surmetic axial-leaded plastic package (Case 59AA), featuring cathode polarity indicated by a band. Leads are tin-plated, solderable at 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 SMAJ170A and 1.5KE170A, SA170ARL offers UL 497B certification and optimized thermal resistance (33.3°C/W) for lead-temperature-limited environments, while maintaining identical 170 V VRWM and tight 189–209 V VBR tolerance.

Availability

SA170ARL is available at Aetrix Electronics and suitable for industrial power supplies, telecom line cards, medical AC/DC adapters, and process control sensor loops requiring stable component supply and certified surge protection.

Supply support for SA170ARL 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-including SA170ARL-is part of onsemi's MiniMOSORB TVS portfolio, engineered specifically for high-reliability, high-surge industrial and telecom infrastructure where UL recognition, precise clamping, and axial-leaded manufacturability are critical.

FAQ

What is the maximum clamping voltage of SA170ARL at its rated peak pulse current?

The SA170ARL has a maximum clamping voltage (VC) of 275 V at its rated peak pulse current (IPP) of 208 A, measured per the 1 ms exponential waveform defined in Figure 4 of the datasheet. This value defines the upper voltage limit imposed on protected circuits during worst-case surge events and is critical for ensuring downstream components remain within their absolute maximum ratings. The SA170ARL maintains this clamping performance across its full operating temperature range.

Does SA170ARL meet UL 497B requirements for isolated loop protection?

Yes, SA170ARL is explicitly included in onsemi's UL 497B recognition (File #E116110, QVGV2 category) for isolated loop circuit protection, as confirmed on page 5 of the SA5.0A/D datasheet. This certification covers passing strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge tests-validating its use in telecom and industrial isolation barriers without requiring additional third-party testing. The SA170ARL carries this qualification as part of the full SA5.0A–SA170A series.

What is the thermal derating behavior of SA170ARL above 75°C lead temperature?

SA170ARL provides 3.0 W steady-state power dissipation at TL ≤ 75°C, with linear derating at 30 mW/°C above that temperature, as shown in Figure 5. Its junction-to-lead thermal resistance is 33.3°C/W, enabling reliable operation in high-ambient environments when mounted with ≥3/8″ lead length. For pulsed operation, peak power remains 500 W at TA = 25°C but must be derated per Figure 2-e.g., to ~350 W at TA = 75°C. These curves are integral to thermal design validation for the SA170ARL.

How does the SA170ARL's breakdown voltage tolerance compare to other TVS diodes in its class?

SA170ARL specifies a tight breakdown voltage (VBR) range of 189 V (min) to 209 V (max) at 1 mA test current-±5.3% around the 199 V nominal value. This ±5% tolerance is tighter than standard 1.5KE-series parts (typically ±10%) and ensures more consistent clamping onset across production lots. That precision directly supports robust design margins in 200 V-rated systems and reduces risk of premature conduction or insufficient protection. The SA170ARL's VBR stability is further enhanced by its specified 1.8 mV/°C temperature coefficient.

Is SA170ARL compatible with lead-free soldering processes?

Yes, SA170ARL is supplied in a Pb-Free Surmetic axial package (indicated by the "RLG" suffix), qualified for lead-free reflow and wave soldering. Its leads tolerate 260°C for 10 seconds at 1/16″ from the case per JEDEC J-STD-020, and the thermosetting plastic body is void-free and corrosion-resistant. The "G" in SA170ARLG explicitly denotes Pb-Free compliance, making the SA170ARL suitable for RoHS-compliant manufacturing without process modification.