onsemi SA15A

Overview

SA15A from ON Semiconductor 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 15 V working peak reverse voltage (VRWM), 24.4 V maximum clamping voltage at 16 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 SA15A datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM matching system operating voltage, clamping voltage margin relative to protected IC V_DD tolerance, surge current capability under IEC 61000-4-5 waveform, and axial leaded Surmetic package compatibility with through-hole PCB layouts and automated insertion.

Technical Context

The SA15A operates as a voltage-clamping device that remains high-impedance below VRWM (15 V) and rapidly avalanches above V_BR (16.7–18.5 V) to limit transient overvoltage. Its low zener impedance and sub-nanosecond response ensure effective suppression of ESD (≥16 kV HBM) and lightning-induced surges without affecting normal signal integrity.

Rated for 500 W nonrepetitive peak power per 1 ms pulse, it sustains 3.0 W steady-state dissipation at T_L ≤ 75°C with 33.3°C/W junction-to-lead thermal resistance. The device is polarity-sensitive (cathode band marked), requires no biasing, and functions exclusively in reverse-biased configuration.

Key Specifications

Pinout & Package

SA15A is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode identified by a colored band. Leads are tin-plated, solderable at 260°C for 10 seconds at 1/16″ from case body. Mounting position is unrestricted.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ15A and P6KE15A, the SA15A offers superior mechanical robustness via axial leads, UL 497B certification for isolated circuits, and tighter clamping voltage-making it preferred for industrial power inputs and medical sensor interfaces where reliability and regulatory compliance are critical.

Availability

SA15A is available at Aetrix Electronics and suitable for industrial power supplies, RS-485 communication interfaces, and medical sensor front-ends requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for regulated markets.

Supply support for SA15A 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

ON Semiconductor (now onsemi) is a global semiconductor supplier specializing in power management, analog, sensors, and discrete devices for automotive, industrial, and cloud power applications.

The SA15A belongs to the MiniMOSORB Zener TVS family, engineered specifically for high-reliability transient suppression in harsh electromagnetic environments-emphasizing low clamping voltage, fast response, and regulatory compliance for industrial and medical end equipment.

FAQ

What is the maximum clamping voltage of the SA15A under surge conditions?

The SA15A exhibits a maximum clamping voltage (V_C) of 24.4 V when subjected to its rated 16 A peak pulse current (I_PP) with a 1 ms waveform. This value is measured per Figure 4 in the official datasheet and defines the upper voltage limit imposed on protected circuitry during transient events. Designers must ensure this clamping level stays below the absolute maximum ratings of downstream components. The SA15A maintains this performance across its qualified temperature range of −55°C to +175°C.

Does the SA15A meet UL safety standards for circuit protection?

Yes, the SA15A carries UL 497B recognition under file #E116110 (QVGV2 category) for isolated loop circuit protection. This certification confirms successful completion of strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge testing-validating its use in safety-critical telecom, industrial control, and medical applications. The UL listing applies explicitly to the SA5.0A–SA170A series, including the SA15A, and is not inferred from package similarity or family branding.

How does the SA15A differ from bidirectional TVS diodes like the SA15CA?

The SA15A is unidirectional and functions only during reverse-bias transients, making it ideal for DC power rails where polarity is fixed. In contrast, the SA15CA is bidirectional and clamps both positive and negative excursions-suited for AC lines or differential data signals. The SA15A offers lower leakage (<1 µA @ VRWM) and tighter clamping than its bidirectional counterpart, but cannot protect against negative-going surges on positive rails without external polarity management.

What is the thermal resistance and steady-state power rating of the SA15A?

The SA15A has a junction-to-lead thermal resistance (R_JL) of 33.3°C/W and a steady-state power dissipation (P_D) of 3.0 W at lead temperature (T_L) ≤ 75°C with 3/8″ lead length. Derating is linear at 30 mW/°C above 75°C. These values assume proper lead heat sinking and are validated per Figure 5 in the datasheet. Exceeding these limits risks thermal runaway and permanent degradation of the SA15A's clamping performance.

Can the SA15A be used in automotive applications?

The SA15A is not AEC-Q200 qualified and lacks automotive-specific validation such as extended temperature cycling or vibration testing. While its operating range (−55°C to +175°C) overlaps with under-hood requirements, ON Semiconductor does not list the SA15A for automotive use in its official product roadmap or qualification reports. For automotive ECUs or infotainment systems, designers should select AEC-Q200-compliant alternatives like the 1.5SMC15A or NUP4105MR6T1G instead of relying on the SA15A.