onsemi SA48A

Overview

SA48A 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 500 W peak pulse power rating (1 ms), 48 V working peak reverse voltage (VRWM), 77.4 V maximum clamping voltage at 6.5 A peak pulse current, <1 µA leakage above 40.8 V, and sub-1 ns response time. It is used in industrial power supplies and medical equipment surge protection.

For engineers reviewing the SA48A datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM matching system operating voltage, clamping voltage margin relative to protected IC V_MAX, surge current capability under IEC 61000-4-5 waveforms, and UL 497B recognition for isolated loop circuit protection.

Technical Context

The SA48A operates as a voltage-clamping device that remains high-impedance below VRWM (48 V) and rapidly transitions to low-impedance conduction when transient voltage exceeds V_BR (53.3–56.1 V at 1 mA). Its Zener-based structure provides precise breakdown with ±5% tolerance and low dynamic impedance (<1 Ω typical), enabling tight clamping during fast-rising ESD or lightning-induced surges.

It is rated for 500 W nonrepetitive peak pulse power per 1 ms waveform (Figure 4), derates linearly above 25°C ambient, and sustains 3.0 W steady-state dissipation at 75°C lead temperature. Thermal resistance from junction to lead is 33.3°C/W, supporting reliable operation in thermally constrained PCB layouts with axial lead mounting.

Key Specifications

Pinout & Package

SA48A is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode indicated by a polarity band. Leads are tin-plated, solderable at 260°C for 10 seconds at 1/16 inch 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 SA48A, SMAJ48A offers smaller footprint but reduced surge handling, while P6SMB48A delivers identical protection in a more compact, widely available SMT package-making it ideal for new designs prioritizing manufacturability without compromising clamping performance.

Availability

SA48A 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 and long-term lifecycle support.

Supply support for SA48A 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 energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, cloud, and medical markets.

The SA48A belongs to the MiniMOSORB SA-series TVS family, engineered specifically for high-reliability transient suppression in harsh industrial and safety-certified applications where UL 497B recognition and precise clamping are mandatory.

FAQ

What is the working peak reverse voltage (VRWM) of the SA48A?

The SA48A has a VRWM of 48 V, meaning it remains non-conductive under normal operating conditions up to this DC or continuous peak reverse voltage. This value is selected to be equal to or greater than the system's maximum steady-state voltage-such as a nominal 48 V telecom supply-to ensure no leakage or premature clamping during regular operation. The SA48A begins conducting only when transients exceed its breakdown voltage range of 53.3–56.1 V.

Does the SA48A meet UL 497B certification?

Yes, the SA48A is UL 497B recognized (File #E116110, QVGV2 category) for isolated loop circuit protection. This certification confirms successful completion of multiple safety tests including strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge testing-unlike basic flammability-only approvals. The SA48A's UL recognition directly supports compliance in medical and telecom applications where isolation barrier integrity is mandated.

What is the maximum clamping voltage of the SA48A and at what current is it specified?

The SA48A has a maximum clamping voltage (V_C) of 77.4 V, measured at a peak pulse current (I_PP) of 6.5 A. This value represents the worst-case voltage imposed on protected circuitry during a full-rated 500 W transient event. Engineers use this figure to verify margin against downstream IC absolute maximum ratings-for example, confirming that 77.4 V stays below the 80 V limit of a typical industrial-grade DC-DC controller.

Is the SA48A RoHS-compliant and Pb-Free?

Yes, the SA48A is offered in Pb-Free (RoHS-compliant) packaging, indicated by the "G" suffix in part numbers such as SA48AG. Its Surmetic axial package uses lead-free terminations compatible with both SnPb and lead-free soldering processes, with maximum lead temperature rated at 260°C for 10 seconds at 1/16 inch from the case body. This ensures compliance with global environmental directives without sacrificing solderability or reliability.

How does the SA48A compare to bidirectional TVS diodes in surge protection?

The SA48A is unidirectional and optimized for DC-biased lines like +48 V telecom rails or sensor supply outputs, where reverse polarity is not expected. Unlike bidirectional variants (e.g., CA48A), it provides lower leakage and sharper Zener knee characteristics-improving accuracy in precision clamping. Bidirectional devices are reserved for AC or floating signal lines subject to voltage reversals; using SA48A in such roles would fail to protect negative transients.