Microchip Technology SMAJ75AE3/TR13

Overview

SMAJ75AE3/TR13 from Microsemi is a unidirectional surface-mount Transient Voltage Suppressor (TVS) designed for primary overvoltage protection of DC power rails and signal lines. It features a 75 V working peak standoff voltage (V_WM), 83.3 V minimum breakdown voltage (V_BR @ 1 mA), 134 A peak pulse current (I_PP @ 10/1000 µs), 121 V maximum clamping voltage (V_C), and 500 W peak pulse power dissipation - deployed in telecom power supplies, industrial I/O modules, and automotive body control units.

For engineers reviewing the SMAJ75AE3/TR13 datasheet, SMAJ75AE3/TR13 pinout, SMAJ75AE3/TR13 application, or SMAJ75AE3/TR13 equivalent, key selection criteria include clamping voltage margin vs. protected IC's absolute maximum rating, standoff voltage alignment with nominal rail voltage (e.g., 48 V or 60 V systems), thermal derating on FR4 PCBs, and RoHS-compliant matte-tin plating compatibility with lead-free reflow profiles.

Technical Context

This unidirectional TVS operates as a voltage-clamped shunt device: under normal bias (≤75 V), it draws ≤4.1 µA standby current; when transient voltage exceeds 83.3 V, it avalanches within <100 ps to clamp at ≤121 V while diverting up to 134 A. Its DO-214AC package provides low thermal resistance (15 °C/W junction-to-lead) and supports 5 W steady-state dissipation at 75 °C lead temperature.

The device complies with IEC61000-4-2 (ESD ±30 kV air/±25 kV contact), IEC61000-4-4 (EFT 4 kV), and IEC61000-4-5 (lightning surge: Class 1–4 depending on source impedance), with bidirectional variants (e.g., SMAJ75CAE3/TR13) available for AC-coupled or symmetrical line protection where polarity reversal occurs.

Key Specifications

Pinout & Package

Package: DO-214AC (SMAJ), surface-mount, void-free thermosetting epoxy case (UL94V-0), C-bend leads with RoHS-compliant matte-tin plating. Dimensions: 4.93–5.48 mm length × 3.99–4.50 mm width × 2.26 mm height; weight 0.064 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ75AE3/TR13, SMAJ75AHE3/TR13 adds military-grade screening at higher cost and longer lead time, while SMAJ75CAE3/TR13 enables symmetrical clamping but sacrifices unidirectional low-leakage advantage on DC rails.

Availability

SMAJ75AE3/TR13 is available at Aetrix Electronics and suitable for telecom power input protection, industrial PLC digital I/O protection, and automotive body control module (BCM) applications requiring stable component supply, RoHS compliance, and full industrial temperature support.

Supply support for SMAJ75AE3/TR13 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

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and radiation-hardened components for aerospace, defense, and industrial markets.

The SMAJ series was engineered for ruggedized transient suppression in harsh environments - emphasizing fast response (<100 ps), high surge current tolerance, and long-term stability under thermal cycling and humidity exposure.

FAQ

What is the clamping voltage of SMAJ75AE3/TR13 at its rated peak pulse current?

The SMAJ75AE3/TR13 has a maximum clamping voltage (V_C) of 121 V when subjected to its rated 134 A peak pulse current (I_PP) under the standard 10/1000 µs waveform. This value is guaranteed across the full operating temperature range and is critical for ensuring protected downstream ICs remain within their absolute maximum voltage ratings during surge events. The SMAJ75AE3/TR13 achieves this clamping performance while maintaining low leakage and fast response.

Is SMAJ75AE3/TR13 RoHS compliant and what does the "e3" suffix indicate?

Yes, SMAJ75AE3/TR13 is RoHS compliant, as confirmed by the "e3" suffix in its part number. This denotes annealed matte-tin plating on the leads, fully compliant with EU RoHS Directive 2011/65/EU and JEDEC J-STD-020B Level 1 moisture sensitivity - eliminating the need for dry packing prior to reflow soldering. The SMAJ75AE3/TR13 meets all applicable substance restrictions and is qualified for lead-free assembly processes up to 260 °C for 10 seconds.

What is the standoff voltage and how does it relate to system design for SMAJ75AE3/TR13?

The SMAJ75AE3/TR13 has a reverse standoff voltage (V_WM) of 75 V - the maximum continuous DC or RMS voltage it can block without significant leakage. In practice, this allows use on nominal 48 V or 60 V DC rails with adequate margin against ripple, tolerance drift, and transient overshoot. Designers must ensure system operating voltage stays ≤75 V to avoid excessive standby current (>4.1 µA) or premature degradation. The SMAJ75AE3/TR13's V_WM is therefore a hard design constraint, not a recommendation.

Can SMAJ75AE3/TR13 be used for IEC61000-4-5 lightning surge protection?

Yes, SMAJ75AE3/TR13 is explicitly rated for secondary lightning surge protection per IEC61000-4-5 with both 42 Ω and 12 Ω source impedances. At 42 Ω, it qualifies for Class 1 (up to 75 V V_WM); at 12 Ω, it supports Class 1 up to 30 V V_WM. While SMAJ75AE3/TR13 itself falls outside the Class 1 12 Ω range, its 134 A I_PP and 121 V V_C enable effective protection when combined with appropriate series impedance in front-end filtering networks. The SMAJ75AE3/TR13 datasheet confirms compliance for these test levels.

What is the thermal resistance and how does it impact PCB layout for SMAJ75AE3/TR13?

The SMAJ75AE3/TR13 has a junction-to-lead thermal resistance (R_θJL) of 15 °C/W and junction-to-ambient resistance (R_θJA) of 80 °C/W when mounted on a standard FR4 board with 1 oz copper and the recommended footprint. This means PCB layout must provide adequate copper area (especially under the leads and cathode/anode pads) to dissipate 5 W steady-state power at 75 °C lead temperature. Poor thermal design risks exceeding 150 °C junction temperature during repeated surges. The SMAJ75AE3/TR13's thermal specs directly dictate minimum pad size and copper pour requirements.