Microchip Technology SMAJ7.5E3/TR13

Overview

SMAJ7.5E3/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 7.5 V reverse standoff voltage (V_WM), 8.33 V minimum breakdown voltage (V_BR), 14.3 V maximum clamping voltage (V_C) at 35 A peak pulse current, and 500 W peak pulse power rating per 10/1000 µs waveform-used in industrial power supplies, automotive body electronics, and telecom interface circuits.

For engineers reviewing the SMAJ7.5E3/TR13 datasheet, SMAJ7.5E3/TR13 pinout, SMAJ7.5E3/TR13 application, or SMAJ7.5E3/TR13 equivalent, key selection criteria include clamping voltage margin relative to protected IC's absolute maximum rating, IEC 61000-4-2 ESD immunity compliance, thermal resistance (15 °C/W junction-to-lead), RoHS-compliant matte-tin plating, and tape-and-reel packaging for automated SMT assembly.

Technical Context

This TVS diode operates as a fast-acting shunt clamp: under normal bias it presents <1 µA leakage at 7.5 V, but triggers within <100 ps when transient voltage exceeds 8.33 V, diverting surge current to ground before downstream components experience damaging overvoltage. Its DO-214AC (SMA) package provides low-inductance path and 15 °C/W thermal resistance to lead-critical for sustaining repetitive 500 W transients without thermal runaway.

The device is rated for -65 °C to +150 °C operating temperature, supports 100% avionics-grade screening (with MA prefix), and complies with IEC 61000-4-2 (±15 kV air/±8 kV contact discharge), IEC 61000-4-4 (40 A/m EFT), and IEC 61000-4-5 secondary lightning (Class 4, 42 Ω source, 12 A surge) when applied per recommended PCB layout.

Key Specifications

Pinout & Package

Package: DO-214AC (SMA), surface-mount, void-free thermosetting epoxy case meeting UL94V-0; cathode indicated by band; weight 0.064 g; moisture sensitivity level (MSL) 1 - no dry pack required per J-STD-020B.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ7.5E3/TR13, SMAJ7.5A-E3/5A offers lower clamping voltage for sensitive 5 V logic, while P6SMB7.5A delivers higher surge current capacity and better thermal performance-both require validation of PCB footprint compatibility and layout parasitics before substitution.

Availability

SMAJ7.5E3/TR13 is available at Aetrix Electronics and suitable for industrial power input protection, automotive body control modules, telecom Ethernet interfaces, medical sensor signal conditioning, and PoE-powered equipment requiring stable component supply and full traceability.

Supply support for SMAJ7.5E3/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 robust, surface-mount transient suppression in space-constrained, high-surge environments-targeting automotive ECUs, industrial PLCs, and telecom infrastructure where reliability under extreme electrical stress is non-negotiable.

FAQ

What is the clamping voltage of SMAJ7.5E3/TR13 and why does it matter?

The SMAJ7.5E3/TR13 has a maximum clamping voltage (V_C) of 14.3 V at 35 A peak pulse current (10/1000 µs). This value defines the highest voltage that will appear across the protected circuit during a surge event. It matters because it must remain safely below the absolute maximum voltage rating of downstream ICs-such as microcontrollers or transceivers-to prevent permanent damage. For example, in a 5 V system with 3.3 V logic, this clamping level provides sufficient margin only if series impedance limits current to ≤35 A.

Is SMAJ7.5E3/TR13 RoHS compliant and what does the "e3" suffix indicate?

Yes, SMAJ7.5E3/TR13 is RoHS compliant. The "e3" suffix explicitly denotes annealed matte-tin plating per JEDEC J-STD-020, confirming lead-free termination and full compliance with EU Directive 2011/65/EU. This plating meets MIL-STD-750 solderability requirements and supports Pb-free reflow profiles up to 260 °C for 10 seconds-essential for modern high-volume SMT assembly lines.

Can SMAJ7.5E3/TR13 be used for bidirectional protection?

No, SMAJ7.5E3/TR13 is a unidirectional TVS diode, indicated by the absence of "C" or "CA" in its part number. It conducts only in reverse breakdown (cathode to anode) and blocks forward current like a standard diode. For bidirectional protection-such as across differential data lines like RS-485 or USB D+/D−-a part with "CA" suffix (e.g., SMAJ7.5CA) must be selected, which provides symmetrical clamping in both polarities.

What is the thermal resistance of SMAJ7.5E3/TR13 and how does it affect layout?

The SMAJ7.5E3/TR13 has a junction-to-lead thermal resistance (R_θJL) of 15 °C/W, measured with recommended FR4 footprint (1 oz Cu). This low value enables efficient heat transfer from the die to the PCB copper pour or ground plane. To maintain reliability under repetitive surges, designers must use adequate copper area (≥100 mm² per pad) and avoid thermal isolation-otherwise, localized heating can degrade clamping performance or cause premature failure.

Does SMAJ7.5E3/TR13 meet IEC 61000-4-5 for lightning surge immunity?

Yes, SMAJ7.5E3/TR13 is validated for IEC 61000-4-5 secondary lightning surge immunity at Class 4 (12 A, 42 Ω source impedance) and Class 1 (up to 42 A, 42 Ω) when implemented per Microsemi's recommended PCB layout and grounding practices. Its 500 W rating and sub-100 ps response ensure effective energy diversion before coupled transients reach sensitive circuitry-making it suitable for industrial and transportation equipment requiring EN 61000-4-5 certification.