Microchip Technology SMAJ24E3/TR13

Overview

SMAJ24E3/TR13 from Microsemi is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for primary and secondary lightning surge protection in DC power rails and signal lines. It features a 24 V working peak standoff voltage (V_WM), 26.7 V minimum breakdown voltage (V_BR), 43.0 V maximum clamping voltage (V_C) at 11.6 A peak pulse current (I_PP), and 500 W peak pulse power rating at 10/1000 µs waveform - deployed in industrial power supplies and telecom interface circuits.

For engineers reviewing the SMAJ24E3/TR13 datasheet, SMAJ24E3/TR13 pinout, SMAJ24E3/TR13 application, or SMAJ24E3/TR13 equivalent, key selection criteria include clamping performance under IEC61000-4-5 Class 3 (42 Ω source), RoHS-compliant matte-tin plating, DO-214AC package thermal resistance (15 °C/W junction-to-lead), and compatibility with automated SMT assembly using EIA-481-1-A 12 mm tape/reel (750 pcs/7″ reel or 2500 pcs/13″ reel).

Technical Context

This TVS operates as a unidirectional avalanche diode with cathode-band polarity marking, optimized for fast transient suppression (<100 ps theoretical response time). Its silicon junction design enables low dynamic impedance during surge events, delivering consistent clamping across temperature (-65 °C to +150 °C operating range) and supporting steady-state dissipation of 5 W at lead temperature (T_L) = 75 °C.

The device complies with IEC61000-4-2 (ESD ±8 kV contact / ±15 kV air), IEC61000-4-4 (EFT 40 A, 5/50 ns), and IEC61000-4-5 (lightning surge: 42 Ω source, Class 3 up to 1 kV). Its DO-214AC package uses void-free thermosetting epoxy (UL94V-0) and C-bend leads with annealed matte-tin plating per MIL-STD-750 Method 2026.

Key Specifications

Pinout & Package

DO-214AC (SMAJ) package: molded thermosetting epoxy case (UL94V-0), C-bend tin-plated leads, cathode indicated by band. Weight: 0.064 g. Moisture sensitivity level: Level 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 SMAJ24A-E3/5A and P6SMB24A, SMAJ24E3/TR13 delivers identical core electrical specs in a RoHS-compliant DO-214AC package optimized for cost-sensitive industrial SMT production, with validated IEC61000-4-5 Class 3 performance and no requirement for extended screening or alternate footprint adaptation.

Availability

SMAJ24E3/TR13 is available at Aetrix Electronics and suitable for industrial power supplies, telecom interface protection, automotive body control modules, and medical equipment DC input stages requiring stable component supply and full traceability.

Supply support for SMAJ24E3/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 and mixed-signal ICs, RF solutions, and discrete protection devices for aerospace, defense, and industrial markets.

The SMAJ series was engineered specifically for surface-mount transient voltage suppression in harsh environments, emphasizing fast response, repeatable clamping, and robust thermal performance in compact DO-214AC packages.

FAQ

What is the clamping voltage of SMAJ24E3/TR13 at its rated peak pulse current?

The SMAJ24E3/TR13 has a maximum clamping voltage (V_C) of 43.0 V at 11.6 A peak pulse current (I_PP) under the standard 10/1000 µs waveform. This value is measured per Microsemi's MSC0270A datasheet and defines the upper voltage limit imposed on protected circuitry during surge events, ensuring downstream components remain within safe operating ranges.

Is SMAJ24E3/TR13 unidirectional or bidirectional, and how is polarity identified?

SMAJ24E3/TR13 is a unidirectional TVS diode, with polarity indicated by a cathode band on the DO-214AC package body. The "A" suffix in the family designation confirms unidirectional construction, and the cathode must be connected to the protected line (e.g., 24 V rail), while the anode connects to ground - incorrect orientation will prevent proper clamping functionality in SMAJ24E3/TR13.

Does SMAJ24E3/TR13 meet IEC61000-4-5 Class 3 lightning surge requirements?

Yes, SMAJ24E3/TR13 is certified for IEC61000-4-5 secondary lightning protection with a 42 Ω source impedance at Class 3 (1 kV test level), as documented in Microsemi's MSC0270A datasheet. This makes SMAJ24E3/TR13 suitable for deployment in industrial Ethernet ports, PLC backplanes, and other systems requiring validated surge immunity without external circuit modifications.

What is the thermal resistance specification for SMAJ24E3/TR13, and how does it impact PCB layout?

SMAJ24E3/TR13 has a junction-to-lead thermal resistance of 15 °C/W when mounted on FR4 with recommended footprint (1 oz Cu). This value guides copper pour sizing and thermal via placement: adequate pad area and thermal vias beneath the leads are essential to maintain T_L ≤ 75 °C during 5 W steady-state operation, directly affecting long-term reliability and surge endurance in SMAJ24E3/TR13.

What does the "TR13" suffix indicate in SMAJ24E3/TR13?

The "TR13" suffix denotes EIA-481-1-A compliant tape-and-reel packaging on a 13-inch reel containing 2500 units, with 12 mm carrier tape width. This format enables automated SMT placement and is distinct from the 7-inch reel option (TR, 750 pcs); both share identical electrical and mechanical specifications, and SMAJ24E3/TR13 is fully compatible with standard pick-and-place feeders calibrated for 12 mm tape.