Diodes Incorporated SMAJ75A-13

Overview

SMAJ75A-13 from Diodes Incorporated is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode with 75V reverse standoff voltage, 83.3–92.1V breakdown voltage at 1mA, and 121V max clamping voltage at 3.3A peak pulse current. It features glass-passivated die construction, fast response time, and UL 94V-0 molded plastic package for surge protection in DC power rails and I/O interfaces.

For engineers reviewing the SMAJ75A-13 datasheet, SMAJ75A-13 pinout, SMAJ75A-13 application, or SMAJ75A-13 equivalent, key selection criteria include clamping voltage margin vs. protected IC V_DD, peak pulse current capability under IEC 61000-4-5 8/20μs waveforms, thermal derating above 25°C ambient, and compatibility with automated SMT reflow profiles per J-STD-020C Level 1.

Technical Context

This TVS diode operates as a unidirectional clamping device-conducting only during negative transients relative to its anode-cathode polarity-enabling precise overvoltage protection on positive-rail systems. Its 400W peak pulse power rating is specified for non-repetitive 8.3ms half-sine surges at ≤4 pulses/minute, with derating to 75% at T_A = 75°C per Fig. 1.

The junction capacitance is <100pF at 0V (Fig. 2), making it suitable for low-speed signal lines and DC power inputs where capacitive loading must remain minimal. Steady-state dissipation is limited to 1.0W at T_L = 75°C, and forward voltage is 3.5V at 35A surge (not applicable in normal operation but critical for fault-energy calculation).

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with cathode band marking; UL 94V-0 rated; moisture sensitivity level 1; weight ≈0.064g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ75CA-13 and SMBJ75A-13, the SMAJ75A-13 offers optimal size-efficiency balance for space-constrained unidirectional DC protection, delivering identical clamping performance in the smallest standard surface-mount TVS outline.

Availability

SMAJ75A-13 is available at Aetrix Electronics and suitable for industrial motor drives, automotive body control modules, telecom power supplies, and renewable energy inverters requiring stable component supply across extended production lifecycles.

Supply support for SMAJ75A-13 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability protection, power management, and signal integrity solutions for industrial, automotive, and computing markets.

The SMAJ series belongs to Diodes' transient voltage suppressor product line, engineered specifically for robust, cost-effective surge protection in high-volume SMT applications where compact size, repeatable clamping, and RoHS compliance are mandatory.

FAQ

What is the meaning of the "-13" suffix in SMAJ75A-13?

The "-13" suffix denotes tape-and-reel packaging: 5,000 units per reel, optimized for automated SMT placement. It does not indicate revision level or RoHS status-the part is inherently RoHS-compliant per Diodes' standard matte tin finish, and no "-F" suffix is required unless explicitly ordered as lead-free with exemption documentation.

Can SMAJ75A-13 be used in bidirectional signal lines like RS-485?

No-SMAJ75A-13 is unidirectional and will conduct continuously if reverse-biased beyond its forward voltage (~3.5V), potentially damaging the line driver. For RS-485 or other bidirectional interfaces, use the bidirectional SMAJ75CA-13 variant, which clamps symmetrically above and below ground reference.

How does thermal derating affect its 400W rating in real-world PCB layouts?

The 400W rating assumes terminals held at ambient temperature. On typical 1oz copper PCBs with minimal thermal relief, power dissipation drops to ~300W at T_A = 50°C and ~200W at T_A = 75°C per Fig. 1. Layout must include ≥2cm² of 1oz copper connected to both pads to maintain rated performance.

Is there a recommended minimum trace width for the anode and cathode connections?

Yes-Diodes recommends ≥15 mil (0.38mm) trace width for both terminals to handle 3.3A peak pulse current without excessive resistive heating or voltage drop. For repeated surges, widen to ≥25 mil and add thermal vias to inner ground planes to improve heat extraction and sustain clamping accuracy.