Diodes Incorporated SMAJ120CA-13-F

Overview

SMAJ120CA-13-F from Diodes Incorporated is a bidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for overvoltage protection in DC power lines and signal interfaces. It features a 120V reverse standoff voltage (VRWM), 133–147V breakdown range (VBR), 193V maximum clamping voltage (VC) at 2.0A peak pulse current (IPP), and operates across –55°C to +150°C. It is used in industrial power supplies to protect downstream regulators from lightning-induced surges.

For engineers reviewing the SMAJ120CA-13-F datasheet, SMAJ120CA-13-F pinout, SMAJ120CA-13-F application, or SMAJ120CA-13-F equivalent, key selection criteria include clamping voltage margin relative to protected IC V_MAX, unidirectional vs. bidirectional polarity requirements, I_PP derating above +25°C, and compatibility with SMA package reflow profiles.

Technical Context

This bidirectional TVS diode uses glass-passivated junction construction to achieve fast response time (<1 ps) and stable clamping under repetitive transients. Its symmetrical breakdown behavior enables protection of AC-coupled or floating signal paths without polarity constraints.

The device complies with IEC 61000-4-2 (ESD) and IEC 61000-4-4 (EFT) immunity standards when applied with proper PCB layout. Thermal performance is defined by a 1.0W steady-state power dissipation limit at lead temperature (T_L) = +75°C and full derating above ambient +25°C.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), molded plastic case with UL 94V-0 flammability rating, cathode band omitted due to bidirectional configuration.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ120CA-13-F, the unidirectional SMAJ120A-13-F offers identical clamping performance but restricts placement flexibility, while SMBJ120CA delivers higher surge margin at the cost of PCB area and thermal resistance-critical for high-reliability industrial deployments where margin and layout constraints diverge.

Availability

SMAJ120CA-13-F is available at Aetrix Electronics and suitable for industrial power input protection, RS-485 interface hardening, and automotive body control module designs requiring stable component supply and traceable sourcing.

Supply support for SMAJ120CA-13-F 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, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and the Americas.

This device belongs to the SMAJ series of surface-mount TVS diodes, engineered specifically for high-reliability transient suppression in harsh industrial, automotive, and communications environments where compact size and repeatable clamping performance are essential.

FAQ

What does the "C" suffix in SMAJ120CA-13-F indicate?

The "C" denotes bidirectional configuration: both terminals behave identically under positive or negative transients, enabling protection of AC-coupled or floating signal paths without polarity orientation concerns. This differs from unidirectional variants (e.g., SMAJ120A-13-F), which require correct anode/cathode placement relative to system ground.

Can SMAJ120CA-13-F be used in place of a unidirectional TVS in a DC power rail?

Yes, but with caution: bidirectional operation introduces ~3.5V forward voltage drop in either direction during clamping, whereas unidirectional devices exhibit near-zero forward drop in one direction. For DC rails where forward conduction must be minimized, verify that the 3.5V VF does not interfere with upstream source regulation or cause unintended latch-up in protected ICs.

What is the maximum allowable PCB trace length between SMAJ120CA-13-F and the protected node?

Trace inductance directly impacts clamping effectiveness. For sub-100ns transients (e.g., ESD), keep total trace length ≤10 mm per leg (input + return) to limit inductive overshoot. Longer traces increase peak voltage seen by the protected IC beyond the rated 193V VC, especially above 100MHz frequency content.

Does SMAJ120CA-13-F meet AEC-Q200 stress testing requirements?

No-this standard part is not AEC-Q200 qualified. Diodes offers a separate automotive-grade variant, SMAJ120CAQ-13-F, which undergoes extended temperature cycling, humidity bias, and mechanical shock testing per AEC-Q200 Rev D. Use the "Q" suffix version for under-hood or safety-critical automotive applications.