Vishay General Semiconductor - Diodes Division SMAJ64A-E3/61

Overview

SMAJ64A-E3/61 from Vishay General Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in SMA (DO-214AC) package, designed for robust overvoltage protection of sensitive electronics. It features a 64 V stand-off voltage (V_WM), 71.1–78.6 V breakdown voltage (V_BR) at 1 mA, 103 V maximum clamping voltage (V_C) at 3.9 A peak pulse current, and 400 W peak pulse power rating with 10/1000 μs waveform - deployed on power rails and signal lines in automotive ECUs and industrial I/O modules.

For engineers reviewing the SMAJ64A-E3/61 datasheet, SMAJ64A-E3/61 pinout, SMAJ64A-E3/61 application, or SMAJ64A-E3/61 equivalent, this page delivers verified electrical parameters, thermal resistance values, polarity marking guidance, AEC-Q101 qualification status, and real-world clamping performance data critical for surge immunity validation and PCB-level ESD/transient design.

Technical Context

This unidirectional TVS operates as a voltage-clamped shunt protector: under normal bias it presents <1 μA leakage at 64 V, then rapidly avalanches when transients exceed V_BR, limiting downstream voltage to ≤103 V at 3.9 A. Its glass-passivated junction ensures stable breakdown and low incremental surge resistance.

Thermally, it exhibits R_θJA = 120 °C/W (on standard 0.2" × 0.2" copper pads) and R_θJL = 30 °C/W, enabling reliable operation up to T_J = +150 °C. The cathode band marking confirms polarity for correct series placement across DC supply paths.

Key Specifications

Pinout & Package

Package: SMA (DO-214AC), surface-mount, low-profile case with matte tin-plated leads compliant with J-STD-002 and JESD 22-B102. Cathode identified by a single black band on the body end.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ64CA-E3/61, SMAJ64A-E3/61 offers polarity-specific optimization for DC systems, while SMBJ64A-E3/52 provides enhanced surge margin at the cost of board area - selection depends on threat profile, layout constraints, and grounding architecture.

Availability

SMAJ64A-E3/61 is available at Aetrix Electronics and suitable for automotive power distribution, industrial sensor interfaces, telecom DC inputs, and consumer appliance motor control requiring stable component supply and AEC-Q101-compliant surge protection.

Supply support for SMAJ64A-E3/61 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

Vishay General Semiconductor is a global leader in discrete semiconductors, specializing in diodes, rectifiers, TVS devices, and optoelectronics with emphasis on reliability and application-specific performance.

The SMAJ series was engineered for high-reliability transient suppression in harsh environments - targeting automotive, industrial, and telecom applications where consistent clamping behavior and long-term stability are mandatory.

FAQ

What is the maximum clamping voltage of SMAJ64A-E3/61 at its rated peak pulse current?

The SMAJ64A-E3/61 has a maximum clamping voltage (V_C) of 103 V at its specified peak pulse current (I_PPM) of 3.9 A, measured using the standardized 10/1000 μs double-exponential waveform. This value is guaranteed across the full operating temperature range and defines the upper voltage limit imposed on protected circuits during surge events. The SMAJ64A-E3/61 achieves this with minimal voltage overshoot due to its low clamping ratio and fast response time.

Is SMAJ64A-E3/61 RoHS-compliant and suitable for lead-free reflow assembly?

Yes, SMAJ64A-E3/61 carries the "E3" suffix indicating RoHS-compliance and qualification for lead-free reflow soldering. It meets MSL Level 1 per J-STD-020 with a maximum peak reflow temperature of 260 °C, supporting standard Pb-free assembly processes without moisture sensitivity concerns. The matte tin-plated leads ensure reliable wetting and joint formation per J-STD-002 and JESD 22-B102 standards - critical for high-yield manufacturing of the SMAJ64A-E3/61.

How does the unidirectional configuration of SMAJ64A-E3/61 affect its placement in a circuit?

The unidirectional configuration of SMAJ64A-E3/61 requires correct orientation: the cathode (marked by a black band) must connect to the line being protected (e.g., 64 V rail), and the anode to ground or lower potential. This ensures avalanche conduction only during positive transients - blocking reverse leakage in normal operation. Incorrect polarity prevents clamping action, leaving circuits vulnerable. The SMAJ64A-E3/61 datasheet specifies this via the cathode band and absolute maximum ratings table.

Does SMAJ64A-E3/61 meet automotive qualification standards?

SMAJ64A-E3/61 itself is commercial-grade; however, the automotive-qualified variant SMAJ64AHE3_X (with "HE3" suffix) is AEC-Q101 qualified. While the base SMAJ64A-E3/61 shares identical electrical and thermal specs, only the HE3 version undergoes extended stress testing including temperature cycling, HTRB, and ESD per AEC-Q101. For automotive designs, specify SMAJ64AHE3_A or equivalent - the SMAJ64A-E3/61 remains suitable for industrial and telecom applications demanding high surge immunity.

What is the thermal resistance junction-to-ambient for SMAJ64A-E3/61, and how does it impact layout?

The SMAJ64A-E3/61 has a typical junction-to-ambient thermal resistance (R_θJA) of 120 °C/W when mounted on the recommended 0.2" × 0.2" (5.0 mm × 5.0 mm) copper pads per terminal. This value assumes no additional copper pour or thermal vias. To maintain T_J ≤ 150 °C under worst-case power dissipation, designers must limit average power or enhance copper area - underscoring why the SMAJ64A-E3/61 is best applied in transient-only scenarios rather than continuous power regulation.