Taiwan Semiconductor Corporation SMAJ7.0A

Overview

SMAJ7.0A from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for clamping fast transients in DC power lines. It features a 7.78 V minimum breakdown voltage (V_BR), 12.0 V maximum clamping voltage (V_C) at 200 A peak pulse current, and 400 W peak pulse power rating with 10/1000 µs waveform - used in SMPS input protection and automotive DC/DC converters.

For engineers reviewing the SMAJ7.0A datasheet, SMAJ7.0A pinout, SMAJ7.0A application, or SMAJ7.0A equivalent, key selection criteria include working stand-off voltage (10 V), low leakage (<7 µA at V_WM), sub-1 ps response time, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, and DO-214AC thermal and mechanical reliability for high-volume automated assembly.

Technical Context

The SMAJ7.0A employs a glass-passivated silicon junction optimized for low dynamic impedance and stable clamping under repetitive surge stress. Its unidirectional configuration provides forward conduction capability up to 40 A I_FSM, with VF ≤ 3.5 V at 25 A, enabling use in both reverse-transient suppression and forward-surge limiting roles.

Thermal design is supported by a 150 °C maximum junction temperature, 1 W steady-state power dissipation, and JESD201 Class 2 whisker resistance. The device meets RoHS and halogen-free requirements per IEC 61249-2-21, and moisture sensitivity level 1 per J-STD-020.

Key Specifications

Pinout & Package

DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, cathode band marking polarity, UL 94V-0 rated compound, and 0.060 g typical weight. Compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ7.0 and SMBJ7.0A, the SMAJ7.0A delivers the lowest clamping voltage (12.0 V) in the smallest DO-214AC footprint, making it optimal for space-constrained 12 V systems requiring tight voltage control during surge events - without sacrificing ISO 7637-2 compliance or automated assembly compatibility.

Availability

SMAJ7.0A is available at Aetrix Electronics and suitable for automotive power distribution, industrial SMPS input stage, LED driver overvoltage protection, and on-board DC/DC converter input applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SMAJ7.0A 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, MOSFETs, and power management devices since 1979.

The SMAJ series was developed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing fast response, repeatable clamping, and robust packaging for automated SMT environments.

FAQ

What is the maximum clamping voltage of SMAJ7.0A under standard test conditions?

The SMAJ7.0A has a maximum clamping voltage (V_C) of 12.0 V when subjected to a 200 A peak pulse current with a 10/1000 µs waveform at T_A = 25 °C. This value is measured per JEDEC standards and guarantees that downstream circuitry sees no more than 12.0 V during specified surge events - critical for protecting 12 V logic rails and interface ICs. The SMAJ7.0A achieves this while maintaining a 10 V working stand-off voltage.

Is SMAJ7.0A unidirectional or bidirectional, and how is polarity identified?

SMAJ7.0A is a unidirectional TVS diode, meaning it conducts only in reverse bias during overvoltage events and behaves as a low-leakage diode in forward bias. Polarity is marked by a cathode band on the DO-214AC (SMA) package body - the banded end connects to the protected line (e.g., +12 V), while the unbanded end connects to ground. This configuration ensures proper clamping directionality and avoids unintended forward conduction in DC systems.

Does SMAJ7.0A meet automotive transient immunity standards?

Yes, SMAJ7.0A meets ISO 7637-2 Pulse 1 (inductive switch-off), Pulse 2a (battery disconnect), Pulse 2b (supply interruption), Pulse 3a (capacitive coupled spike), and Pulse 3b (inductive coupled spike) requirements. Its 400 W peak pulse power rating, sub-1 ps response, and 12.0 V clamping voltage enable robust protection in 12 V vehicle networks - confirmed in Taiwan Semiconductor's characterization data and widely deployed in ECU and body control module designs.

What is the leakage current specification for SMAJ7.0A at its working voltage?

The SMAJ7.0A specifies a maximum reverse leakage current (I_R) of 7 µA at its working stand-off voltage (V_WM) of 10 V and T_A = 25 °C. This ultra-low leakage ensures minimal power loss in always-on systems and avoids interference with high-impedance monitoring circuits such as battery voltage dividers or supervisor IC inputs - a key advantage over higher-leakage alternatives in low-power automotive and industrial applications.

Can SMAJ7.0A be used in place of SMAJ7.0, and what is the key performance difference?

Yes, SMAJ7.0A can replace SMAJ7.0 in most designs, but the key difference is clamping performance: SMAJ7.0A clamps at 12.0 V versus SMAJ7.0's 13.3 V under identical 200 A, 10/1000 µs conditions. This 1.3 V reduction improves margin for downstream 12 V ICs with 13.2 V absolute maximum ratings. Both share identical V_WM (10 V), V_BR range, and DO-214AC packaging - making SMAJ7.0A the preferred choice where tighter voltage control is required.