Taiwan Semiconductor Corporation SMAJ24CH

Overview

SMAJ24CH from Taiwan Semiconductor is a unidirectional 400W transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 24V working stand-off voltage (V_WM), 26.7–32.6V breakdown voltage (V_BR), and 43.0V maximum clamping voltage (V_C) at 9.3A peak pulse current. It delivers AEC-Q101 qualification, <1.0ps response time, and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.

For engineers reviewing the SMAJ24CH datasheet, SMAJ24CH pinout, SMAJ24CH application, or SMAJ24CH equivalent, this device is selected for robust overvoltage protection in DC/DC converters, SMPS inputs, lighting drivers, and automotive body electronics where fast clamping, low leakage (<1µA @ 24V), and high surge immunity are required.

Technical Context

The SMAJ24CH operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its V_BR range (26.7–32.6V @ 1mA). Its glass-passivated junction ensures stable breakdown and low leakage, while the DO-214AC package supports automated placement and meets JESD201 Class 2 whisker resistance.

It sustains 400W peak pulse power per 10/1000µs waveform (derated above 25°C), clamps transients to ≤43.0V at 9.3A, and maintains operation across –55°C to +150°C junction temperature-enabling use in under-hood automotive environments and industrial power supplies.

Key Specifications

Pinout & Package

DO-214AC (SMA) surface-mount package with cathode band marking; 2-terminal unidirectional configuration; matte tin-plated leads compliant with J-STD-002 solderability; weight ≈0.060 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ24A and SMBJ24CH, the SMAJ24CH offers optimal balance of AEC-Q101 compliance, DO-214AC footprint, and 400W surge capability-making it preferred for space-constrained automotive and industrial 24V systems where standardized SMA placement and proven qualification are critical.

Availability

SMAJ24CH is available at Aetrix Electronics and suitable for automotive body electronics, industrial 24V DC/DC converters, LED lighting drivers, and telecom power shelf protection requiring stable component supply and full AEC-Q101 traceability.

Supply support for SMAJ24CH 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.

The SMAJ series is designed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing AEC-Q101 qualification, fast response, and robust surge handling in compact surface-mount packages.

FAQ

What is the clamping voltage of SMAJ24CH and how is it measured?

The SMAJ24CH has a maximum clamping voltage (V_C) of 43.0 V, measured at a peak pulse current (I_PPM) of 9.3 A using the standardized 10/1000 µs double-exponential surge waveform. This value is guaranteed across the full operating temperature range and represents the highest voltage the device allows to appear across protected circuitry during a transient event. The SMAJ24CH achieves this clamping performance while maintaining <1 µA leakage at its 24 V working stand-off voltage.

Is SMAJ24CH unidirectional or bidirectional, and how is polarity identified?

SMAJ24CH is a unidirectional TVS diode, intended for DC line protection where reverse voltage is not expected. Polarity is marked by a cathode band on the DO-214AC (SMA) package body; the banded end connects to the protected line (e.g., 24V rail), and the anode connects to ground. Bidirectional variants use "CAH" suffix (e.g., SMAJ24CAH), which are electrically symmetric and lack polarity marking.

Does SMAJ24CH meet automotive qualification standards?

Yes, SMAJ24CH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b for automotive electrical disturbance immunity. Its construction-including glass-passivated junction, JESD201 Class 2 whisker resistance, and moisture sensitivity level 1-supports reliable deployment in engine control units, body control modules, and ADAS power domains.

What is the peak pulse power rating of SMAJ24CH and under what conditions?

The SMAJ24CH is rated for 400 W peak pulse power (P_PPM) under the industry-standard 10/1000 µs waveform (rise time 10 µs, decay to 50% in 1000 µs). This rating applies at T_A = 25°C and derates linearly above that ambient temperature per the published pulse derating curve. At 78 V and above, the rating drops to 300 W-though SMAJ24CH operates well below that threshold.

Can SMAJ24CH be used in place of SMAJ24A in existing designs?

SMAJ24CH and SMAJ24A share identical V_WM (24 V), package (DO-214AC), and pinout, but differ in V_BR range (26.7–32.6 V vs. 26.7–29.5 V) and clamping voltage (43.0 V vs. 38.9 V). While not drop-in compatible due to higher V_C, SMAJ24CH may be substituted where higher clamping margin is acceptable and AEC-Q101 qualification is mandatory-always verify system-level surge margin and thermal performance with the SMAJ24CH datasheet.