Taiwan Semiconductor Corporation SA40H

Overview

SA40H from Taiwan Semiconductor is a unidirectional transient voltage suppressor (TVS) diode in DO-204AC (DO-15) package, rated for 500W peak pulse power at 10/1000μs, with 40V working stand-off voltage (VWM), 44.4–54.3V breakdown voltage (VBR), and 71.4V maximum clamping voltage (VC) at 7.3A peak pulse current - designed for automotive-grade ESD and load-dump protection in power supply rails and signal lines.

For engineers reviewing the SA40H datasheet, SA40H pinout, SA40H application, or SA40H equivalent, this AEC-Q101 qualified TVS delivers verified clamping performance, low leakage (<1μA @ 40V), fast response (<1.0ps), and robust surge handling in automotive body electronics, industrial sensor interfaces, and DC power input stages where reliability under ISO 7637-2 transients is critical.

Technical Context

The SA40H operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its VBR range (44.4–54.3V), clamping transient energy to ≤71.4V at 7.3A. It features a junction temperature limit of 175°C and is rated for non-repetitive 8.3ms half-sine surge currents up to 70A.

Its DO-204AC (DO-15) package supports lead-free soldering per J-STD-002, meets UL 94V-0 flammability, and complies with JESD201 Class 2 whisker resistance - confirming suitability for high-reliability automotive PCB assemblies exposed to thermal cycling and mechanical vibration.

Key Specifications

Pinout & Package

DO-204AC (DO-15) package: axial-leaded, molded epoxy case with cathode band marking polarity. Leads are pure tin-plated, solderable per J-STD-002, and meet JESD201 Class 2 whisker resistance. Weight ≈0.400 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ40A and P6SMB40A, SA40H offers superior thermal robustness due to DO-204AC's higher thermal mass and proven axial-leaded reliability in high-vibration automotive harness connections - making it preferred for under-hood power rail protection where mechanical stability and long-term surge endurance are prioritized over footprint size.

Availability

SA40H is available at Aetrix Electronics and suitable for automotive body electronics, industrial 48V power supplies, LED lighting drivers, and smart sensor nodes requiring stable component supply with full AEC-Q101 traceability and long-lifecycle support.

Supply support for SA40H 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 semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs - headquartered in Hsinchu, Taiwan, with global distribution and AEC-Q101 certification capabilities.

The SA Series was developed specifically for automotive and industrial transient suppression, emphasizing high-energy clamping, AEC-Q101 qualification, and compatibility with harsh-environment PCB assembly processes - targeting 12V/24V/48V system protection where reliability outweighs cost-per-unit.

FAQ

What does the "H" suffix in SA40H signify?

The "H" suffix in SA40H explicitly denotes AEC-Q101 qualification per the manufacturer's ordering code specification. This means SA40H has undergone accelerated stress testing including high-temperature operating life, temperature cycling, and unbiased highly accelerated stress testing - confirming suitability for automotive electronic modules where functional safety and long-term reliability are mandatory. SA40H is not a generic variant; the "H" is a certified qualification marker.

Is SA40H unidirectional or bidirectional, and how is polarity marked?

SA40H is a unidirectional TVS diode, intended for DC rail protection where transients occur only in one polarity (e.g., positive-going load dump or negative-going ESD). Polarity is marked by a cathode band on the DO-204AC (DO-15) package body - the banded end connects to the protected line (e.g., 48V rail), while the unbanded end connects to system ground. Bidirectional variants use "CA" suffix (e.g., SA40CA).

What is the maximum clamping voltage of SA40H under standard test conditions?

The maximum clamping voltage (VC) of SA40H is 71.4 V, measured at 7.3 A peak pulse current using the 10/1000 μs double-exponential waveform per IEC 61000-4-5. This value is guaranteed across the full operating temperature range and represents the highest voltage seen at the protected node during worst-case surge events - critical for ensuring downstream components rated to 75V or higher remain within safe operating limits.

Can SA40H be used in parallel for higher surge current handling?

No - SA40H is not characterized or recommended for parallel operation. Due to inherent VBR tolerances (44.4–54.3V), paralleling multiple SA40H units risks current imbalance, where the unit with lowest VBR conducts disproportionately and may fail prematurely. For higher surge capability, select a higher-rated part (e.g., SA43H or SA45H) or implement staged protection with upstream fusing and coordinated impedance.

Does SA40H meet UL 94V-0 flammability requirements?

Yes - SA40H's DO-204AC (DO-15) molding compound is certified to UL 94V-0 flammability rating, as stated in the Mechanical Data section. This confirms the epoxy encapsulant self-extinguishes within 10 seconds after flame removal and produces no flaming drips - satisfying automotive and industrial safety standards for component-level fire resistance in enclosed enclosures and wiring harnesses.