Taiwan Semiconductor Corporation SA51

Overview

SA51 from Taiwan Semiconductor is a unidirectional 51 V working stand-off transient voltage suppressor (TVS) diode in DO-204AC (DO-15) package, rated for 500 W peak pulse power at 10/1000 μs, with 56.7–69.3 V breakdown voltage, 91.1 V clamping voltage at 5.7 A, and <1 μA reverse leakage above 10 V - deployed for automotive ESD and inductive load surge protection.

For engineers reviewing the SA51 datasheet, SA51 pinout, SA51 application, or SA51 equivalent, this page delivers verified electrical parameters, DO-15 terminal polarity mapping, clamping performance under standardized transients, thermal derating behavior, and AEC-Q101-comparable alternatives for automotive-grade circuit hardening.

Technical Context

The SA51 operates as a unidirectional avalanche diode, triggered when reverse voltage exceeds its 56.7–69.3 V breakdown range at 1 mA test current. It clamps transients to ≤91.1 V at 5.7 A peak pulse current, maintaining low dynamic impedance during 10/1000 μs surges.

Designed for single-polarity DC rail protection, it features a cathode-band-marked DO-204AC package, junction temperature range of –55°C to +175°C, and meets JESD201 Class 2 whisker resistance - supporting under-hood automotive environments where fast response (<1 ps zero-to-V_BR) and high surge robustness are critical.

Key Specifications

Pinout & Package

DO-204AC (DO-15) package with axial leads: Cathode identified by band marking; Anode is unmarked lead. Leads are pure tin-plated, solderable per J-STD-002, and meet 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 SA51, SMAJ51A offers surface-mount compatibility and tighter breakdown control but sacrifices 100 W peak power headroom; 1.5SMC51A delivers triple the surge capacity in a larger package, demanding revised mechanical integration and thermal management.

Availability

SA51 is available at Aetrix Electronics and suitable for automotive ECU protection, industrial sensor interface hardening, and LED driver overvoltage suppression requiring stable component supply across production lifecycles.

Supply support for SA51 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, and rectifiers with global distribution and AEC-Q101 validation capability.

The SA Series was developed specifically for automotive and industrial transient suppression, emphasizing high surge robustness, tight parametric consistency, and reliability under extended temperature and humidity stress.

FAQ

What is the maximum clamping voltage of the SA51 under standard 10/1000 μs surge conditions?

The SA51 clamps to a maximum of 91.1 V when subjected to a 10/1000 μs waveform at its rated peak pulse current of 5.7 A. This value is measured per ANSI/IEEE C62.35 and guarantees protection for downstream components rated up to 100 V. The SA51 achieves this clamping performance while maintaining low dynamic impedance and sub-nanosecond response time.

Is the SA51 unidirectional or bidirectional, and how is polarity marked?

The SA51 is a unidirectional TVS diode, with cathode identified by a distinct band marking on the DO-204AC (DO-15) package body. The banded lead connects to the protected line (e.g., 51 V rail), while the unmarked lead connects to ground. Bidirectional variants carry "CA" suffixes (e.g., SA51CA), which the SA51 does not include.

Does the SA51 meet AEC-Q101 qualification, and what does that mean for automotive use?

The base SA51 is not AEC-Q101 qualified; however, the SA51H variant is explicitly qualified per AEC-Q101 Rev D. This includes stress testing for temperature cycling, humidity bias, mechanical shock, and ESD - validating suitability for under-hood automotive applications. For production automotive designs, SA51H is the recommended ordering code.

What is the reverse leakage current of the SA51 at its full working voltage of 51 V?

At 51 V reverse voltage and 25°C ambient, the SA51 exhibits reverse leakage current of less than 1 μA - confirmed in the manufacturer's electrical characteristics table. This ultra-low leakage prevents loading of precision 51 V reference circuits or high-impedance sensor bias networks, ensuring signal integrity remains uncompromised during normal operation.

How does the SA51's thermal derating behave above 25°C ambient temperature?

The SA51's peak pulse power rating decreases linearly above 25°C ambient, following the derating curve in Figure 2 of the datasheet: at 75°C, it retains ~80% of its 500 W rating, and at 125°C, ~50%. This behavior is tied to junction temperature limits (T_J max = 175°C) and must be accounted for in thermally dense automotive modules where local board temperatures exceed ambient.