Taiwan Semiconductor Corporation SA85CA

Overview

SA85CA from Taiwan Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in DO-204AC (DO-15) package, rated for 500W peak pulse power at 10/1000μs, with 85V working stand-off voltage (VWM), 94.4–115V breakdown voltage (VBR), and 151V maximum clamping voltage (VC) at 3.4A peak pulse current - deployed for ESD and electrical fast transient protection in automotive lighting and power supply interfaces.

For engineers reviewing the SA85CA datasheet, SA85CA pinout, SA85CA application, or SA85CA equivalent, key selection criteria include bidirectional clamping behavior, AEC-Q101 qualification status, junction temperature range (−55°C to +175°C), low leakage (<1μA at 85V), and compatibility with 10/1000μs surge waveforms in harsh industrial and automotive environments.

Technical Context

The SA85CA implements a silicon avalanche diode structure optimized for bidirectional transient suppression, with symmetrical VBR min/max (94.4V/115V) and matched clamping performance in both polarities. It operates across −55°C to +175°C junction temperature and maintains <1μA reverse leakage at its 85V VWM rating.

Its 500W peak pulse power rating is defined per 10/1000μs waveform (per Fig.3), derated linearly above 25°C ambient per Fig.2, and supports unidirectional forward surge current up to 70A (8.3ms half-sine) - though SA85CA itself is bidirectional and does not specify VF or IFSM in that mode.

Key Specifications

Pinout & Package

SA85CA is a 2-terminal bidirectional TVS diode in DO-204AC (DO-15) axial package. No polarity marking; terminals are functionally symmetric. Leads are pure tin-plated, solderable per J-STD-002, and meet JESD 201 Class 2 whisker resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMAJ85CA and 1.5KE85CA, SA85CA offers optimal balance of AEC-Q101 qualification, DO-15 form factor, and 500W capability - making it the preferred choice for cost-sensitive, space-constrained automotive and industrial modules requiring proven reliability without overengineering.

Availability

SA85CA is available at Aetrix Electronics and suitable for automotive lighting systems, industrial PLC analog inputs, DC fast charging communication interfaces, and smart grid metering equipment requiring stable component supply and AEC-Q101 compliance.

Supply support for SA85CA 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 validation capabilities.

The SA Series was designed specifically for high-reliability transient suppression in automotive and industrial environments, emphasizing bidirectional symmetry, extended temperature operation, and halogen-free compliance from wafer to package.

FAQ

What is the clamping voltage of SA85CA at its rated peak pulse current?

The SA85CA exhibits a maximum clamping voltage (VC) of 151 V when subjected to its rated peak pulse current of 3.4 A under the standard 10/1000 μs waveform. This value is measured per IEC 61000-4-5 and ensures downstream components see no more than 151 V during surge events - critical for protecting 100 V-rated semiconductors in 48 V automotive systems. The SA85CA maintains this clamping performance bidirectionally.

Is SA85CA qualified to AEC-Q101, and what does that mean for automotive use?

Yes, SA85CA is AEC-Q101 qualified - confirmed by Taiwan Semiconductor's L2105 documentation and ordering code suffix "H" (e.g., SA85CAH). This qualification validates performance across temperature cycling, high-temperature reverse bias, and ESD testing per automotive reliability standards, enabling use in engine control units, body electronics, and ADAS subsystems without additional qualification effort. The SA85CA meets ASIL-B interface requirements.

How does SA85CA differ from unidirectional SA85A in terms of circuit application?

SA85CA is bidirectional with symmetrical breakdown and clamping in both polarities, making it ideal for AC lines, differential signals, or floating grounds where voltage transients can swing positive or negative. In contrast, SA85A is unidirectional and requires correct polarity orientation - it conducts only during negative transients relative to its cathode band. SA85CA eliminates orientation errors and simplifies layout in bidirectional protection schemes like USB-C CC lines or RS-485 buses.

What is the maximum junction temperature and thermal derating behavior of SA85CA?

The SA85CA has a maximum junction temperature (TJ) of +175°C and operates from −55°C to +175°C. Its 500 W peak pulse power is rated at TA = 25°C and must be linearly derated above that ambient per Figure 2 in the datasheet - e.g., ~70% derating at 100°C ambient. Steady-state power dissipation is limited to 3 W at TL = 75°C with 9.5 mm lead lengths, requiring appropriate copper pour for thermal management in continuous surge scenarios.

Can SA85CA be used in place of SA85A in an existing design?

SA85CA can replace SA85A only if the application requires bidirectional protection and the PCB layout accommodates non-polarized placement - since SA85CA lacks a cathode band and functions identically in either orientation. However, SA85CA should not be substituted into unidirectional circuits relying on forward conduction (e.g., DC rail clamping with series blocking diodes), as its bidirectional nature may alter fault current paths. Always verify clamping behavior under actual surge conditions before replacement.