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Taiwan Semiconductor Corporation SA85A
- Part No.:
- SA85A
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA85A.pdf
- Description:
- TVS DIODE 85VWM 137VC DO204AC
- Quantity:
- Payment:
- Shipping:
Inventory:9,771
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Product details
Overview
SA85A 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 85V working stand-off voltage (VWM), 94.4–115V breakdown voltage (VBR), and 151V maximum clamping voltage (VC) at 3.4A peak pulse current - used to protect automotive power rails and industrial I/O interfaces against EFT and lightning-induced surges.
For engineers reviewing the SA85A datasheet, SA85A pinout, SA85A application, or SA85A equivalent, key selection criteria include clamping voltage margin relative to system rail, leakage current below 1μA at 85V, AEC-Q101 qualification status, thermal derating above 25°C, and compatibility with 10/1000μs surge waveforms per IEC 61000-4-5.
Technical Context
The SA85A operates as a unidirectional avalanche diode, triggering when reverse voltage exceeds its specified VBR range (94.4–115V @ 1mA). Its low dynamic impedance ensures rapid clamping response (<1.0ps from 0V to VBR), limiting transient energy delivered to downstream circuitry during fast-rising ESD or EFT events.
Designed for primary-side overvoltage protection in 24V and 48V automotive subsystems, it sustains 175°C junction temperature and meets JESD201 Class 2 whisker resistance. The device exhibits +114 mV/°C temperature coefficient of VBR and requires no external biasing - functioning as a passive crowbar element across protected lines.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 85 V - maximum continuous reverse operating voltage before conduction begins; sets upper limit for safe DC bias on protected line |
| VBR min/max | 94.4 / 115 V @ 1 mA - guaranteed avalanche onset window; determines minimum overvoltage threshold for clamping activation |
| VC @ IPPM | 151 V @ 3.4 A - peak clamped voltage under 10/1000μs surge; defines worst-case stress on downstream ICs |
| PPK | 500 W - non-repetitive surge power handling at TA = 25°C; derates linearly above ambient per Fig.2 |
| IR @ VWM | <1 μA - reverse leakage at rated stand-off; ensures negligible standby power loss and signal integrity in high-impedance circuits |
| TJ max | +175 °C - maximum junction temperature; enables operation in engine bay or industrial control enclosures without forced cooling |
| Package | DO-204AC (DO-15) - industry-standard axial leaded package with tin-plated leads compliant to J-STD-002 solderability |
Pinout & Package
DO-204AC (DO-15) package: axial-leaded, molded epoxy case meeting UL 94V-0; cathode indicated by band; weight ≈ 0.400 g; terminals are pure tin plated for reliable solder wetting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry / Surge return path | Connected to ground or low-impedance return plane; carries full surge current during clamping |
| Cathode | Protected line connection | Connected to line under protection (e.g., 24V supply rail); voltage referenced to anode during clamping |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive applications including powertrain and body electronics per stress test requirements |
| Clamping ratio VC/VBR | 1.32 typical (151V / 115V) - tight ratio ensures predictable overvoltage suppression without excessive margin overhead |
| Response time | <1.0 ps - enables effective suppression of sub-nanosecond ESD transients per IEC 61000-4-2 |
| RoHS & halogen-free | Compliant with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU - suitable for green manufacturing |
| Surge waveform support | Rated for 10/1000μs (IEC 61000-4-5) and 8.3ms half-sine (JEDEC JESD22-A112) - covers lightning and inductive switch-off events |
Applications
| Automotive Power Rail Protection | Industrial PLC I/O Protection |
|---|---|
Use Scenario: 24V battery-supplied ECUs exposed to load dump and alternator transients up to ±100V. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and regulator input to clamp surges before LDO or DC/DC converter. Use Value: Limits peak voltage to ≤151V, preventing damage to 36V-rated input stages while maintaining <1μA leakage during normal operation. | Use Scenario: Digital input modules receiving 24V dry-contact signals in factory automation cabinets. IC Role / Device Role / Timing Role: Standoff protector on field-side signal line, shunting EFT bursts (IEC 61000-4-4) to common ground. Use Value: Clamps 4kV EFT pulses within 1ps, preserving signal integrity and avoiding false triggering of optocouplers or Schmitt triggers. |
| LED Driver Overvoltage Clamp | Motor Drive Gate Driver Protection |
Use Scenario: Constant-current LED drivers powered from 48V bus in streetlight or signage systems. IC Role / Device Role / Timing Role: Primary-side TVS across input capacitor to absorb inductive kickback from upstream switching regulators. Use Value: Absorbs 500W surges without degradation, enabling use of smaller bulk capacitors and eliminating need for secondary Zener clamps. | Use Scenario: Half-bridge gate driver ICs controlling 48V BLDC motors in power tools or HVAC actuators. IC Role / Device Role / Timing Role: Bidirectional protection not applicable; SA85A used unidirectionally across high-side driver supply to clamp negative transients from Miller coupling. Use Value: Prevents -151V undershoot on VDDH rail during fast turn-off, avoiding latch-up or oxide stress in level-shift circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ85A | Same DO-214AC package; slightly higher VC (156V) and lower IPPM (3.2A); identical VWM/VBR range | Designed for surface-mount assembly; requires PCB rework for through-hole replacement | Select SMAJ85A only when migrating to SMT layout; SA85A remains optimal for legacy through-hole designs. |
| P6SMB85A | DO-214AA package; same VWM/VBR specs; VC = 152V @ 3.3A; RoHS-compliant but not AEC-Q101 qualified | Lacks automotive qualification; suitable for industrial but not safety-critical vehicle systems | Choose P6SMB85A for cost-sensitive industrial applications where AEC-Q101 is not mandated. |
Compared with SMAJ85A and P6SMB85A, the SA85A offers verified AEC-Q101 qualification and DO-15 through-hole compatibility - critical for automotive service parts and industrial retrofits requiring mechanical robustness and long-term supply stability.
Availability
SA85A is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC I/O hardening, LED driver overvoltage clamping, and motor drive gate driver protection requiring stable component supply across multi-year production cycles.
Supply support for SA85A 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, serving global automotive, industrial, and consumer markets since 1979.
The SA Series TVS diodes are engineered specifically for high-reliability transient suppression in harsh environments - emphasizing low clamping ratio, AEC-Q101 compliance, and robust surge endurance across extended temperature ranges.
FAQ
What is the clamping voltage of SA85A under a 10/1000μs surge?
The SA85A clamps to a maximum of 151 V when subjected to a 10/1000μs waveform at its rated peak pulse current of 3.4 A. This value is measured per IEC 61000-4-5 and is guaranteed across the full operating temperature range. The clamping performance of SA85A ensures downstream components see less than 151 V during surge events, protecting sensitive regulators and interface ICs.
Is SA85A unidirectional or bidirectional?
SA85A is a unidirectional TVS diode, designed for protection of positive-polarity DC lines such as 24V or 48V power rails. Its cathode band marks the terminal connected to the protected line, with the anode tied to ground. Unlike bidirectional variants (e.g., SA85CA), SA85A does not conduct in forward bias beyond ~3.5 V and provides no protection against negative-going transients.
Does SA85A meet AEC-Q101 reliability standards?
Yes, SA85A is AEC-Q101 qualified - confirmed in the official SA Series datasheet (Version L2105). It has passed stress tests including high-temperature operating life, temperature cycling, and unbiased highly accelerated stress testing. This qualification makes SA85A suitable for automotive applications including body control modules, lighting controllers, and infotainment power supplies.
What is the maximum junction temperature rating for SA85A?
The SA85A has a maximum junction temperature (TJ max) of +175 °C, allowing reliable operation in under-hood automotive environments and sealed industrial enclosures. Thermal derating follows the curve in Figure 2 of the datasheet: peak pulse power decreases linearly above 25°C ambient, reaching ~300W at +85°C case temperature. This rating is integral to the SA85A design for sustained surge resilience.
How does SA85A differ from SA85 (non-A version)?
The SA85A variant features tighter VBR tolerance (94.4–104 V vs. 94.4–115 V for SA85) and lower clamping voltage (137 V vs. 151 V at rated IPPM), resulting in improved protection margin. Both share identical VWM (85 V), package (DO-15), and AEC-Q101 qualification. SA85A is preferred where precise clamping and reduced overshoot are critical, such as in 36V-input DC/DC front-ends.
SA85A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- SA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 3.8A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-204AC (DO-15)
SA85A FAQ
1.How can I place an order for SA85A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA85A on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for SA85A reliable?
The price and inventory of SA85A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA85A is usually 5 days.
3.What payment methods are accepted for SA85A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA85A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA85A?
SA85A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA85A order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for SA85A?
For technical support, including SA85A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA85A requirements.
6.How does Aetrix verify that SA85A is sourced from the original manufacturer or authorized distributors?
All SA85A products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SA85A meets industry standards.
7.What is the process for return or replacement of SA85A?
All SA85A units undergo pre-shipment inspection (PSI). If there is an issue with SA85A, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The SA85A part is unused and in its original packaging.
Return procedure for SA85A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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