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onsemi SA85A
- Part No.:
- SA85A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA85A.pdf
- Description:
- TVS DIODE 85VWM 137VC DO15
- Quantity:
- Payment:
- Shipping:
Inventory:8,914
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Product details
Overview
SA85A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode in DO-15 package, with 85 V reverse stand-off voltage (VRWM), 94.4–104.0 V breakdown voltage (VBR), 137.0 V clamping voltage at peak pulse current, and <1.0 μA reverse leakage above 10 V. It protects DC power rails and signal lines in industrial motor drives against ESD and lightning-induced surges.
For engineers reviewing the SA85A datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, DO-15 terminal mapping, clamping performance under 10/1000 μs transients, thermal derating curves, and direct alternatives for overvoltage protection design.
Technical Context
The SA85A employs a glass-passivated junction to achieve low incremental surge resistance and fast response time-less than 1.0 ps from 0 V to breakdown for unidirectional operation. Its clamping behavior is characterized on the standardized 10/1000 μs double-exponential waveform per R.E.A., with guaranteed VC ≤ 137.0 V at IPPM = 3.6 A.
Designed for single-pulse surge immunity, it supports non-repetitive forward surge current up to 70 A (8.3 ms half-sine), operates up to +175 °C junction temperature, and exhibits typical IR < 1.0 μA at VRWM = 85 V-enabling low-power standby compatibility in battery-backed systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 500 W on 10/1000 μs waveform - sustains high-energy lightning surges without failure |
| Reverse Stand-off Voltage | 85 V - sets maximum continuous operating voltage before clamping initiates |
| Breakdown Voltage | 94.4–104.0 V at 1.0 mA - defines reliable turn-on threshold with tight tolerance |
| Clamping Voltage | 137.0 V at 3.6 A peak pulse - limits downstream voltage stress during surge events |
| Reverse Leakage | <1.0 μA at 85 V - minimizes quiescent power loss in always-on protection circuits |
| Junction Temperature | +175 °C max - enables use in high-ambient environments like motor control enclosures |
| Package | DO-15 - industry-standard axial leaded package with cathode band marking |
Pinout & Package
SA85A uses the DO-15 package: axial-leaded, glass-passivated, epoxy-encapsulated diode with cathode indicated by a color band. Lead length is 0.375" for thermal rating compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to protected line's lower potential side (e.g., GND or return path) |
| Cathode | Clamping terminal / surge sink | Connected to protected line's higher potential side (e.g., +85 V rail); color-banded end |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Enables stable VBR tolerance and long-term reliability under thermal cycling |
| 500 W peak pulse rating | Meets IEC 61000-4-5 Level 4 (4 kV line-to-line) surge immunity requirements |
| Sub-1.0 ps response time | Clamps before transient energy couples into sensitive IC inputs or gate drivers |
| Low incremental surge resistance | Minimizes voltage overshoot during fast-rising transients (e.g., inductive switch-off) |
| 1.0 μA max IR at VRWM | Permits direct placement across low-current sensor outputs without loading error |
Applications
| Industrial Motor Drives | DC Power Supply Inputs |
|---|---|
Use Scenario: Protection of gate driver supply rails against MOSFET switching transients and bus fault feedback. IC Role / Device Role / Timing Role: Unidirectional TVS clamping device placed between +15 V bias rail and ground. Use Value: Limits transient overshoot to ≤137 V, preventing gate oxide damage to isolated gate drivers. |
Use Scenario: Input-stage surge suppression on 85–100 V DC input to telecom rectifier modules. IC Role / Device Role / Timing Role: Primary overvoltage clamp on bulk DC input prior to filtering and regulation. Use Value: Absorbs 500 W surges without degradation, maintaining system uptime during AC line faults. |
| Automotive Body Control Modules | Industrial PLC I/O Terminals |
Use Scenario: CAN bus power rail protection in 12 V/24 V vehicle subsystems exposed to load dump. IC Role / Device Role / Timing Role: Standoff-rated TVS on switched 24 V supply feeding CAN transceivers. Use Value: Withstands ISO 7637-2 Pulse 5a (load dump) up to 137 V peak, preserving communication integrity. |
Use Scenario: Field-side protection on digital input terminals receiving 24 V DC signals from sensors. IC Role / Device Role / Timing Role: Unidirectional clamping element between input line and common reference. Use Value: Blocks >85 V transients while adding <1.0 μA leakage-no impact on 4–20 mA loop accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Littelfuse SMAJ85A | Same DO-15 package, identical VRWM (85 V), VBR (94.4–104.0 V), and VC (137 V), but rated for 400 W (not 500 W) | Lower peak power margin reduces margin for multi-pulse or extended-duration surges | Select when cost sensitivity outweighs need for full 500 W IEC 61000-4-5 compliance |
| Vishay SMA6J85A | DO-214AC (SMA) package, same electrical specs, but surface-mount; thermal resistance differs due to package geometry | Requires PCB rework for through-hole replacement; better suited for new SMT designs | Choose for space-constrained layouts where axial leads are impractical |
Compared with SA85A, SMAJ85A offers identical clamping but reduced surge endurance, while SMA6J85A matches performance in an SMT form factor-neither is pin-compatible, but both serve the same functional role in overvoltage protection networks.
Availability
SA85A is available at Aetrix Electronics and suitable for industrial motor drives, DC power supply inputs, and automotive body control modules requiring stable component supply and long-lifecycle availability.
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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete devices, acquired by ON Semiconductor in 2016.
The SA85A belongs to Fairchild's SAxxA series of 500 W unidirectional TVS diodes, engineered for robust transient immunity in industrial and automotive power systems where reliability under repetitive surge stress is critical.
FAQ
What is the clamping voltage of SA85A at its rated peak pulse current?
The SA85A has a maximum clamping voltage (VC) of 137.0 V when subjected to its peak pulse current of 3.6 A on the 10/1000 μs waveform. This value is measured per R.E.A. standard and ensures predictable voltage limiting during surge events. The SA85A maintains this clamping performance across its specified operating temperature range up to +175 °C junction temperature.
Is SA85A bidirectional or unidirectional?
SA85A is a unidirectional transient voltage suppressor, indicated by the absence of the "C" suffix (which denotes bidirectional variants like SA85CA). It conducts only in reverse breakdown-cathode must be connected to the higher-potential side of the protected circuit. Its fast response time (<1.0 ps) and low leakage (<1.0 μA at 85 V) are optimized for DC rail protection, not AC line applications.
What package type does SA85A use, and how is polarity marked?
SA85A uses the DO-15 axial-leaded package. Polarity is marked by a visible color band (typically black or dark gray) on the cathode end of the diode body. The anode is the unmarked lead. This marking aligns with JEDEC standards and ensures correct orientation during manual or automated assembly. Lead length is specified at 0.375" for thermal derating compliance.
Can SA85A replace SA85CA in a circuit?
No-SA85A is unidirectional and cannot substitute for SA85CA, which is bidirectional and symmetrical in both conduction directions. Replacing SA85CA with SA85A would leave one polarity unprotected, risking component failure during negative-going transients. SA85A is intended for DC applications with defined polarity; SA85CA is required for AC-coupled or floating signal lines.
What is the maximum operating junction temperature for SA85A?
The SA85A has a maximum operating junction temperature (TJ) of +175 °C, as specified in Fairchild's Absolute Maximum Ratings table. This allows deployment in high-temperature environments such as motor drive heatsinks or enclosed industrial controllers. Derating of peak pulse power begins above +75 °C ambient, per the published pulse derating curve in the datasheet.
SA85A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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):
- 3.6A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 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.
SA85A Tags
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