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Taiwan Semiconductor Corporation SMAJ85H
- Part No.:
- SMAJ85H
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ85H.pdf
- Description:
- TVS DIODE 85VWM 151VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,534
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Product details
Overview
SMAJ85H from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for robust overvoltage protection in DC power rails and signal lines. It features a 85 V working stand-off voltage (VWM), 94.4–115 V breakdown voltage (VBR), 151 V maximum clamping voltage (VC) at 2.0 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - deployed in automotive-grade SMPS and on-board DC/DC converters.
For engineers reviewing the SMAJ85H datasheet, SMAJ85H pinout, SMAJ85H application, or SMAJ85H equivalent, this device is selected for its AEC-Q101 qualification, sub-1 ps response time, <1 µA leakage above 10 V, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, and DO-214AC (SMA) package suitability for automated placement in high-reliability industrial and automotive power systems.
Technical Context
The SMAJ85H operates as a unidirectional avalanche diode with glass-passivated junction, optimized for fast clamping of transient surges induced by load dump, inductive switching, or ESD events. Its electrical behavior is defined by precise VBR (94.4–115 V @ 1 mA), VC = 151 V @ IPPM = 2.0 A, and thermal derating per Fig.2 to maintain safe operation up to TJ = 150 °C.
It meets ISO 7637-2 immunity requirements for automotive electronics and supports bidirectional variants via CH/CAH suffixes (e.g., SMAJ85CH), though SMAJ85H itself is unidirectional with cathode band polarity marking. Steady-state power dissipation is rated at 1 W, and peak forward surge current withstands 40 A (8.3 ms half-sine).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 85 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR min/max | 94.4 V / 115 V @ 1 mA - Ensures reliable turn-on margin above system nominal rail |
| VC @ IPPM | 151 V @ 2.0 A - Limits protected circuit voltage during 10/1000 µs transients |
| PPPM | 400 W - Peak surge energy handling capability under standardized test waveform |
| IR @ VWM | <1 µA - Negligible leakage current preserves efficiency in low-power standby modes |
| TJ max | 150 °C - Enables operation in under-hood automotive environments and enclosed power modules |
| Package | DO-214AC (SMA) - Industry-standard SMD outline compatible with JEDEC MS-013, 0.060 g weight |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, polarity indicated by cathode band (unidirectional only), RoHS and halogen-free compliant, moisture sensitivity level 1 per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path) in unidirectional configuration |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., +12 V rail); clamps to anode when VAK exceeds VBR |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive electronic systems including engine control, body electronics, and ADAS power domains |
| Clamping response time | <1.0 ps - Enables suppression of nanosecond-scale ESD and fast-rising transients before IC damage occurs |
| ISO 7637-2 compliance | Covers Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) immunity testing |
| Glass passivated junction | Enhances long-term reliability and stability of VBR and leakage under thermal cycling and humidity stress |
| Automated placement compatibility | DO-214AC footprint and lead geometry support high-speed pick-and-place assembly without tombstoning or misalignment |
Applications
| Automotive Power Rail Protection | Industrial SMPS Input Stage |
|---|---|
Use Scenario: Protecting 12 V/24 V battery-fed ECUs against load dump spikes up to ±120 V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between power rail and chassis ground to clamp transients within safe semiconductor limits. Use Value: SMAJ85H's 151 V clamping voltage ensures downstream regulators and microcontrollers remain below absolute maximum ratings during 35 V–120 V surges. | Use Scenario: Safeguarding AC-DC adapter primary-side rectifier output and secondary-side DC bus in industrial power supplies. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing repetitive switching noise and lightning-induced surges on isolated DC outputs. Use Value: With 400 W peak power rating and <1 µA leakage, SMAJ85H maintains efficiency while delivering repeatable clamping performance across 100,000+ surge cycles. |
| On-Board DC/DC Converter Input | LED Driver Supply Line Protection |
Use Scenario: Securing input terminals of buck/boost converters in automotive lighting modules subjected to PWM-induced transients. IC Role / Device Role / Timing Role: Fast-response unidirectional suppressor shunting inductive kickback from MOSFET gate drivers and inductor flyback. Use Value: Sub-1 ps response and 94.4–115 V VBR window ensure immediate conduction before converter ICs experience latch-up or gate oxide rupture. | Use Scenario: Shielding constant-current LED driver ICs from voltage reversals and ESD during hot-plug connection in architectural lighting systems. IC Role / Device Role / Timing Role: Reverse-polarity and surge protector mounted at driver input, leveraging cathode-band polarity for correct orientation. Use Value: DO-214AC package enables compact layout near connectors; 150 °C TJ rating sustains reliability in thermally constrained LED housing environments. |
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 VWM (85 V), but tighter VBR range (94.4–104 V); slightly lower VC (137 V @ 2.2 A) | Better clamping margin for 12 V systems with tight downstream voltage tolerances | Select SMAJ85A if design requires lower clamping voltage and accepts reduced surge current headroom |
| ON Semiconductor SMAJ85CA | Bidirectional variant (VRWM = 85 V, symmetrical clamping); same package and power rating | Required where AC-coupled signals or dual-polarity transients (e.g., CAN bus, sensor lines) must be suppressed | Choose SMAJ85CA only when bidirectional protection is mandated - SMAJ85H is not pin-compatible due to polarity dependency |
Compared with SMAJ85H, SMAJ85A offers improved clamping precision at the cost of lower surge current tolerance, while SMAJ85CA provides symmetrical protection but requires redesign for polarity-agnostic placement - neither is drop-in replaceable without verifying layout and system-level surge directionality.
Availability
SMAJ85H is available at Aetrix Electronics and suitable for automotive power rail protection, industrial SMPS input stages, and on-board DC/DC converter inputs requiring stable component supply with AEC-Q101 qualification and ISO 7637-2 compliance.
Supply support for SMAJ85H 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, specializing in TVS diodes, rectifiers, MOSFETs, and power management devices.
The SMAJ series was developed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing AEC-Q101 qualification, fast response, and robust packaging for automated manufacturing.
FAQ
What is the maximum clamping voltage of the SMAJ85H under standard 10/1000 µs surge conditions?
The SMAJ85H has a maximum clamping voltage (VC) of 151 V when subjected to its rated peak pulse current of 2.0 A using the 10/1000 µs waveform. This value is measured per Fig.5 in the official Taiwan Semiconductor datasheet (Version A2102) and defines the upper voltage limit imposed on protected circuits during transient events.
Is the SMAJ85H suitable for bidirectional transient suppression?
No - the SMAJ85H is a unidirectional TVS diode, intended for protection of DC rails with defined polarity. For bidirectional applications such as AC lines or differential buses, the SMAJ85CH or SMAJ85CA variants must be used. The SMAJ85H cathode band marking confirms its unidirectional orientation and prohibits reverse-bias operation beyond VWM.
Does the SMAJ85H meet automotive qualification standards?
Yes - the SMAJ85H is explicitly AEC-Q101 qualified and certified to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements. These qualifications validate its suitability for use in automotive electronic control units, body modules, and infotainment power supplies where robustness against load dump and switching transients is mandatory.
What is the thermal derating behavior of the SMAJ85H above 25°C ambient temperature?
The SMAJ85H follows the pulse derating curve in Fig.2 of the Taiwan Semiconductor datasheet: peak pulse power decreases linearly from 400 W at 25°C to approximately 200 W at 100°C ambient. This derating ensures safe junction temperature (TJ ≤ 150°C) during repeated surge events and must be applied in thermal design calculations for high-temperature enclosures or under-hood installations.
Can the SMAJ85H be used in place of the SMAJ85AH variant?
No - the SMAJ85H and SMAJ85AH differ in breakdown voltage tolerance: SMAJ85H has VBR = 94.4–115 V, while SMAJ85AH is tighter at 94.4–104 V. Their clamping voltages also differ (151 V vs. 137 V). Substituting SMAJ85H for SMAJ85AH may result in higher clamping stress on downstream components and should only occur after full system-level surge validation.
SMAJ85H Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Taiwan Semiconductor Corporation
- Package/Case:
- DO-214AC, SMA
- Series:
- SMAJ
- 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:
- 151V
- Current - Peak Pulse (10/1000µs):
- 2A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ85H FAQ
1.How can I place an order for SMAJ85H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ85H 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 SMAJ85H reliable?
The price and inventory of SMAJ85H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ85H is usually 5 days.
3.What payment methods are accepted for SMAJ85H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ85H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ85H?
SMAJ85H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ85H 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 SMAJ85H?
For technical support, including SMAJ85H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ85H requirements.
6.How does Aetrix verify that SMAJ85H is sourced from the original manufacturer or authorized distributors?
All SMAJ85H 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 SMAJ85H meets industry standards.
7.What is the process for return or replacement of SMAJ85H?
All SMAJ85H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ85H, 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 SMAJ85H part is unused and in its original packaging.
Return procedure for SMAJ85H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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