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Taiwan Semiconductor Corporation SMAJ85CAH
- Part No.:
- SMAJ85CAH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ85CAH.pdf
- Description:
- TVS DIODE 85VWM 137VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,563
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Product details
Overview
SMAJ85CAH from Taiwan Semiconductor is a bidirectional 400W transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for automotive-grade overvoltage protection with 85V working stand-off voltage, 94.4–104V breakdown range, and 137V clamping voltage at 2.2A peak impulse current. It meets AEC-Q101 qualification and ISO 7637-2 Pulse 1/2a/2b/3a/3b for robust vehicle electrical system protection.
For engineers reviewing the SMAJ85CAH datasheet, SMAJ85CAH pinout, SMAJ85CAH application, or SMAJ85CAH equivalent, key selection criteria include bidirectional clamping capability, 150°C junction temperature rating, moisture sensitivity level 1 compliance, RoHS/halogen-free status, and suitability for DC/DC converter input rail protection in harsh automotive environments.
Technical Context
The SMAJ85CAH implements a glass-passivated silicon junction optimized for fast transient response (<1.0 ps from 0 V to VBR min) and low leakage (<1 µA at 85 V). Its bidirectional configuration enables symmetrical clamping in AC-coupled or floating signal lines without polarity dependency.
It delivers 400W peak pulse power under 10/1000 µs waveform up to 78 V, derating to 300W above 78 V per specification; thermal performance is supported by a -55°C to +150°C operating junction temperature range and UL 94V-0 molding compound.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 85 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR @ IT=1 mA | 94.4–104 V - Verified breakdown threshold ensuring reliable turn-on during transients |
| VC @ IPPM=2.2 A | 137 V - Clamped voltage limiting downstream circuit stress during 10/1000 µs surge |
| PPPM | 400 W - Peak pulse power handling capacity for short-duration automotive load dump events |
| IR @ VWM | <1 µA - Minimal leakage current preserving efficiency in high-impedance monitoring circuits |
| TJ max | +150 °C - Enables placement near heat sources in engine control units and body electronics |
| Package | DO-214AC (SMA) - Surface-mount footprint compatible with automated assembly and IPC-7351B land pattern |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, polarity indicated by cathode band (bidirectional operation means both terminals are functionally symmetric; no anode/cathode distinction applies).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (symmetrical) | Bidirectional transient conduction path | Both terminals serve identical clamping function - no polarity-sensitive routing required on PCB |
| Case | Non-connected mechanical structure | No internal thermal or electrical connection to die; thermal path relies on solder joint conduction |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood and chassis applications per stress test requirements including temperature cycling, HTRB, and ESD |
| Glass passivated junction | Enhances long-term reliability and stability of VBR under humidity and thermal cycling vs. epoxy-passivated alternatives |
| Fast response time <1.0 ps | Clamps ESD and lightning-induced transients before sensitive ICs experience overstress |
| ISO 7637-2 compliance | Guarantees protection against standardized automotive electrical disturbances including load dump, jump start, and alternator ripple |
| Moisture sensitivity level 1 | Enables standard SMT reflow without baking or dry pack handling, reducing manufacturing cost and risk |
Applications
| On-board DC/DC Converter Input Protection | Automotive Lighting Driver EMI Suppression |
|---|---|
Use Scenario: Protects 12 V/24 V input stage of buck converters powering ADAS cameras or infotainment displays from load dump and battery reversal spikes. IC Role / Device Role / Timing Role: Bidirectional TVS placed directly at converter input capacitor to clamp transients before they reach controller IC and power MOSFETs. Use Value: Limits peak voltage to 137 V during 400 W surges, preventing gate oxide damage and maintaining regulation integrity across temperature. | Use Scenario: Suppresses switching noise and inductive kickback in LED driver modules for headlamps and DRLs subjected to PWM dimming and CAN bus coupling. IC Role / Device Role / Timing Role: Placed across LED string or driver supply rails to absorb fast-rising edge transients generated by high-side switch turn-off. Use Value: Sub-1 ps response ensures clamping occurs within first nanosecond of transient onset, reducing conducted EMI into adjacent sensors and communication lines. |
| Engine Control Unit (ECU) Sensor Interface Protection | Body Control Module (BCM) LIN Bus Line Protection |
Use Scenario: Shields analog sensor inputs (e.g., MAP, TPS, O2) in ECUs from coupled transients originating from fuel injectors, ignition coils, and solenoid drivers. IC Role / Device Role / Timing Role: Connected between sensor signal line and ground to shunt transient energy while preserving DC accuracy via <1 µA leakage at 85 V. Use Value: Maintains signal integrity under repeated 10/1000 µs pulses up to 2.2 A, avoiding false fault codes or calibration drift. | Use Scenario: Protects LIN physical layer transceivers from electrostatic discharge and bus contention spikes in door modules and seat controllers. IC Role / Device Role / Timing Role: Bidirectional placement across LIN bus pair (LIN-H/L) to clamp common-mode and differential transients without disrupting 19.2 kbps signaling. Use Value: Symmetrical clamping ensures equal protection regardless of bus polarity, supporting fail-safe diagnostics during ESD events per ISO 10605. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ85CA | Same electrical specs but not AEC-Q101 qualified; lacks automotive stress validation | Restricted to industrial or consumer applications where automotive reliability is not mandated | Select SMAJ85CAH when automotive qualification and ISO 7637-2 compliance are mandatory |
| SMCJ85CA | Higher 1500 W peak power rating in DO-214AB (SMB) package; larger footprint and thermal mass | Better suited for higher-energy transients (e.g., 12 V battery jump-start), but requires PCB layout change | Choose SMAJ85CAH for space-constrained automotive modules needing 400 W in SMA footprint |
Compared with SMAJ85CA and SMCJ85CA, the SMAJ85CAH uniquely balances AEC-Q101 qualification, ISO 7637-2 compliance, and DO-214AC packaging-making it optimal for volume automotive electronics where board space, reliability, and standards adherence are jointly critical.
Availability
SMAJ85CAH is available at Aetrix Electronics and suitable for automotive lighting systems, engine control units, body control modules, and on-board DC/DC converters requiring stable component supply across extended temperature and lifecycle demands.
Supply support for SMAJ85CAH 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 automotive-qualified components since 1979.
The SMAJ series was developed specifically for AEC-Q101-compliant transient suppression in automotive power distribution and signal interface applications, emphasizing reliability under thermal cycling, humidity, and electrical stress.
FAQ
What does the 'CAH' suffix indicate in SMAJ85CAH?
The 'CAH' suffix denotes a bidirectional (C), AEC-Q101 qualified (A), and halogen-free (H) variant of the SMAJ85 series. SMAJ85CAH provides symmetrical clamping for AC or floating circuits and meets automotive reliability and environmental standards required for under-hood and chassis applications.
Is SMAJ85CAH suitable for protecting CAN bus lines?
SMAJ85CAH is not recommended for direct CAN bus line protection due to its 137 V clamping voltage, which exceeds typical CAN transceiver absolute maximum ratings (±40 V). It is intended for higher-voltage power rail and sensor interface protection-not low-voltage data buses like CAN or LIN.
Does SMAJ85CAH require heatsinking in typical automotive applications?
No, SMAJ85CAH does not require external heatsinking in standard automotive use cases. Its 1 W steady-state power dissipation and DO-214AC package are thermally adequate when mounted on standard 1 oz copper PCBs with recommended pad layout; thermal derating begins only above 25°C ambient per Fig.2.
How does SMAJ85CAH differ from unidirectional SMAJ85AH?
SMAJ85CAH is bidirectional with symmetrical clamping in both polarities, while SMAJ85AH is unidirectional and conducts only in reverse bias. SMAJ85CAH eliminates polarity concerns in floating or AC-coupled circuits, whereas SMAJ85AH requires correct orientation and offers lower forward voltage (3.5 V) if forward conduction is needed.
What is the moisture sensitivity level (MSL) rating for SMAJ85CAH?
SMAJ85CAH has a moisture sensitivity level (MSL) of 1 per J-STD-020, meaning it can be stored indefinitely at ≤30°C/60% RH and processed using standard SMT reflow profiles without pre-baking-reducing manufacturing complexity and cost in high-volume automotive assembly.
SMAJ85CAH 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:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 85V
- Voltage - Breakdown (Min):
- 94.4V
- Voltage - Clamping (Max) @ Ipp:
- 137V
- Current - Peak Pulse (10/1000µs):
- 2.2A
- 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)
SMAJ85CAH FAQ
1.How can I place an order for SMAJ85CAH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ85CAH 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 SMAJ85CAH reliable?
The price and inventory of SMAJ85CAH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ85CAH is usually 5 days.
3.What payment methods are accepted for SMAJ85CAH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ85CAH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ85CAH?
SMAJ85CAH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ85CAH 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 SMAJ85CAH?
For technical support, including SMAJ85CAH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ85CAH requirements.
6.How does Aetrix verify that SMAJ85CAH is sourced from the original manufacturer or authorized distributors?
All SMAJ85CAH 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 SMAJ85CAH meets industry standards.
7.What is the process for return or replacement of SMAJ85CAH?
All SMAJ85CAH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ85CAH, 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 SMAJ85CAH part is unused and in its original packaging.
Return procedure for SMAJ85CAH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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