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Taiwan Semiconductor Corporation SMAJ170H
- Part No.:
- SMAJ170H
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ170H.pdf
- Description:
- TVS DIODE 170VWM 304VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,129
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Product details
Overview
SMAJ170H from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for automotive-grade overvoltage protection in DC power rails. It features a 170 V working stand-off voltage (VWM), 189–231 V breakdown voltage (VBR @ 1 mA), 304 V maximum clamping voltage (VC) at 1 A peak impulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - meeting ISO 7637-2 Pulse 1/2a/2b/3a/3b requirements for vehicle electronics.
For engineers reviewing the SMAJ170H datasheet, SMAJ170H pinout, SMAJ170H application, or SMAJ170H equivalent, key selection criteria include its AEC-Q101 qualification, DO-214AC (SMA) package compatibility with automated placement, sub-1 ps response time, <1 µA reverse leakage at VWM, and robust clamping performance under repetitive surge stress in on-board DC/DC converters and SMPS inputs.
Technical Context
The SMAJ170H operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve fast transient suppression with minimal capacitance. Its clamping behavior is defined by a tightly controlled VBR range (189–231 V) and low dynamic impedance, enabling reliable protection of downstream MOSFETs and controllers during load dump or inductive switching events.
It is rated for 150 °C maximum junction temperature and supports bidirectional variants via CH/CAH suffixes (e.g., SMAJ170CH), though SMAJ170H itself is unidirectional with cathode band marking. The device complies with JESD201 Class 2 whisker resistance and moisture sensitivity level 1 per J-STD-020.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 170 V - Maximum continuous DC or RMS voltage the device blocks without conduction |
| VBR @ IT = 1 mA | 189–231 V - Breakdown threshold where avalanche conduction begins; ensures margin above system operating voltage |
| VC @ IPPM = 1 A | 304 V - Clamped voltage during 10/1000 µs surge; defines worst-case stress on protected ICs |
| PPPM | 400 W - Peak pulse power handling per standard 10/1000 µs waveform; derates linearly above 25 °C ambient |
| IR @ VWM | <1 µA - Reverse leakage at stand-off voltage; minimizes quiescent power loss in high-impedance rails |
| Response Time | <1.0 ps - Time from 0 V to VBR,min; enables suppression before sensitive circuitry experiences overvoltage |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with 0.060 g mass and UL 94V-0 molding compound |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, cathode indicated by a band on the body. Leads are solderable per J-STD-002; polarity must be observed during PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Input/Line side (cathode-banded end is cathode) | Connected to protected line; conducts surge current toward ground when clamping |
| Cathode | Ground reference / return path | Connected to system ground plane; establishes reference for clamping voltage and defines unidirectional polarity |
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 and leakage under thermal/humidity stress |
| ISO 7637-2 compliance | Withstands Pulse 1 (inductive load dump), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling) waveforms |
| Moisture sensitivity level 1 | No floor life limitation or bake requirement prior to reflow; compatible with standard SMT assembly processes |
| Halogen-free & RoHS compliant | Meets IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for environmentally constrained designs |
Applications
| Automotive Power Distribution | Industrial SMPS Input Protection |
|---|---|
Use Scenario: Protecting 24 V and 48 V battery-fed ECUs against load dump surges up to ±120 V per ISO 7637-2 Pulse 5a. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor to clamp transients before they reach DC/DC controller ICs. Use Value: Limits peak voltage to ≤304 V during 1 A surge, preventing gate oxide damage to upstream MOSFETs and ensuring ASIL-B functional safety compliance. |
Use Scenario: Safeguarding AC/DC adapter primary-side rectifier outputs and secondary-side DC bus lines from switching noise and lightning-induced surges. IC Role / Device Role / Timing Role: Standoff protector across bulk capacitors to absorb repetitive 10/1000 µs pulses without degradation. Use Value: Maintains <1 µA leakage at 170 V, minimizing standby power loss while delivering 400 W pulse handling for EN 61000-4-5 Level 3 immunity. |
| On-Board DC/DC Converters | LED Driver Power Inputs |
Use Scenario: Input rail protection in 48 V-to-12 V buck converters used in ADAS camera modules and infotainment head units. IC Role / Device Role / Timing Role: Fast-response clamping device placed immediately after input connector to suppress ESD and coupled transients from harness wiring. Use Value: Sub-1 ps response ensures clamping initiates before controller ICs experience overvoltage, preserving PWM timing integrity and preventing latch-up. |
Use Scenario: Overvoltage safeguard for constant-current LED drivers in commercial lighting systems exposed to grid fluctuations and switching transients. IC Role / Device Role / Timing Role: Parallel-connected TVS across driver input terminals to shunt energy away from current-sense resistors and op-amps. Use Value: 304 V clamping voltage provides ≥25 V margin above 277 VAC-derived DC bus, avoiding false triggering while protecting precision analog feedback paths. |
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 SMAJ170A | Same VWM (170 V), but tighter VBR range (189–209 V); lower clamping voltage (275 V @ 1 A) | Better suited for systems requiring lower clamping margin; slightly reduced surge margin due to narrower VBR tolerance | Select SMAJ170A if design prioritizes lower VC over maximum surge headroom |
| ON Semiconductor SMAJ170A | Identical electrical specs and DO-214AC package; AEC-Q101 certified; same 304 V VC rating | No functional difference; alternate supply chain with identical footprint and qualification | Choose for dual-sourcing flexibility without layout or validation changes |
Compared with SMAJ170H, SMAJ170A variants offer tighter VBR control and lower clamping voltage but retain full AEC-Q101 compliance and DO-214AC compatibility - making them drop-in alternatives only when VBR distribution and clamping margin align with system tolerances.
Availability
SMAJ170H is available at Aetrix Electronics and suitable for automotive power distribution, industrial SMPS input protection, and on-board DC/DC converter designs requiring stable component supply with AEC-Q101 assurance and ISO 7637-2 compliance.
Supply support for SMAJ170H 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, and rectifiers with global automotive and industrial certifications.
The SMAJ series was developed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing AEC-Q101 qualification, robust surge handling, and SMT manufacturability.
FAQ
What is the maximum clamping voltage of SMAJ170H under standard surge conditions?
The SMAJ170H has a maximum clamping voltage (VC) of 304 V when subjected to a 1 A peak impulse current with a 10/1000 µs waveform. This value is measured per JEDEC standards and defines the upper voltage limit imposed on protected circuitry during transient events - critical for ensuring downstream ICs remain within absolute maximum ratings.
Is SMAJ170H suitable for bidirectional transient protection?
No, SMAJ170H is a unidirectional TVS diode, marked with a cathode band and intended for DC rail protection where polarity is fixed. For bidirectional applications such as AC lines or data buses, the SMAJ170CH variant (with CH suffix) must be used - it shares the same VWM and clamping performance but conducts in both directions.
Does SMAJ170H meet automotive qualification standards?
Yes, SMAJ170H is AEC-Q101 qualified and tested per the full stress test schedule including HTGB, HTRB, TCT, and ESD. It also meets ISO 7637-2 Pulse 1/2a/2b/3a/3b requirements, making it suitable for use in automotive power modules, body control units, and ADAS subsystems.
What is the thermal derating behavior of SMAJ170H above 25°C ambient?
SMAJ170H peak pulse power (400 W) is linearly derated above 25°C ambient per Figure 2 in the datasheet, reaching zero at 150°C junction temperature. At 85°C ambient, its usable PPPM drops to approximately 260 W - requiring thermal design consideration when deployed in enclosed or high-temperature environments.
Can SMAJ170H be used in place of SMAJ170AH?
No - SMAJ170H and SMAJ170AH differ in breakdown voltage tolerance: SMAJ170H has VBR = 189–231 V, while SMAJ170AH is tighter at 189–209 V. Their clamping voltages also differ (304 V vs. 275 V). Substitution requires verification that the wider VBR range and higher VC of SMAJ170H meet system overvoltage margin requirements.
SMAJ170H 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):
- 170V
- Voltage - Breakdown (Min):
- 189V
- Voltage - Clamping (Max) @ Ipp:
- 304V
- Current - Peak Pulse (10/1000µs):
- 1A
- 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)
SMAJ170H FAQ
1.How can I place an order for SMAJ170H through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ170H 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 SMAJ170H reliable?
The price and inventory of SMAJ170H are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ170H is usually 5 days.
3.What payment methods are accepted for SMAJ170H?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ170H transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ170H?
SMAJ170H orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ170H 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 SMAJ170H?
For technical support, including SMAJ170H datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ170H requirements.
6.How does Aetrix verify that SMAJ170H is sourced from the original manufacturer or authorized distributors?
All SMAJ170H 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 SMAJ170H meets industry standards.
7.What is the process for return or replacement of SMAJ170H?
All SMAJ170H units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ170H, 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 SMAJ170H part is unused and in its original packaging.
Return procedure for SMAJ170H:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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