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Taiwan Semiconductor Corporation SMAJ70CH
- Part No.:
- SMAJ70CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ70CH.pdf
- Description:
- TVS DIODE 70VWM 125VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:6,812
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Product details
Overview
SMAJ70CH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 70V working stand-off voltage (VWM), 77.8–95.1V breakdown voltage (VBR), and 125V maximum clamping voltage (VC) at 3.2A peak impulse current. It delivers AEC-Q101 qualification and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive power line protection.
For engineers reviewing the SMAJ70CH datasheet, SMAJ70CH pinout, SMAJ70CH application, or SMAJ70CH equivalent, key selection criteria include clamping performance under 10/1000μs surge, unidirectional polarity marking, DO-214AC thermal derating above 25°C, and compliance with automotive EMC transients and J-STD-020 moisture sensitivity level 1.
Technical Context
The SMAJ70CH operates as a unidirectional avalanche diode, activated only when reverse voltage exceeds VBR (min 77.8V), providing low-impedance shunt path to ground during ESD or load-dump events. Its glass-passivated junction ensures stable breakdown and <1.0ps response time from 0V to VBR min.
Designed for single-die configuration in DO-214AC, it supports steady-state power dissipation of 1W and peak pulse power of 400W (10/1000μs), derated linearly above TA = 25°C per Fig.2. Maximum junction temperature is 150°C, with operating range from –55°C to +150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 70 V - Maximum continuous reverse voltage before clamping begins; defines system operating margin |
| VBR @ IT=1mA | 77.8–95.1 V - Breakdown threshold range; ensures reliable turn-on within spec across process variation |
| VC @ IPPM=3.2A | 125 V - Clamped voltage during 10/1000μs surge; limits downstream IC stress to safe level |
| PPPM | 400 W - Peak pulse power handling (10/1000μs); supports automotive load-dump immunity |
| IR @ VWM | 1 μA - Reverse leakage at 70V; negligible power loss in standby, critical for battery-coupled systems |
| Package | DO-214AC (SMA) - Standardized surface-mount outline; compatible with automated placement and reflow |
| Polarity | Cathode band marked - Unidirectional conduction; requires correct orientation in PCB layout |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, UL 94V-0 rated, weight ≈0.060g. Cathode band denotes terminal 1 (cathode); terminal 2 is anode. Polarity must be observed for unidirectional operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to protected line; conducts surge current to ground when reverse-biased beyond VBR |
| 2 | Anode | Connected to system ground; completes low-impedance path during transient event |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualified | Validated for automotive underhood applications including temperature cycling, humidity, and mechanical shock |
| Glass passivated junction | Enhances long-term reliability and stability of VBR over lifetime and environmental stress |
| Fast response time <1.0ps | Clamps ESD and fast transients before sensitive downstream circuitry is damaged |
| Meets ISO 7637-2 Pulse 1/2a/2b/3a/3b | Complies with automotive standard for conducted transients on 12V/24V supply lines |
| J-STD-020 Level 1 moisture sensitivity | Zero bake requirement prior to reflow; simplifies SMT manufacturing flow |
Applications
| Automotive Power Line Protection | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protecting microcontroller power rails in engine control units (ECUs) against load dump (ISO 7637-2 Pulse 5a) and alternator switching transients. IC Role / Device Role / Timing Role: Unidirectional TVS placed between battery rail and input filter capacitor; clamps surges within nanoseconds. Use Value: Limits voltage seen by LDOs and MCUs to ≤125V, preventing latch-up or gate oxide damage during 12V system transients. | Use Scenario: Safeguarding isolated DC/DC converter primary-side inputs in factory automation controllers exposed to inductive kickback. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing repetitive 400W pulses without degradation; placed upstream of input EMI filter. Use Value: Enables robust operation under 10/1000μs surges up to 3.2A while maintaining <1μA leakage at 70V standby. |
| LED Driver Supply Protection | Telecom Power Adapter Interface |
Use Scenario: Shielding constant-current LED driver ICs in automotive lighting modules from battery reversal and jump-start spikes. IC Role / Device Role / Timing Role: Unidirectional clamp referenced to chassis ground; cathode tied to +12V supply line. Use Value: Withstands 150°C junction temperature and maintains clamping integrity after repeated 125V/3.2A events. | Use Scenario: Front-end surge suppression in wall-mounted telecom adapters subjected to AC line transients and EFT bursts. IC Role / Device Role / Timing Role: Secondary-side TVS on DC output rail; absorbs coupled noise from primary-side switching and external surges. Use Value: Delivers 400W peak power rating with 1μA IR at 70V, minimizing standby power loss in energy-efficient designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ70A | Lower VBR range (77.8–86.0V) and higher clamping voltage (113V at 3.5A); same DO-214AC package | Optimized for tighter clamping tolerance where lower VC is prioritized over wider VBR margin | Select SMAJ70A if design requires lower VC under identical IPPM, accepting reduced VBR spread |
| SMBJ70A | Same VWM/VBR specs but in larger DO-214AA (SMB) package; 600W peak power rating | Used where higher surge energy absorption or improved thermal dissipation is required | Choose SMBJ70A for industrial applications needing >400W headroom or extended thermal time constants |
Compared with SMAJ70CH, SMAJ70A offers lower clamping voltage at slightly reduced VBR consistency, while SMBJ70A provides higher pulse power and thermal mass in a physically larger footprint-neither is pin-compatible, requiring PCB layout revision.
Availability
SMAJ70CH is available at Aetrix Electronics and suitable for automotive electronics, industrial DC/DC converters, LED lighting systems, and telecom power adapters requiring stable component supply and AEC-Q101-compliant surge protection.
Supply support for SMAJ70CH 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 MOSFETs, with global distribution and AEC-Q certified production lines.
The SMAJ series is designed specifically for high-reliability transient suppression in automotive and industrial power systems, emphasizing fast response, stable clamping, and robust packaging for automated assembly.
FAQ
What is the polarity configuration of SMAJ70CH?
SMAJ70CH is a unidirectional TVS diode with cathode indicated by a banded end (Pin 1). It conducts only when reverse-biased beyond its breakdown voltage (77.8–95.1V), making it suitable for DC line protection where polarity is fixed. The band must align with the protected line in PCB layout to ensure proper clamping behavior during transients.
Does SMAJ70CH meet automotive qualification standards?
Yes, SMAJ70CH is AEC-Q101 qualified and explicitly tested to meet ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b for automotive conducted transients. Its DO-214AC package complies with J-STD-020 moisture sensitivity level 1, eliminating bake requirements before reflow soldering in automotive manufacturing environments.
What is the maximum clamping voltage of SMAJ70CH and at what test condition?
The maximum clamping voltage (VC) of SMAJ70CH is 125 V, measured at a peak impulse current (IPPM) of 3.2 A using the standardized 10/1000 μs double-exponential waveform. This value ensures downstream components see no more than 125 V during worst-case surge events, supporting robust design margins in 12V and 24V automotive systems.
How does SMAJ70CH differ from SMAJ70AH?
SMAJ70CH has a VBR range of 77.8–95.1 V and clamps at 125 V (3.2 A), while SMAJ70AH specifies VBR of 77.8–86.0 V and clamps at 113 V (3.5 A). SMAJ70CH offers wider breakdown tolerance and higher clamping voltage, whereas SMAJ70AH provides tighter VBR control and lower VC-both share identical VWM (70 V), package (DO-214AC), and AEC-Q101 qualification.
Can SMAJ70CH be used in bidirectional applications?
No, SMAJ70CH is unidirectional only. For bidirectional surge protection, Taiwan Semiconductor specifies parts with "CAH" or "CH" suffixes (e.g., SMAJ70CAH), which feature symmetrical breakdown in both directions. Using SMAJ70CH in AC or reversible-polarity circuits will result in forward conduction during one half-cycle and no protection during the other.
SMAJ70CH 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):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 125V
- Current - Peak Pulse (10/1000µs):
- 3.2A
- 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)
SMAJ70CH FAQ
1.How can I place an order for SMAJ70CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ70CH 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 SMAJ70CH reliable?
The price and inventory of SMAJ70CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ70CH is usually 5 days.
3.What payment methods are accepted for SMAJ70CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ70CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ70CH?
SMAJ70CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ70CH 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 SMAJ70CH?
For technical support, including SMAJ70CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ70CH requirements.
6.How does Aetrix verify that SMAJ70CH is sourced from the original manufacturer or authorized distributors?
All SMAJ70CH 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 SMAJ70CH meets industry standards.
7.What is the process for return or replacement of SMAJ70CH?
All SMAJ70CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ70CH, 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 SMAJ70CH part is unused and in its original packaging.
Return procedure for SMAJ70CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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