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Taiwan Semiconductor Corporation SMAJ51CAH
- Part No.:
- SMAJ51CAH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51CAH.pdf
- Description:
- TVS DIODE 51VWM 82.4VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:7,147
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Product details
Overview
SMAJ51CAH from Taiwan Semiconductor is a bidirectional transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for automotive-grade overvoltage protection. It features a 51 V working stand-off voltage (VWM), 56.7–62.7 V breakdown voltage (VBR), 82.4 V clamping voltage (VC) at 4.9 A peak impulse current, and 400 W peak pulse power (10/1000 µs). It is AEC-Q101 qualified and used in on-board DC/DC converters to protect sensitive power rails.
For engineers reviewing the SMAJ51CAH datasheet, SMAJ51CAH pinout, SMAJ51CAH application, or SMAJ51CAH equivalent, key selection criteria include bidirectional clamping capability, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, moisture sensitivity level 1, and RoHS/halogen-free qualification - all confirmed for this specific variant.
Technical Context
The SMAJ51CAH is a unidirectional/bidirectional TVS diode with glass-passivated junction and fast response time (<1.0 ps from 0 V to VBR min). Its bidirectional configuration (denoted by "CAH" suffix) enables symmetrical clamping in both polarities, supporting robust protection against reverse-polarity transients and double-ended surges without external polarity management.
It operates across –55 °C to +150 °C junction temperature range, with <1 µA maximum reverse leakage at VWM, and meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability requirements. The device is rated for 400 W peak pulse power up to 78 V, derating linearly above 25 °C ambient per Fig.2.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before clamping initiates |
| VBR @ IT = 1 mA | 56.7–62.7 V - Confirmed breakdown threshold ensuring reliable turn-on during overvoltage events |
| VC @ IPPM = 4.9 A | 82.4 V - Clamped voltage limiting downstream circuit stress during 10/1000 µs surge |
| PPPM | 400 W - Peak pulse power handling for standardized automotive transients (ISO 7637-2) |
| IR @ VWM | <1 µA - Minimal leakage preserving efficiency in low-power standby modes |
| Package | DO-214AC (SMA) - Surface-mount footprint compatible with automated placement and IPC-7351B land patterns |
| AEC-Q101 | Qualified - Validated for automotive underhood and powertrain applications per stress test requirements |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, cathode band marking polarity for unidirectional variants; SMAJ51CAH is bidirectional and marked with "CZ" code per datasheet - no cathode band required. Weight: 0.060 g. Moisture sensitivity level: J-STD-020 Level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode / Cathode (bidirectional) | Surge current path terminal | Reversible conduction path - either terminal accepts positive or negative transient energy without polarity constraint |
| Case / Body | Thermal and mechanical reference | Non-electrical; provides thermal dissipation path and mechanical anchoring via soldered leads |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating rails without external diode pairing |
| AEC-Q101 qualification | Validated reliability for automotive power electronics including engine control units and body controllers |
| Fast response time <1.0 ps | Clamps transients before propagation into protected ICs - critical for CAN/LIN bus and MCU I/O lines |
| ISO 7637-2 compliance (Pulse 1/2a/2b/3a/3b) | Meets full suite of automotive load-dump and switching surge immunity requirements |
| Halogen-free & RoHS | Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU for green manufacturing |
Applications
| On-board DC/DC Converter Protection | Automotive Lighting ECU |
|---|---|
Use Scenario: Protecting 12 V input rail of buck converter supplying microcontroller and sensors in ADAS domain controller. IC Role / Device Role / Timing Role: Transient voltage suppressor placed at converter input to clamp load dump and inductive kickback surges. Use Value: Limits voltage excursion to ≤82.4 V during 400 W pulses, preventing MOSFET gate oxide rupture and regulator latch-up. | Use Scenario: Safeguarding LED driver ICs in headlamp modules subjected to battery reversal and jump-start spikes. IC Role / Device Role / Timing Role: Bidirectional TVS absorbing ±100 V transients from faulty jump-start connections or alternator regulation faults. Use Value: Eliminates need for dual unidirectional devices - reduces BOM count and PCB area while maintaining full polarity coverage. |
| Infotainment Power Supply | Body Control Module (BCM) Input Stage |
Use Scenario: Shielding USB-C PD port and audio codec power rails from conducted noise coupled through vehicle harness. IC Role / Device Role / Timing Role: Front-end TVS suppressing fast-rising ESD and RF-induced transients before LDO regulators. Use Value: Sub-1 ps response ensures clamping occurs prior to 15 kV ESD event reaching sensitive analog front-end circuitry. | Use Scenario: Protecting LIN bus transceiver and microcontroller supply pins from battery disconnect transients in door module. IC Role / Device Role / Timing Role: Standoff-rated TVS shunting Pulse 2b (inductive switch-off) energy directly to ground. Use Value: 51 V VWM aligns with 42 V nominal 36 V battery systems, enabling safe operation during normal cranking and cold-cranking conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51CA | Same electrical specs but non-AEC-Q101 qualified; lacks automotive stress validation | Restricted to industrial/commercial use only; not approved for automotive production | Select SMAJ51CAH when AEC-Q101 compliance is mandatory for OEM Tier-1 programs |
| SMBJ51CA | Same VWM/VC but higher PPPM (600 W), larger SMB package (DO-214AA) | Requires PCB layout change; better suited for higher-energy transients in engine bay | Choose SMBJ51CA only if system-level testing confirms >400 W surge margin is required |
Compared with SMAJ51CA and SMBJ51CA, the SMAJ51CAH uniquely delivers AEC-Q101 qualification in the compact DO-214AC footprint - enabling automotive-compliant surge protection without sacrificing board space or requiring redesign.
Availability
SMAJ51CAH is available at Aetrix Electronics and suitable for automotive infotainment systems, body control modules, and on-board DC/DC converters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SMAJ51CAH 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 distribution and AEC-Q101 certification capability.
The SMAJ series was developed specifically for automotive and industrial transient suppression, emphasizing high-reliability packaging, fast clamping, and compliance with ISO 7637-2 and AEC-Q101 standards.
FAQ
What does the "CAH" suffix indicate in SMAJ51CAH?
The "CAH" suffix denotes a bidirectional TVS diode with AEC-Q101 qualification and halogen-free construction. Unlike unidirectional "AH" variants, SMAJ51CAH clamps symmetrically in both polarities - essential for protecting floating or AC-coupled nodes. This is confirmed in the datasheet's "Devices for Bipolar Applications" section and verified by its "CZ" marking code.
Is SMAJ51CAH suitable for ISO 7637-2 Pulse 5a (load dump) protection?
No - SMAJ51CAH is rated for ISO 7637-2 Pulses 1, 2a, 2b, 3a, and 3b only. Pulse 5a (load dump) requires higher energy handling (up to 1000 W) and typically uses specialized load-dump suppressors like TSD or P6SMB series. SMAJ51CAH's 400 W rating and 82.4 V clamping are insufficient for sustained 12 V system load dump events.
What is the maximum clamping voltage of SMAJ51CAH under standard test conditions?
The maximum clamping voltage of SMAJ51CAH is 82.4 V, measured at 4.9 A peak impulse current (IPPM) using a 10/1000 µs waveform. This value is specified in the Electrical Specifications table on page 3 of the Taiwan Semiconductor datasheet (Version A2102) and defines the upper voltage limit imposed on protected circuits during surge events.
Does SMAJ51CAH require a heatsink for continuous operation?
No - SMAJ51CAH is rated for 1 W steady-state power dissipation (PD) at 25 °C ambient and relies on PCB copper pour for thermal management. Its DO-214AC package has sufficient thermal resistance (RθJA ≈ 150 °C/W) for typical transient-only duty cycles. Heatsinking is unnecessary unless operating continuously near PD limit in high-ambient environments (>85 °C).
How does SMAJ51CAH differ from SMAJ51A in terms of polarity and marking?
SMAJ51CAH is bidirectional and marked "CZ"; SMAJ51A is unidirectional and marked "AX". The "C" prefix indicates bidirectional configuration, enabling symmetrical clamping without cathode band orientation constraints. This distinction is explicitly defined in the datasheet's "Devices for Bipolar Applications" note and verified in the Marking Code table.
SMAJ51CAH 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):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 4.9A
- 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)
SMAJ51CAH FAQ
1.How can I place an order for SMAJ51CAH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51CAH 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 SMAJ51CAH reliable?
The price and inventory of SMAJ51CAH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51CAH is usually 5 days.
3.What payment methods are accepted for SMAJ51CAH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51CAH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51CAH?
SMAJ51CAH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51CAH 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 SMAJ51CAH?
For technical support, including SMAJ51CAH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51CAH requirements.
6.How does Aetrix verify that SMAJ51CAH is sourced from the original manufacturer or authorized distributors?
All SMAJ51CAH 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 SMAJ51CAH meets industry standards.
7.What is the process for return or replacement of SMAJ51CAH?
All SMAJ51CAH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51CAH, 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 SMAJ51CAH part is unused and in its original packaging.
Return procedure for SMAJ51CAH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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