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Taiwan Semiconductor Corporation SMAJ51C
- Part No.:
- SMAJ51C
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51C.pdf
- Description:
- 400W, 63V, 10%, BIDIRECTIONAL, T
- Quantity:
- Payment:
- Shipping:
Inventory:2,308
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Product details
Overview
SMAJ51C from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, with 51V working stand-off voltage (VWM), 56.7–69.3V breakdown voltage (VBR @ 1mA), and 91.1V maximum clamping voltage (VC) at 4.4A peak pulse current. It delivers fast response (<1.0ps), low leakage (<1µA @ 51V), and meets ISO 7637-2 Pulse 1/2a/2b/3a/3b for automotive electronics protection.
For engineers reviewing the SMAJ51C datasheet, SMAJ51C pinout, SMAJ51C application, or SMAJ51C equivalent, key selection considerations include clamping performance under 10/1000µs surge, unidirectional polarity marking, DO-214AC thermal derating above 25°C, and compliance with JESD201 Class 2 whisker resistance and UL 94V-0 molding compound.
Technical Context
The SMAJ51C operates as a unidirectional avalanche diode, conducting only when reverse voltage exceeds VBR to clamp transients toward VC while limiting energy dissipation via its 400W (10/1000µs) peak pulse rating. Its glass-passivated junction ensures stable breakdown and low leakage across -55°C to +150°C operating range.
Designed for single-die configuration in DO-214AC, it features matte tin-plated leads solderable per J-STD-002, polarity marked by cathode band, and moisture sensitivity level 1 per J-STD-020 - enabling robust automated placement without baking requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before clamping begins; defines system-level DC bus tolerance margin. |
| VBR min/max | 56.7 V / 69.3 V @ 1 mA - Validated avalanche onset range; ensures reliable turn-on within specified tolerance under production test conditions. |
| VC @ IPPM | 91.1 V @ 4.4 A - Clamped voltage during 10/1000µs surge; determines worst-case overvoltage stress on downstream ICs. |
| PPPM | 400 W (10/1000µs) - Peak transient power handling; supports IEC 61000-4-5 Level 4 surge immunity design. |
| IR @ VWM | <1 µA - Reverse leakage at rated stand-off; negligible power loss and signal integrity impact in high-impedance circuits. |
| TJ max | +150 °C - Maximum junction temperature; enables operation in under-hood automotive or enclosed industrial environments. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with 0.060g mass; compatible with reflow profiles per J-STD-020 Level 1. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with axial leadframe, cathode indicated by band-marked end. Leads are matte tin-plated, compliant with J-STD-002 solderability and JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential side (e.g., ground or return path); conducts during positive surges in bidirectional configurations (not applicable to SMAJ51C). |
| Cathode | Reverse-biased clamping terminal | Connected to protected line (e.g., 51V rail); avalanches into conduction when reverse voltage exceeds VBR, shunting surge current to ground. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR over temperature and lifetime; eliminates parameter drift due to surface contamination or humidity ingress. |
| Clamping response time <1.0 ps | Protects sensitive logic and analog inputs before transient energy couples into IC substrate or I/O structures. |
| ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance | Validated for automotive ECU, infotainment, and body control module designs requiring OEM-level EMC robustness. |
| RoHS & halogen-free (IEC 61249-2-21) | Meets global environmental regulations without compromising thermal or electrical performance in high-reliability assemblies. |
| Moisture sensitivity level 1 | Eliminates pre-bake requirement prior to reflow; reduces manufacturing cycle time and avoids thermal stress on PCB substrates. |
Applications
| Automotive Power Distribution | Industrial DC/DC Converter Input |
|---|---|
Use Scenario: Protection of 48V battery-fed power distribution modules against load dump and alternator ripple. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input rail and chassis ground to clamp ISO 7637-2 Pulse 5a surges up to 100V. Use Value: Limits clamped voltage to 91.1V at 4.4A, preventing damage to upstream MOSFET drivers and monitoring ICs operating at 51V nominal. |
Use Scenario: Input-side surge suppression for isolated 24V-to-5V DC/DC converters in programmable logic controllers. IC Role / Device Role / Timing Role: Standoff-rated TVS absorbing 10/1000µs transients induced by relay switching or inductive load disconnection. Use Value: Maintains VWM = 51V margin above 48V max input, ensuring no false triggering while delivering 400W peak power dissipation capability. |
| LED Driver Power Stage | Telecom Power Interface |
Use Scenario: Overvoltage protection for constant-current LED driver ICs powered from 48V telecom-grade supplies. IC Role / Device Role / Timing Role: Unidirectional clamping device connected between LED string anode and supply rail to absorb inductive kickback. Use Value: Low IR (<1µA) prevents standby current drain; 91.1V VC ensures LED controller ICs with 60V ABSMAX remain within safe operating area. |
Use Scenario: Front-end protection of PoE-powered equipment receiving 57V DC over Ethernet cabling. IC Role / Device Role / Timing Role: Primary surge limiter on PSE-side interface, coordinated with secondary TVS and common-mode chokes. Use Value: DO-214AC footprint allows compact layout near RJ45 connector; UL 94V-0 compound meets IPC-7351B flammability requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51A | Lower VBR range (56.7–62.7V), tighter tolerance; same VWM (51V), lower VC (82.4V @ 4.9A). | Better clamping ratio (VC/VBR ≈ 1.31 vs. 1.38), suited for systems requiring stricter overvoltage margins. | Select SMAJ51A when clamping voltage headroom is critical and tighter VBR consistency improves yield in high-volume production. |
| SMBJ51A | Same VWM/VBR/VC specs but in larger DO-214AA (SMB) package; higher PPPM (600W @ 10/1000µs). | Higher thermal mass supports repeated surge events; requires larger PCB footprint and different pad layout. | Choose SMBJ51A for applications with frequent transients or elevated ambient temperatures where DO-214AC thermal limits may be exceeded. |
Compared with SMAJ51C, SMAJ51A offers improved clamping precision at the cost of slightly reduced surge current capacity, while SMBJ51A trades board space for greater thermal resilience and peak power handling - making SMAJ51C optimal for space-constrained, single-event surge scenarios in automotive and industrial power rails.
Availability
SMAJ51C is available at Aetrix Electronics and suitable for automotive power distribution, industrial DC/DC converter input stages, LED driver protection, telecom power interfaces, and PoE-powered equipment requiring stable component supply with full traceability and lifecycle management.
Supply support for SMAJ51C 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 components.
The SMAJ series was developed for high-reliability transient suppression in automotive and industrial environments, emphasizing ISO 7637-2 compliance, tight parametric tolerances, and automated assembly compatibility.
FAQ
What is the polarity configuration of the SMAJ51C?
The SMAJ51C is a unidirectional TVS diode, with cathode identified by a band-marked end. It conducts only when reverse voltage exceeds its breakdown threshold, making it suitable for DC rail protection where polarity is fixed. This differs from bidirectional variants (e.g., SMAJ51CA), which suppress surges in both directions without regard to polarity.
Does the SMAJ51C meet automotive EMC standards?
Yes, the SMAJ51C meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b requirements for transient immunity in 12V and 24V automotive systems. Its 400W peak pulse power rating and verified clamping behavior under standardized waveforms make it appropriate for ECU, body control, and lighting module designs per OEM specifications.
What is the maximum clamping voltage of the SMAJ51C and at what current is it specified?
The SMAJ51C has a maximum clamping voltage (VC) of 91.1 V, measured at a peak pulse current (IPPM) of 4.4 A under the standard 10/1000 µs waveform. This value represents the worst-case voltage seen by downstream circuitry during a surge event and is guaranteed across the full operating temperature range.
Can the SMAJ51C be used in bidirectional signal lines?
No - the SMAJ51C is unidirectional and must be oriented with cathode toward the protected line. For bidirectional data or AC-coupled signal lines, a bidirectional variant such as SMAJ51CA (with "C" or "CA" suffix) is required. Using SMAJ51C on bidirectional paths risks forward conduction during normal operation or incomplete protection during negative transients.
What is the thermal derating behavior of the SMAJ51C above 25°C ambient?
The SMAJ51C's peak pulse power rating derates linearly above TA = 25°C, per Figure 2 in the official datasheet. At 85°C ambient, its 400W rating reduces to approximately 260W; at 125°C, it falls to ~140W. Designers must apply this derating curve when sizing for high-temperature enclosures or under-hood automotive locations.
SMAJ51C 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:
- 91.1V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ51C FAQ
1.How can I place an order for SMAJ51C through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51C 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 SMAJ51C reliable?
The price and inventory of SMAJ51C are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51C is usually 5 days.
3.What payment methods are accepted for SMAJ51C?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51C transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51C?
SMAJ51C orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51C 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 SMAJ51C?
For technical support, including SMAJ51C datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51C requirements.
6.How does Aetrix verify that SMAJ51C is sourced from the original manufacturer or authorized distributors?
All SMAJ51C 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 SMAJ51C meets industry standards.
7.What is the process for return or replacement of SMAJ51C?
All SMAJ51C units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51C, 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 SMAJ51C part is unused and in its original packaging.
Return procedure for SMAJ51C:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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