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Taiwan Semiconductor Corporation SMAJ51CH
- Part No.:
- SMAJ51CH
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ51CH.pdf
- Description:
- TVS DIODE 51VWM 91.1VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:8,268
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Product details
Overview
SMAJ51CH from Taiwan Semiconductor is a unidirectional 400W surface-mount transient voltage suppressor (TVS) diode designed for automotive-grade overvoltage protection in DC power rails. It features a 51V working stand-off voltage (VWM), 56.7–69.3V breakdown range (VBR), and clamps to ≤91.1V at 4.4A peak impulse current under 10/1000μs waveform - deployed in on-board DC/DC converters and SMPS inputs.
For engineers reviewing the SMAJ51CH datasheet, SMAJ51CH pinout, SMAJ51CH application, or SMAJ51CH equivalent, key selection criteria include AEC-Q101 qualification, ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance, DO-214AC (SMA) package compatibility, and bidirectional variant availability (SMAJ51CAH) for symmetrical surge suppression.
Technical Context
The SMAJ51CH employs a glass-passivated silicon junction optimized for fast transient response (<1.0ps rise time from 0V to VBR(min)) and low leakage (<1μA at VWM). Its unidirectional configuration provides asymmetric clamping with forward conduction capability up to 3.5V at 25A, enabling integration into polarity-sensitive DC supply lines.
Thermal design is constrained by a 150°C maximum junction temperature and 1W steady-state power dissipation, requiring PCB copper area and airflow planning for repetitive surge events. Derating curves confirm 400W peak pulse power only at TA = 25°C, falling to ~300W above 78V VWM per specification note.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 51 V - Maximum continuous reverse operating voltage before clamping initiates; sets minimum system rail margin. |
| VBR @ IT=1mA | 56.7–69.3 V - Breakdown threshold range defining turn-on consistency across production lots. |
| VC @ IPPM=4.4A | ≤91.1 V - Clamped voltage during 10/1000μs surge; determines protected circuit's maximum stress level. |
| PPPM | 400 W - Peak pulse power handling with 10/1000μs waveform; defines single-event energy absorption capacity. |
| IR @ VWM | <1 μA - Reverse leakage at rated stand-off voltage; ensures minimal standby power loss in high-impedance rails. |
| Package | DO-214AC (SMA) - Industry-standard surface-mount outline with cathode band marking; compatible with J-STD-002 soldering. |
| AEC-Q101 | Qualified - Validated for automotive electronics per stress test requirements including temperature cycling and HTRB. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with matte tin-plated leads, polarity indicated by cathode band. Weight ≈ 0.060g. Meets UL 94V-0 flammability rating and JESD201 Class 2 whisker resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current input / Surge return path | Connected to ground or low-side reference; conducts during positive transients when cathode is biased higher. |
| Cathode | Protected line connection / Clamping node | Connected to the rail being protected (e.g., +12V); clamps to VC when overvoltage exceeds VBR. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q101 qualification | Validated for automotive under-hood and infotainment applications with extended temperature cycling and reliability testing. |
| Fast response time | <1.0 ps from 0 V to VBR(min) - Enables suppression of nanosecond-scale ESD and load-dump transients before IC damage occurs. |
| ISO 7637-2 compliance | Meets Pulse 1 (inductive switch-off), Pulse 2a/2b (battery disconnect), and Pulse 3a/3b (capacitive coupling) waveforms. |
| Glass passivated junction | Enhances long-term stability and moisture resistance vs. epoxy-passivated alternatives; supports J-STD-020 MSL Level 1. |
| Low clamping ratio | VC/VBR(min) ≈ 1.61 - Tight voltage margin between breakdown and clamping improves system-level overvoltage margin control. |
Applications
| Automotive On-Board Charger Input | Industrial SMPS DC Bus Protection |
|---|---|
Use Scenario: Protects 48V input stage of bidirectional OBC against ISO 7637-2 load dump pulses up to 120V. IC Role / Device Role / Timing Role: Unidirectional TVS placed between DC+ and chassis ground; clamps transients within 1.0ps to limit bus voltage to ≤91.1V. Use Value: Prevents MOSFET gate oxide rupture and controller latch-up by maintaining <95V stress during 400W surges. |
Use Scenario: Shields primary-side controller ICs in 24V industrial SMPS from switching noise and inductive kickback. IC Role / Device Role / Timing Role: Standoff-rated TVS across bulk capacitor terminals; activates only during >56.7V excursions with sub-ns response. Use Value: Eliminates need for RC snubbers while sustaining <1μA leakage at nominal 24V operation. |
| LED Driver Power Input | Telematics Module Power Rail |
Use Scenario: Safeguards constant-current LED driver ICs in vehicle lighting systems exposed to battery reversal and jump-start spikes. IC Role / Device Role / Timing Role: Unidirectional clamp referenced to ground; blocks reverse polarity up to −51V while clamping positive surges. Use Value: Maintains functional safety without series diode loss, enabling >98% efficiency in 12V headlamp designs. |
Use Scenario: Secures 5V/3.3V power domain of LTE/C-V2X telematics modules against conducted EMI from CAN/LIN buses. IC Role / Device Role / Timing Role: Secondary-stage TVS after DC/DC converter; filters fast-edge transients coupled via shared ground planes. Use Value: Reduces system-level EMC test failures by limiting common-mode voltage overshoot to <91.1V during 10/1000μs bursts. |
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 SMAJ51A | Same DO-214AC package, identical VWM/VBR/VC specs, but not AEC-Q101 qualified. | Limited to commercial/industrial use; unsuitable for automotive OEM programs requiring PPAP documentation. | Select SMAJ51CH when automotive qualification, ISO 7637-2 validation, or traceable lot history is required. |
| ON Semiconductor SMAJ51CA | Bidirectional variant (SMAJ51CA) with symmetric ±51V VWM; same clamping performance but no polarity marking. | Required for AC-coupled or floating-rail protection where polarity reversal must be suppressed in both directions. | Choose SMAJ51CH for unidirectional DC rails with defined ground reference; select SMAJ51CA only if bidirectional clamping is needed. |
Compared with Littelfuse SMAJ51A and ON Semi SMAJ51CA, the SMAJ51CH uniquely combines AEC-Q101 qualification, ISO 7637-2 compliance, and unidirectional clamping in a single DO-214AC device - making it the default choice for automotive power rail protection where regulatory validation and polarity-aware design are mandatory.
Availability
SMAJ51CH is available at Aetrix Electronics and suitable for automotive on-board chargers, industrial SMPS units, LED lighting drivers, and telematics module power rails requiring stable component supply with full AEC-Q101 traceability.
Supply support for SMAJ51CH 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, serving automotive, industrial, and consumer markets since 1979.
The SMAJ series is part of TSC's AEC-Q101-qualified TVS portfolio engineered specifically for automotive power-line surge immunity - emphasizing robustness, tight parametric distribution, and compliance with ISO 7637-2 and JESD22-A114 standards.
FAQ
What is the polarity configuration of SMAJ51CH?
The SMAJ51CH is a unidirectional transient voltage suppressor diode, with cathode marked by a band on the DO-214AC package. It conducts in forward bias (anode-to-cathode) and clamps reverse overvoltages above its breakdown voltage. This configuration is intended for DC power rails with fixed polarity, unlike bidirectional variants such as SMAJ51CAH. The SMAJ51CH datasheet confirms unidirectional operation in the "Devices for Bipolar Applications" section.
Does SMAJ51CH meet automotive qualification standards?
Yes, SMAJ51CH is AEC-Q101 qualified and meets ISO 7637-2 Pulse 1, 2a, 2b, 3a, and 3b test requirements - explicitly stated in the FEATURES section of the official Taiwan Semiconductor datasheet. It also complies with JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1, supporting reflow assembly in automotive production environments.
What is the clamping voltage of SMAJ51CH at its rated peak pulse current?
The SMAJ51CH clamps to a maximum of 91.1 V at its rated peak impulse current of 4.4 A under the standard 10/1000μs waveform. This value is specified in the ELECTRICAL SPECIFICATIONS table for part number SMAJ51H (CY marking code), and applies identically to SMAJ51CH per Taiwan Semiconductor's ordering nomenclature and parameter mapping.
Can SMAJ51CH replace SMAJ51A in an existing design?
SMAJ51CH is mechanically and electrically pin-compatible with SMAJ51A in the DO-214AC package and shares identical VWM, VBR, and VC specifications. However, SMAJ51CH adds AEC-Q101 qualification and ISO 7637-2 validation - making it a drop-in upgrade for automotive applications. For commercial designs without qualification requirements, SMAJ51A remains acceptable, but SMAJ51CH offers broader compliance coverage.
What is the maximum junction temperature rating for SMAJ51CH?
The SMAJ51CH has a maximum junction temperature (TJ(MAX)) of +150°C, as confirmed in the ABSOLUTE MAXIMUM RATINGS table. This rating enables operation in under-hood automotive environments and high-temperature industrial enclosures. Thermal derating begins above TA = 25°C per Figure 2 in the datasheet, requiring appropriate PCB copper area for sustained power dissipation.
SMAJ51CH 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:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q101
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
SMAJ51CH FAQ
1.How can I place an order for SMAJ51CH through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ51CH 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 SMAJ51CH reliable?
The price and inventory of SMAJ51CH are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ51CH is usually 5 days.
3.What payment methods are accepted for SMAJ51CH?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ51CH transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ51CH?
SMAJ51CH orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ51CH 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 SMAJ51CH?
For technical support, including SMAJ51CH datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ51CH requirements.
6.How does Aetrix verify that SMAJ51CH is sourced from the original manufacturer or authorized distributors?
All SMAJ51CH 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 SMAJ51CH meets industry standards.
7.What is the process for return or replacement of SMAJ51CH?
All SMAJ51CH units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ51CH, 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 SMAJ51CH part is unused and in its original packaging.
Return procedure for SMAJ51CH:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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