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onsemi 1SMA51CAT3G
- Part No.:
- 1SMA51CAT3G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- -
- Datasheet:
-
1SMA51CAT3G.pdf
- Description:
- TRANS VOLTAGE SUPPRESSOR DIODE
- Quantity:
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Inventory:4,165
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Product details
Overview
1SMA51CAT3G from ON Semiconductor is a bidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power rails and signal lines. It features a 51 V working peak reverse voltage (VRWM), 82.4 V clamping voltage at 4.9 A peak pulse current, 130 pF junction capacitance at 0 V bias, and sub-1 ns response time. It is used in automotive power supply protection, industrial PLC I/O modules, and medical equipment surge interfaces.
For engineers reviewing the 1SMA51CAT3G datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to IC absolute maximum ratings, IPP capability under IEC 61000-4-5 waveforms, and low-junction-capacitance suitability for data-line protection.
Technical Context
The 1SMA51CAT3G operates as a bidirectional avalanche diode, leveraging Zener breakdown in both polarities to clamp transient overvoltages symmetrically. Its 56.7–62.67 V breakdown range (at 1 mA) ensures robust turn-on behavior across temperature and process variation, while its 82.4 V clamping voltage at 4.9 A defines the maximum voltage seen by downstream circuitry during a 10/1000 µs surge event.
Thermal design relies on a 250 °C/W junction-to-ambient thermal resistance (RJA) and 50 °C/W junction-to-lead (RJL), with derating applied above 25 °C ambient or 75 °C lead temperature. The device meets Class 3 ESD immunity (>16 kV HBM) and is qualified to AEC-Q101 for automotive use when ordered as SZ1SMA51CAT3G.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 51 V - Maximum continuous reverse operating voltage before clamping begins; must exceed system DC rail or signal swing. |
| VBR @ IT | 56.7–62.67 V @ 1 mA - Confirmed Zener breakdown range; ensures reliable conduction onset across manufacturing lot and temperature. |
| VC @ IPP | 82.4 V @ 4.9 A - Clamped voltage during 10/1000 µs surge; determines maximum stress on protected IC inputs or power stages. |
| PPK | 400 W @ 1 ms - Peak surge power handling; validates compliance with IEC 61000-4-5 Level 4 (4 kV line-to-ground) testing. |
| CJ | 130 pF @ 0 V - Junction capacitance at zero bias; impacts high-frequency signal integrity in data-line applications (e.g., CAN, RS-485). |
| Response Time | <1 ns - Time from transient onset to clamping activation; critical for protecting fast logic and analog front-ends. |
| ESD Rating | >16 kV HBM - Human Body Model rating; qualifies for direct interface with user-accessible ports in consumer/industrial equipment. |
Pinout & Package
1SMA51CAT3G uses the SMA (DO-214AC) surface-mount package (Case 403D-02), measuring 4.57 mm × 2.60 mm × 2.20 mm (L × W × H), with flat handling surface and cathode polarity notch. Mounting position is unrestricted; compatible with top-slide or bottom-board placement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry terminal during positive transient | Connects to protected node; forms symmetrical clamping path with cathode during bidirectional surges. |
| Cathode | Current entry terminal during negative transient | Marked by notch; ties to ground or reference plane; completes low-impedance return path for surge current. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Protects AC-coupled or floating signal lines (e.g., RS-232, audio, sensor bridges) without polarity constraints. |
| 400 W peak power rating | Sustains IEC 61000-4-5 4 kV surge events on 50 Ω source impedance without degradation or failure. |
| Low zener impedance | Ensures stable clamping voltage under varying surge current; minimizes overshoot beyond VC. |
| AEC-Q101 qualification (SZ variant) | Validated for automotive under-hood and infotainment power rail protection with extended temperature and reliability testing. |
| Pb-free SURMETIC™ package | RoHS-compliant molding compound with corrosion-resistant finish and solderability verified per J-STD-020. |
Applications
| Automotive Power Rail Protection | Industrial PLC Analog Input Protection |
|---|---|
Use Scenario: Suppresses load-dump transients (up to 120 V, 400 ms) on 12 V battery-fed ECUs and body control modules. IC Role / Device Role: Primary overvoltage clamp placed between power input and DC-DC converter input stage. Use Value: Limits voltage to ≤82.4 V during surge, preventing damage to 60 V-rated MOSFETs and LDOs downstream of the TVS. |
Use Scenario: Shields 4–20 mA current-loop receiver inputs from field-wiring induced surges in factory automation cabinets. IC Role / Device Role: Bidirectional shunt protector mounted directly at terminal block entry point. Use Value: Maintains signal integrity below 130 pF capacitance while clamping ±1 kV EFT bursts to safe levels for precision op-amps. |
| Medical Equipment ESD Interface | Telecom Line Card Surge Suppression |
Use Scenario: Guards USB and serial debug ports on patient monitors against hospital-grade ESD events (>15 kV contact discharge). IC Role / Device Role: First-stage transient suppressor before EMI filter and level-shifter ICs. Use Value: Delivers >16 kV HBM immunity without adding series resistance or distorting low-speed digital signals. |
Use Scenario: Protects Ethernet PHY and PoE controller inputs on network edge switches exposed to lightning-induced surges on RJ45 lines. IC Role / Device Role: Secondary clamping device after gas discharge tube (GDT) primary protection. Use Value: Provides fast <1 ns response to truncate residual transients that bypass slower GDTs, limiting voltage to 82.4 V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SZ1SMA51CAT3G | AEC-Q101 qualified; identical electrical specs but with automotive-specific traceability, PPAP documentation, and site-controlled manufacturing. | Required for automotive OEM BOMs; supports ASIL-B functional safety architectures via documented process controls. | Select when automotive qualification, change control, or PPAP submission is mandated. |
| 1.5SMC51A | Higher 1500 W peak power rating; larger SMC (DO-214AB) package; 84.5 V clamping at 17.5 A; 120 pF capacitance. | Better suited for higher-energy surges (e.g., 10/1000 µs, 6 kV); less suitable for space-constrained PCBs due to 7.11 mm × 6.22 mm footprint. | Choose for industrial mains-connected equipment where 400 W is insufficient and board area permits larger package. |
Compared with 1SMA51CAT3G, SZ1SMA51CAT3G adds automotive compliance without electrical trade-offs, while 1.5SMC51A trades compact size for higher surge capacity-making the 1SMA51CAT3G optimal for cost-sensitive, space-limited 51 V rail protection where 400 W suffices.
Availability
1SMA51CAT3G is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC analog input circuits, and medical equipment ESD interfaces requiring stable component supply, RoHS compliance, and consistent lead-time performance.
Supply support for 1SMA51CAT3G 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
ON Semiconductor (now part of onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.
The 1SMA51CAT3G belongs to the SMA-series transient voltage suppressor family, engineered for cost-effective, high-reliability overvoltage protection in space-constrained surface-mount applications across automotive, industrial, and medical end-equipment.
FAQ
What is the clamping voltage of the 1SMA51CAT3G under standard surge conditions?
The 1SMA51CAT3G exhibits a maximum clamping voltage (VC) of 82.4 V when subjected to its rated peak pulse current (IPP) of 4.9 A, measured using the standardized 10/1000 µs double-exponential surge waveform. This value defines the upper voltage limit imposed on protected circuitry during transient events and is confirmed in the Electrical Characteristics table on page 3 of the official ON Semiconductor datasheet for 1SMA51CAT3G.
Is the 1SMA51CAT3G suitable for bidirectional signal line protection?
Yes, the 1SMA51CAT3G is explicitly designed as a bidirectional TVS diode, enabling symmetrical clamping for AC-coupled or floating nodes such as RS-485 differential pairs, audio lines, or bridge sensor outputs. Its matched Zener characteristics in both polarities ensure consistent protection without requiring external polarity configuration, unlike unidirectional variants in the same 1SMAxxAT3G series.
What package type does the 1SMA51CAT3G use, and what are its key mechanical dimensions?
The 1SMA51CAT3G uses the SMA (DO-214AC) surface-mount package, designated Case 403D-02. Its nominal dimensions are 4.32 mm length × 2.60 mm width × 2.20 mm height, with a 1.45 mm lead width and 0.28 mm lead thickness. The package features a flat handling surface and cathode polarity notch, supporting automated pick-and-place and reflow soldering per J-STD-020 moisture sensitivity level 1.
How does the 1SMA51CAT3G compare to the 1.5SMC51A in terms of surge handling capability?
The 1SMA51CAT3G delivers 400 W peak power dissipation, whereas the 1.5SMC51A handles 1500 W-nearly four times higher-due to its larger SMC (DO-214AB) package and higher IPP rating of 17.5 A. However, the 1.5SMC51A's 84.5 V clamping voltage and 120 pF capacitance differ slightly, and its 7.11 mm × 6.22 mm footprint requires significantly more PCB area than the 1SMA51CAT3G's compact SMA outline.
Does the 1SMA51CAT3G meet automotive qualification standards?
The base 1SMA51CAT3G is not AEC-Q101 qualified; however, its automotive-grade counterpart SZ1SMA51CAT3G shares identical electrical specifications and is fully AEC-Q101 qualified with PPAP capability. The "SZ" prefix denotes automotive-specific process controls, traceability, and extended reliability testing-required for inclusion in automotive OEM BOMs but optional for industrial or medical designs.
1SMA51CAT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- -
- Series:
- *
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- -
- Unidirectional Channels:
- -
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- -
- Voltage - Breakdown (Min):
- -
- Voltage - Clamping (Max) @ Ipp:
- -
- Current - Peak Pulse (10/1000µs):
- -
- Power - Peak Pulse:
- -
- Power Line Protection:
- -
- Applications:
- -
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
1SMA51CAT3G FAQ
1.How can I place an order for 1SMA51CAT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA51CAT3G 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 1SMA51CAT3G reliable?
The price and inventory of 1SMA51CAT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA51CAT3G is usually 5 days.
3.What payment methods are accepted for 1SMA51CAT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA51CAT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA51CAT3G?
1SMA51CAT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA51CAT3G 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 1SMA51CAT3G?
For technical support, including 1SMA51CAT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA51CAT3G requirements.
6.How does Aetrix verify that 1SMA51CAT3G is sourced from the original manufacturer or authorized distributors?
All 1SMA51CAT3G 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 1SMA51CAT3G meets industry standards.
7.What is the process for return or replacement of 1SMA51CAT3G?
All 1SMA51CAT3G units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA51CAT3G, 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 1SMA51CAT3G part is unused and in its original packaging.
Return procedure for 1SMA51CAT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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