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onsemi SA51A
- Part No.:
- SA51A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA51A.pdf
- Description:
- TVS DIODE 51VWM 82.4VC AXIAL
- Quantity:
- Payment:
- Shipping:
Inventory:3,600
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Product details
Overview
SA51A from onsemi is a unidirectional 500 W peak power MiniMOSORB Zener transient voltage suppressor (TVS) designed for clamping high-energy transients in DC power lines and signal paths. It features a 51 V working peak reverse voltage (VRWM), 62.7 V maximum breakdown voltage (VBR) at 1 mA, 82.4 V clamping voltage (VC) at 6.1 A peak pulse current (IPP), and sub-1 ns response time. It is used in industrial power supplies and medical equipment input protection.
For engineers reviewing the SA51A datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ system operating voltage, VC margin relative to protected IC absolute maximum ratings, UL 497B certification for isolated loop circuits, and axial leaded Surmetic package compatibility with through-hole PCB layouts.
Technical Context
The SA51A operates as a unidirectional Zener-based TVS diode, conducting only during reverse overvoltage events above its breakdown threshold while remaining high-impedance under normal bias. Its low zener impedance and fast <1.0 ns response enable effective suppression of ESD and lightning-induced surges per IEC 61000-4-2/4-5.
It is rated for 500 W nonrepetitive peak pulse power (1 ms), 3.0 W steady-state dissipation at 75°C lead temperature, and supports surge currents up to 6.1 A (IPP) with clamping limited to 82.4 V. Thermal resistance from junction-to-lead is 33.3°C/W, enabling reliable operation in convection-cooled industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 51 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's max DC or peak AC voltage. |
| VBR (min/typ/max) | 56.7 / 59.7 / 62.7 V @ 1 mA - Confirmed Zener breakdown range; defines turn-on threshold consistency across production lots. |
| VC @ IPP | 82.4 V @ 6.1 A - Clamped voltage during 1 ms surge; determines maximum stress imposed on downstream components. |
| Peak Power | 500 W @ 1 ms - Energy-handling capability for single-event transients; derates to 3.0 W continuous at TL = 75°C. |
| Response Time | <1.0 ns - Enables suppression of fast-rising ESD pulses before sensitive circuitry is damaged. |
| Leakage Current | <1 μA @ VRWM - Negligible standby power loss and minimal impact on high-impedance sensing nodes. |
| UL Recognition | UL 497B (QVGV2) - Certified for isolated loop circuit protection; validates performance in telecom and medical isolation barriers. |
Pinout & Package
SA51A is housed in an axial-leaded Surmetic plastic package (Case 59AA), with cathode identified by a polarity band. Leads are tin-plated, solderable at 260°C for 10 seconds at 1/16″ from case. Mounting position is unrestricted.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Reference terminal for forward conduction path | Connected to lower-potential side (e.g., GND or return) in unidirectional clamp configuration. |
| Cathode | Zener junction output terminal | Connected to protected line; conducts reverse current when voltage exceeds VRWM, shunting surge to ground. |
Key Features
| Feature | Design Value |
|---|---|
| 500 W peak pulse rating | Supports robust protection against IEC 61000-4-5 Level 4 surges (4 kV/2 Ω) on 24–48 V DC rails without derating. |
| UL 497B recognition | Validates compliance for use in safety-critical isolated interfaces (e.g., RS-485, CAN bus front-ends) in medical and industrial systems. |
| ESD rating >16 kV HBM | Meets or exceeds IEC 61000-4-2 Level 4 (15 kV air/8 kV contact) without external series impedance. |
| Low zener impedance | Ensures stable clamping voltage across varying surge current magnitudes-critical for protecting fixed-threshold ICs like microcontrollers. |
| Pb-Free Surmetic package | RoHS-compliant axial lead construction with corrosion-resistant finish and verified solderability per J-STD-020. |
Applications
| Industrial Power Supply Input Protection | Medical Equipment Isolated Interface Protection |
|---|---|
Use Scenario: 48 V DC input stage of programmable logic controller (PLC) power module exposed to load dump and inductive switching transients. IC Role / Device Role: Unidirectional TVS diode placed between input rail and chassis ground to clamp positive-going surges. Use Value: Limits transient voltage to ≤82.4 V, preserving integrity of upstream rectifier and downstream DC-DC controller rated for 100 V abs max. |
Use Scenario: RS-485 data line crossing isolation barrier in patient-monitoring device, requiring UL 497B-certified protection. IC Role / Device Role: Primary surge clamp on isolated bus side, coordinated with secondary-side TVS and common-mode chokes. Use Value: UL 497B validation ensures compliance with IEC 60601-1 creepage/clearance and fault-current withstand requirements. |
| Process Control Sensor Signal Conditioning | Business Machine AC/DC Adapter Output Protection |
Use Scenario: 24 V analog sensor supply line in factory automation system subject to cable discharge and relay bounce. IC Role / Device Role: Localized TVS at sensor connector to suppress sub-100 ns transients before reaching precision ADC reference buffer. Use Value: Sub-1 ns response prevents latch-up in op-amps and maintains ±0.1% measurement accuracy during EMC testing. |
Use Scenario: +12 V output rail of wall-mounted AC/DC adapter powering point-of-sale terminals. IC Role / Device Role: Final-stage overvoltage clamp before USB-C PD negotiation circuitry and microcontroller power domain. Use Value: 51 V VRWM provides 100% margin over nominal 12 V output while allowing safe tolerance stack-up and ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ51A | Same VRWM (51 V) and VC (82.4 V), but SMA surface-mount package (vs. axial leaded); 400 W peak power rating. | Requires SMT reflow process and board space optimization; unsuitable for manual repair or high-vibration through-hole mounting. | Select SMAJ51A only when board area constraints prohibit axial components and thermal management supports lower peak power. |
| 1.5KE51A | Higher peak power (1500 W), same VRWM (51 V), but larger DO-201 package; 84 V clamping voltage at 18.3 A IPP. | Better suited for high-energy utility-grade surges; less precise clamping margin due to higher VC and slower response (~1.5 ns). | Choose 1.5KE51A where surge energy exceeds 500 W capability-e.g., outdoor telecom cabinets-but verify VC margin with protected IC specs. |
Compared with SMAJ51A and 1.5KE51A, the SA51A offers optimal balance of axial-mount reliability, UL 497B certification, and tight clamping control for mid-energy industrial transients-making it preferred for medical and certified industrial designs where traceability and safety compliance are mandatory.
Availability
SA51A is available at Aetrix Electronics and suitable for industrial power supply input protection, medical equipment isolated interface protection, and process control sensor signal conditioning requiring stable component supply and long-term lifecycle support.
Supply support for SA51A 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
onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The SA51A belongs to the MiniMOSORB TVS diode family, engineered specifically for high-reliability transient suppression in safety-critical and regulated applications-including UL 497B-certified isolated loops and medical-grade power systems.
FAQ
What is the maximum clamping voltage of the SA51A under surge conditions?
The SA51A exhibits a maximum clamping voltage (VC) of 82.4 V when subjected to its rated peak pulse current (IPP) of 6.1 A with a 1 ms waveform. This value is measured per Figure 4 in the official datasheet and represents the upper limit of voltage seen by downstream circuitry during worst-case transient events. Designers must ensure this clamping level remains below the absolute maximum ratings of protected components. The SA51A consistently delivers this VC across production lots under standardized test conditions.
Does the SA51A meet UL 497B certification, and what does that cover?
Yes, the SA51A is UL 497B recognized (File #E116110, category QVGV2) for isolated loop circuit protection. This certification verifies successful completion of strike voltage breakdown, endurance conditioning, dielectric withstand, and discharge tests-specifically validating its suitability in safety-isolated interfaces such as medical equipment data ports and industrial fieldbus systems. UL 497B coverage applies across the full SA5.0A–SA170A series, including the SA51A.
What is the thermal resistance and steady-state power rating of the SA51A?
The SA51A has a junction-to-lead thermal resistance (RJL) of 33.3°C/W and a steady-state power dissipation (PD) of 3.0 W at a lead temperature (TL) of 75°C, derating linearly above that temperature. This enables reliable operation in convection-cooled industrial enclosures without forced airflow. The SA51A's axial Surmetic package facilitates direct heat transfer from the die to PCB copper or chassis via leads-critical for maintaining long-term reliability in thermally demanding applications.
How does the SA51A compare to bidirectional TVS diodes in terms of application scope?
The SA51A is unidirectional and optimized for DC power line and single-polarity signal protection-e.g., 24 V PLC inputs or RS-485 bus lines referenced to ground. Unlike bidirectional variants (e.g., SA51CA), it does not suppress negative-going transients. Its design avoids leakage current in forward bias, making it preferable for circuits where forward conduction could disrupt bias networks. The SA51A should not be substituted for bidirectional types without verifying system-level polarity behavior and surge directionality.
Is the SA51A RoHS compliant and compatible with standard soldering processes?
Yes, the SA51A is supplied in a Pb-Free Surmetic axial package (indicated by the "G" suffix) and complies with RoHS Directive 2011/65/EU. Its leads are tin-plated and rated for soldering at 260°C for 10 seconds at 1/16″ from the case body, fully aligned with IPC-J-STD-020 moisture sensitivity and reflow guidelines. The SA51A's void-free thermosetting plastic encapsulation ensures mechanical robustness and corrosion resistance in humid or chemically aggressive industrial environments.
SA51A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- MiniMosorb™
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 51V
- Voltage - Breakdown (Min):
- 56.7V
- Voltage - Clamping (Max) @ Ipp:
- 82.4V
- Current - Peak Pulse (10/1000µs):
- 6.1A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- Axial
SA51A FAQ
1.How can I place an order for SA51A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA51A 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 SA51A reliable?
The price and inventory of SA51A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA51A is usually 5 days.
3.What payment methods are accepted for SA51A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA51A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA51A?
SA51A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA51A 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 SA51A?
For technical support, including SA51A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA51A requirements.
6.How does Aetrix verify that SA51A is sourced from the original manufacturer or authorized distributors?
All SA51A 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 SA51A meets industry standards.
7.What is the process for return or replacement of SA51A?
All SA51A units undergo pre-shipment inspection (PSI). If there is an issue with SA51A, 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 SA51A part is unused and in its original packaging.
Return procedure for SA51A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA51A Tags
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ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
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ESD5Z3.3T1G
onsemi
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D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
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DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
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D5V0L1B2WS-7
Diodes Incorporated
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