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onsemi SA70A
- Part No.:
- SA70A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA70A.pdf
- Description:
- TVS DIODE 70VWM 113VC DO15
- Quantity:
- Payment:
- Shipping:
Inventory:9,633
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Product details
Overview
SA70A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode designed for primary-level overvoltage protection in DC power lines and signal interfaces. It features a 70 V reverse stand-off voltage (VRWM), 77.8–86.0 V breakdown voltage (VBR), 113 V clamping voltage at peak pulse current, and low leakage (<1 µA above 10 V). It is used in industrial power supplies to protect downstream regulators and microcontrollers from ESD and lightning-induced surges.
For engineers reviewing the SA70A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping performance under 10/1000 µs surge, junction temperature rating up to +175°C, DO-15 package compatibility, and unidirectional polarity for DC rail protection.
Technical Context
The SA70A operates as a silicon avalanche diode with glass-passivated junction, enabling fast response (<1.0 ps from 0 V to BV) and stable clamping during transient events. Its 500 W peak pulse power rating is defined on the standardized 10/1000 µs waveform per R.E.A., and it maintains low incremental surge resistance for consistent voltage limiting across varying surge magnitudes.
Designed for unidirectional operation, the SA70A uses cathode-band marking on the DO-15 package and exhibits typical reverse leakage of ≤1 µA at VRWM = 70 V. Its thermal design supports 1.0 W steady-state dissipation with 0.375" lead length at TA = 75°C and full operation up to TJ = +175°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 500 W on 10/1000 µs waveform - defines maximum single-event surge energy handling capability |
| Reverse Stand-off Voltage | 70 V - maximum continuous DC or RMS voltage before significant leakage begins |
| Breakdown Voltage | 77.8–86.0 V at 1.0 mA - onset of avalanche conduction; ensures reliable triggering above normal operating voltage |
| Clamping Voltage | 113 V at IPPM - maximum voltage seen by protected circuit during rated surge event |
| Junction Temperature | +175°C - enables use in high-ambient industrial or automotive under-hood environments |
| Package | DO-15 - industry-standard axial-leaded package with cathode band; compatible with through-hole assembly and manual repair |
| Leakage Current | <1 µA at 70 V - negligible standby power loss and minimal impact on high-impedance sensing nodes |
Pinout & Package
SA70A is housed in a DO-15 axial-leaded package with cathode indicated by a color band. The device has two terminals: anode and cathode. Polarity must be observed during PCB layout to ensure correct unidirectional clamping behavior.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point during forward conduction; connected to ground or low-side reference | Provides return path during clamping; must be routed to lowest-impedance ground plane for effective surge shunting |
| Cathode | Protected line connection; marked with color band | Connected to the line being protected (e.g., +12 V rail); clamps to anode when voltage exceeds VRWM |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Enhances long-term reliability and moisture resistance in humid or contaminated environments |
| Fast response time | <1.0 ps from 0 V to breakdown - limits voltage overshoot before protection engages |
| Low incremental surge resistance | Ensures predictable clamping voltage across wide range of surge currents without runaway |
| 500 W peak pulse rating | Supports IEC 61000-4-5 Level 4 (4 kV line-to-line, 2 Ω source impedance) compliance with margin |
| High junction temperature rating | +175°C operation allows placement near heat sources (e.g., power inductors, MOSFETs) without derating |
Applications
| Industrial Power Supply Protection | Automotive Body Control Module |
|---|---|
Use Scenario: Protecting 24 V DC input rails in programmable logic controllers against load dump and ISO 7637-2 transients. IC Role / Device Role / Timing Role: Primary overvoltage clamp placed upstream of DC/DC converters and LDOs. Use Value: Limits transient voltage to ≤113 V, preventing damage to 36 V-rated input stages and ensuring system uptime. | Use Scenario: Safeguarding CAN transceiver power pins against battery line disturbances during ignition and alternator load dump. IC Role / Device Role / Timing Role: Unidirectional TVS on VCC rail feeding isolated CAN interface ICs. Use Value: Clamps 12 V rail surges to safe levels within nanoseconds, preserving signal integrity and avoiding bus reset events. |
| Telecom Remote Power Feeds | Renewable Energy Charge Controllers |
Use Scenario: Protecting PoE-powered remote radios from induced surges on 48 V DC feed lines exposed to outdoor lightning coupling. IC Role / Device Role / Timing Role: First-stage surge suppression before active DC/DC regulation and Ethernet PHY power conditioning. Use Value: Absorbs 500 W pulses without degradation, maintaining >10⁵ surge cycles lifetime per IEC 61000-4-5. | Use Scenario: Shielding solar charge controller inputs from voltage spikes caused by PV array switching or grid fault coupling. IC Role / Device Role / Timing Role: Line-side TVS on MPPT input stage rated for 70–100 V PV string voltages. Use Value: Withstands repeated 70 V+ transients while maintaining <1 µA leakage, minimizing daytime parasitic losses. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ70A | Same VRWM (70 V), same unidirectional DO-214AA package, but lower 600 W peak pulse rating and higher clamping (115 V) | Preferred where board space is constrained and surface-mount assembly is required | Select SMBJ70A only if footprint and reflow compatibility outweigh minor clamping voltage increase |
| P6KE70A | Same VRWM (70 V), DO-15 package, but lower 600 W rating and significantly higher clamping (120 V at same IPPM) | Legacy alternative with wider availability but reduced protection margin | Choose P6KE70A only for cost-sensitive, non-critical applications where 7 V higher clamping is acceptable |
Compared with SMBJ70A and P6KE70A, the SA70A delivers tighter clamping (113 V vs. ≥115 V), superior surge robustness (500 W at lower thermal resistance), and optimized leakage for precision DC systems-making it preferred for industrial and automotive front-end protection where voltage margin is critical.
Availability
SA70A is available at Aetrix Electronics and suitable for industrial power supply protection, automotive body control modules, telecom remote power feeds, and renewable energy charge controllers requiring stable component supply and long-lifecycle support.
Supply support for SA70A 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
Fairchild Semiconductor was a leading designer and manufacturer of high-performance analog and discrete semiconductors, acquired by ON Semiconductor in 2016. Its TVS portfolio emphasized ruggedness, precision clamping, and industrial-grade reliability.
The SAxxA series was developed specifically for primary-level surge protection in harsh-environment DC systems, targeting applications demanding high pulse power, low leakage, and extended temperature operation beyond commercial grade.
FAQ
What is the clamping voltage of the SA70A under maximum rated surge conditions?
The SA70A has a maximum clamping voltage (VC) of 113 V when subjected to its rated peak pulse current (IPPM) on the 10/1000 µs waveform. This value is measured at the specified test current and represents the highest voltage the protected circuit will experience during a full-rated transient event. The SA70A maintains this clamping performance consistently due to its low incremental surge resistance and stable avalanche characteristics.
Is the SA70A suitable for bidirectional signal line protection?
No, the SA70A is a unidirectional TVS diode and is not suitable for bidirectional signal line protection. It contains a cathode band and conducts only when the cathode is positive relative to the anode. For bidirectional protection, Fairchild's SA70CA variant must be used. Using SA70A on AC or differential signal lines risks failure during negative excursions, as it lacks reverse-blocking capability in that configuration.
What is the maximum steady-state power dissipation for the SA70A?
The SA70A is rated for 1.0 W of steady-state power dissipation when mounted with 0.375" lead length at an ambient temperature of 75°C. This rating assumes free-air convection and standard PCB pad geometry. Derating is required above 75°C ambient, following the published steady-state power derating curve in the datasheet. The SA70A is not intended for continuous power dissipation but rather for transient suppression.
Does the SA70A meet IEC 61000-4-5 surge immunity requirements?
Yes, the SA70A's 500 W peak pulse power rating on the 10/1000 µs waveform aligns with IEC 61000-4-5 Level 4 testing (4 kV line-to-line, 2 Ω source impedance), provided it is correctly applied in circuit with appropriate PCB layout and series impedance. Its 113 V clamping voltage ensures protected devices see well-below-destructive stress levels. System-level validation is still required, but the SA70A provides foundational compliance headroom.
How does the SA70A compare to the SA70CA in terms of electrical behavior?
The SA70A is unidirectional with cathode-band marking and clamps only for positive transients on the cathode; the SA70CA is bidirectional and clamps symmetrically for both polarities. Their VRWM, VBR, and VC values are identical in magnitude, but SA70CA applies equally in both directions. SA70A offers lower leakage in DC applications, while SA70CA is mandatory for AC or data-line protection. Both share the same DO-15 package and thermal specs.
SA70A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-204AC, DO-15, Axial
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 70V
- Voltage - Breakdown (Min):
- 77.8V
- Voltage - Clamping (Max) @ Ipp:
- 113V
- Current - Peak Pulse (10/1000µs):
- 4.4A
- Power - Peak Pulse:
- 500W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- DO-15
SA70A FAQ
1.How can I place an order for SA70A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA70A 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 SA70A reliable?
The price and inventory of SA70A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA70A is usually 5 days.
3.What payment methods are accepted for SA70A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA70A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA70A?
SA70A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA70A 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 SA70A?
For technical support, including SA70A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA70A requirements.
6.How does Aetrix verify that SA70A is sourced from the original manufacturer or authorized distributors?
All SA70A 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 SA70A meets industry standards.
7.What is the process for return or replacement of SA70A?
All SA70A units undergo pre-shipment inspection (PSI). If there is an issue with SA70A, 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 SA70A part is unused and in its original packaging.
Return procedure for SA70A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA70A Tags
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onsemi
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Diodes Incorporated
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onsemi
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Diodes Incorporated
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Diodes Incorporated
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Diodes Incorporated
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onsemi
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DESD5V0U1BB-7
Diodes Incorporated
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Diodes Incorporated
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Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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