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onsemi SA170A
- Part No.:
- SA170A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA170A.pdf
- Description:
- TVS DIODE 170VWM 275VC DO15
- Quantity:
- Payment:
- Shipping:
Inventory:6,425
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Product details
Overview
SA170A from Fairchild Semiconductor is a unidirectional 500 W transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power lines and signal interfaces. It features a 170 V reverse stand-off voltage (VRWM), 189–209 V breakdown voltage (VBR) at 1.0 mA, 275 V clamping voltage (VC) at peak pulse current, and operates up to +175 °C junction temperature - deployed in industrial power supplies and telecom surge protection circuits.
For engineers reviewing the SA170A datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, DO-15 package details, bidirectional variant context (SA170CA), clamping performance under 10/1000 µs transients, and real-world selection guidance for high-voltage surge suppression.
Technical Context
The SA170A uses a glass-passivated silicon junction optimized for fast transient response (<1.0 ps rise time from 0 V to VBR) and low incremental surge resistance. Its unidirectional configuration provides asymmetric clamping - conducting only during reverse overvoltage events while maintaining <1.0 µA leakage above 10 V at VRWM.
Rated for 500 W peak pulse power on the standardized 10/1000 µs waveform, it sustains non-repetitive forward surge currents up to 70 A (8.3 ms half-sine) and operates across –65 °C to +175 °C storage and junction temperature ranges - supporting ruggedized industrial and outdoor equipment designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (PPPM) | 500 W on 10/1000 µs waveform - defines maximum single-event surge energy absorption capability without failure. |
| Reverse Stand-off Voltage (VRWM) | 170 V - maximum continuous DC or RMS voltage the device blocks before entering avalanche conduction. |
| Breakdown Voltage (VBR) | 189–209 V at 1.0 mA - guaranteed avalanche initiation range; determines precise clamping onset threshold. |
| Clamping Voltage (VC) | 275 V at IPPM - maximum voltage seen across protected circuit during full-rated surge, defining worst-case overvoltage exposure. |
| Peak Pulse Current (IPPM) | 1.8 A - calculated peak current corresponding to 500 W into 275 V clamping, used for PCB trace and fuse sizing. |
| Junction Temperature (TJ) | +175 °C - enables operation in high-ambient environments such as enclosed power cabinets or automotive engine bays. |
| Leakage Current (IR) | ≤1.0 µA at VRWM - ensures minimal standby power loss and signal integrity in high-impedance monitoring paths. |
Pinout & Package
SA170A is housed in a DO-15 axial-leaded package with cathode indicated by a color band. The device has two terminals: anode and cathode - configured for unidirectional clamping where cathode connects to the protected line and anode to ground.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Reference/return path | Connected to system ground; completes conduction path during reverse overvoltage events. |
| Cathode | Protected line interface | Connected to the line being safeguarded (e.g., DC input rail); carries clamped surge current to ground. |
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 VBR - ensures clamping activation prior to sensitive downstream IC damage. |
| Low incremental surge resistance | Minimizes voltage overshoot during high di/dt transients, improving clamping precision. |
| 500 W peak pulse rating | Supports IEC 61000-4-5 Level 4 (4 kV line-to-line, 2 kV line-to-ground) surge compliance. |
| DO-15 mechanical compatibility | Enables drop-in replacement with legacy 1N5388B–1N5408 family in existing through-hole layouts. |
Applications
| Industrial AC/DC Power Input Protection | Telecom Line Interface Surge Suppression |
|---|---|
|
Use Scenario: Protecting rectified DC bus in DIN-rail mounted power supplies against lightning-induced surges on 230 VAC mains input. IC Role / Device Role / Timing Role: Primary shunt TVS placed after bridge rectifier and before bulk capacitor to clamp differential-mode transients. Use Value: Withstands 500 W pulses and clamps to ≤275 V, preventing overvoltage stress on 400 V-rated electrolytic capacitors and PWM controllers. |
Use Scenario: Safeguarding RS-485 transceiver inputs in outdoor base station remote units exposed to induced surges on twisted-pair cabling. IC Role / Device Role / Timing Role: Unidirectional TVS on each data line referenced to local ground, suppressing common-mode surges coupled from adjacent power cables. Use Value: 170 V VRWM allows safe operation with ±12 V RS-485 common-mode range while clamping >200 V transients before transceiver damage occurs. |
| Renewable Energy Inverter DC Link Protection | Railway Signaling Power Supply Clamping |
|
Use Scenario: Shielding DC link capacitors in solar string inverters from grid-switching transients and nearby lightning strikes. IC Role / Device Role / Timing Role: High-energy TVS connected between positive and negative DC rails to absorb bipolar surges via external coupling paths. Use Value: 275 V VC limits voltage excursion below 300 V rating of 350 V DC-link film capacitors, extending service life under repeated surge stress. |
Use Scenario: Securing 110 V DC signaling power feeds in trackside relay cabinets subjected to traction return current spikes and EMI. IC Role / Device Role / Timing Role: Standoff-rated TVS installed at cabinet entry point to divert fast-rising rail transients before reaching electromechanical relays and monitoring sensors. Use Value: 170 V VRWM matches nominal 110 V DC supply with 50 % margin, while 1.0 µA IR avoids loading low-power fail-safe monitoring circuits. |
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 SMAJ170A | Same DO-15 package, identical 170 V VRWM and 275 V VC, but rated for 400 W (not 500 W) peak pulse power. | Suitable for lower-energy threat environments (IEC 61000-4-5 Level 3); not recommended for Level 4 compliance-critical designs. | Select SMAJ170A only when system-level surge testing confirms <400 W transient energy; retain SA170A for full 500 W margin. |
| Vishay 1.5KE180A | Higher 180 V VRWM, 200–221 V VBR, 292 V VC, and same 500 W rating - but in larger DO-201AD package with longer leads. | Requires PCB layout revision due to 5.6 mm body length vs. SA170A's 4.2 mm; thermal dissipation differs under sustained surge duty. | Choose 1.5KE180A only if higher standoff margin is required and board space permits DO-201AD footprint; otherwise prefer SA170A for DO-15 compatibility. |
Compared with SMAJ170A and 1.5KE180A, the SA170A uniquely delivers 500 W pulse handling in the compact DO-15 outline with verified 170 V standoff - making it optimal for space-constrained, high-reliability industrial power entry designs requiring full IEC 61000-4-5 Level 4 immunity.
Availability
SA170A is available at Aetrix Electronics and suitable for industrial power supplies, telecom infrastructure equipment, renewable energy inverters, and railway signaling systems requiring stable component supply and long-lifecycle availability.
Supply support for SA170A 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 U.S.-based analog and power semiconductor manufacturer acquired by ON Semiconductor in 2016; its legacy TVS portfolio remains widely deployed in industrial and infrastructure applications.
The SAxxxA series was engineered specifically for high-energy, high-voltage DC line protection - emphasizing robustness, repeatable clamping, and thermal stability in harsh ambient conditions.
FAQ
What is the clamping voltage of the SA170A under full-rated surge conditions?
The SA170A exhibits a maximum clamping voltage (VC) of 275 V when subjected to its rated peak pulse current on the 10/1000 µs waveform. This value is measured at the specified IPPM derived from 500 W power dissipation and represents the upper bound voltage seen by downstream components during worst-case transient events - critical for ensuring protected ICs remain within absolute maximum ratings.
Is the SA170A suitable for bidirectional surge protection?
No - the SA170A is a unidirectional TVS diode intended for DC line protection where polarity is fixed. For bidirectional AC or symmetrical signal line protection, the SA170CA variant must be used instead, as it provides identical clamping performance in both polarities and omits the cathode band marking per datasheet specification.
How does the SA170A compare to the 1N5388B in terms of surge capability?
The SA170A replaces legacy 1N5388B with significantly enhanced surge performance: 500 W peak pulse power versus 150 W, 275 V clamping versus ~300 V, and tighter VBR tolerance (189–209 V vs. ±5 %). Its glass-passivated junction also improves long-term stability over the older epoxy-passivated 1N5388B - making SA170A the preferred upgrade for modern high-reliability designs.
What is the maximum operating temperature for the SA170A junction?
The SA170A has a maximum operating junction temperature (TJ) of +175 °C, enabling reliable operation in thermally demanding environments such as enclosed power converters, motor drive cabinets, and outdoor telecom enclosures. This rating is validated per JEDEC test conditions and supports derated power handling up to that limit as shown in Figure 2 of the datasheet.
Does the SA170A require heatsinking in typical applications?
No additional heatsinking is required for the SA170A under single-pulse or infrequent surge conditions, as its 500 W rating applies to transient events, not steady-state dissipation. However, for repetitive surge scenarios exceeding 4 pulses per minute, thermal design must account for average power using the derating curve in Figure 2 - and PCB copper area should meet minimum 0.375" lead length thermal guidelines per datasheet.
SA170A 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):
- 170V
- Voltage - Breakdown (Min):
- 189V
- Voltage - Clamping (Max) @ Ipp:
- 275V
- Current - Peak Pulse (10/1000µs):
- 1.8A
- 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
SA170A FAQ
1.How can I place an order for SA170A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA170A 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 SA170A reliable?
The price and inventory of SA170A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA170A is usually 5 days.
3.What payment methods are accepted for SA170A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA170A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA170A?
SA170A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA170A 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 SA170A?
For technical support, including SA170A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA170A requirements.
6.How does Aetrix verify that SA170A is sourced from the original manufacturer or authorized distributors?
All SA170A 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 SA170A meets industry standards.
7.What is the process for return or replacement of SA170A?
All SA170A units undergo pre-shipment inspection (PSI). If there is an issue with SA170A, 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 SA170A part is unused and in its original packaging.
Return procedure for SA170A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA170A Tags
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ESD9B5.0ST5G
onsemi
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DESD3V3E1BL-7B
Diodes Incorporated
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onsemi
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Diodes Incorporated
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Diodes Incorporated
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DESD5V0U1BA-7
Diodes Incorporated
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ESD5Z5.0T1G
onsemi
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DESD5V0U1BB-7
Diodes Incorporated
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Diodes Incorporated
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PESD2V0Y1BSFYL
Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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Diodes Incorporated
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