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onsemi SA20A
- Part No.:
- SA20A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-204AC, DO-15, Axial
- Datasheet:
-
SA20A.pdf
- Description:
- TVS DIODE 20VWM 32.4VC DO15
- Quantity:
- Payment:
- Shipping:
Inventory:5,804
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Product details
Overview
SA20A 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 20 V reverse stand-off voltage (VRWM), 22.2–24.5 V breakdown voltage (VBR) at 1.0 mA, clamps to ≤32.4 V at 15.4 A peak pulse current (IPPM), and operates with junction temperature up to +175°C in DO-15 package.
For engineers reviewing the SA20A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage under 10/1000 μs surge, low leakage (<1.0 μA at 20 V), fast response time (<1.0 ps), glass-passivated junction reliability, and compatibility with JEDEC-standard surge waveforms.
Technical Context
The SA20A functions as a unidirectional avalanche diode that enters breakdown when transient voltage exceeds its VBR range, diverting surge current away from protected circuitry. Its low incremental surge resistance ensures stable clamping performance across varying IPPM levels, and its glass-passivated junction enhances long-term stability under repeated surge stress.
Designed for single-pulse or low-duty-cycle surge events, the SA20A supports non-repetitive peak forward surge current up to 70 A (8.3 ms half-sine) and maintains thermal integrity via 1.0 W steady-state power dissipation at 75°C ambient with 0.375" lead length.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power (10/1000 μs) | 500 W - sustains high-energy transients without failure in industrial or automotive load-dump scenarios |
| Reverse Stand-off Voltage (VRWM) | 20 V - maximum continuous operating voltage before significant leakage begins |
| Breakdown Voltage (VBR) | 22.2–24.5 V at 1.0 mA - defines onset of avalanche conduction with tight tolerance for predictable triggering |
| Clamping Voltage (VC) | ≤32.4 V at 15.4 A IPPM - limits downstream voltage stress during worst-case surge conditions |
| Reverse Leakage (IR) | <1.0 μA at 20 V - minimizes standby power loss and avoids false triggering in low-power systems |
| Response Time | <1.0 ps - enables sub-nanosecond reaction to ESD or fast-rising transients |
| Junction Temperature Range | −65°C to +175°C - supports operation in under-hood automotive, industrial motor drives, and outdoor power equipment |
Pinout & Package
SA20A is housed in a DO-15 axial-leaded package with cathode indicated by a color band. The device has two terminals: anode and cathode. No internal connections beyond the PN junction; polarity must be observed for correct unidirectional clamping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Current entry point during forward conduction; connected to protected line ground or low-side reference | Must be tied to lower potential side of protected circuit to enable proper clamping action |
| Cathode | Current exit point during reverse-biased avalanche; marked by color band | Connected to the line being protected (e.g., 24 V rail); conducts surge current to ground when VRWM exceeded |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Improves moisture resistance and long-term reliability in humid or thermally cycled environments |
| 500 W peak pulse power (10/1000 μs) | Meets IEC 61000-4-5 Level 4 surge immunity requirements for industrial ports |
| Low incremental surge resistance | Ensures consistent clamping voltage across wide IPPM range, reducing design margin uncertainty |
| Fast response time <1.0 ps | Protects sensitive analog front-ends and high-speed digital receivers from nanosecond-scale ESD events |
| DO-15 package with axial leads | Enables through-hole mounting compatible with legacy PCB layouts and manual repair workflows |
Applications
| Industrial Motor Drives | Automotive Body Control Modules |
|---|---|
|
Use Scenario: Protection of 24 V DC control inputs against load dump and inductive switching spikes in PLC I/O modules. IC Role / Device Role / Timing Role: Primary unidirectional TVS clamp placed between input terminal and ground plane. Use Value: Limits transient voltage to ≤32.4 V during 500 W surges, preventing damage to optocouplers and microcontroller GPIOs rated for 36 V absolute max. |
Use Scenario: Surge suppression on LIN bus power supply lines exposed to battery transients in door module ECUs. IC Role / Device Role / Timing Role: Unidirectional overvoltage protector on VBAT feed to LIN transceiver IC. Use Value: Withstands 70 A non-repetitive surge (8.3 ms) while maintaining <1.0 μA leakage at 13.5 V nominal, preserving sleep-mode current budget. |
| Telecom Power Feeds | Renewable Energy Charge Controllers |
|
Use Scenario: Input-stage protection on 24 V PoE-powered remote radios subjected to lightning-induced surges on outdoor cabling. IC Role / Device Role / Timing Role: First-line TVS on DC input before DC-DC converter and LDO regulators. Use Value: Clamps 10/1000 μs transients to ≤32.4 V, enabling use of cost-effective 36 V-rated MOSFETs and capacitors downstream. |
Use Scenario: Overvoltage clamp on PV array input of 24 V solar charge controller exposed to grid-switching transients. IC Role / Device Role / Timing Role: Unidirectional surge suppressor between PV+ and chassis ground. Use Value: Operates reliably from −40°C to +125°C ambient with 175°C junction rating, supporting outdoor deployment in desert and alpine climates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ20A | Same VRWM (20 V), but lower PPPM (400 W); DO-214AC package with surface-mount footprint | Requires PCB redesign for SMT assembly; less robust for high-energy 500 W surges | Select SMAJ20A only if board space constraints prohibit axial DO-15 and surge energy remains ≤400 W |
| P6KE20A | Identical VRWM (20 V), same DO-15 package, but lower PPPM (600 W rated at 10/1000 μs); higher VC (36.8 V at 13.9 A) | Higher clamping voltage reduces protection margin for 3.3 V/5 V logic; better suited for 28 V systems | Choose P6KE20A when higher surge headroom is needed and downstream components tolerate ≥36.8 V clamping |
Compared with SMAJ20A and P6KE20A, the SA20A delivers optimal balance of 500 W surge handling, low 32.4 V clamping, and proven DO-15 reliability-making it preferred for through-hole industrial controls where layout flexibility and surge margin are critical.
Availability
SA20A is available at Aetrix Electronics and suitable for industrial motor drives, automotive body electronics, telecom power feeds, and renewable energy charge controllers requiring stable component supply and long-lifecycle support.
Supply support for SA20A 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 of high-performance analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy TVS portfolio remains widely deployed in industrial and automotive systems.
The SAxxA series was engineered specifically for robust, cost-effective DC line protection in harsh environments-emphasizing high surge power, tight VBR tolerance, and thermal resilience in standard axial packages.
FAQ
What is the clamping voltage of SA20A at its rated peak pulse current?
The SA20A clamps to a maximum of 32.4 V when subjected to its rated peak pulse current of 15.4 A on a 10/1000 μs waveform. This value is measured per industry-standard test conditions and defines the upper voltage limit imposed on protected circuitry during surge events. The SA20A's low clamping ratio (VC/VBR ≈ 1.4) reflects efficient avalanche energy absorption without excessive voltage overshoot.
Is SA20A suitable for bidirectional signal line protection?
No, SA20A is a unidirectional TVS diode and is not suitable for bidirectional signal line protection. It conducts only in reverse breakdown and blocks forward current above ~0.7 V. For bidirectional protection-such as RS-485, CAN, or USB data lines-the SA20CA variant (with 'C' suffix) must be used, as it provides symmetrical clamping in both polarities.
What is the maximum steady-state power dissipation of SA20A at elevated ambient temperatures?
The SA20A dissipates up to 1.0 W continuously at TA = 75°C with 0.375" lead length, derating linearly to zero at 175°C per the published steady-state power derating curve. At 100°C ambient, its usable power drops to approximately 0.67 W. This thermal profile makes SA20A appropriate for enclosed industrial enclosures where airflow is limited but junction temperature remains within the +175°C limit.
Does SA20A meet any international surge immunity standards?
Yes, the SA20A's 500 W peak pulse power rating on the 10/1000 μs waveform aligns with IEC 61000-4-5 Ed. 3 Annex A test profiles for Level 4 surge immunity (2 kV line-to-earth, 1 kV line-to-line). When properly mounted with short traces and adequate grounding, SA20A enables compliant protection for industrial Ethernet ports, PLC analog inputs, and 24 V fieldbus interfaces.
How does the glass passivation in SA20A improve long-term reliability?
The glass passivation layer on the SA20A's PN junction prevents moisture ingress and electrochemical migration under high humidity or thermal cycling. This construction significantly extends operational life in outdoor or under-hood automotive applications, where conventional epoxy-passivated devices may suffer parametric drift or premature failure after prolonged exposure to 85°C/85% RH conditions.
SA20A 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):
- 20V
- Voltage - Breakdown (Min):
- 22.2V
- Voltage - Clamping (Max) @ Ipp:
- 32.4V
- Current - Peak Pulse (10/1000µs):
- 15.4A
- 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
SA20A FAQ
1.How can I place an order for SA20A through Aetrix?
Please submit a Request for Quotation (RFQ) for SA20A 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 SA20A reliable?
The price and inventory of SA20A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SA20A is usually 5 days.
3.What payment methods are accepted for SA20A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SA20A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SA20A?
SA20A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SA20A 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 SA20A?
For technical support, including SA20A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SA20A requirements.
6.How does Aetrix verify that SA20A is sourced from the original manufacturer or authorized distributors?
All SA20A 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 SA20A meets industry standards.
7.What is the process for return or replacement of SA20A?
All SA20A units undergo pre-shipment inspection (PSI). If there is an issue with SA20A, 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 SA20A part is unused and in its original packaging.
Return procedure for SA20A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SA20A Tags
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Nexperia USA Inc.
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Toshiba Semiconductor and Storage
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