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onsemi P4SMA18A
- Part No.:
- P4SMA18A
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
P4SMA18A.pdf
- Description:
- TVS DIODE 15.3VWM 25.2VC DO214AC
- Quantity:
- Payment:
- Shipping:
Inventory:3,954
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Product details
Overview
P4SMA18A from Fairchild Semiconductor is a unidirectional 400 W transient voltage suppressor (TVS) diode designed for primary overvoltage protection in DC power lines and signal interfaces. It features a 15.3 V reverse stand-off voltage (VRWM), 17.1–18.9 V breakdown voltage at 1.0 mA (VBR), and clamps transients to ≤25.2 V at 15.9 A peak pulse current on a 10/1000 µs waveform - used in industrial power supply input stages and automotive body control modules.
For engineers reviewing the P4SMA18A datasheet, pinout, applications, or equivalent options, key selection criteria include clamping voltage margin relative to protected IC VDD rails, thermal resistance (RΘJA = 120 °C/W), junction temperature range (–65 to +150 °C), and DO-214AC package compatibility with automated SMT placement.
Technical Context
The P4SMA18A operates as a silicon avalanche diode optimized for fast-response transient suppression. Its unidirectional configuration provides protection only against negative-going transients on positive-rail applications, requiring correct cathode orientation during PCB layout.
It delivers 400 W peak pulse power on the standardized 10/1000 µs waveform, with a maximum clamping voltage of 25.2 V at 15.9 A IPPM and a low leakage current of 1 µA at VRWM = 15.3 V - enabling reliable hold-off during normal operation while limiting fault energy during surge events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Peak Pulse Power | 400 W on 10/1000 µs waveform - defines maximum transient energy absorption capability without failure |
| Clamping Voltage VC | 25.2 V @ 15.9 A - sets upper voltage limit seen by downstream circuitry during surge |
| Breakdown Voltage VBR | 17.1–18.9 V @ 1.0 mA - ensures reliable avalanche initiation above normal operating voltage |
| Reverse Stand-off VRWM | 15.3 V - maximum continuous reverse voltage before significant leakage begins |
| Thermal Resistance RΘJA | 120 °C/W - determines junction temperature rise under sustained power dissipation |
| Operating Junction Temp | –65 to +150 °C - supports deployment in extended-temperature industrial and automotive environments |
Pinout & Package
Package: DO-214AC (SMA), surface-mount, molded plastic case with cathode indicated by color band. Standardized footprint compatible with IPC-7351B SMA outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Positive terminal during forward conduction | Connected to protected line's lower-potential side (e.g., ground or return path) |
| Cathode | Protected-side terminal during reverse-biased clamping | Connected to the line being protected (e.g., +12 V rail); marked by color band |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse rating | Enables robust protection against IEC 61000-4-5 Level 4 surges (4 kV/2 Ω) on 12 V systems |
| Low clamping ratio (VC/VBR ≈ 1.4) | Minimizes overvoltage stress on downstream components relative to breakdown threshold |
| 1 µA max reverse leakage @ VRWM | Prevents excessive standby current draw in battery-powered or low-power circuits |
| DO-214AC package | Supports high-volume automated assembly and offers superior thermal performance vs. DO-41 |
Applications
| Industrial Power Input Protection | Automotive Body Control Module |
|---|---|
Use Scenario: Protecting 24 V DC input stage of PLC I/O module against load dump and inductive switching transients. IC Role / Device Role / Timing Role: Primary unidirectional TVS clamp placed between input rail and chassis ground. Use Value: Limits transient voltage to ≤25.2 V, preventing damage to upstream DC-DC controller and downstream logic. | Use Scenario: Safeguarding LIN bus transceiver power pins in door module against battery reversal and jump-start spikes. IC Role / Device Role / Timing Role: Rail-clamping TVS on VCC line, oriented anode-to-ground, cathode-to-VCC. Use Value: Maintains 15.3 V stand-off during normal 12 V operation while clamping 30 V+ surges within safe limits. |
| Telecom Line Card Interface | Medical Equipment Power Entry |
Use Scenario: Secondary surge protection on 48 V phantom power feed to PoE-powered devices. IC Role / Device Role / Timing Role: Unidirectional TVS on DC input rail upstream of EMI filter and primary converter. Use Value: Absorbs 400 W pulses without degradation, preserving long-term reliability under repeated lightning-induced surges. | Use Scenario: Overvoltage safeguard on isolated 24 V auxiliary supply feeding patient-monitoring analog front-end. IC Role / Device Role / Timing Role: Final-stage TVS on secondary-side DC rail, ensuring <1 µA leakage avoids signal integrity impact. Use Value: Guarantees ≤25.2 V clamping during ESD or surge events, meeting IEC 60601-1 creepage and safety margin requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18A | 600 W peak pulse power; same VRWM (15.3 V) and VC (25.2 V); SMB package (larger footprint) | Higher energy handling suits 48 V telecom or higher-duty-cycle industrial use | Select when system-level surge testing exceeds 400 W or board space allows SMB footprint |
| 1.5SMC18A | 1500 W peak pulse power; identical electrical specs (VRWM, VBR, VC); larger SMC package | Required for IEC 61000-4-5 Level 5 or repetitive surge environments | Choose when long-term reliability under frequent transients is critical and PCB area permits SMC outline |
Compared with SMBJ18A and 1.5SMC18A, the P4SMA18A offers optimal balance of compact DO-214AC size, 400 W capability, and cost efficiency for single-event surge protection in space-constrained 12–24 V systems - without over-specifying package or power rating.
Availability
P4SMA18A is available at Aetrix Electronics and suitable for industrial power input protection, automotive body control modules, telecom line card interfaces, and medical equipment power entry requiring stable component supply and consistent parametric performance across production lots.
Supply support for P4SMA18A 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 semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.
The P4SMA18A belongs to Fairchild's P4SMA series of unidirectional TVS diodes, engineered for cost-effective, high-reliability surge protection in DC power and interface lines across industrial and automotive applications.
FAQ
What is the polarity configuration of the P4SMA18A?
The P4SMA18A is a unidirectional TVS diode, meaning it functions as a reverse-biased avalanche clamp. Its cathode (marked by a color band) connects to the line being protected, and the anode connects to ground or the lower-potential reference. It does not conduct in forward bias during normal operation, and forward surge rating (IFSM = 40 A) applies only to non-repetitive events.
What does the "18A" marking on the P4SMA18A device indicate?
The "18A" marking on the P4SMA18A corresponds to its nominal breakdown voltage - specifically, a VBR range of 17.1–18.9 V at 1.0 mA test current. This designation follows Fairchild's standard coding for the P4SMA series, where "18" denotes the approximate 18 V breakdown and "A" indicates the tighter tolerance bin (±5% around nominal).
Can the P4SMA18A be used in bidirectional protection applications?
No, the P4SMA18A is strictly unidirectional and unsuitable for bidirectional protection. For AC or dual-polarity signal lines, a dedicated bidirectional TVS such as P4SMA18CA must be used. Substituting P4SMA18A in such roles risks failure during positive transients due to lack of forward-clamping capability.
How does the P4SMA18A's thermal resistance affect PCB layout?
The P4SMA18A has RΘJA = 120 °C/W, meaning junction temperature rises significantly under sustained power. To maintain reliability, PCB layout must include ≥25 mm² of copper pour connected to both leads, avoid enclosing the device in tight enclosures, and ensure ambient temperature remains ≤75 °C during worst-case surge duty cycles.
Is the P4SMA18A compliant with RoHS and lead-free soldering standards?
Yes, the P4SMA18A manufactured under Rev. A (2001) predates mandatory RoHS, but Fairchild's later production lots and ON Semiconductor's continued manufacturing comply with RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level (MSL) 1. Always verify MSL and Pb-free status via current ON Semiconductor datasheet revision for P4SMA18A.
P4SMA18A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 15.3V
- Voltage - Breakdown (Min):
- 17.1V
- Voltage - Clamping (Max) @ Ipp:
- 25.2V
- Current - Peak Pulse (10/1000µs):
- 15.9A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
P4SMA18A FAQ
1.How can I place an order for P4SMA18A through Aetrix?
Please submit a Request for Quotation (RFQ) for P4SMA18A 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 P4SMA18A reliable?
The price and inventory of P4SMA18A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for P4SMA18A is usually 5 days.
3.What payment methods are accepted for P4SMA18A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for P4SMA18A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for P4SMA18A?
P4SMA18A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your P4SMA18A 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 P4SMA18A?
For technical support, including P4SMA18A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your P4SMA18A requirements.
6.How does Aetrix verify that P4SMA18A is sourced from the original manufacturer or authorized distributors?
All P4SMA18A 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 P4SMA18A meets industry standards.
7.What is the process for return or replacement of P4SMA18A?
All P4SMA18A units undergo pre-shipment inspection (PSI). If there is an issue with P4SMA18A, 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 P4SMA18A part is unused and in its original packaging.
Return procedure for P4SMA18A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
P4SMA18A Tags
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