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Home > Products > Circuit Protection > Transient Voltage Suppressors (TVS) > TVS Diodes

Taiwan Semiconductor Corporation P4SMA18

Name: P4SMA18
Brand: Taiwan Semiconductor Corporation
SKU: P4SMA18
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: P4SMA18

Manufacturer:: Taiwan Semiconductor Corporation

Category:: TVS Diodes

Package:: DO-214AC, SMA

Datasheet:: P4SMA18.pdf

Description:: 400W, 18V, 10%, UNIDIRECTIONAL,

Quantity:: RFQ Add To RFQ list

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Inventory:2,823

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Product details

Overview

P4SMA18 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, designed for clamping fast-rising ESD and surge transients in DC power rails and signal lines. It features a 16.2–19.8 V breakdown voltage (V_BR), 14.5 V working stand-off voltage (V_WM), 26.5 V maximum clamping voltage (V_C) at 16.0 A peak pulse current, and 400 W peak pulse power rating per 10/1000 µs waveform - suitable for protecting SMPS inputs, DC/DC converter feedback paths, and industrial sensor interfaces.

For engineers reviewing the P4SMA18 datasheet, P4SMA18 pinout, P4SMA18 application, or P4SMA18 equivalent, this device delivers verified clamping performance under ISO 7637-2 Pulse 1/2a/2b/3a/3b, supports automated SMT placement, and provides low leakage (<1 µA at V_WM) with fast sub-1 ps response time - critical for robust overvoltage protection in automotive and industrial power systems.

Technical Context

The P4SMA18 operates as a unidirectional avalanche diode, conducting only in reverse bias above its specified V_BR threshold to divert transient energy to ground. Its glass-passivated junction ensures stable breakdown characteristics and long-term reliability under repetitive surge stress.

It is rated for 150 °C maximum junction temperature, -55 °C to +150 °C operating range, and meets JESD201 Class 2 whisker resistance and J-STD-020 Moisture Sensitivity Level 1 - confirming suitability for lead-free reflow and high-reliability board assembly without preconditioning.

Key Specifications

Parameter	Value and Actual Design Meaning
V_WM	14.5 V - Maximum continuous reverse voltage before significant leakage; defines safe operating margin below clamping onset
V_BR @ I_T=1.0 mA	16.2–19.8 V - Measured breakdown range at 1 mA test current; determines precise turn-on threshold for transient suppression
V_C @ I_PPM=16.0 A	26.5 V - Clamped voltage during 10/1000 µs surge; limits downstream IC stress to ≤26.5 V under 400 W transient
I_R @ V_WM	<1 µA - Reverse leakage at stand-off voltage; ensures negligible standby power loss in battery-powered systems
P_PPM	400 W - Peak pulse power handling per standard 10/1000 µs waveform; validates protection against ISO 7637-2 Pulse 5a surges
T_J max	150 °C - Maximum junction temperature; enables operation in enclosed industrial enclosures without derating below 100 °C ambient

Pinout & Package

Package: DO-214AC (SMA), surface-mount, single-diode configuration with cathode band marking. Matte tin-plated leads comply with J-STD-002 solderability and UL 94V-0 flammability.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Forward conduction terminal	Connected to protected line (e.g., V_IN or signal); conducts during forward surge or ESD event
Cathode	Reverse-biased clamping terminal	Connected to ground or lower-potential rail; initiates avalanche conduction when V_REV exceeds V_BR

Key Features

Feature	Design Value
Glass passivated junction	Ensures stable V_BR tolerance and long-term reliability under thermal cycling and humidity exposure
Sub-1 ps response time	Clamps ESD events (IEC 61000-4-2) before sensitive logic or analog circuitry sustains damage
ISO 7637-2 compliance	Validated for automotive load-dump and inductive-switching transients (Pulse 1/2a/2b/3a/3b)
RoHS & halogen-free	Meets IEC 61249-2-21 and EU RoHS directives for environmentally compliant industrial and automotive production

Applications

Switching Mode Power Supply (SMPS) Input Protection	On-Board DC/DC Converter Feedback Line
Use Scenario: Protects primary-side rectifier output and bulk capacitor input from line-induced surges and load dump transients. IC Role / Device Role / Timing Role: Unidirectional TVS clamping element placed between rectified DC bus and ground. Use Value: Limits transient voltage to ≤26.5 V, preventing overvoltage failure of PWM controller ICs and MOSFET gate oxides.	Use Scenario: Shields feedback resistor divider and error amplifier input in isolated or non-isolated DC/DC modules. IC Role / Device Role / Timing Role: Low-capacitance clamping diode across feedback node to suppress coupling noise and ringback spikes. Use Value: Maintains regulation accuracy by preventing false triggering of error amplifiers during fast transients (e.g., load step).
Industrial Sensor Signal Conditioning	LED Driver Constant-Current Loop
Use Scenario: Installed on 4–20 mA or 0–10 V analog sensor outputs exposed to field wiring transients. IC Role / Device Role / Timing Role: Bidirectional-capable (with CA suffix variant) or unidirectional clamp referenced to system ground. Use Value: Preserves signal integrity with <1 µA leakage at 14.5 V, avoiding offset errors in precision measurement circuits.	Use Scenario: Placed across LED string or constant-current source to absorb inductive kickback from driver MOSFET switching. IC Role / Device Role / Timing Role: Transient energy sink parallel to LED load, activated only during overvoltage events. Use Value: Extends LED module lifetime by limiting reverse voltage stress to ≤26.5 V during MOSFET turn-off transitions.

Switching Mode Power Supply (SMPS) Input Protection

On-Board DC/DC Converter Feedback Line

Use Scenario: Protects primary-side rectifier output and bulk capacitor input from line-induced surges and load dump transients.

IC Role / Device Role / Timing Role: Unidirectional TVS clamping element placed between rectified DC bus and ground.

Use Value: Limits transient voltage to ≤26.5 V, preventing overvoltage failure of PWM controller ICs and MOSFET gate oxides.

Use Scenario: Shields feedback resistor divider and error amplifier input in isolated or non-isolated DC/DC modules.

IC Role / Device Role / Timing Role: Low-capacitance clamping diode across feedback node to suppress coupling noise and ringback spikes.

Use Value: Maintains regulation accuracy by preventing false triggering of error amplifiers during fast transients (e.g., load step).

Industrial Sensor Signal Conditioning

LED Driver Constant-Current Loop

Use Scenario: Installed on 4–20 mA or 0–10 V analog sensor outputs exposed to field wiring transients.

IC Role / Device Role / Timing Role: Bidirectional-capable (with CA suffix variant) or unidirectional clamp referenced to system ground.

Use Value: Preserves signal integrity with <1 µA leakage at 14.5 V, avoiding offset errors in precision measurement circuits.

Use Scenario: Placed across LED string or constant-current source to absorb inductive kickback from driver MOSFET switching.

IC Role / Device Role / Timing Role: Transient energy sink parallel to LED load, activated only during overvoltage events.

Use Value: Extends LED module lifetime by limiting reverse voltage stress to ≤26.5 V during MOSFET turn-off transitions.

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 (Bourns)	DO-214AA (SMB) package; 18 V nominal V_BR; 600 W P_PPM; bidirectional standard	Higher power rating but larger footprint; requires PCB layout change	Select when higher surge margin is needed and SMB pad layout is available
1.5SMC18A (ON Semiconductor)	DO-214AB (SMC) package; 18 V nominal V_BR; 1500 W P_PPM; same unidirectional polarity	3× larger package size and 3.7× higher peak power; not drop-in compatible	Choose for extreme surge environments (e.g., railway traction power) where SMA footprint is insufficient

Compared with P4SMA18, SMBJ18A offers higher surge capacity in a slightly larger DO-214AA package, while 1.5SMC18A delivers significantly greater power handling in a DO-214AB form factor - neither is pin-compatible, but both serve overlapping protection roles in industrial and automotive subsystems where layout flexibility permits package upgrade.

Availability

P4SMA18 is available at Aetrix Electronics and suitable for switching mode power supplies, on-board DC/DC converters, and industrial sensor interfaces requiring stable component supply with full traceability and lifecycle management.

Supply support for P4SMA18 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated semiconductor manufacturer specializing in discrete power devices, TVS diodes, rectifiers, and MOSFETs for industrial, automotive, and consumer applications.

The P4SMA18 belongs to TSC's P4SMAx series of 400 W surface-mount TVS diodes, engineered specifically for compact, high-efficiency overvoltage protection in space-constrained power conversion and interface circuits.

FAQ

What is the breakdown voltage range of the P4SMA18?

The P4SMA18 has a guaranteed breakdown voltage (V_BR) range of 16.2 V to 19.8 V at 1.0 mA test current, measured per ANSI/IEEE C62.35 standards. This range reflects manufacturing tolerance and ensures consistent clamping behavior across production lots. The P4SMA18 maintains this specification under standard test conditions (T_A = 25 °C) and is validated using square-wave pulses of 300 µs duration.

Is the P4SMA18 unidirectional or bidirectional?

The P4SMA18 is a unidirectional TVS diode, intended for use in DC circuits where transient suppression is required only in reverse bias. Its cathode band marking indicates polarity, and it conducts avalanche current only when reverse voltage exceeds V_BR. For bidirectional applications, the P4SMA18CA variant (not P4SMA18) must be selected, as explicitly stated in the datasheet's "Devices for Bipolar Applications" section.

What is the maximum clamping voltage of the P4SMA18 under surge conditions?

The P4SMA18 exhibits a maximum clamping voltage (V_C) of 26.5 V when subjected to a 10/1000 µs peak impulse current of 16.0 A. This value is measured at the device terminals and represents the upper limit of voltage seen by downstream circuitry during standardized surge events. It directly determines the safe operating voltage margin for protected ICs and passive components.

Does the P4SMA18 meet automotive surge immunity standards?

Yes, the P4SMA18 meets ISO 7637-2 requirements for Pulse 1 (inductive load disconnect), Pulse 2a/2b (switching transients), and Pulse 3a/3b (capacitive coupling), as confirmed in the official Taiwan Semiconductor datasheet Version S2102. Its 400 W peak pulse rating and sub-1 ps response time make it suitable for front-end protection in automotive body control modules, infotainment power supplies, and sensor interfaces.

What is the moisture sensitivity level (MSL) of the P4SMA18?

The P4SMA18 is rated MSL Level 1 per J-STD-020, meaning it has unlimited floor life and may be assembled using standard lead-free reflow profiles without baking or dry-pack requirements. This classification is enabled by its DO-214AC (SMA) molding compound and matte tin-plated terminations, which resist moisture absorption during storage and handling prior to soldering.

P4SMA18 Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Package/Case:: DO-214AC, SMA

Series:: P4SMA

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Zener

Unidirectional Channels:: 1

Bidirectional Channels:: -

Voltage - Reverse Standoff (Typ):: 14.5V

Voltage - Breakdown (Min):: 16.2V

Voltage - Clamping (Max) @ Ipp:: 26.5V

Current - Peak Pulse (10/1000µs):: 16A

Power - Peak Pulse:: 400W

Power Line Protection:: No

Applications:: General Purpose

Capacitance @ Frequency:: -

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: DO-214AC (SMA)

P4SMA18 FAQ

1.How can I place an order for P4SMA18 through Aetrix?

Please submit a Request for Quotation (RFQ) for P4SMA18 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 P4SMA18 reliable?

The price and inventory of P4SMA18 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for P4SMA18 is usually 5 days.

3.What payment methods are accepted for P4SMA18?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for P4SMA18 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for P4SMA18?

P4SMA18 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your P4SMA18 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 P4SMA18?

For technical support, including P4SMA18 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your P4SMA18 requirements.

6.How does Aetrix verify that P4SMA18 is sourced from the original manufacturer or authorized distributors?

All P4SMA18 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 P4SMA18 meets industry standards.

7.What is the process for return or replacement of P4SMA18?

All P4SMA18 units undergo pre-shipment inspection (PSI). If there is an issue with P4SMA18, 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 P4SMA18 part is unused and in its original packaging.

Return procedure for P4SMA18:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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