Counterfeit and defect prevention
Visual and packaging inspection
Electrical performance verification
Service Email:
[email protected]
>
P4SMAJ18A
Diotec Semiconductor
TVS SMA 18V 400W UNIDIR
1955 Pcs New Original In Stock
29.2V Clamp 13.7A Ipp Tvs Diode Surface Mount SMA/DO-214AC
Request Quote
(Ships tomorrow)
*Quantity
Minimum 1
Minimum 1
5.0 / 5.0
- (350 Ratings)
P4SMAJ18A
Product Overview
9446797
DiGi Electronics Part Number
P4SMAJ18A-DGManufacturer
Diotec Semiconductor
P4SMAJ18A
Description
TVS SMA 18V 400W UNIDIRInventory
1955 Pcs New Original In Stock
29.2V Clamp 13.7A Ipp Tvs Diode Surface Mount SMA/DO-214AC
Quantity
Minimum 1
Minimum 1
Purchase and inquiry
Warranty & Returns
How to Order
Shipping & Delivery
Quality Assurance
365 - Day Quality Guarantee - Every part fully backed.
90 - Day Refund or Exchange - Defective parts? No hassle.
Limited Stock, Order Now - Get reliable parts without worry.
Global Shipping & Secure Packaging
Worldwide Delivery in 3-5 Business Days
100% ESD Anti-Static Packaging
Real-Time Tracking for Every Order
Secure & Flexible Payment
Credit Card, VISA, MasterCard, PayPal, Western Union, Telegraphic Transfer(T/T) and more
All payments encrypted for security
P4SMAJ18A Technical Specifications
Category
Transient Voltage Suppressors (TVS), TVS Diodes
Packaging
Tape & Reel (TR)
Series
-
Product Status
Active
Type
Zener
Unidirectional Channels
1
Voltage - Reverse Standoff (Typ)
18V
Voltage - Breakdown (Min)
20V
Voltage - Clamping (Max) @ Ipp
29.2V
Current - Peak Pulse (10/1000µs)
13.7A
Power - Peak Pulse
400W
Power Line Protection
No
Applications
General Purpose
Capacitance @ Frequency
-
Operating Temperature
-50°C ~ 150°C (TJ)
Mounting Type
Surface Mount
Package / Case
DO-214AC, SMA
Supplier Device Package
SMA/DO-214AC
Datasheet & Documents
HTML Datasheet
P4SMAJ18A-DG
Environmental & Export Classification
RoHS Status
ROHS3 Compliant
Moisture Sensitivity Level (MSL)
Not Applicable
REACH Status
REACH Unaffected
HTSUS
8541.10.0000
Additional Information
Other Names
2796-P4SMAJ18ATR
4878-P4SMAJ18ADKR
2796-P4SMAJ18ATR-DG
4878-P4SMAJ18ATR
4878-P4SMAJ18ACT
Standard Package
7,500
Alternative Parts
View DetailsPART NUMBER
MANUFACTURER
QUANTITY AVAILABLE
DiGi PART NUMBER
UNIT PRICE
SUBSTITUTE TYPE
Reviews
5.0/5.0-(Show up to 5 Ratings)
грудня 02, 2025
Service après-vente au service du client, très apprécié.
грудня 02, 2025
The craftsmanship in their products is impressive; you can tell they prioritize quality control at every stage.
грудня 02, 2025
DiGi Electronics excels in delivering consistent quality, ensuring customer satisfaction every time.
грудня 02, 2025
The affordability of their offerings makes maintaining my tech setup affordable.
Publish Evalution
Evalution Message
Please enter your review message.
Please post honest comments and do not post ilegal comments.
Frequently Asked Questions (FAQ)
Can the P4SMAJ18A be safely used as a drop-in replacement for the PTVS18VS1UR in a 24V industrial power input protection circuit, and what are the key reliability risks if the system experiences frequent inductive load switching?
While both the P4SMAJ18A and PTVS18VS1UR are 18V unidirectional TVS diodes in SMA packages, direct substitution requires careful evaluation. The P4SMAJ18A has a higher clamping voltage (29.2V at 13.7A) compared to the PTVS18VS1UR’s lower dynamic resistance and typically tighter clamping under fast transients. In a 24V system with frequent inductive switching (e.g., relays or motors), the P4SMAJ18A may allow more voltage overshoot, risking marginal stress on downstream components like MCUs or regulators. Additionally, the P4SMAJ18A is rated for 400W peak pulse power (10/1000µs), whereas the PTVS18VS1UR is optimized for faster 8/20µs waveforms common in surge events. If your transients are primarily slow energy dumps (e.g., relay coils), the P4SMAJ18A may suffice, but for IEC 61000-4-5 surge compliance, the PTVS18VS1UR’s superior response could be critical. Always validate with transient testing under real-world conditions.
What layout and PCB design considerations are critical when using the P4SMAJ18A for protecting a low-voltage ADC input from ESD and fast transients, and how does its unidirectional nature impact grounding strategy?
When using the P4SMAJ18A to protect sensitive ADC inputs, minimize loop inductance by placing the diode as close as possible to the connector or entry point, with short, wide traces to the ground plane. Since the P4SMAJ18A is unidirectional, it only clamps positive transients relative to its cathode; negative spikes below -0.7V will forward-bias the diode and may not be effectively suppressed unless paired with a series resistor or a bidirectional TVS. For mixed-signal systems, connect the TVS ground directly to the analog ground plane near the ADC to avoid ground bounce. Avoid routing sensitive analog traces under or near the TVS footprint to prevent capacitive coupling. Also, ensure the ground return path has low impedance—use multiple vias if necessary—to maintain clamping effectiveness during fast ESD events (e.g., IEC 61000-4-2).
How does the P4SMAJ18A perform in high-temperature environments (e.g., automotive under-hood applications), and what derating or thermal management steps should be taken given its -50°C to 150°C operating range?
The P4SMAJ18A is rated for junction temperatures up to 150°C, making it suitable for harsh environments like automotive under-hood applications. However, its peak pulse power rating (400W) is specified at 25°C and must be derated at higher temperatures—typically by 0.5–0.7% per °C above 25°C. At 125°C ambient, effective pulse handling may drop by 50% or more, increasing the risk of thermal runaway during repeated or extended transients. To mitigate this, ensure adequate copper pour under the SMA package for heat spreading, avoid placing heat-sensitive components nearby, and consider using a TVS with higher thermal mass or active cooling if surge events are frequent. Also, verify long-term reliability through HTRB (High-Temperature Reverse Bias) testing if used near the upper temperature limit.
Is the P4SMAJ18A suitable for protecting USB 2.0 data lines, and how does its capacitance and clamping behavior compare to low-capacitance alternatives like the NXP PESD18VS1UT?
The P4SMAJ18A is not ideal for USB 2.0 data line protection due to its relatively high junction capacitance (typically >50pF, though not specified in the datasheet), which can distort high-speed differential signals and cause impedance mismatches, leading to signal integrity issues or failed USB compliance testing. In contrast, devices like the NXP PESD18VS1UT are designed specifically for high-speed interfaces with capacitance below 1pF. Additionally, the P4SMAJ18A’s clamping voltage of 29.2V exceeds the absolute maximum ratings of most USB PHYs (typically 3.6V or 5V). For USB protection, use ultra-low capacitance, precision-clamped TVS arrays. Reserve the P4SMAJ18A for power rail or low-speed signal protection where capacitance and precise clamping are less critical.
What are the risks of using the P4SMAJ18A in a 12V automotive system where load dump events (ISO 7637-2 Pulse 5) are expected, and how should it be coordinated with upstream fusing or regulators?
Using the P4SMAJ18A alone in a 12V automotive system exposed to ISO 7637-2 load dump (which can reach 87V for 400ms) presents significant risks. The P4SMAJ18A’s breakdown voltage starts at 20V and clamps at 29.2V—far below the 87V transient peak—so it will conduct heavily but may fail due to excessive energy dissipation. A single P4SMAJ18A cannot absorb the full 400W·ms energy of a load dump without additional support. To mitigate this, combine it with a series PTC fuse or polyfuse to limit current, and place a robust DC-DC regulator or buck converter downstream that can tolerate the clamped voltage and provide secondary regulation. Alternatively, use a higher-voltage TVS (e.g., 33V or 40V class) rated for automotive load dump, or a multi-stage protection scheme with a bulk capacitor and MOSFET-based active clamp. Always perform system-level surge testing to validate survival under worst-case conditions.
Quality Assurance (QC)
DiGi ensures the quality and authenticity of every electronic component through professional inspections and batch sampling, guaranteeing reliable sourcing, stable performance, and compliance with technical specifications, helping customers reduce supply chain risks and confidently use components in production.
P4SMAJ18A CAD Models
Diotec Semiconductor P4SMAJ18A PCB symbols & footprints
productDetail
