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

Taiwan Semiconductor Corporation SMAJ48

Name: SMAJ48
Brand: Taiwan Semiconductor Corporation
SKU: SMAJ48
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SMAJ48

Manufacturer:: Taiwan Semiconductor Corporation

Category:: TVS Diodes

Package:: DO-214AC, SMA

Datasheet:: SMAJ48.pdf

Description:: 400W, 59.2V, 10%, UNIDIRECTIONAL

Quantity:: RFQ Add To RFQ list

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Inventory:9,250

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Product details

Overview

SMAJ48 from Taiwan Semiconductor is a unidirectional 48 V stand-off transient voltage suppressor (TVS) diode in DO-214AC (SMA) package, rated for 400 W peak pulse power (10/1000 µs), 53.3–65.1 V breakdown voltage at 1 mA, and 85.5 V maximum clamping voltage at 4.7 A, used to protect DC/DC converters and power supply rails against ESD and surge events.

For engineers reviewing the SMAJ48 datasheet, SMAJ48 pinout, SMAJ48 application, or SMAJ48 equivalent, key selection criteria include working voltage margin (48 V V_WM), clamping performance (85.5 V V_C @ 4.7 A), ISO 7637-2 compliance, DO-214AC thermal and mechanical compatibility, and unidirectional polarity marking.

Technical Context

The SMAJ48 operates as a unidirectional avalanche diode with glass-passivated junction, delivering sub-nanosecond response (<1.0 ps from 0 V to V_BR) and low leakage (<1 µA at 48 V). Its clamping behavior follows standardized 10/1000 µs waveform testing per IEC 61000-4-5 and automotive ISO 7637-2 Pulse 1/2a/2b/3a/3b requirements.

Designed for surface-mount automated placement, it features matte tin-plated leads compliant with J-STD-002 solderability, JESD 201 Class 2 whisker resistance, and UL 94V-0 molding compound. Polarity is indicated by cathode band; operating junction temperature spans –55 °C to +150 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
V_WM	48 V - Maximum continuous reverse operating voltage before conduction begins; sets minimum system rail margin.
V_BR @ I_T = 1 mA	53.3–65.1 V - Breakdown voltage range defining reliable avalanche onset; ensures consistent turn-on across production lots.
V_C @ I_PPM = 4.7 A	85.5 V - Clamped voltage during 10/1000 µs surge; determines protected circuit's maximum transient exposure.
P_PPM	400 W - Peak pulse power rating (10/1000 µs); defines surge energy absorption capacity without failure.
I_R @ V_WM	<1 µA - Reverse leakage at 48 V; ensures negligible standby current in always-on power rails.
Package	DO-214AC (SMA) - Industry-standard SMT outline with 0.060 g mass, optimized for thermal dissipation and board-level reliability.

Pinout & Package

DO-214AC (SMA) surface-mount package with axial lead configuration: Cathode marked by band on body; anode and cathode terminals are non-polarized in layout but functionally asymmetric due to unidirectional operation.

Pin/Terminal	Circuit Role	Design Meaning
Anode	Transient return path	Connected to ground or low-impedance reference; completes clamping loop during overvoltage event.
Cathode	Protected line connection	Connected to the 48 V rail being safeguarded; blocks normal operation, conducts only during overvoltage.

Key Features

Feature	Design Value
Fast response time	<1.0 ps - Enables protection of high-speed digital interfaces and switching regulators before damage occurs.
Glass passivated junction	Enhanced reliability and moisture resistance - Supports long-term stability in humid industrial environments per J-STD-020 Level 1.
ISO 7637-2 compliance	Validated for automotive load dump and inductive switching transients (Pulse 1/2a/2b/3a/3b) - Suitable for vehicle DC/DC modules.
RoHS & halogen-free	Meets IEC 61249-2-21 and EU RoHS directives - Enables compliance in consumer, industrial, and automotive end equipment.

Applications

Switching Mode Power Supply (SMPS)	On-board DC/DC Converter
Use Scenario: Protection of primary-side MOSFET gate drivers and secondary-side rectifier outputs against switching-induced voltage spikes and cross-talk. IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed across input/output rails to limit transient overshoot during hard-switching transitions. Use Value: Maintains 48 V rail integrity under 400 W surges, preventing latch-up or gate oxide rupture in downstream ICs.	Use Scenario: Safeguarding isolated 48 V-to-12 V or 48 V-to-5 V buck converter outputs in telecom base stations and server PSUs. IC Role / Device Role / Timing Role: Standoff protector on regulated output node, activated only during line transients or hot-swap events. Use Value: Limits clamped voltage to 85.5 V, ensuring downstream LDOs and PMICs remain within absolute maximum ratings.
Lighting Application	Adapters
Use Scenario: Overvoltage suppression in constant-current LED drivers subjected to lightning-induced surges on AC mains input or 48 V PoE+ feed lines. IC Role / Device Role / Timing Role: Primary-side TVS on bulk capacitor rail to absorb repetitive 10/1000 µs pulses without degradation. Use Value: Withstands ≥1000 surges at rated power per JEDEC standards, extending driver lifetime in outdoor signage.	Use Scenario: Input-stage protection in universal-input AC/DC adapters powering 48 V systems such as USB-C PD docks and industrial chargers. IC Role / Device Role / Timing Role: Secondary-side clamp on DC output connector to prevent user-induced ESD or cable coupling transients from reaching connected devices. Use Value: Low 1 µA leakage avoids no-load power waste; DO-214AC footprint enables compact adapter PCB layouts.

Switching Mode Power Supply (SMPS)

On-board DC/DC Converter

Use Scenario: Protection of primary-side MOSFET gate drivers and secondary-side rectifier outputs against switching-induced voltage spikes and cross-talk.

IC Role / Device Role / Timing Role: Unidirectional TVS clamp placed across input/output rails to limit transient overshoot during hard-switching transitions.

Use Value: Maintains 48 V rail integrity under 400 W surges, preventing latch-up or gate oxide rupture in downstream ICs.

Use Scenario: Safeguarding isolated 48 V-to-12 V or 48 V-to-5 V buck converter outputs in telecom base stations and server PSUs.

IC Role / Device Role / Timing Role: Standoff protector on regulated output node, activated only during line transients or hot-swap events.

Use Value: Limits clamped voltage to 85.5 V, ensuring downstream LDOs and PMICs remain within absolute maximum ratings.

Lighting Application

Adapters

Use Scenario: Overvoltage suppression in constant-current LED drivers subjected to lightning-induced surges on AC mains input or 48 V PoE+ feed lines.

IC Role / Device Role / Timing Role: Primary-side TVS on bulk capacitor rail to absorb repetitive 10/1000 µs pulses without degradation.

Use Value: Withstands ≥1000 surges at rated power per JEDEC standards, extending driver lifetime in outdoor signage.

Use Scenario: Input-stage protection in universal-input AC/DC adapters powering 48 V systems such as USB-C PD docks and industrial chargers.

IC Role / Device Role / Timing Role: Secondary-side clamp on DC output connector to prevent user-induced ESD or cable coupling transients from reaching connected devices.

Use Value: Low 1 µA leakage avoids no-load power waste; DO-214AC footprint enables compact adapter PCB layouts.

Equivalent & Alternatives

The following parts are listed as comparable options for similar transient suppression applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SMAJ48A	Narrower V_BR range (53.3–58.9 V) and lower clamping voltage (77.4 V @ 5.2 A); tighter tolerance improves precision clamping.	Better suited for systems requiring tighter voltage margins below 80 V, e.g., 48 V battery management inputs.	Select SMAJ48A when clamping consistency and reduced V_C outweigh need for higher I_PPM headroom.
SMBJ48	Same V_WM/V_BR specs but in larger DO-214AA (SMB) package; 600 W P_PPM rating (10/1000 µs).	Preferred where higher surge energy handling is required and PCB space allows SMB footprint.	Choose SMBJ48 for enhanced robustness in harsh environments (e.g., industrial motor drives) where 400 W may be marginal.

Compared with SMAJ48A and SMBJ48, the SMAJ48 balances cost-effective DO-214AC packaging, verified 400 W surge capability, and broad automotive/industrial qualification-making it optimal for space-constrained 48 V power rails where standard clamping performance suffices.

Availability

SMAJ48 is available at Aetrix Electronics and suitable for switching mode power supplies, on-board DC/DC converters, and lighting applications requiring stable component supply, full traceability, and lifecycle continuity.

Supply support for SMAJ48 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 analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, specializing in TVS diodes, rectifiers, and power MOSFETs for industrial and automotive markets.

The SMAJ series was developed specifically for surface-mount transient suppression in compact, high-reliability power conversion systems-emphasizing fast response, low leakage, and international surge standard compliance.

FAQ

What is the maximum clamping voltage of the SMAJ48 under a 10/1000 µs surge?

The SMAJ48 has a maximum clamping voltage (V_C) of 85.5 V when subjected to its rated peak pulse current of 4.7 A using the standardized 10/1000 µs waveform. This value is measured per IEC 61000-4-5 and defines the highest voltage the protected circuit will experience during a worst-case transient event. The SMAJ48 maintains this clamping performance across its qualified operating temperature range.

Is the SMAJ48 unidirectional or bidirectional, and how is polarity identified?

The SMAJ48 is a unidirectional TVS diode, meaning it conducts only in reverse bias during overvoltage events. Polarity is identified by a cathode band marked on the DO-214AC (SMA) package body; the banded end connects to the protected 48 V rail, while the unbanded end connects to ground. Bidirectional variants use "CA" suffixes (e.g., SMAJ48CA), which the SMAJ48 does not carry.

Does the SMAJ48 meet automotive transient immunity standards?

Yes, the SMAJ48 meets ISO 7637-2 for automotive electrical disturbances, covering Pulse 1 (inductive load disconnect), Pulse 2a/2b (load dump simulation), and Pulses 3a/3b (capacitive coupling). Its 400 W peak pulse power rating, fast <1.0 ps response, and specified clamping behavior under 10/1000 µs waveforms make it suitable for protecting ECUs, body control modules, and DC/DC converters in 12 V/48 V vehicle architectures.

What is the junction temperature limit and derating behavior of the SMAJ48?

The SMAJ48 has a maximum operating junction temperature (T_J) of +150 °C and a storage range of –55 °C to +150 °C. Its peak pulse power rating derates linearly above 25 °C ambient, per Figure 2 in the official datasheet; at 85 °C ambient, the usable P_PPM drops to approximately 280 W. Continuous power dissipation is limited to 1 W, making it unsuitable for sustained overvoltage conditions.

How does the SMAJ48 compare to the SMAJ48A in terms of electrical performance?

The SMAJ48A offers a tighter breakdown voltage range (53.3–58.9 V vs. 53.3–65.1 V for SMAJ48) and lower clamping voltage (77.4 V @ 5.2 A vs. 85.5 V @ 4.7 A), resulting in more precise and less stressful transient suppression. Both share identical V_WM (48 V), package (DO-214AC), and compliance qualifications. The SMAJ48A's higher test current (1 mA vs. 1 mA) and narrower V_BR improve design predictability in margin-critical 48 V systems.

SMAJ48 Specifications

Product attributes: Attribute value

Manufacturer:: Taiwan Semiconductor Corporation

Package/Case:: DO-214AC, SMA

Series:: SMAJ

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: Zener

Unidirectional Channels:: 1

Bidirectional Channels:: -

Voltage - Reverse Standoff (Typ):: 48V

Voltage - Breakdown (Min):: 53.3V

Voltage - Clamping (Max) @ Ipp:: 85.5V

Current - Peak Pulse (10/1000µs):: 4.7A

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)

SMAJ48 FAQ

1.How can I place an order for SMAJ48 through Aetrix?

Please submit a Request for Quotation (RFQ) for SMAJ48 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 SMAJ48 reliable?

The price and inventory of SMAJ48 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ48 is usually 5 days.

3.What payment methods are accepted for SMAJ48?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ48 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SMAJ48?

SMAJ48 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SMAJ48 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 SMAJ48?

For technical support, including SMAJ48 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ48 requirements.

6.How does Aetrix verify that SMAJ48 is sourced from the original manufacturer or authorized distributors?

All SMAJ48 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 SMAJ48 meets industry standards.

7.What is the process for return or replacement of SMAJ48?

All SMAJ48 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ48, 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 SMAJ48 part is unused and in its original packaging.

Return procedure for SMAJ48:

1.Submit a request within 90 days.

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

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