My Inquiry
My Account
Taiwan Semiconductor Corporation SMAJ22
- Part No.:
- SMAJ22
- Manufacturer:
- Taiwan Semiconductor Corporation
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
SMAJ22.pdf
- Description:
- 400W, 27.1V, 10%, UNIDIRECTIONAL
- Quantity:
- Payment:
- Shipping:
Inventory:4,806
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SMAJ22 from Taiwan Semiconductor is a unidirectional surface-mount transient voltage suppressor (TVS) diode designed for primary-side overvoltage protection in DC power rails. It features a 22 V working stand-off voltage (VWM), 24.4–29.8 V breakdown voltage (VBR), 39.4 V maximum clamping voltage (VC) at 10.2 A peak pulse current, and 400 W peak pulse power rating with a 10/1000 µs waveform - suitable for automotive load-dump and ISO 7637-2 Pulse 1/2a/2b/3a/3b compliance.
For engineers reviewing the SMAJ22 datasheet, SMAJ22 pinout, SMAJ22 application, or SMAJ22 equivalent, this device is evaluated for robustness in switching mode power supplies, on-board DC/DC converters, lighting drivers, and adapter-level surge protection where fast response (<1 ps), low leakage (<1 µA @ 22 V), and DO-214AC package compatibility are critical selection criteria.
Technical Context
The SMAJ22 operates as a unidirectional avalanche diode, leveraging glass-passivated junction technology to achieve stable breakdown behavior and low capacitance. Its clamping action begins at VBR min = 24.4 V under 1 mA test current and limits transients to ≤39.4 V at 10.2 A IPPM, enabling reliable protection of downstream 24 V logic and power ICs.
Thermally rated for TJ = –55 °C to +150 °C and housed in a DO-214AC (SMA) package with matte tin-plated leads, the SMAJ22 supports automated placement and meets JESD201 Class 2 whisker resistance and UL 94V-0 flammability standards - essential for industrial and automotive-grade board assembly.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VWM | 22 V - Maximum continuous reverse operating voltage before leakage exceeds 1 µA; defines safe DC rail margin for 24 V systems. |
| VBR min / max | 24.4 V / 29.8 V @ 1 mA - Ensures consistent avalanche initiation across production lots; guarantees turn-on within 10% tolerance. |
| VC @ IPPM | 39.4 V @ 10.2 A - Clamping voltage during 10/1000 µs surge; protects 3.3 V/5 V/12 V logic interfaces when placed upstream of LDOs or DC/DC controllers. |
| PPPM | 400 W - Peak pulse power handling per 10/1000 µs waveform; sufficient for ISO 7637-2 Pulse 1 (–150 V/0.5 Ω) and Pulse 2b (−100 V/2 Ω) events. |
| IR @ VWM | <1 µA - Ultra-low reverse leakage preserves battery life and minimizes standby power loss in always-on circuits. |
| Package | DO-214AC (SMA) - Standardized surface-mount outline with 2.54 mm lead pitch; compatible with IPC-7351B footprint and reflow profiles. |
Pinout & Package
DO-214AC (SMA) package: molded plastic case with cathode band marking; anode and cathode terminals aligned along body axis; moisture sensitivity level 1 (per J-STD-020); weight ≈ 0.060 g.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Transient current sink | Connected to protected line (e.g., 24 V rail); conducts surge current to ground during overvoltage events. |
| Anode | Reference node | Typically tied to system ground; establishes reference for clamping threshold and enables unidirectional operation. |
Key Features
| Feature | Design Value |
|---|---|
| Glass-passivated junction | Ensures stable VBR over temperature and lifetime; eliminates parameter drift due to humidity or bias stress. |
| Fast response time <1 ps | Clamps ESD and lightning-induced transients before sensitive ICs experience latch-up or gate oxide damage. |
| Meets ISO 7637-2 Pulse 1/2a/2b/3a/3b | Validated for automotive 12 V/24 V system immunity; supports OEM compliance without additional filtering stages. |
| RoHS & halogen-free | Complies with IEC 61249-2-21 and EU RoHS Directive 2011/65/EU; suitable for green manufacturing and export markets. |
Applications
| Switching Mode Power Supply (SMPS) | On-board DC/DC Converter |
|---|---|
Use Scenario: Input-stage surge suppression on 24 V primary side of isolated flyback or forward converter. IC Role / Device Role / Timing Role: Unidirectional TVS diode placed between input rail and ground to clamp load-dump spikes and inductive kickback. Use Value: Limits transient voltage to ≤39.4 V, preventing damage to primary-side controller ICs (e.g., UC384x, UCC28C4x) and MOSFET gate oxides. | Use Scenario: Protection of point-of-load (POL) buck regulator inputs in telecom or industrial backplanes. IC Role / Device Role / Timing Role: Standoff-rated clamping device absorbing coupled noise from adjacent high-current switching paths. Use Value: Maintains VWM = 22 V margin above nominal 24 V rail while delivering 400 W pulse handling - eliminating need for series impedance or RC snubbers. |
| Lighting Application | Adapter-Level Protection |
Use Scenario: Overvoltage guard for LED driver ICs in outdoor streetlight or architectural lighting systems. IC Role / Device Role / Timing Role: Primary-line TVS suppressing surges induced by nearby lightning strikes or grid switching. Use Value: Withstands repeated 10/1000 µs pulses up to 400 W, extending system MTBF in harsh outdoor environments. | Use Scenario: Secondary-side transient suppression in AC/DC wall adapters powering IoT sensors or USB-C PD accessories. IC Role / Device Role / Timing Role: Fast-clamping diode on 5 V/9 V/12 V output rail to protect connected devices from output overvoltage faults. Use Value: Low IR (<1 µA) avoids loading regulated outputs; DO-214AC footprint enables compact layout in space-constrained adapter PCBs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ22A | Narrower VBR range (24.4–26.9 V vs. 24.4–29.8 V); tighter 5% tolerance; same VWM, VC, and PPPM. | Better suited for precision-clamp designs requiring minimal VBR spread across temperature and lot variance. | Select SMAJ22A when design margins demand tighter breakdown consistency; SMAJ22 remains optimal for cost-sensitive, high-volume applications. |
| P6SMB22A | Same DO-214AA package (not DO-214AC); 22 V VWM; 24.4–26.9 V VBR; 39.4 V VC; 400 W PPPM; higher IR (≤5 µA). | Compatible mechanical fit but requires pad layout verification; slightly higher leakage may affect ultra-low-power systems. | Use P6SMB22A only after confirming footprint compatibility and validating leakage impact on standby current budget. |
Compared with SMAJ22A and P6SMB22A, the SMAJ22 offers broader VBR tolerance for relaxed design margins, lower leakage than P6SMB22A, and guaranteed DO-214AC (SMA) package compliance - making it ideal for automotive and industrial applications where process variation and long-term reliability are prioritized over tight VBR binning.
Availability
SMAJ22 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 support.
Supply support for SMAJ22 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, MOSFETs, and power management components.
The SMAJ series was developed specifically for high-reliability transient suppression in automotive, industrial, and consumer power systems - emphasizing robustness under ISO 7637-2 stress, low leakage, and automated assembly compatibility.
FAQ
What is the maximum clamping voltage of the SMAJ22 under standard test conditions?
The SMAJ22 has a maximum clamping voltage (VC) of 39.4 V when subjected to a 10/1000 µs waveform at 10.2 A peak pulse current (IPPM), measured per IEC 61000-4-5 and ISO 7637-2 standards. This value ensures downstream 24 V-rated ICs remain within safe operating limits during surge events. The SMAJ22 maintains this clamping performance across its full operating temperature range (–55 °C to +150 °C).
Is the SMAJ22 unidirectional or bidirectional, and how is polarity identified?
The SMAJ22 is a unidirectional TVS diode, intended for DC line protection with defined anode and cathode terminals. Polarity is marked by a cathode band on the DO-214AC (SMA) package body - the banded end is the cathode and must be connected toward the protected line (e.g., 24 V rail), while the anode connects to ground. Bidirectional variants use "CA" suffixes (e.g., SMAJ22CA), which the SMAJ22 does not carry.
Does the SMAJ22 meet automotive surge immunity standards?
Yes, the SMAJ22 meets ISO 7637-2 requirements for Pulse 1 (inductive load dump), Pulse 2a (sudden load disconnect), Pulse 2b (supply line interruption), Pulse 3a (capacitive coupling), and Pulse 3b (inductive coupling). Its 400 W peak pulse power rating, fast <1 ps response, and specified clamping behavior under 10/1000 µs waveforms make it suitable for 12 V and 24 V automotive subsystems including body control modules and lighting ECUs.
What is the thermal limit and derating behavior of the SMAJ22?
The SMAJ22 has a maximum junction temperature (TJ MAX) of +150 °C and a storage temperature range of –55 °C to +150 °C. Its peak pulse power rating of 400 W is specified at TA = 25 °C and must be linearly derated above that ambient temperature per Figure 2 in the official datasheet - e.g., ~320 W at 75 °C ambient. Steady-state power dissipation is limited to 1 W, so sustained overvoltage conditions require external current limiting.
Can the SMAJ22 be used in place of the SMAJ22A, and what is the key trade-off?
The SMAJ22 can be substituted for the SMAJ22A in most applications, but with a trade-off in VBR tolerance: SMAJ22 specifies VBR from 24.4 V to 29.8 V (±~11%), while SMAJ22A narrows this to 24.4 V–26.9 V (±~5%). If your design relies on tight clamping onset (e.g., to avoid false triggering near 24 V rail), SMAJ22A is preferred; otherwise, SMAJ22 provides greater process margin and lower unit cost. Both share identical VWM, VC, PPPM, and DO-214AC packaging.
SMAJ22 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):
- 22V
- Voltage - Breakdown (Min):
- 24.4V
- Voltage - Clamping (Max) @ Ipp:
- 39.4V
- Current - Peak Pulse (10/1000µs):
- 10.2A
- 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)
SMAJ22 FAQ
1.How can I place an order for SMAJ22 through Aetrix?
Please submit a Request for Quotation (RFQ) for SMAJ22 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 SMAJ22 reliable?
The price and inventory of SMAJ22 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMAJ22 is usually 5 days.
3.What payment methods are accepted for SMAJ22?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMAJ22 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMAJ22?
SMAJ22 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMAJ22 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 SMAJ22?
For technical support, including SMAJ22 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMAJ22 requirements.
6.How does Aetrix verify that SMAJ22 is sourced from the original manufacturer or authorized distributors?
All SMAJ22 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 SMAJ22 meets industry standards.
7.What is the process for return or replacement of SMAJ22?
All SMAJ22 units undergo pre-shipment inspection (PSI). If there is an issue with SMAJ22, 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 SMAJ22 part is unused and in its original packaging.
Return procedure for SMAJ22:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMAJ22 Tags
-
ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
-
D5V0H1B2LP-7B
Diodes Incorporated
-
D5V0P1B2LP-7B
Diodes Incorporated
-
DESD5V0U1BA-7
Diodes Incorporated
-
ESD5Z5.0T1G
onsemi
-
DESD5V0U1BB-7
Diodes Incorporated
-
D12V0L1B2LP-7B
Diodes Incorporated
-
PESD2V0Y1BSFYL
Nexperia USA Inc.
-
DF2S5M4CT,L3F
Toshiba Semiconductor and Storage
-
D5V0L1B2WS-7
Diodes Incorporated
Tech Hub
Comparator circuit design covering voltage thresholds, input limits, open-collector outputs, LM393 wiring, op-amp differences, hysteresis, timing, window detection and practical fault diagnosis.
Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
