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onsemi 1SMA33AT3
- Part No.:
- 1SMA33AT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA33AT3.pdf
- Description:
- TVS DIODE 33VWM 53.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:7,781
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Product details
Overview
1SMA33AT3 from ON Semiconductor is a unidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping overvoltage transients in DC power rails and signal lines. It features a 33 V working peak reverse voltage (VRWM), 53.3 V clamping voltage at 7.5 A peak pulse current, and sub-1 ns response time. It is used in automotive power supply protection, industrial PLC I/O modules, and medical equipment surge interfaces.
For engineers reviewing the 1SMA33AT3 datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM margin vs. system operating voltage, clamping voltage headroom relative to protected IC absolute maximum ratings, thermal derating above 75°C, and junction capacitance (375 pF @ 0 V) in high-speed signal line applications.
Technical Context
The 1SMA33AT3 operates as a unidirectional Zener-based TVS diode, leveraging avalanche breakdown to clamp transients above its VRWM of 33 V. Its 53.3 V clamping voltage is guaranteed at 7.5 A IPP under 10/1000 µs waveform, with low zener impedance enabling stable voltage limiting during surge events.
It uses a planar silicon junction structure in an SMA (DO-214AC) package with cathode polarity band marking. Thermal performance is defined by 20 °C/W junction-to-lead resistance and 250 °C/W junction-to-ambient resistance on FR-4 board with minimum footprint, supporting reliable operation up to 150 °C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 33 V - Maximum continuous reverse operating voltage before clamping begins; must exceed circuit's max DC or peak AC voltage. |
| VBR @ IT=1 A | 36.7–40.6 V - Breakdown voltage range confirming Zener conduction onset; ensures predictable turn-on behavior across production lot. |
| VC @ IPP=7.5 A | 53.3 V - Clamping voltage under 10/1000 µs surge; defines worst-case voltage seen by downstream components during ESD or lightning-induced transients. |
| PPK | 400 W - Peak pulse power handling for 1 ms non-repetitive surge; determines survivability against IEC 61000-4-5 Level 4 surges. |
| CJ @ 0 V, 1 MHz | 375 pF - Junction capacitance affecting high-frequency signal integrity; limits use in >10 Mbps data lines without filtering trade-offs. |
| ESD Rating | Class 3 (>16 kV HBM) - Confirms robustness against human-body model ESD events; suitable for front-end ports exposed to handling. |
Pinout & Package
SMA (DO-214AC) surface-mount package: molded plastic case with flat handling surface, cathode indicated by polarity band, low profile (max height 2.20 mm), and RoHS-compliant Pb-free construction. Mounting position is unrestricted; compatible with top-slide or bottom-board placement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Anode of internal Zener junction | Connected to higher-potential node (e.g., VIN rail); clamps when voltage exceeds VRWM relative to anode. |
| Anode (non-banded end) | Cathode of internal Zener junction | Typically tied to ground or lower-potential reference; completes clamping path during transient events. |
Key Features
| Feature | Design Value |
|---|---|
| 400 W peak pulse power | Enables single-device protection against IEC 61000-4-5 4 kV surge (2 Ω source) on 24 V systems without parallel staging. |
| 33 V VRWM with 53.3 V clamping | Provides ≥12 V margin below typical 60 V automotive load-dump clamping thresholds while limiting protected IC stress. |
| Sub-1 ns response time | Ensures clamping activation prior to propagation of fast ESD transients (<100 ps rise time), preventing latch-up in CMOS receivers. |
| 375 pF junction capacitance | Permits use on RS-485 buses up to 250 kbps without signal distortion; requires series R or RC filter for >1 Mbps interfaces. |
| AEC-Q101 qualified (SZ variant) | Validates reliability for automotive under-hood applications including engine control units and body electronics modules. |
Applications
| Automotive Power Rail Protection | Industrial PLC Digital Input Protection |
|---|---|
Use Scenario: 12 V/24 V battery-fed ECUs subjected to ISO 7637-2 pulse 1 (−150 V, 2 Ω, 50 ms) and pulse 3a (±150 V, 50 Ω, 150 ns). IC Role / Device Role / Timing Role: Unidirectional TVS placed between power rail and chassis ground to shunt negative transients and clamp positive load-dump spikes. Use Value: Limits rail voltage to ≤53.3 V during 7.5 A surge, protecting 36 V-rated CAN transceivers and microcontroller power domains. |
Use Scenario: 24 V digital input channels in programmable logic controllers exposed to field-wiring inductive kickback and ESD. IC Role / Device Role / Timing Role: Front-end transient suppressor on each optocoupler input, mounted adjacent to connector. Use Value: Absorbs 400 W surges without degradation, maintaining <1 µA leakage at 33 V to preserve input threshold accuracy over temperature. |
| Medical Equipment ESD Interface | Telecom Power Supply Clamp |
Use Scenario: USB and serial port connectors on diagnostic imaging devices requiring IEC 61000-4-2 Level 4 (±15 kV contact) immunity. IC Role / Device Role / Timing Role: Secondary-level TVS after common-mode choke, clamping differential-mode ESD on VBUS and D+/D− lines. Use Value: Responds in <1 ns to divert >16 kV HBM energy, reducing coupled voltage to <53.3 V at IC pins while adding only 375 pF loading. |
Use Scenario: Output stage of 48 V telecom rectifiers subject to lightning-induced surges per GR-1089-CORE. IC Role / Device Role / Timing Role: Primary overvoltage clamp on +48 V output bus, coordinated with upstream MOV and fuse. Use Value: Clamps 10/1000 µs surges to 53.3 V with 400 W rating, preventing damage to downstream DC-DC converters rated for 60 V max input. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ33A | Same VRWM (33 V) and VC (53.3 V), but SMB package (DO-214AA); 600 W peak power rating. | Higher surge capacity suits harsher environments (e.g., railway traction power); larger footprint may conflict with dense PCB layouts. | Select SMBJ33A when 600 W surge margin is required and board space permits SMB footprint. |
| 1.5SMC33A | Same electrical specs (VRWM=33 V, VC=53.3 V), but SMC (DO-214AB) package; 1500 W peak power rating. | Designed for high-energy industrial mains protection; significantly larger size and thermal mass limit use in portable or space-constrained designs. | Choose 1.5SMC33A only for applications demanding >1 kW surge capability and where SMC mounting is feasible. |
Compared with SMBJ33A and 1.5SMC33A, the 1SMA33AT3 offers optimal balance of 400 W surge handling, compact SMA footprint, and proven reliability in automotive and industrial control-making it preferred where board area and cost are constrained but 400 W compliance suffices.
Availability
1SMA33AT3 is available at Aetrix Electronics and suitable for automotive electronics, industrial PLCs, and medical device power interface protection requiring stable component supply and long-term lifecycle support.
Supply support for 1SMA33AT3 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
ON Semiconductor is a global semiconductor manufacturer specializing in power management, analog, sensor, and discrete devices for automotive, industrial, and communications markets.
The 1SMA33AT3 belongs to ON Semiconductor's SMA-series unidirectional TVS family, engineered for robust transient suppression in space-constrained, high-reliability applications such as automotive ECUs and industrial control I/O modules.
FAQ
What is the maximum clamping voltage of the 1SMA33AT3 under standard surge conditions?
The 1SMA33AT3 has a maximum clamping voltage (VC) of 53.3 V when subjected to a 10/1000 µs waveform at 7.5 A peak pulse current (IPP). This value is guaranteed across temperature and production lot, defining the upper voltage limit imposed on protected circuits during transient events. The 1SMA33AT3 maintains this clamping performance without degradation up to 150 °C junction temperature.
Is the 1SMA33AT3 suitable for bidirectional transient suppression?
No, the 1SMA33AT3 is strictly unidirectional and conducts only when reverse-biased beyond its VRWM of 33 V. It does not suppress positive transients on grounded lines or negative transients on VCC-referenced nodes. For bidirectional protection, ON Semiconductor offers the 1SMA33CAT3 (complementary dual-diode configuration); the 1SMA33AT3 must be paired with a second device or replaced with a bidirectional variant for symmetrical surge handling.
What is the junction-to-lead thermal resistance of the 1SMA33AT3, and why does it matter?
The 1SMA33AT3 has a thermal resistance from junction to lead (RJL) of 20 °C/W, measured with zero lead length on a 1″ square copper pad. This parameter governs heat transfer from the silicon die to the PCB copper, directly impacting steady-state power dissipation capability: at 75 °C lead temperature, the device supports 1.5 W continuous power. Proper thermal pad design is essential to maintain reliability during repeated surge events.
How does the 375 pF junction capacitance of the 1SMA33AT3 affect high-speed data line protection?
The 375 pF junction capacitance of the 1SMA33AT3 introduces signal attenuation and rise-time degradation on high-speed lines; it is suitable for RS-232 (≤230 kbps) and RS-485 (≤250 kbps) but not for USB 2.0 or Ethernet PHY interfaces. When used on faster lines, the 1SMA33AT3 must be combined with series impedance (e.g., 10–33 Ω resistor) to isolate capacitance, or replaced with lower-capacitance TVS arrays like the NUP4105MR6T1G for <10 pF requirements.
Does the 1SMA33AT3 meet automotive qualification standards?
The base 1SMA33AT3 is not AEC-Q101 qualified; however, its automotive-grade counterpart SZ1SMA33AT3G is fully AEC-Q101 qualified and PPAP capable. Both share identical electrical specifications and SMA package dimensions, but only the SZ-prefix version undergoes extended temperature cycling, humidity testing, and failure analysis required for under-hood automotive deployment. For automotive programs, specify SZ1SMA33AT3G-not 1SMA33AT3-to ensure compliance.
1SMA33AT3 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):
- 33V
- Voltage - Breakdown (Min):
- 36.7V
- Voltage - Clamping (Max) @ Ipp:
- 53.3V
- Current - Peak Pulse (10/1000µs):
- 7.5A
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- 375pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA33AT3 FAQ
1.How can I place an order for 1SMA33AT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA33AT3 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 1SMA33AT3 reliable?
The price and inventory of 1SMA33AT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA33AT3 is usually 5 days.
3.What payment methods are accepted for 1SMA33AT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA33AT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA33AT3?
1SMA33AT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA33AT3 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 1SMA33AT3?
For technical support, including 1SMA33AT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA33AT3 requirements.
6.How does Aetrix verify that 1SMA33AT3 is sourced from the original manufacturer or authorized distributors?
All 1SMA33AT3 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 1SMA33AT3 meets industry standards.
7.What is the process for return or replacement of 1SMA33AT3?
All 1SMA33AT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA33AT3, 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 1SMA33AT3 part is unused and in its original packaging.
Return procedure for 1SMA33AT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA33AT3 Tags
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