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onsemi 1SMA33CAT3
- Part No.:
- 1SMA33CAT3
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA33CAT3.pdf
- Description:
- TVS DIODE 33VWM 53.3VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:2,282
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Product details
Overview
1SMA33CAT3 from ON Semiconductor is a bidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for clamping high-energy 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 <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 1SMA33CAT3 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, package dimensions, real-world clamping behavior, ESD robustness (Class 3, >16 kV HBM), and direct alternative part comparisons for overvoltage protection design-in.
Technical Context
The 1SMA33CAT3 operates as a bidirectional avalanche diode, symmetrically clamping both positive and negative transients above its breakdown voltage range (36.7–40.56 V). Its low zener impedance and fast <1 ns response enable effective suppression of EFT (IEC 61000-4-4) and ESD (IEC 61000-4-2) events without affecting normal circuit operation.
It is rated for 400 W peak pulse power (10/1000 µs waveform), with thermal resistance of 250 °C/W (junction-to-ambient) on FR-4 board and 50 °C/W (junction-to-lead). The device uses ON Semiconductor's SURMETIC® SMA package (Case 403D), optimized for surface-mount reliability and automated placement.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 33 V - Maximum continuous reverse operating voltage before clamping begins; sets minimum system rail margin. |
| VBR (min/typ/max) | 36.7 / 38.63 / 40.56 V - Breakdown occurs within this band at 1 mA test current; defines turn-on threshold tolerance. |
| VC @ IPP | 53.3 V @ 7.5 A - Clamping voltage during 10/1000 µs surge; determines maximum stress on downstream ICs. |
| PPK | 400 W - Peak pulse power handling capability; validates compliance with IEC 61000-4-5 Level 3 (1 kV/2 Ω). |
| CJ (at 0 V) | 190 pF - Junction capacitance at zero bias; impacts high-frequency signal integrity in data line protection. |
| IR @ VRWM | 2.5 µA - Reverse leakage at rated working voltage; ensures minimal standby power loss in battery-powered systems. |
| Response Time | <1 ns - Time to reach clamping voltage after transient onset; critical for protecting fast logic and ADC inputs. |
Pinout & Package
Package: SMA (Case 403D), surface-mount, bidirectional, cathode-indicated by band marking. Dimensions: 4.06–4.57 mm length × 2.29–2.92 mm width × 1.97–2.20 mm height. Pb-free, RoHS-compliant, AEC-Q101 qualified.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient return path (bidirectional) | Connects to protected line; conducts during negative surges relative to cathode. |
| Cathode | Transient return path (bidirectional) | Marked with band; conducts during positive surges relative to anode; symmetrical conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating signal lines without polarity concerns. |
| 400 W peak pulse rating | Supports IEC 61000-4-5 surge testing up to 1 kV open-circuit / 0.5 kV short-circuit with 2 Ω source impedance. |
| ESD rating Class 3 (>16 kV HBM) | Eliminates need for additional ESD diodes in front-end interfaces exposed to human contact. |
| Low profile SMA package | 0.76–1.52 mm height enables use in space-constrained automotive ECUs and portable medical devices. |
| AEC-Q101 qualification | Validated for automotive under-hood and infotainment applications requiring extended temperature (-65°C to +150°C) reliability. |
Applications
| Automotive Power Rail Protection | Industrial PLC Analog Input Protection |
|---|---|
Use Scenario: Protecting 12 V/24 V vehicle power distribution networks from load dump and alternator ripple transients. IC Role / Device Role / Timing Role: Bidirectional TVS placed between power rail and ground to clamp ±100 V spikes within 1 ns. Use Value: Prevents latch-up or permanent damage to microcontrollers and CAN transceivers during ISO 7637-2 Pulse 5a events. | Use Scenario: Shielding 4–20 mA current loop inputs in programmable logic controllers from field wiring induced surges. IC Role / Device Role / Timing Role: Low-capacitance (190 pF) TVS across input terminals to suppress EFT bursts without distorting analog signal fidelity. Use Value: Maintains measurement accuracy while meeting IEC 61000-4-4 Level 4 immunity requirements (4 kV contact discharge). |
| Medical Equipment ESD Interface | AC-DC Adapter Overvoltage Clamp |
Use Scenario: Guarding USB and serial ports on diagnostic imaging devices against operator ESD events. IC Role / Device Role / Timing Role: Bidirectional clamping diode mounted directly at connector, shunting >16 kV HBM discharges to ground. Use Value: Achieves IEC 61000-4-2 Level 4 compliance without adding series impedance that degrades signal rise time. | Use Scenario: Suppressing output overvoltage transients in offline AC-DC adapters caused by transformer saturation or feedback failure. IC Role / Device Role / Timing Role: Parallel-connected TVS across secondary-side output capacitor to clamp sustained overvoltage to ≤53.3 V. Use Value: Prevents catastrophic failure of downstream DC-DC converters and protects connected loads during fault conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SZ1SMA33CAT3G | Identical electrical specs; AEC-Q101 certified with PPAP documentation support. | Required for automotive OEM designs needing full traceability and process control. | Select when automotive qualification and change control per AEC-Q101 are mandatory. |
| 1SMA33AT3G | Unidirectional version; same VRWM (33 V), but only clamps positive transients (anode grounded). | Suitable only where polarity is fixed and negative transients are absent or handled separately. | Choose only if circuit topology guarantees unidirectional surge exposure and grounding allows anode-to-ground configuration. |
Compared with 1SMA33CAT3, SZ1SMA33CAT3G adds automotive-grade documentation and process controls without altering electrical performance, while 1SMA33AT3G trades bidirectionality for slightly lower capacitance (185 pF) but requires strict polarity-aware layout.
Availability
1SMA33CAT3 is available at Aetrix Electronics and suitable for automotive power rail protection, industrial PLC analog input protection, and medical equipment ESD interface applications requiring stable component supply and long-term manufacturing continuity.
Supply support for 1SMA33CAT3 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 energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, and consumer markets.
The 1SMAxxCAT3G series belongs to ON Semiconductor's SURMETIC® TVS portfolio, engineered specifically for high-reliability transient suppression in harsh environments including automotive under-hood, factory automation, and medical diagnostics equipment.
FAQ
What is the clamping voltage of the 1SMA33CAT3 under a standard 10/1000 µs surge?
The 1SMA33CAT3 has a maximum clamping voltage (VC) of 53.3 V when subjected to a 7.5 A peak pulse current with a 10/1000 µs waveform. This value is guaranteed per the datasheet's Electrical Characteristics table and represents the upper limit of voltage seen by protected circuitry during surge events, ensuring downstream components remain within safe operating limits.
Is the 1SMA33CAT3 suitable for automotive applications?
Yes, the 1SMA33CAT3 is suitable for non-safety-critical automotive applications. While the base 1SMA33CAT3 variant is not AEC-Q101 certified, its identical counterpart SZ1SMA33CAT3G is fully qualified. The 1SMA33CAT3 shares the same electrical specs, SURMETIC® package, and -65°C to +150°C operating range, making it appropriate for infotainment, body control, and lighting modules where full PPAP is not mandated.
How does the bidirectional nature of the 1SMA33CAT3 affect its PCB layout?
The 1SMA33CAT3 is symmetrically bidirectional, meaning either terminal can serve as anode or cathode depending on transient polarity-no orientation dependency exists beyond the cathode band marking for consistency. Layout requires equal trace impedance to ground from both terminals, and no series resistors or polarity-sensitive filtering upstream, unlike unidirectional TVS devices such as 1SMA33AT3G.
What is the junction capacitance of the 1SMA33CAT3 and how does it impact high-speed signal lines?
The 1SMA33CAT3 exhibits a typical junction capacitance of 190 pF at 0 V bias. This value limits its use on high-speed digital lines (e.g., USB 2.0, HDMI) where sub-5 pF loading is required, but it remains appropriate for lower-frequency analog signals (e.g., 4–20 mA loops, RS-485 at ≤1 Mbps) and DC power rails where capacitance does not degrade functionality.
Can the 1SMA33CAT3 replace the 1SMA33AT3G in a design?
No-the 1SMA33CAT3 cannot directly replace the 1SMA33AT3G without circuit review. The 1SMA33AT3G is unidirectional (anode grounded), while the 1SMA33CAT3 is bidirectional. Substituting introduces unintended conduction paths during normal operation if the grounding scheme assumes unidirectional behavior, potentially causing leakage or latch-up. Verify topology and grounding before interchange.
1SMA33CAT3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- 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:
- -
- Capacitance @ Frequency:
- 190pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA33CAT3 FAQ
1.How can I place an order for 1SMA33CAT3 through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA33CAT3 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 1SMA33CAT3 reliable?
The price and inventory of 1SMA33CAT3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA33CAT3 is usually 5 days.
3.What payment methods are accepted for 1SMA33CAT3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA33CAT3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA33CAT3?
1SMA33CAT3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA33CAT3 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 1SMA33CAT3?
For technical support, including 1SMA33CAT3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA33CAT3 requirements.
6.How does Aetrix verify that 1SMA33CAT3 is sourced from the original manufacturer or authorized distributors?
All 1SMA33CAT3 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 1SMA33CAT3 meets industry standards.
7.What is the process for return or replacement of 1SMA33CAT3?
All 1SMA33CAT3 units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA33CAT3, 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 1SMA33CAT3 part is unused and in its original packaging.
Return procedure for 1SMA33CAT3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA33CAT3 Tags
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