My Inquiry
My Account
onsemi 1SMA18CAT3G
- Part No.:
- 1SMA18CAT3G
- Manufacturer:
- onsemi
- Category:
- TVS Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
1SMA18CAT3G.pdf
- Description:
- TVS DIODE 18VWM 29.2VC SMA
- Quantity:
- Payment:
- Shipping:
Inventory:13,267
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
1SMA18CAT3G from ON Semiconductor is a bidirectional 400 W peak power Zener transient voltage suppressor (TVS) designed for overvoltage protection of sensitive electronics. It features a 18 V working peak reverse voltage (VRWM), 29.2 V clamping voltage at 13.7 A peak pulse current, and <1 ns response time. It is used in automotive power supplies, industrial control interfaces, and medical equipment input stages.
For engineers reviewing the 1SMA18CAT3G datasheet, pinout, applications, or equivalent options, key selection criteria include VRWM ≥ circuit operating voltage, VC margin relative to IC absolute maximum ratings, surge current capability under 10/1000 µs waveform, and junction capacitance (335 pF at 0 V) for high-speed signal line compatibility.
Technical Context
The 1SMA18CAT3G operates as a bidirectional avalanche diode, symmetrically clamping both positive and negative transients above its breakdown threshold. Its low zener impedance and fast <1 ns response enable effective suppression of ESD (Class 3, >16 kV HBM) and lightning-induced surges without affecting normal signal integrity.
It is rated for 400 W non-repetitive peak power at 1 ms pulse width (10/1000 µs waveform), with thermal derating to 0.5 W DC power at TA = 25°C and 1.5 W at TL = 75°C. The device uses ON Semiconductor's SURMETIC® SMA package (Case 403D), optimized for surface-mount reliability and thermal dissipation on FR-4 PCBs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRWM | 18 V - Maximum continuous reverse operating voltage before clamping begins; must exceed system DC/peak voltage. |
| VBR (min/typ/max) | 20.0 / 21.06 / 22.11 V @ 1.0 mA - Confirmed avalanche onset range; ensures predictable turn-on behavior. |
| VC @ IPP | 29.2 V @ 13.7 A - Clamping voltage during 10/1000 µs surge; defines maximum voltage seen by protected circuit. |
| IPP | 13.7 A - Peak pulse current supported at rated clamping voltage; determines surge energy handling (400 W). |
| CJ (0 V) | 335 pF - Junction capacitance at zero bias; impacts high-frequency signal integrity on data lines. |
| Response Time | <1 ns - Time from transient onset to clamping activation; critical for ESD and fast-rising spikes. |
| ESD Rating | Class 3 (>16 kV) per HBM - Validated robustness against human-body model electrostatic discharge events. |
Pinout & Package
Package: SMA (Case 403D), surface-mount, Pb-free, low-profile plastic package with flat handling surface for accurate placement and top/bottom board mounting capability. Cathode polarity notch does not indicate electrical polarity; device is bidirectional.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Transient current sink (negative half-cycle) | Conducts during negative voltage excursions; symmetrical with cathode for bidirectional clamping. |
| Cathode | Transient current sink (positive half-cycle) | Conducts during positive voltage excursions; identical electrical role to anode due to bidirectional design. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional clamping | Enables single-device protection of AC-coupled or floating signal lines without polarity concerns. |
| 400 W peak power rating | Supports IEC 61000-4-5 Level 4 surge immunity (4 kV line-to-line, 2 Ω source impedance) in properly designed layouts. |
| 335 pF junction capacitance | Compatible with RS-485, CAN, and industrial Ethernet PHYs where capacitance ≤500 pF is required. |
| AEC-Q101 qualified (SZ variant) | Validated for automotive under-hood and infotainment applications; 1SMA18CAT3G shares same die and process. |
| Flat handling surface | Ensures consistent pick-and-place accuracy and solder joint uniformity in automated SMT assembly. |
Applications
| Automotive Power Input Protection | Industrial RS-485 Interface |
|---|---|
Use Scenario: Protecting 12 V battery-fed ECUs from load dump (ISO 7637-2 Pulse 5a) and jump-start transients. IC Role / Device Role: Primary overvoltage clamp placed at connector entry point before DC-DC converter input. Use Value: Limits voltage to ≤29.2 V during 13.7 A surge, preventing damage to downstream regulators and microcontrollers. | Use Scenario: Shielding RS-485 transceivers (e.g., SN65HVD230) from ESD and cable-induced surges in factory automation networks. IC Role / Device Role: Bidirectional TVS across differential bus lines (A/B) and common-mode to ground. Use Value: 335 pF capacitance avoids signal edge degradation at 10 Mbps; <1 ns response prevents latch-up during contact discharge. |
| Medical Equipment ESD Protection | AC-DC Adapter Input Stage |
Use Scenario: Safeguarding front-panel USB and serial ports on diagnostic devices against clinical ESD events (IEC 61000-4-2 ±8 kV contact). IC Role / Device Role: Localized TVS on each I/O line, mounted adjacent to connector. Use Value: Class 3 (>16 kV HBM) rating exceeds IEC 61000-4-2 requirements; bidirectional operation eliminates polarity routing errors. | Use Scenario: Suppressing line surges (IEC 61000-4-5) on primary-side rectifier outputs in universal-input switch-mode power supplies. IC Role / Device Role: Clamp across bulk capacitor terminals to limit transient overvoltage during lightning strikes. Use Value: 400 W peak power handles 10/1000 µs surges up to 13.7 A without thermal runaway or parameter shift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar transient voltage suppression applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18CA | Same VRWM (18 V), higher PPK (600 W), larger SMB package (Case 403AC), 350 pF CJ | Higher surge margin for harsher environments; requires larger PCB footprint | Select when 600 W surge rating is mandatory and board space allows SMB footprint. |
| 1.5SMC18CA | Same VRWM (18 V), higher PPK (1500 W), larger SMC package (Case 403AB), 400 pF CJ | Designed for mains-level surge suppression; overqualified for signal-line use | Choose only when legacy SMC layout exists or extreme surge immunity (e.g., outdoor telecom) is required. |
Compared with SMBJ18CA and 1.5SMC18CA, the 1SMA18CAT3G offers optimal balance of 400 W surge capability, compact SMA footprint, and 335 pF capacitance-making it preferred for space-constrained industrial and automotive signal-line protection where moderate surge levels apply.
Availability
1SMA18CAT3G is available at Aetrix Electronics and suitable for automotive power inputs, industrial RS-485 interfaces, and medical equipment ESD protection requiring stable component supply and full traceability.
Supply support for 1SMA18CAT3G 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 logic solutions for automotive, industrial, and cloud power applications.
The 1SMA18CAT3G belongs to ON Semiconductor's SMA-series TVS family, engineered for cost-effective, high-reliability overvoltage protection in space-sensitive consumer, industrial, and automotive systems.
FAQ
What is the clamping voltage of the 1SMA18CAT3G under standard surge conditions?
The 1SMA18CAT3G has a specified clamping voltage (VC) of 29.2 V at 13.7 A peak pulse current (IPP), measured using the 10/1000 µs waveform per IEC 61000-4-5. This value represents the maximum voltage imposed on the protected circuit during a standardized surge event and is confirmed in the Electrical Characteristics table on page 3 of the official ON Semiconductor datasheet for the 1SMA18CAT3G.
Is the 1SMA18CAT3G unidirectional or bidirectional?
1SMA18CAT3G is a bidirectional transient voltage suppressor, meaning it provides symmetrical clamping for both positive- and negative-polarity transients. Its marking code "RTC" and designation "CAT3G" (where "C" indicates bidirectional configuration) confirm this functionality. Unlike unidirectional variants such as 1SMA18AT3G, the 1SMA18CAT3G has no polarity-dependent orientation during PCB placement.
What is the junction capacitance of the 1SMA18CAT3G, and how does it affect high-speed data lines?
The 1SMA18CAT3G exhibits a typical junction capacitance (CJ) of 335 pF at 0 V bias and 1 MHz, as measured per the datasheet. This value is low enough to avoid significant signal distortion on industrial data buses like RS-485 running up to 10 Mbps, but may require careful layout (short traces, ground shielding) when used on USB 2.0 or CAN FD lines where sub-100 pF is preferred.
Does the 1SMA18CAT3G meet automotive qualification standards?
While the 1SMA18CAT3G itself is not AEC-Q101 certified, its SZ-prefix variant SZ1SMA18CAT3G is fully AEC-Q101 qualified and PPAP capable. Both share identical die, electrical specifications, and packaging; only the SZ version undergoes additional automotive-specific testing and traceability controls. For automotive production, engineers should specify SZ1SMA18CAT3G-but 1SMA18CAT3G remains suitable for prototyping and non-safety-critical automotive subsystems.
What is the maximum operating temperature range for the 1SMA18CAT3G?
The 1SMA18CAT3G is rated for an operating and storage temperature range of −65 °C to +150 °C, as stated in the Maximum Ratings table. This wide range supports deployment in under-hood automotive environments, industrial enclosures exposed to ambient extremes, and medical devices requiring sterilization-compatible thermal profiles. Derating curves in Figure 3 confirm usable surge performance up to +125 °C ambient.
1SMA18CAT3G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Package/Case:
- DO-214AC, SMA
- Series:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional 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:
- 335pF @ 1MHz
- Operating Temperature:
- -65°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SMA
1SMA18CAT3G FAQ
1.How can I place an order for 1SMA18CAT3G through Aetrix?
Please submit a Request for Quotation (RFQ) for 1SMA18CAT3G 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 1SMA18CAT3G reliable?
The price and inventory of 1SMA18CAT3G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1SMA18CAT3G is usually 5 days.
3.What payment methods are accepted for 1SMA18CAT3G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1SMA18CAT3G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1SMA18CAT3G?
1SMA18CAT3G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1SMA18CAT3G 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 1SMA18CAT3G?
For technical support, including 1SMA18CAT3G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1SMA18CAT3G requirements.
6.How does Aetrix verify that 1SMA18CAT3G is sourced from the original manufacturer or authorized distributors?
All 1SMA18CAT3G 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 1SMA18CAT3G meets industry standards.
7.What is the process for return or replacement of 1SMA18CAT3G?
All 1SMA18CAT3G units undergo pre-shipment inspection (PSI). If there is an issue with 1SMA18CAT3G, 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 1SMA18CAT3G part is unused and in its original packaging.
Return procedure for 1SMA18CAT3G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1SMA18CAT3G 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
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 …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
