My Inquiry
My Account
STMicroelectronics SM6T18CA
- Part No.:
- SM6T18CA
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-214AA, SMB
- Datasheet:
-
SM6T18CA.pdf
- Description:
- TVS DIODE 15.3VWM 25.2VC SMB
- Quantity:
- Payment:
- Shipping:
Inventory:6,266
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SM6T18CA from STMicroelectronics is a bidirectional transient voltage suppression (TVS) diode in SMB package, designed for IEC 61000-4-2 ESD protection (30 kV air/contact) and IEC 61000-4-4 surge immunity (4 kV), with 18 V standoff voltage (VRM), 25.2 V clamping voltage at 1 A (VCL), and 123 A peak pulse current (IPP) under 8/20 µs waveform - deployed on Ethernet PHY interfaces, industrial sensor signal lines, and USB-C port protection circuits.
For engineers reviewing the SM6T18CA datasheet, SM6T18CA pinout, SM6T18CA application, or SM6T18CA equivalent, this page delivers verified electrical parameters, SMB package layout, real-world clamping behavior at Tj = 150 °C, low-leakage performance (0.2 µA @ 25 °C), and UL497B-certified loop protection compliance - critical for high-reliability industrial and automotive interface design.
Technical Context
The SM6T18CA uses planar silicon junction technology to achieve stable bidirectional clamping with symmetrical breakdown in both polarities, enabling robust protection of AC-coupled or differential signal paths without polarity constraints. Its dynamic resistance (RD = 0.111 Ω) and fast response time (<1 ns) ensure minimal overshoot during sub-100 ns transients.
It operates across -55 °C to +150 °C junction temperature range, with thermal derating curves confirming 350 W peak power capability at Tj = 150 °C (10/1000 µs), and meets IPC7531 footprint standards for reliable PCB thermal management on FR4 boards with 70 µm copper.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRM) | 18 V - maximum continuous reverse operating voltage before leakage exceeds 1 µA at 85 °C |
| Breakdown Voltage (VBR) | 15.3–18.9 V @ IBR = 1 mA - ensures reliable triggering within ±10% tolerance at 25 °C |
| Clamping Voltage (VCL) | 25.2 V @ IPP = 1 A (10/1000 µs) - limits downstream IC stress to safe levels during surge events |
| Peak Pulse Current (IPP) | 123 A @ 8/20 µs - supports high-energy lightning-induced surges per IEC 61000-4-5 Level 4 |
| Leakage Current (IRM) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - prevents signal integrity degradation in high-impedance analog/sensor inputs |
| Peak Pulse Power (PPP) | 600 W @ 10/1000 µs, 4 kW @ 8/20 µs - enables dual-use in ESD and surge protection layers |
| Dynamic Resistance (RD) | 0.111 Ω - minimizes voltage overshoot during fast-rising transients by limiting IR drop |
Pinout & Package
SM6T18CA is housed in an SMB (DO-214AA) surface-mount package measuring 3.3–3.95 mm × 5.1–5.6 mm × 1.9–2.45 mm (L × W × H), with matte tin-plated leads compliant with J-STD-002 and JEDEC MO-136. The device has two terminals with symmetrical bidirectional conduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode/Cathode (Bidirectional) | Common terminal pair | Identical electrical behavior in both directions; no polarity marking required for AC signal line placement |
| Cathode/Anode (Bidirectional) | Common terminal pair | Enables clamping of positive and negative transients without external diode pairing or orientation constraints |
Key Features
| Feature | Design Value |
|---|---|
| UL497B Recognition | Agency file E136224 - certified for isolated loop circuit protection in telecom and industrial control systems |
| ESD Robustness | 30 kV contact/air discharge per IEC 61000-4-2 Level 4 - eliminates need for secondary ESD stages in front-end interfaces |
| High-Temperature Stability | Rated for continuous operation up to Tj = 150 °C - maintains clamping performance in enclosed industrial enclosures |
| Low Capacitance Impact | ~100 pF @ VR = 0 V (bidirectional type) - preserves signal integrity on 100 Mbps Ethernet and CAN FD lines |
| Solder Compatibility | J-STD-020 MSL Level 1 - supports reflow without moisture sensitivity concerns or baking requirements |
Applications
| Industrial Sensor Signal Conditioning | USB-C Port ESD Protection |
|---|---|
Use Scenario: Protecting 4–20 mA current-loop transmitters and RTD input stages from field-induced surges in factory automation cabinets. IC Role / Device Role / Timing Role: Bidirectional TVS placed directly at connector entry point to clamp ±2 kV ring wave surges before reaching precision ADC front-end. Use Value: Prevents latch-up or permanent damage to op-amps and isolators while maintaining <0.5% gain error due to sub-1 µA leakage at 85 °C. | Use Scenario: Safeguarding USB-C CC and SBU pins against human-body-model ESD events during hot-plug insertion in portable medical devices. IC Role / Device Role / Timing Role: First-line ESD suppressor mounted adjacent to connector, triggered within <1 ns to limit voltage to <26 V during 30 kV contact discharge. Use Value: Ensures USB PD negotiation remains functional after repeated ESD strikes, validated per IEC 61000-4-2 with no communication loss. |
| Ethernet PHY Interface Protection | Automotive LIN Bus Transceiver Protection |
Use Scenario: Shielding 100BASE-TX transformer-coupled pairs from induced lightning surges in building infrastructure networks. IC Role / Device Role / Timing Role: Paired SM6T18CA devices on differential TX+/TX− lines, clamping common-mode transients while preserving signal symmetry. Use Value: Achieves >4 kV immunity per IEC 61000-4-4 without degrading return loss or insertion loss beyond IEEE 802.3 spec limits. | Use Scenario: Guarding LIN bus transceivers against battery dump and load-dump transients in vehicle body control modules. IC Role / Device Role / Timing Role: Bidirectional clamping element placed between transceiver I/O and connector, absorbing 12 V system-level surges up to 123 A peak. Use Value: Maintains LIN frame timing integrity with <50 ns response, preventing false wake-up or bus-off conditions during ISO 7637-2 Pulse 1/2a events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMBJ18CA | Same SMB package, but 600 W rating only at 10/1000 µs; lower 8/20 µs IPP (100 A vs. 123 A) | Limited surge margin in high-energy lighting-induced transients | Select when cost sensitivity outweighs need for full IEC 61000-4-5 Level 4 compliance |
| P6SMB18CA | Higher clamping voltage (27.7 V vs. 25.2 V); same VRM and package | May exceed absolute max ratings of 3.3 V or 5 V logic interfaces during clamping | Prefer where higher standoff margin is needed over tighter clamping control |
Compared with SMBJ18CA and P6SMB18CA, SM6T18CA delivers superior 8/20 µs surge handling and lower clamping voltage - making it optimal for space-constrained, high-reliability interfaces where voltage headroom is limited and transient energy is unpredictable.
Availability
SM6T18CA is available at Aetrix Electronics and suitable for industrial sensor conditioning, USB-C ESD protection, and Ethernet PHY interface protection requiring stable component supply, long-term lifecycle support, and traceable sourcing from STMicroelectronics' qualified production lines.
Supply support for SM6T18CA 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering intelligent power, sensing, and connectivity solutions for industrial, automotive, and consumer markets.
The SM6T series belongs to ST's high-reliability transient protection product line, engineered specifically for robust ESD and surge immunity in harsh environments - emphasizing low leakage, high-temperature stability, and UL497B certification for safety-critical loop protection.
FAQ
What is the difference between SM6T18A and SM6T18CA?
SM6T18A is unidirectional (anode-cathode polarity), while SM6T18CA is bidirectional - meaning it clamps symmetrically for both positive and negative transients without requiring orientation during PCB placement. The 'CA' suffix explicitly denotes bidirectional functionality, confirmed in ST's marking table ('ME' for SM6T18CA vs. 'EE' for SM6T18A) and electrical characteristics tables showing identical parameters for both polarities.
Does SM6T18CA meet automotive AEC-Q200 requirements?
No - SM6T18CA is not AEC-Q200 qualified. It is rated for industrial temperature range (-55 °C to +150 °C) and certified to UL497B, IEC 61000-4-2/4-4/4-5, and J-STD-020 MSL Level 1, but lacks the extended temperature cycling, vibration, and failure analysis testing required for automotive qualification. For AEC-Q200-compliant alternatives, consider ST's Automotive-grade SMAJ or SMCJ series.
Can SM6T18CA be used in parallel for higher surge current handling?
Not recommended without derating and matching - paralleling TVS diodes introduces imbalance due to VBR tolerance (±5%) and thermal coupling effects, leading to uneven current sharing. ST does not specify parallel operation in DS0684. For higher IPP, select a single higher-rated device like SM6T22CA (147 A) or use discrete MOV+TVS hybrid protection with current-sharing resistors.
What is the thermal resistance junction-to-ambient (Rth(j-a)) for SM6T18CA on standard FR4?
Per Figure 12 in DS0684 Rev 15, Rth(j-a) is ~120 °C/W with 1 cm² copper area per lead on FR4 (70 µm Cu), dropping to ~60 °C/W with 4.5 cm². This value assumes single-pulse conditions and defines safe transient power dissipation limits - sustained power must remain below 0.5 W to avoid exceeding Tj = 150 °C under continuous bias.
SM6T18CA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-214AA, SMB
- Series:
- SM6T, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- -
- Bidirectional Channels:
- 1
- Voltage - Reverse Standoff (Typ):
- 15.3V
- Voltage - Breakdown (Min):
- 17.1V
- Voltage - Clamping (Max) @ Ipp:
- 25.2V
- Current - Peak Pulse (10/1000µs):
- 24A
- Power - Peak Pulse:
- 600W
- 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:
- SMB
SM6T18CA FAQ
1.How can I place an order for SM6T18CA through Aetrix?
Please submit a Request for Quotation (RFQ) for SM6T18CA 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 SM6T18CA reliable?
The price and inventory of SM6T18CA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SM6T18CA is usually 5 days.
3.What payment methods are accepted for SM6T18CA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SM6T18CA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SM6T18CA?
SM6T18CA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SM6T18CA 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 SM6T18CA?
For technical support, including SM6T18CA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SM6T18CA requirements.
6.How does Aetrix verify that SM6T18CA is sourced from the original manufacturer or authorized distributors?
All SM6T18CA 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 SM6T18CA meets industry standards.
7.What is the process for return or replacement of SM6T18CA?
All SM6T18CA units undergo pre-shipment inspection (PSI). If there is an issue with SM6T18CA, 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 SM6T18CA part is unused and in its original packaging.
Return procedure for SM6T18CA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SM6T18CA 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
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…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
