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STMicroelectronics SMM4F18A-TR
- Part No.:
- SMM4F18A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-222AA
- Datasheet:
-
SMM4F18A-TR.pdf
- Description:
- TVS DIODE 18VWM 39.3VC DO222-AA
- Quantity:
- Payment:
- Shipping:
Inventory:11,799
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Product details
Overview
SMM4F18A-TR from STMicroelectronics is a unidirectional 400 W transient voltage suppression diode designed for primary-level surge protection in DC power rails and signal lines. It features a standoff voltage of 18 V, clamping voltage of 29.2 V at 14 A (10/1000 µs), dynamic resistance of 0.436 Ω, and operates up to 175 °C junction temperature-enabling robust protection in automotive body control modules and industrial PLC I/O interfaces.
For engineers reviewing the SMM4F18A-TR datasheet, SMM4F18A-TR pinout, SMM4F18A-TR application, or SMM4F18A-TR equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low leakage (<0.2 µA @ 25 °C), flat STmite Flat package compatibility with high-density layouts, and IEC 61000-4-2 level 4 ESD immunity (±30 kV contact/air).
Technical Context
The SMM4F18A-TR uses planar silicon avalanche technology to achieve precise breakdown at 20.9–23.1 V (min–max VBR) with tight tolerance and low temperature coefficient (αT = 9.2 × 10−4/°C). Its unidirectional configuration supports anode-to-cathode surge conduction only, requiring correct polarity placement on protected lines.
Thermal design is enabled by its 0.85 mm profile and optimized thermal impedance: Zth(j-a) = ~100 °C/W for single pulses on FR4 with 70 µm copper, and Rth(j-a) drops to <2.5 °C/W with ≥4 cm² copper per lead-critical for sustained surge handling at Tj = 175 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRWM) | 18 V - Maximum continuous reverse operating voltage before clamping begins |
| Breakdown Voltage (VBR) | 20.9–23.1 V @ 1 mA - Ensures reliable triggering margin above nominal rail voltage |
| Clamping Voltage (VCL) | 29.2 V @ 14 A (10/1000 µs) - Limits downstream voltage stress during 400 W transients |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs), 2.5 kW (8/20 µs) - Supports both lightning-induced and EFT surge profiles |
| Leakage Current (IR) | 0.2 µA @ 25 °C, 1 µA @ 85 °C - Minimizes standby power loss in battery-backed systems |
| Junction Temperature Range | −55 to +175 °C - Enables deployment in under-hood automotive and industrial environments |
| Package Dimensions | 2.05 × 3.90 × 0.95 mm (L × W × H) - Ultra-thin STmite Flat footprint saves PCB area vs. SMA/SMB |
Pinout & Package
STmite Flat surface-mount package: 2-terminal unidirectional TVS diode with cathode bar marking. Package outline complies with IPC7531 and JEDEC MO-275 standards; recommended footprint includes 0.75 mm pad width and 2.04 mm center-to-center spacing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (marked side opposite cathode bar) | Surge current return path | Connected to ground or low-impedance reference; completes conduction loop during transient |
| Cathode (bar-marked end) | Protected line connection | Connected to input rail or signal line; clamps voltage relative to anode reference |
Key Features
| Feature | Design Value |
|---|---|
| Flat STmite package (0.85 mm height) | Enables routing under connectors and in ultra-thin consumer/automotive modules |
| IEC 61000-4-2 level 4 compliance | Guarantees ±30 kV contact and air discharge immunity without external circuit redesign |
| High Tj rating (175 °C) | Supports operation in engine control units and motor drives where ambient exceeds 125 °C |
| Low dynamic resistance (0.436 Ω) | Reduces clamping voltage rise under high-current surges, improving protection margin |
| Matt tin lead finish | Ensures solderability and reliability per J-STD-020 MSL level 1 (unlimited floor life) |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Digital Input Card |
|---|---|
|
Use Scenario: Protecting 12 V supply inputs against load dump and ISO 7637-2 pulse 5a/b surges. IC Role / Device Role / Timing Role: Primary clamping device placed directly at connector entry point before LDO regulators. Use Value: Clamps to 29.2 V at 14 A while maintaining <0.2 µA leakage-preserving sleep-mode current budget. |
Use Scenario: Safeguarding 24 V digital input channels from field-wiring induced transients and EFT bursts. IC Role / Device Role / Timing Role: Unidirectional TVS placed between input terminal and optocoupler input stage. Use Value: Withstands repeated 4 kV IEC 61000-4-4 bursts and delivers <1 µA leakage at 85 °C-ensuring long-term channel integrity. |
| USB-C Power Delivery Port | Smart Meter Communication Interface |
|
Use Scenario: Protecting VBUS line in USB-C receptacles against hot-plug and cable discharge events. IC Role / Device Role / Timing Role: Standoff-rated TVS aligned with PD specification's 20 V max VBUS tolerance. Use Value: 18 V VRWM provides 2 V margin below 20 V PD limit while delivering 29.2 V clamping-preventing overvoltage damage to PD controller ICs. |
Use Scenario: Shielding RS-485 transceivers in utility meters from lightning-induced surges on long outdoor runs. IC Role / Device Role / Timing Role: First-stage protection ahead of GDT or secondary TVS array on differential bus lines. Use Value: 2.5 kW (8/20 µs) capability handles partial energy of lightning surges; flat package allows dense layout near connector. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ18A | Higher clamping voltage (32.4 V @ 12.3 A), larger SMA package (2.4 mm height), lower PPP (400 W same, but derated faster above 25 °C) | Less suitable for space-constrained automotive modules; requires more board area and thermal relief | Select when legacy SMA footprint compatibility is required and 3.2 mm height is acceptable |
| 1.5SMC18A | Same VRWM and VBR, but higher VCL (32.4 V @ 12.3 A), larger SMC package (2.7 mm height), higher leakage (1 µA @ 25 °C) | Lower thermal efficiency limits use in high-ambient-temperature industrial enclosures | Choose only if existing SMC footprint reuse is mandatory and clamping margin permits 32.4 V |
Compared with SMAJ18A and 1.5SMC18A, the SMM4F18A-TR delivers tighter clamping (29.2 V vs. ≥32.4 V), 3× lower profile (0.85 mm), and superior high-temperature leakage stability-making it optimal for next-gen compact, thermally demanding designs.
Availability
SMM4F18A-TR is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O protection, and smart meter communication interfaces requiring stable component supply across multi-year production cycles.
Supply support for SMM4F18A-TR 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, specializing in automotive, industrial, and power discrete technologies with vertical manufacturing capabilities.
The SMM4F series belongs to ST's high-reliability TVS portfolio targeting harsh-environment applications; it was engineered specifically for ultra-thin, high-temperature surge protection in automotive and industrial control systems.
FAQ
What is the maximum peak pulse current (IPP) the SMM4F18A-TR can handle?
The SMM4F18A-TR sustains 14.0 A under 10/1000 µs waveform and 76 A under 8/20 µs waveform, as verified in Table 2 of DS5630 Rev 6. These values reflect actual measured clamping performance at Tamb = 25 °C and define safe single-pulse surge limits before parametric shift or failure.
Does the SMM4F18A-TR meet automotive AEC-Q200 requirements?
No-while the SMM4F18A-TR operates up to 175 °C junction temperature and is widely used in automotive applications, it is not AEC-Q200 qualified. ST offers the SMAJ18A-Q variant for AEC-Q200-compliant designs; this part lacks qualification documentation per the datasheet and official ST product status pages.
How does the dynamic resistance (RD) affect clamping performance?
With RD = 0.436 Ω, the SMM4F18A-TR adds minimal voltage rise beyond VBR during surge conduction: VCL = VBR(max) + RD × IPP. This ensures predictable clamping at 29.2 V for 14 A pulses, reducing risk of overvoltage damage to downstream ICs compared to higher-RD alternatives.
Can the SMM4F18A-TR be used in bidirectional configurations?
No-it is strictly unidirectional, with cathode-bar marking indicating polarity-sensitive installation. For bidirectional protection, ST recommends the SMM4F18CA variant (center-tapped, symmetrical clamping); using SMM4F18A-TR in reverse-biased mode risks permanent breakdown due to lack of reverse avalanche rating.
SMM4F18A-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- DO-222AA
- Series:
- SMM4F, TRANSIL™
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Zener
- Unidirectional Channels:
- 1
- Bidirectional Channels:
- -
- Voltage - Reverse Standoff (Typ):
- 18V
- Voltage - Breakdown (Min):
- 20.9V
- Voltage - Clamping (Max) @ Ipp:
- 39.3V
- Current - Peak Pulse (10/1000µs):
- 59A (8/20µs)
- Power - Peak Pulse:
- 400W
- Power Line Protection:
- No
- Applications:
- General Purpose
- Capacitance @ Frequency:
- -
- Operating Temperature:
- -55°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO222-AA
SMM4F18A-TR FAQ
1.How can I place an order for SMM4F18A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMM4F18A-TR 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 SMM4F18A-TR reliable?
The price and inventory of SMM4F18A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMM4F18A-TR is usually 5 days.
3.What payment methods are accepted for SMM4F18A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMM4F18A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMM4F18A-TR?
SMM4F18A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMM4F18A-TR 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 SMM4F18A-TR?
For technical support, including SMM4F18A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMM4F18A-TR requirements.
6.How does Aetrix verify that SMM4F18A-TR is sourced from the original manufacturer or authorized distributors?
All SMM4F18A-TR 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 SMM4F18A-TR meets industry standards.
7.What is the process for return or replacement of SMM4F18A-TR?
All SMM4F18A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMM4F18A-TR, 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 SMM4F18A-TR part is unused and in its original packaging.
Return procedure for SMM4F18A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMM4F18A-TR Tags
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ESD9B5.0ST5G
onsemi
-
DESD3V3E1BL-7B
Diodes Incorporated
-
ESD5Z3.3T1G
onsemi
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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
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