My Inquiry
My Account
STMicroelectronics SMM4F8.5A-TR
- Part No.:
- SMM4F8.5A-TR
- Manufacturer:
- STMicroelectronics
- Category:
- TVS Diodes
- Package:
- DO-222AA
- Datasheet:
-
SMM4F8.5A-TR.pdf
- Description:
- TVS DIODE 8.5VWM 19.5VC DO222-AA
- Quantity:
- Payment:
- Shipping:
Inventory:2,910
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SMM4F8.5A-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 8.5 V, clamping voltage of 14.4 V at 27.7 A (10/1000 µs), and operates up to 175 °C junction temperature-enabling robust protection in automotive body electronics and industrial power supplies.
For engineers reviewing the SMM4F8.5A-TR datasheet, SMM4F8.5A-TR pinout, SMM4F8.5A-TR application, or SMM4F8.5A-TR equivalent, key selection criteria include clamping performance under 10/1000 µs surges, low leakage (<1 µA at 85 °C), flat STmite Flat package compatibility with high-density PCB layouts, and IEC 61000-4-2 level 4 ESD immunity (±30 kV).
Technical Context
The SMM4F8.5A-TR uses planar silicon technology to achieve low dynamic resistance (0.141 Ω) and stable clamping across temperature (αT = 7.3 × 10−4/°C). Its unidirectional configuration supports anode-grounded protection schemes in positive-rail applications.
It delivers 400 W peak pulse power at Tj = 25 °C and retains 160 W capability at Tj = 175 °C (10/1000 µs), validated per IEC 61000-4-2 (±30 kV contact/air) and IEC 61000-4-4 (4 kV). The STmite Flat package enables thermal dissipation via copper land area, with Rth(j-a) dropping from 100 °C/W (no copper) to <2.5 °C/W (5 cm² per lead).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Standoff Voltage (VRWM) | 8.5 V - Maximum continuous reverse operating voltage before breakdown |
| Breakdown Voltage (VBR) | 9.5–10.5 V at 1 mA - Ensures reliable triggering above normal rail noise |
| Clamping Voltage (VCL) | 14.4 V at 27.7 A (10/1000 µs) - Limits downstream voltage stress during surge events |
| Peak Pulse Power (PPP) | 400 W (10/1000 µs) - Sustains industry-standard lightning-surge energy without failure |
| Leakage Current (IR) | 1 µA max at 85 °C - Minimizes standby power loss in battery-backed systems |
| Junction Temperature Range | −55 °C to +175 °C - Supports under-hood automotive and industrial ambient conditions |
| ESD Rating | ±30 kV per IEC 61000-4-2 (contact/air) - Exceeds level 4 immunity requirements |
Pinout & Package
The SMM4F8.5A-TR is housed in the STmite Flat surface-mount package (JEDEC MO-275 compatible), measuring 1.90 mm × 3.80 mm × 0.85 mm (L × W × H) with matte tin-plated leads and cathode-bar polarity marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (A) | Surge current return path | Connected to ground or low-impedance reference; carries full surge current during clamping |
| Cathode (K) | Protected line connection | Connected to the line being protected (e.g., 12 V rail); voltage clamped relative to anode |
Key Features
| Feature | Design Value |
|---|---|
| Flat STmite Flat package | 0.85 mm profile enables use in ultra-thin consumer and automotive modules with strict Z-height constraints |
| High-temperature operation | Rated to 175 °C junction temperature-supports placement near power converters and motors without derating |
| Low dynamic resistance | 0.141 Ω (10/1000 µs) ensures minimal VCL rise under high-current transients |
| IEC 61000-4-2 level 4 compliance | ±30 kV contact/air discharge immunity-meets automotive EMC requirements without external filtering |
| MSL Level 1 rating | Unlimited floor life at ≤30 °C/60% RH-eliminates bake requirements prior to reflow |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC Digital Input |
|---|---|
|
Use Scenario: Protecting 12 V CAN/LIN bus power rails against load-dump and ISO 7637-2 pulses. IC Role / Device Role / Timing Role: Primary unidirectional TVS placed between fused 12 V supply and local LDO/regulator input. Use Value: Clamps 14.4 V at 27.7 A to prevent overvoltage damage to downstream PMICs and microcontrollers during 10/1000 µs surges. |
Use Scenario: Safeguarding 24 V digital input channels from field-wiring induced transients in factory automation. IC Role / Device Role / Timing Role: Front-end transient suppressor on optocoupler input side, upstream of series current-limiting resistor. Use Value: Withstands repeated 4 kV IEC 61000-4-4 bursts while maintaining <1 µA leakage at 85 °C for stable logic threshold detection. |
| USB-C Power Delivery Adapter | Smart Meter Power Supply |
|
Use Scenario: Guarding 5–20 V PP output rails in USB PD sink adapters against hot-plug and cable ESD events. IC Role / Device Role / Timing Role: Unidirectional TVS on VCONN and CC lines, leveraging low capacitance (<100 pF at 1 V) to preserve signal integrity. Use Value: Delivers ±30 kV IEC 61000-4-2 protection without degrading USB-C communication timing or insertion loss. |
Use Scenario: Securing AC/DC auxiliary supply inputs in utility smart meters exposed to outdoor lightning-induced surges. IC Role / Device Role / Timing Role: First-stage protector on 12 V DC backup rail, coordinated with MOV and gas discharge tube in multi-stage architecture. Use Value: Provides fast-response clamping (tR < 1 ns) and 160 W power handling at 175 °C to ensure long-term reliability in sealed, thermally constrained enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar unidirectional TVS diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMAJ8.5A | Higher VCL (15.0 V @ 25.4 A), larger SMA package (2.5 mm height), MSL Level 1 but no STmite Flat footprint | Less suitable for space-constrained designs; requires larger PCB pad area and higher Z-height clearance | Select when legacy SMA layout exists and thermal budget allows higher clamping voltage |
| SMCJ8.5A | Same VRWM, but 1500 W PPP, larger SMC package (7.1 mm × 6.2 mm), higher leakage (5 µA @ 85 °C) | Better for high-energy surges but incompatible with fine-pitch routing and thin-profile assemblies | Choose only where surge threat exceeds 400 W and board real estate permits SMC footprint |
Compared with SMAJ8.5A and SMCJ8.5A, the SMM4F8.5A-TR offers superior board-space efficiency (0.85 mm height), lower clamping voltage, and tighter thermal resistance control-making it optimal for next-generation compact, high-reliability power interfaces where both surge margin and physical integration are critical.
Availability
SMM4F8.5A-TR is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC digital inputs, USB-C power delivery adapters, and smart meter power supplies requiring stable component supply across extended temperature and surge environments.
Supply support for SMM4F8.5A-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 management solutions with vertical manufacturing and broad IP portfolio.
The SMM4F series belongs to ST's STmite Flat TVS product line, engineered specifically for high-density, high-temperature PCB applications demanding low-profile surge protection with guaranteed IEC/ISO compliance and long-term reliability.
FAQ
What is the maximum surge current the SMM4F8.5A-TR can handle under standard test conditions?
The SMM4F8.5A-TR sustains 27.7 A peak pulse current (IPP) under the 10/1000 µs waveform at 25 °C, with clamping voltage limited to 14.4 V. At elevated junction temperatures (175 °C), its peak pulse power drops to 160 W, corresponding to ~11.1 A at the same VCL. This is verified per IEC 61000-4-5 Annex A test setup.
Does the SMM4F8.5A-TR require derating for operation above 25 °C ambient?
Yes-its peak pulse power must be derated linearly from 400 W at 25 °C to 160 W at 175 °C junction temperature, per Figure 3 in DS5630. Derating is based on actual Tj, not ambient; thermal design must account for PCB copper area and airflow to maintain safe Tj under surge duty cycles.
Can the SMM4F8.5A-TR be used in bidirectional protection configurations?
No-it is strictly unidirectional, with cathode marked and optimized for positive-rail clamping. For bidirectional protection, ST recommends the SMBJ8.5CA or SMCJ8.5CA series, which feature symmetrical breakdown and clamping in both polarities and are physically distinct devices.
Is the STmite Flat package compatible with standard reflow soldering profiles?
Yes-the device is qualified for lead-free reflow per JEDEC J-STD-020 MSL Level 1 and follows ST's recommended profile: peak temperature 240–245 °C, time above 217 °C ≤ 60 s (max 90 s), ramp rate ≤3 °C/s. The matte tin finish ensures reliable wetting without voiding on IPC-7531-compliant footprints.
SMM4F8.5A-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):
- 8.5V
- Voltage - Breakdown (Min):
- 9.5V
- Voltage - Clamping (Max) @ Ipp:
- 19.5V
- Current - Peak Pulse (10/1000µs):
- 124A (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:
- STmite Flat (DO222-AA)
SMM4F8.5A-TR FAQ
1.How can I place an order for SMM4F8.5A-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for SMM4F8.5A-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 SMM4F8.5A-TR reliable?
The price and inventory of SMM4F8.5A-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMM4F8.5A-TR is usually 5 days.
3.What payment methods are accepted for SMM4F8.5A-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMM4F8.5A-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SMM4F8.5A-TR?
SMM4F8.5A-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SMM4F8.5A-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 SMM4F8.5A-TR?
For technical support, including SMM4F8.5A-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMM4F8.5A-TR requirements.
6.How does Aetrix verify that SMM4F8.5A-TR is sourced from the original manufacturer or authorized distributors?
All SMM4F8.5A-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 SMM4F8.5A-TR meets industry standards.
7.What is the process for return or replacement of SMM4F8.5A-TR?
All SMM4F8.5A-TR units undergo pre-shipment inspection (PSI). If there is an issue with SMM4F8.5A-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 SMM4F8.5A-TR part is unused and in its original packaging.
Return procedure for SMM4F8.5A-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SMM4F8.5A-TR 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…
