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STMicroelectronics STTH108A
- Part No.:
- STTH108A
- Manufacturer:
- STMicroelectronics
- Category:
- Single Diodes
- Package:
- DO-214AC, SMA
- Datasheet:
-
STTH108A.pdf
- Description:
- DIODE GEN PURP 800V 1A SMA
- Quantity:
- Payment:
- Shipping:
Inventory:25,452
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Product details
Overview
STTH108A from STMicroelectronics is an ultrafast high-voltage planar silicon rectifier diode in DO-41 package, rated for 800 V repetitive peak reverse voltage, 1 A average forward current, and 25 A surge current (8.3 ms), with soft-switching behavior to minimize EMI in snubber and freewheeling circuits of offline SMPS.
For engineers reviewing the STTH108A datasheet, STTH108A pinout, STTH108A application, or STTH108A equivalent, key selection criteria include reverse recovery time (75 ns), forward voltage drop (1.25 V max at 125 °C), thermal resistance (45 °C/W junction-to-lead), and DO-41 mechanical compatibility in compact power supply layouts.
Technical Context
The STTH108A employs planar epitaxial construction to achieve ultrafast reverse recovery (trr = 75 ns) and soft recovery waveform, reducing switching losses and EMI generation during turn-off in high-frequency flyback and forward converters. Its 175 °C maximum junction temperature supports operation in thermally constrained environments.
Designed for unidirectional conduction in clamping and demagnetization paths, it delivers low conduction loss via VF(max) = 1.25 V at IF = 1 A and TJ = 125 °C, and withstands high transient stress with IFSM = 25 A (8.3 ms sine half-wave), making it suitable for industrial AC/DC adapters and auxiliary power rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VRRM | 800 V - blocks up to 800 V reverse voltage without breakdown in clamp/snubber applications |
| IF(AV) | 1 A at TL = 130 °C - continuous DC output current capability under standard heatsinking |
| trr | 75 ns - enables efficient operation up to ~200 kHz switching frequencies with minimal tail current |
| VF(max) | 1.25 V at TJ = 125 °C - limits conduction loss to ≤1.25 W at 1 A, critical for thermal budget in sealed enclosures |
| IFS M | 25 A (8.3 ms) - survives inrush and fault transients in 115/230 VAC input stages |
| Rth(j-l) | 45 °C/W - defines thermal path efficiency from junction to lead; requires ≥10 mm lead length for rated derating |
| Tj(max) | 175 °C - allows operation in high-ambient industrial environments without forced cooling |
Pinout & Package
STTH108A is housed in a DO-41 plastic axial-leaded package with cathode band marking. Lead length is specified as 10 mm for thermal rating compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward current entry node | Connected to switch node (e.g., MOSFET drain) in freewheeling path; must handle full load current and surge |
| Cathode | Forward current exit node | Connected to output rail or ground return; marked by colored band; carries same current as anode with polarity-defined conduction |
Key Features
| Feature | Design Value |
|---|---|
| Soft switching recovery | Reduces EMI emissions by limiting di/dt during turn-off, easing EMC filter design in Class B power supplies |
| High surge current rating | 25 A single half-sine surge withstand enables robustness against line transients and transformer reset spikes |
| Low forward voltage drop | 1.25 V max at 125 °C minimizes power dissipation in 1 A auxiliary windings, improving light-load efficiency |
| Planar technology | Ensures consistent trr and VF across production lots, supporting stable timing in synchronous rectifier control loops |
Applications
| SMPS Freewheeling Diode | Snubber Network Clamp |
|---|---|
Use Scenario: Used across the primary winding of flyback transformers to provide a path for magnetizing current decay during MOSFET off-time. IC Role / Device Role / Timing Role: Unidirectional conduction element enabling energy transfer from primary to secondary; timing-critical due to trr < 75 ns. Use Value: Soft recovery prevents voltage overshoot spikes >100 V, reducing stress on primary-side MOSFET and simplifying RCD snubber sizing. | Use Scenario: Placed in parallel with switching FETs or transformer windings to absorb leakage inductance energy during turn-off. IC Role / Device Role / Timing Role: Clamp diode in RCD or active clamp topologies; operates only during brief high-dV/dt transitions. Use Value: 800 V VRRM and 25 A IFSM ensure reliable clamping under worst-case 230 VAC surges without avalanche degradation. |
| DC-DC Auxiliary Supply Rectifier | Industrial AC/DC Adapter Output Stage |
Use Scenario: Rectifies low-power auxiliary winding output (e.g., +12 V bias supply) in isolated offline converters. IC Role / Device Role / Timing Role: Low-current output rectifier; selected for VF stability over temperature to maintain regulation accuracy. Use Value: VF variation < 0.36 V from 25 °C to 125 °C ensures ±2% output voltage drift across operating range. | Use Scenario: Final-stage rectifier in universal-input (85–265 VAC) industrial power supplies delivering 5–24 V at ≤1 A. IC Role / Device Role / Timing Role: Main output rectifier in non-synchronous buck-derived topologies; handles continuous 1 A load with thermal margin. Use Value: 175 °C Tj(max) and DO-41 package allow operation at 70 °C ambient without derating, meeting EN 60950-1 thermal safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar ultrafast high-voltage rectifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STTH1R08 | Same die, SMA package (JEDEC DO-214AC); Rth(j-l) = 30 °C/W vs. 45 °C/W; VF identical | Better thermal performance but larger footprint; requires PCB pad redesign | Choose when board space permits and thermal headroom is critical |
| UF4007 | Higher trr (100 ns), higher VF (1.7 V typ), lower IFSM (30 A but shorter tp) | Less EMI suppression; higher conduction loss; common in cost-sensitive consumer designs | Acceptable for ≤100 kHz designs where soft recovery is not mandatory |
Compared with STTH108A, STTH1R08 offers superior thermal resistance in SMA packaging but demands layout revision, while UF4007 trades soft recovery and lower VF for broader availability and lower cost-making STTH108A optimal for EMI-sensitive 150–200 kHz industrial SMPS.
Availability
STTH108A is available at Aetrix Electronics and suitable for offline SMPS freewheeling, snubber clamping, and auxiliary power supply rectification requiring stable component supply, long-term manufacturability, and RoHS-compliant DO-41 packaging.
Supply support for STTH108A 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, designing and manufacturing analog, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.
The STTH series targets high-reliability power conversion applications, with STTH108A specifically engineered for ultrafast, high-voltage rectification in compact, thermally demanding offline power supplies.
FAQ
What is the cathode marking convention for STTH108A?
The cathode is identified by a distinct colored band near one end of the DO-41 body. This band must be oriented toward the positive rail or output node in freewheeling configurations. Mechanical drawings confirm band position aligns with JEDEC DO-41 standard, verified in ST's Doc ID 9342 Rev 3, Figure 7.
Can STTH108A replace UF4007 in existing designs?
Yes, STTH108A is a direct physical and electrical replacement for UF4007 in DO-41 sockets, offering lower VF (1.25 V vs. 1.7 V), faster trr (75 ns vs. 100 ns), and softer recovery-reducing EMI and improving efficiency-but requires validation of surge margin since IFSM differs (25 A vs. 30 A at same tp).
What is the recommended minimum copper area per lead for thermal performance?
Per Figure 5 in the datasheet, 1 cm² of 35 µm copper per lead reduces Rth(j-a) from 110 °C/W to ~70 °C/W. For full-rated 1 A operation at 70 °C ambient, ≥3 cm² per lead is advised to maintain TJ ≤ 150 °C with natural convection.
Is STTH108A suitable for automotive applications?
No-STTH108A is not qualified to AEC-Q101 and lacks automotive-grade screening, traceability, or extended temperature validation. ST's official documentation states non-automotive grade parts are intended for industrial and consumer use only, with explicit exclusion from safety-critical vehicle systems.
STTH108A Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- DO-214AC, SMA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Technology:
- Standard
- Voltage - DC Reverse (Vr) (Max):
- 800 V
- Current - Average Rectified (Io):
- 1A
- Voltage - Forward (Vf) (Max) @ If:
- 1.65 V @ 1 A
- Speed:
- Fast Recovery =< 500ns, > 200mA (Io)
- Reverse Recovery Time (trr):
- 75 ns
- Current - Reverse Leakage @ Vr:
- 5 µA @ 800 V
- Capacitance @ Vr, F:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-214AC (SMA)
- Operating Temperature - Junction:
- 175°C (Max)
STTH108A FAQ
1.How can I place an order for STTH108A through Aetrix?
Please submit a Request for Quotation (RFQ) for STTH108A 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 STTH108A reliable?
The price and inventory of STTH108A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STTH108A is usually 5 days.
3.What payment methods are accepted for STTH108A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STTH108A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for STTH108A?
STTH108A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your STTH108A 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 STTH108A?
For technical support, including STTH108A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STTH108A requirements.
6.How does Aetrix verify that STTH108A is sourced from the original manufacturer or authorized distributors?
All STTH108A 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 STTH108A meets industry standards.
7.What is the process for return or replacement of STTH108A?
All STTH108A units undergo pre-shipment inspection (PSI). If there is an issue with STTH108A, 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 STTH108A part is unused and in its original packaging.
Return procedure for STTH108A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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