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Home > Products > Discrete Semiconductor Products > Diodes > Rectifiers > Single Diodes

STMicroelectronics STTH108

Name: STTH108
Brand: STMicroelectronics
SKU: STTH108
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STTH108

Manufacturer:: STMicroelectronics

Category:: Single Diodes

Package:: DO-204AL, DO-41, Axial

Datasheet:: STTH108.pdf

Description:: DIODE GEN PURP 800V 1A DO41

Quantity:: RFQ Add To RFQ list

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Inventory:5,290

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Product details

Overview

STTH108 from STMicroelectronics is an ultrafast high-voltage planar silicon rectifier diode rated for 800 V repetitive peak reverse voltage, 1 A average forward current, and 75 ns reverse recovery time, with soft switching behavior optimized for snubbering and freewheeling in offline switch-mode power supplies.

For engineers reviewing the STTH108 datasheet, STTH108 pinout, STTH108 application, or STTH108 equivalent, key selection criteria include its low forward voltage drop (1.25 V max at 125 °C), high surge current capability (25 A for DO-41), thermal resistance (45 °C/W junction-to-ambient), and dual-package availability (DO-41 and SMA).

Technical Context

The STTH108 employs planar junction technology to achieve fast, soft reverse recovery with minimal tail current-critical for reducing EMI in high-frequency switching converters. Its 75 ns trr (at IF = 0.5 A, Irr = 0.25 A) and 200 ns tfr support operation up to several hundred kHz in flyback and forward topologies.

Thermal design is enabled by a maximum junction temperature of 175 °C and package-specific thermal resistances: 45 °C/W (DO-41, lead length 10 mm) and 30 °C/W (SMA, lead length 10 mm), allowing reliable conduction under pulsed or continuous loads.

Key Specifications

Parameter	Value and Actual Design Meaning
VRRM	800 V - supports primary-side rectification in universal-input 85–265 VAC SMPS without derating
IF(AV)	1 A - continuous DC output current capability at TL = 130 °C (DO-41) or 110 °C (SMA)
trr	75 ns - enables efficient high-frequency switching with reduced switching losses and EMI
VF(max)	1.25 V at Tj = 125 °C - limits conduction loss to ≤1.25 W at 1 A, easing thermal management
IFSM	25 A (DO-41), 20 A (SMA), t = 8.3 ms - withstands inrush and transient overloads in AC/DC front-ends
Rth(j-a)	45 °C/W (DO-41), 30 °C/W (SMA) - defines heatsinking requirements for ambient-limited operation
IR	50 µA max at Tj = 125 °C, VR = 800 V - ensures low leakage in high-impedance clamp/snubber nodes

Pinout & Package

STTH108 is available in two standard through-hole packages: DO-41 (plastic axial) and SMA (JEDEC DO-214AC surface-mount). The cathode is marked by a band on both variants. Pinout is two-terminal: Anode (A) and Cathode (K); no internal connections or control pins.

Pin/Terminal	Circuit Role	Design Meaning
Anode (A)	Forward current entry point	Connected to positive side of AC input or inductive load return path in freewheeling
Cathode (K)	Forward current exit / reverse-blocking terminal	Connected to switching node (e.g., MOSFET drain) in clamp circuits or output rail in rectification

Key Features

Feature	Design Value
Soft switching recovery	Minimizes voltage overshoot and ringing during turn-off, reducing need for RC snubbers
High surge current rating	25 A single half-sine surge (8.3 ms) supports robust startup and fault tolerance in AC/DC adapters
Low VF at elevated temperature	1.25 V max at 125 °C maintains efficiency in thermally constrained enclosures
Planar junction construction	Ensures consistent trr and VF across production lots, critical for repeatable EMI performance
ECOPACK® compliance	Meets RoHS and halogen-free requirements without compromising thermal or electrical performance

Applications

Switch-Mode Power Supply Freewheeling

Clamp Diode in Flyback Converters

Use Scenario: Used as the secondary-side freewheeling diode in isolated 12–24 V, 10–25 W offline flyback converters.

IC Role / Device Role / Timing Role: Conducts inductor energy return during MOSFET off-time; blocks reverse voltage during on-time.

Use Value: 75 ns trr and soft recovery reduce output voltage ripple and EMI filter component count by >30% vs. standard fast recovery diodes.

Use Scenario: Placed across primary winding with RCD snubber to absorb leakage inductance energy in 65–100 kHz flyback designs.

IC Role / Device Role / Timing Role: Clamps voltage spike at MOSFET drain during turn-off; conducts only during transient overvoltage events.

Use Value: 800 V VRRM and 25 A IFSM prevent breakdown under worst-case leakage spikes while maintaining low standby loss.

Snubber Network in Forward Converters

Demagnetization Diode in Inductive Load Drivers

Use Scenario: Integrated into passive RCD snubber across main transformer in 100–200 kHz forward converters for telecom PSUs.

IC Role / Device Role / Timing Role: Provides low-loss, high-speed discharge path for snubber capacitor after each switching cycle.

Use Value: Low VF (1.25 V) and fast trr minimize snubber conduction loss and improve overall converter efficiency by 0.4–0.7%.

Use Scenario: Used to dissipate stored magnetic energy when de-energizing solenoids or relay coils in industrial PLC output modules.

IC Role / Device Role / Timing Role: Freewheeling path for inductive kickback; must handle repetitive 1 A pulses with minimal voltage overshoot.

Use Value: Soft recovery and 175 °C Tj rating ensure long-term reliability under repeated 100 Hz–1 kHz switching in harsh ambient conditions.

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, identical VRRM (800 V), trr (75 ns), but rated IF(AV) = 1 A at TL = 150 °C (vs. 130 °C for STTH108)	Higher thermal margin in compact DO-41 layouts where lead temperature exceeds 130 °C	Select STTH1R08 when board-level thermal management is limited and junction temperature must stay below 175 °C under full load
UF4007	Lower VRRM (1000 V), higher VF (1.7 V typ), slower trr (75 ns same, but less soft), no specified IFSM at 8.3 ms	Acceptable for low-cost, non-critical clamping where EMI is not tightly constrained	Choose UF4007 only for cost-sensitive, low-frequency (<50 kHz) applications where soft recovery is not required

Compared with STTH1R08, STTH108 offers tighter thermal derating control at lower lead temperatures; versus UF4007, it delivers superior EMI performance and verified surge robustness-making it preferred for certified, high-density SMPS designs.

Availability

STTH108 is available at Aetrix Electronics and suitable for offline AC/DC adapters, industrial power supplies, and automotive auxiliary power modules requiring stable component supply, long lifecycle support, and dual-package flexibility (DO-41 and SMA).

Supply support for STTH108 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The STTH series belongs to ST's high-voltage ultrafast rectifier product line, engineered specifically for EMI-sensitive, high-efficiency switch-mode power conversion in space-constrained and thermally demanding environments.

FAQ

What is the maximum allowable junction temperature for STTH108?

The absolute maximum operating junction temperature (Tj) for STTH108 is 175 °C, as specified in Table 2 of the official datasheet (Doc ID 9342 Rev 3). This rating applies across both DO-41 and SMA packages and must be maintained using appropriate PCB copper area and ambient thermal design per Figures 5–6.

Does STTH108 have a cathode marking, and how is it identified?

Yes, STTH108 features a visible cathode band on both DO-41 and SMA packages. On DO-41, the band is a painted stripe near one lead; on SMA, it is a molded band at the cathode end of the epoxy body. This marking aligns with JEDEC standards and is confirmed in Section "Package information" (page 4) of the datasheet.

Can STTH108 replace UF4007 in existing designs?

STTH108 can replace UF4007 in most 800 V-class applications, but requires verification of thermal performance: its lower VF (1.25 V vs. 1.7 V) reduces conduction loss, yet its 25 A IFSM rating is defined at 8.3 ms (vs. unspecified for UF4007), making it more suitable for surge-prone inputs. Layout and snubber tuning may be needed due to softer recovery.

What is the reverse leakage current specification for STTH108 at elevated temperature?

At Tj = 125 °C and VR = 800 V, STTH108 exhibits a maximum reverse leakage current (IR) of 50 µA, as stated in Table 4 (Static electrical characteristics). This value is critical for clamp circuit stability and was measured under standardized test conditions per JEDEC JESD24-10.

STTH108 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: DO-204AL, DO-41, Axial

Packaging:: Cut Tape (CT)

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:: Through Hole

Supplier Device Package:: DO-41

Operating Temperature - Junction:: 175°C (Max)

STTH108 FAQ

1.How can I place an order for STTH108 through Aetrix?

Please submit a Request for Quotation (RFQ) for STTH108 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 STTH108 reliable?

The price and inventory of STTH108 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STTH108 is usually 5 days.

3.What payment methods are accepted for STTH108?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STTH108 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STTH108?

STTH108 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STTH108 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 STTH108?

For technical support, including STTH108 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STTH108 requirements.

6.How does Aetrix verify that STTH108 is sourced from the original manufacturer or authorized distributors?

All STTH108 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 STTH108 meets industry standards.

7.What is the process for return or replacement of STTH108?

All STTH108 units undergo pre-shipment inspection (PSI). If there is an issue with STTH108, 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 STTH108 part is unused and in its original packaging.

Return procedure for STTH108:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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