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

STMicroelectronics STTH812DI

Name: STTH812DI
Brand: STMicroelectronics
SKU: STTH812DI
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: STTH812DI

Manufacturer:: STMicroelectronics

Category:: Single Diodes

Package:: TO-220-2 Insulated, TO-220AC

Datasheet:: STTH812DI.pdf

Description:: DIODE GP 1.2KV 8A TO220AC INS

Quantity:: RFQ Add To RFQ list

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Inventory:1,509

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Product details

Overview

STTH812DI from STMicroelectronics is an ultrafast recovery silicon rectifier diode in insulated TO-220FPAC package, rated for 1200 V repetitive peak reverse voltage, 8 A average forward current (at Tc = 75 °C), and 50 ns typical reverse recovery time at 125 °C. It delivers soft recovery, low conduction and switching losses, and operates reliably in high-frequency industrial power supplies and motor control freewheeling circuits.

For engineers reviewing the STTH812DI datasheet, STTH812DI pinout, STTH812DI application, or STTH812DI equivalent, key selection criteria include its 2000 VRMS electrical insulation rating, 12 pF junction capacitance, 5.4 °C/W junction-to-case thermal resistance, and suitability for snubber and demagnetization functions where isolation and fast recovery are critical.

Technical Context

This diode employs a planar passivated junction structure optimized for ultrafast soft recovery-critical for minimizing EMI and voltage overshoot in hard-switched topologies. Its dynamic behavior is characterized by a softness factor ≥2 at 125 °C and dIF/dt = –200 A/µs, ensuring controlled turn-off with reduced ringing.

Thermal performance is defined by Rth(j–c) = 5.4 °C/W in TO-220FPAC configuration, enabling stable operation up to 175 °C junction temperature. Reverse leakage remains ≤50 µA at 125 °C under full 1200 V bias, supporting robust thermal runaway margin in high-reliability systems.

Key Specifications

Parameter	Value and Actual Design Meaning
V_RRM	1200 V - Withstands repetitive reverse voltage up to 1200 V without breakdown, suitable for 800 V DC bus designs with safety margin.
I_F(AV)	8 A at T_c = 75 °C - Sustains continuous forward current of 8 A with case temperature held at 75 °C using standard heatsinking.
t_rr (typ)	50 ns at T_j = 125 °C - Enables operation in 100–500 kHz switching converters with minimal switching loss and EMI generation.
R_th(j–c)	5.4 °C/W - Requires ≤13.9 W dissipation to limit junction temperature rise to 75 °C above case, guiding heatsink sizing.
Insulation Rating	2000 V_RMS - Provides reinforced isolation between mounting tab and internal semiconductor, meeting basic safety requirements for AC-connected equipment.
C_j	12 pF - Low junction capacitance minimizes displacement current during high-dV/dt transitions, reducing gate drive coupling risk.
V_F (typ)	1.25 V at I_F = 8 A, T_j = 150 °C - Contributes to <10 W conduction loss at full rated current, improving system efficiency.

Pinout & Package

STTH812DI uses the TO-220FPAC package: insulated plastic housing with electrically isolated metal tab, 2000 V_RMS dielectric strength, and 12 pF junction-to-case capacitance. Mounting torque: 0.55 N·m (max 0.7 N·m).

Pin/Terminal	Circuit Role	Design Meaning
Anode (Lead 1)	Forward current entry point	Connected to high-side switching node or transformer secondary; must withstand peak forward surge of 100 A.
Cathode (Lead 2)	Forward current exit / reverse blocking terminal	Typically tied to DC bus or ground reference; carries full load current and sustains 1200 V reverse bias.
Isolated Tab (Mounting Surface)	Thermal path only - no electrical connection	Electrically isolated from die; enables direct heatsink mounting without insulating washer, simplifying thermal design.

Key Features

Feature	Design Value
Ultrafast soft recovery	trr = 50 ns (typ) with S ≥ 2 ensures low-voltage overshoot and reduced EMI in hard-switched SMPS and motor drives.
High junction temperature rating	Tj(max) = 175 °C enables operation in compact enclosures or high-ambient environments without derating.
Low leakage current	IR ≤ 50 µA at 125 °C and VRRM improves thermal stability and reduces standby power loss in auxiliary supplies.
Insulated TO-220FPAC package	2000 VRMS isolation and 12 pF capacitance eliminate need for insulating pads while maintaining low parasitic coupling.

Applications

Industrial Power Supply Rectification

Motor Drive Freewheeling

Use Scenario: High-efficiency 3 kW AC–DC front-end with PFC stage feeding isolated DC bus.

IC Role / Device Role / Timing Role: Output rectifier in boost PFC and main DC–DC stage, handling 8 A continuous and 100 A surge currents.

Use Value: 50 ns trr and soft recovery minimize switching losses and snubber stress, directly improving overall system efficiency by ~0.8% at full load.

Use Scenario: 7.5 kW three-phase inverter driving induction motor with regenerative braking.

IC Role / Device Role / Timing Role: Freewheeling diode across IGBTs, conducting reverse recovery current during turn-on transitions.

Use Value: S ≥ 2 softness factor suppresses voltage spikes >600 V, eliminating need for external RC snubbers on each leg.

Snubber Network Diode

Transformer Demagnetization

Use Scenario: RCD clamp circuit in flyback converter operating at 250 kHz with 400 V input.

IC Role / Device Role / Timing Role: Clamp diode conducting brief high-dI/dt pulses during MOSFET turn-off.

Use Value: 100 A IFRM rating and 50 ns trr ensure reliable energy transfer into clamp capacitor without oscillation or failure.

Use Scenario: Forward converter with active reset, requiring precise demagnetization path for transformer core.

IC Role / Device Role / Timing Role: Reset diode conducting primary-side reverse current during MOSFET off-time.

Use Value: Low VF (1.25 V typ) and fast tfr (400 ns) reduce reset losses and improve duty-cycle accuracy vs. slower alternatives.

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultrafast 1200 V diode applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STTH8R06D	600 V VRRM, same TO-220AC package, 60 ns trr at 125 °C	Limited to ≤400 V DC bus; unsuitable for 800 V systems	Select only if system reverse voltage ≤600 V and isolation not required.
IXYS MUR8120E	1200 V VRRM, TO-220AC (non-insulated), 65 ns trr, 3.1 °C/W Rth(j–c)	Requires insulating pad for heatsink mounting; higher thermal resistance than STTH812DI's isolated tab	Prefer when cost sensitivity outweighs isolation benefit and heatsink layout permits insulator use.

Compared with STTH812DI, STTH8R06D trades voltage rating for lower cost in sub-600 V designs, while MUR8120E offers comparable voltage but requires external isolation and delivers inferior thermal performance-making STTH812DI optimal for space-constrained, isolated, high-reliability 1200 V applications.

Availability

STTH812DI is available at Aetrix Electronics and suitable for industrial power supplies, motor control inverters, and snubber networks requiring stable component supply, long-term lifecycle support, and certified traceable sourcing.

Supply support for STTH812DI 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

STTH812DI belongs to ST's high-voltage ultrafast diode product line, engineered specifically for high-efficiency, high-reliability rectification and freewheeling in industrial power conversion systems operating up to 1200 V.

FAQ

What is the maximum allowable case temperature for continuous operation?

The STTH812DI is rated for 8 A average forward current at Tc = 75 °C in TO-220FPAC package. Exceeding this temperature requires linear derating per the datasheet curve; at Tc = 100 °C, maximum IF(AV) drops to approximately 5.5 A to maintain Tj ≤ 175 °C.

Does the insulated tab require thermal interface material?

Yes-although electrically isolated, the TO-220FPAC tab must be mounted to a heatsink using thermally conductive, electrically insulating material (e.g., silicone grease + ceramic washer or phase-change pad) to achieve the specified Rth(j–c) = 5.4 °C/W and prevent thermal runaway.

Can STTH812DI replace STTH812D in existing designs?

No-STTH812D uses non-insulated TO-220AC, while STTH812DI uses insulated TO-220FPAC. The pinout differs (STTH812D has tab = cathode; STTH812DI tab is isolated), and thermal resistance is higher (5.4 vs. 1.9 °C/W), requiring PCB layout and thermal redesign.

What is the softness factor test condition for datasheet compliance?

The softness factor S ≥ 2 is measured at Tj = 125 °C, IF = 8 A, dIF/dt = –200 A/µs, and VR = 600 V. This condition reflects worst-case motor drive freewheeling transients and confirms controlled recovery without current tailing or snap-off.

STTH812DI Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-2 Insulated, TO-220AC

Packaging:: Tube

Product Status:: Active

Technology:: Standard

Voltage - DC Reverse (Vr) (Max):: 1200 V

Current - Average Rectified (Io):: 8A

Voltage - Forward (Vf) (Max) @ If:: 2.2 V @ 8 A

Speed:: Fast Recovery =< 500ns, > 200mA (Io)

Reverse Recovery Time (trr):: 100 ns

Current - Reverse Leakage @ Vr:: 8 µA @ 1200 V

Capacitance @ Vr, F:: -

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220AC ins

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

STTH812DI FAQ

1.How can I place an order for STTH812DI through Aetrix?

Please submit a Request for Quotation (RFQ) for STTH812DI 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 STTH812DI reliable?

The price and inventory of STTH812DI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STTH812DI is usually 5 days.

3.What payment methods are accepted for STTH812DI?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STTH812DI transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for STTH812DI?

STTH812DI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your STTH812DI 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 STTH812DI?

For technical support, including STTH812DI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STTH812DI requirements.

6.How does Aetrix verify that STTH812DI is sourced from the original manufacturer or authorized distributors?

All STTH812DI 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 STTH812DI meets industry standards.

7.What is the process for return or replacement of STTH812DI?

All STTH812DI units undergo pre-shipment inspection (PSI). If there is an issue with STTH812DI, 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 STTH812DI part is unused and in its original packaging.

Return procedure for STTH812DI:

1.Submit a request within 90 days.

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

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