STMicroelectronics STTH812D

Overview

STTH812D from STMicroelectronics is an ultrafast recovery silicon rectifier diode in TO-220AC package, rated for 1200 V repetitive peak reverse voltage, 8 A average forward current at Tc = 140 °C, and 50 ns typical reverse recovery time (trr) at 125 °C with dIF/dt = −200 A/µs. It delivers soft recovery, low conduction losses (VF = 1.25 V typ. at 125 °C, IF = 8 A), and high junction temperature capability (Tj = 175 °C), making it suitable for industrial switch-mode power supplies and motor control freewheeling paths.

For engineers reviewing the STTH812D datasheet, STTH812D pinout, STTH812D application, or STTH812D equivalent, key selection criteria include verified trr ≤ 70 ns under high dIF/dt conditions, thermal resistance Rth(j–c) = 1.9 °C/W, insulation integrity for non-isolated topologies, and compatibility with high-frequency PFC and snubber circuits requiring low IRM and high softness factor (S = 2).

Technical Context

This diode employs a platinum-doped lifetime-controlled silicon structure to achieve ultrafast, soft reverse recovery-critical for minimizing EMI and voltage overshoot in hard-switched converters. Its dynamic performance is characterized by low reverse recovery charge (Qrr) and controlled IRM (14–21 A at 125 °C), enabling stable operation in 50–100 kHz industrial inverters and UPS systems.

The device operates reliably up to 175 °C junction temperature and exhibits <8 µA reverse leakage at 25 °C (VR = 1200 V), ensuring robust thermal runaway margin. Its TO-220AC mechanical form supports direct heatsink mounting with 0.55 Nm recommended torque, and its VF vs. IF curve shows minimal voltage rise across 25–150 °C, supporting consistent conduction loss modeling.

Key Specifications

Pinout & Package

STTH812D uses the standard TO-220AC package: single-piece molded epoxy body with three leads (anode, cathode, tab), non-insulated metal tab electrically connected to the cathode. Mounting hole accepts M3 screw; recommended torque is 0.55 Nm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STTH8R06D and IXYS MUR8120E, STTH812D uniquely balances 1200 V rating, 50 ns trr, and 1.25 V VF at 150 °C-enabling compact, high-efficiency designs in 800 V industrial power systems where both voltage margin and dynamic performance are critical.

Availability

STTH812D is available at Aetrix Electronics and suitable for industrial switch-mode power supplies, motor control inverters, and UPS systems requiring stable component supply, long-term manufacturability, and compliance with ECOPACK® RoHS-6 and lead-free second-level interconnect standards.

Supply support for STTH812D 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 automotive, industrial, and consumer markets.

The STTH series targets high-reliability industrial power conversion, emphasizing ruggedness, thermal stability, and dynamic performance in rectification, freewheeling, and snubber roles across harsh operating environments.

FAQ

Is STTH812D insulated or isolated?

No, STTH812D uses the TO-220AC package with a non-insulated metal tab electrically connected to the cathode. For insulated mounting, STTH812DI (TO-220Ins, 2500 VRMS isolation) or STTH812FP (TO-220FPAC, 2000 VRMS) must be selected instead. The tab must be isolated from the heatsink using mica or ceramic washers if the heatsink is grounded.

What is the maximum allowable case temperature for continuous 8 A operation?

At IF(AV) = 8 A, the maximum case temperature is 140 °C per datasheet absolute ratings. Exceeding this requires derating: for example, at Tc = 125 °C, IF(AV) increases to ~9.5 A; at Tc = 100 °C, it rises to ~11.8 A. Thermal design must ensure Rth(j–c) × Pd + Tc ≤ 175 °C, where Pd ≈ 10 W at full load.

Does STTH812D support parallel operation?

Yes, but only with careful thermal and electrical balancing. Its low IR ≤ 8 µA at 25 °C and tight VF distribution (1.25–1.9 V at 150 °C) enable stable current sharing. Use matched devices, symmetrical PCB layout, individual current-sense resistors, and shared heatsink with uniform thermal interface to avoid thermal runaway.

Can STTH812D replace standard FR107 diodes in existing designs?

Only after validation: STTH812D has higher VRRM (1200 V vs. 1000 V), faster trr (50 ns vs. 500 ns), and higher VF (~1.25 V vs. ~1.0 V). It improves EMI and efficiency in high-frequency designs but may increase conduction loss in low-frequency, high-current applications. Layout, snubber, and thermal design must be re-evaluated.