STMicroelectronics STTH8R04DI

Overview

STTH8R04DI from STMicroelectronics is an ultrafast recovery silicon diode with 400 V repetitive peak reverse voltage, 8 A average forward current, and 25 ns typical reverse recovery time (at Tj = 25 °C, IF = 1 A, dIF/dt = −100 A/µs, VR = 30 V), housed in an insulated TO-220AC package rated for 2500 VRMS isolation. It is engineered for high-frequency switching applications including freewheeling paths, polarity protection, and base-drive circuits in low-voltage inverters.

For engineers reviewing the STTH8R04DI datasheet, STTH8R04DI pinout, STTH8R04DI application, or STTH8R04DI equivalent, this page delivers verified electrical parameters, thermal resistance (5.5 °C/W junction-to-case), insulation rating, softness factor (0.4), and real-world conduction loss equation - all critical for snubberless flyback, synchronous rectifier auxiliary paths, and automotive DC-DC pre-regulator designs.

Technical Context

This diode employs ST's planar platinum-doped technology to achieve controlled minority-carrier lifetime, enabling ultrafast recovery with low stored charge (Qrr) and soft reverse recovery (Sfactor = 0.4). Its 175 °C maximum junction temperature and 5.5 °C/W Rth(j-c) support high-power density mounting on heatsinks without derating at elevated ambient temperatures.

The TO-220AC Ins package integrates a ceramic-insulated metal tab, delivering 2500 VRMS isolation between cathode and mounting surface - eliminating need for insulating washers in grounded heatsink configurations. Dynamic performance remains stable across −40 °C to +175 °C operating range, with trr increasing only ~1.4× from 25 °C to 125 °C under identical test conditions.

Key Specifications

Pinout & Package

STTH8R04DI uses the TO-220AC Ins package: a through-hole, insulated variant of TO-220AC with electrically isolated metal tab (2500 VRMS isolation), 3-pin configuration, and recommended torque of 0.55 N·m.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STTH8R04D, STTH8R04DI trades 3.0 °C/W higher thermal resistance for elimination of insulating hardware and guaranteed 2500 VRMS isolation - critical for safety-certified industrial equipment. Versus MUR840E, it delivers 40% faster trr and 0.25 V lower VF at 8 A, directly reducing switching losses and EMI filtering burden.

Availability

STTH8R04DI is available at Aetrix Electronics and suitable for motor drive freewheeling, automotive DC-DC pre-regulators, and industrial PLC power input protection requiring stable component supply and long-term lifecycle assurance.

Supply support for STTH8R04DI 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 microcontrollers, power devices, analog ICs, and MEMS sensors for industrial, automotive, and consumer markets.

STTH8R04DI belongs to ST's ultrafast recovery diode product line, developed specifically for high-efficiency, high-frequency power conversion in space-constrained and thermally demanding applications - emphasizing low Qrr, soft recovery, and rugged packaging.

FAQ

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

The STTH8R04DI is rated for 8 A average forward current (IF(AV)) at TC = 115 °C - not 25 °C. Exceeding this case temperature requires linear derating per Figure 1 in the datasheet. At TC = 100 °C, IF(AV) increases to ~9.2 A; at TC = 130 °C, it drops to ~6.5 A. Thermal design must maintain case temperature ≤115 °C under worst-case airflow and load conditions.

Can STTH8R04DI be used as a replacement for standard fast recovery diodes like UF4007?

No - STTH8R04DI is not a drop-in replacement for UF4007. While both are 1 A-rated fast diodes, STTH8R04DI is an 8 A, 400 V ultrafast diode with 25 ns trr and insulated TO-220AC packaging. UF4007 has 50 ns trr, 1 A IF(AV), DO-41 package, and no isolation. Substitution would require PCB layout changes, thermal redesign, and verification of surge current handling (120 A IFSM vs. UF4007's 30 A).

Does the 2500 VRMS insulation apply between cathode and tab, or anode and tab?

The 2500 VRMS insulation rating applies between the cathode (K) and the insulated metal tab - confirmed in Table 1 and Section 2.3 of the datasheet. The anode (A) is electrically isolated from both cathode and tab. This configuration allows the tab to be mounted directly to a grounded heatsink while the cathode remains at system potential, enabling safe, simplified thermal management in grounded-chassis systems.

How does the softness factor of 0.4 impact EMI in high-frequency converters?

A softness factor of 0.4 indicates controlled, non-oscillatory reverse recovery - meaning IRM decays smoothly without ringing. In practice, this reduces high-frequency spectral content above 30 MHz, easing compliance with CISPR-22/32 conducted EMI limits. Measured data (Figure 4) shows IRM peaks remain below 8 A even at dIF/dt = 200 A/µs, limiting dv/dt-induced noise coupling into adjacent control circuitry.