STMicroelectronics STTH8R04FP

Overview

STTH8R04FP from STMicroelectronics is an ultrafast recovery silicon planar diode rated for 400 V repetitive peak reverse voltage, 8 A average forward current, and 25 ns typical reverse recovery time at 125 °C with 8 A IF and −200 A/µs dIF/dt. It uses platinum-doped junction technology and is packaged in insulated TO-220AC (TO-220AC Ins) with 2500 VRMS isolation, designed for freewheeling, polarity protection, and base-drive circuits in low-voltage high-frequency inverters.

For engineers reviewing the STTH8R04FP datasheet, STTH8R04FP pinout, STTH8R04FP application, or STTH8R04FP equivalent, this device is selected for high-efficiency switching power supplies, motor drive snubbers, and DC-DC converter output rectification where low conduction loss (VF = 0.9 V typ. at 25 °C), soft recovery (Sfactor ≥ 0.4), and high junction temperature capability (Tj max = 175 °C) are critical.

Technical Context

This diode employs Pt-diffused planar junction technology to achieve ultrafast soft recovery with controlled minority carrier lifetime, enabling reduced EMI and lower switching losses in hard-switched topologies. Its thermal resistance of 5.5 °C/W (junction-to-case) and 175 °C maximum operating junction temperature support high-power density designs without forced cooling.

The insulated TO-220AC package provides galvanic isolation between the cathode tab and mounting surface, allowing direct heatsink attachment without insulating washers. Dynamic parameters-including trr = 25 ns (typ.), IRM = 5.5–8.0 A, and Qrr = 35–50 nC-are characterized across temperature and dIF/dt to enable accurate loss modeling in PWM-driven circuits.

Key Specifications

Pinout & Package

STTH8R04FP is supplied in the insulated TO-220AC package (TO-220AC Ins), featuring electrically isolated metal tab (cathode) rated for 2500 VRMS isolation. Mounting torque must be limited to 0.55 N·m (recommended) / 0.70 N·m (max) to avoid package damage.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STTH8R04FP, STTH8R06D trades speed for voltage headroom, while MUR840E sacrifices isolation for marginally better VF-making STTH8R04FP optimal for space-constrained, isolated, high-frequency freewheeling where safety and EMI control are prioritized.

Availability

STTH8R04FP is available at Aetrix Electronics and suitable for motor drive freewheeling, DC-DC converter output rectification, and input polarity protection requiring stable component supply and guaranteed long-term availability.

Supply support for STTH8R04FP 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.

STTH8R04FP belongs to ST's ultrafast recovery diode product line, engineered specifically for high-efficiency switching power conversion in industrial motor drives, renewable energy inverters, and telecom power supplies.

FAQ

What is the maximum junction temperature and how does it affect thermal design?

The STTH8R04FP has a maximum junction temperature of 175 °C. This allows operation at elevated ambient temperatures without derating, provided the junction-to-case thermal resistance (5.5 °C/W) and heatsink thermal resistance are sized to keep Tj ≤ 175 °C under worst-case power dissipation. At 8 A average current, conduction loss is ~7.2 W, requiring a heatsink with θSA ≤ 16.5 °C/W for 70 °C ambient.

Is the cathode tab electrically isolated, and what is its isolation rating?

Yes-the TO-220AC Ins package features a fully insulated cathode tab rated for 2500 VRMS isolation between the tab and internal die. This eliminates the need for insulating pads or washers when mounting directly to a grounded heatsink, simplifying mechanical assembly and improving thermal performance by removing interfacial resistance layers.

How does the softness factor impact EMI in high-frequency inverters?

The softness factor (Sfactor ≥ 0.4) quantifies the ratio of reverse recovery tail current to peak reverse current. A higher Sfactor indicates gentler current decay, reducing di/dt-induced voltage overshoot and high-frequency ringing on DC bus lines. In 20–100 kHz motor drives, this lowers conducted EMI by up to 12 dBµV, easing EMC filter design and certification.

Can STTH8R04FP replace standard fast recovery diodes in existing 400 V designs?

Yes-STTH8R04FP is a direct upgrade for legacy fast recovery diodes (e.g., BYV26E, UF4007) in 400 V systems, offering 40% faster trr (25 ns vs. ~40–60 ns), lower VF (0.9 V vs. 1.2–1.5 V), and soft recovery. No layout changes are needed beyond verifying mounting torque and heatsink compatibility with the insulated TO-220AC footprint.