STMicroelectronics STTH310S

Overview

STTH310S from STMicroelectronics is an ultrafast high-voltage planar silicon rectifier diode optimized for free-wheeling, clamping, snubbing, and demagnetization in switching power supplies. It delivers 3 A average forward current, 1000 V repetitive peak reverse voltage, 75 ns max reverse recovery time, 0.98 V typical forward voltage at 150 °C, and operates up to 175 °C junction temperature - enabling high-efficiency operation in auxiliary power supplies and SMPS output stages.

For engineers reviewing the STTH310S datasheet, STTH310S pinout, STTH310S application, or STTH310S equivalent, key selection criteria include its soft-switching EMI performance, surge robustness (55 A IFSM), thermal resistance (20 °C/W junction-to-lead), ECOPACK2 compliance, and SMC package suitability for automated assembly in industrial and telecom power converters.

Technical Context

This diode employs ST's planar ultrafast technology to achieve low conduction loss and controlled reverse recovery with soft switching characteristics. Its trr ≤ 75 ns at IF = 0.5 A, Irr = 0.25 A, and IR = 1 A ensures minimal switching noise and reduced snubber stress in high-frequency flyback and forward converters.

The device supports two package variants: DO-201AD (1.16 g, ammopack/tape-and-reel) and SMC (0.245 g, tape-and-reel). STTH310S specifically denotes the SMC-packaged version, featuring a 5.55–6.25 mm body width, 7.75–8.15 mm length, and recommended 8.19 mm PCB footprint length - optimized for thermal dissipation on FR4 with 35 µm copper.

Key Specifications

Pinout & Package

STTH310S is housed in the SMC (DO-214AB) surface-mount package: a compact, lead-free, UL94 V0-compliant epoxy body measuring 5.55–6.25 mm × 7.75–8.15 mm × 2.90–3.20 mm (L × W × H), with gull-wing leads for reflow compatibility and thermal relief.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultrafast high-voltage rectifier applications.

Compared with STTH3R06S and VS-3EYH01-M3/45, STTH310S uniquely balances 1000 V rating, SMC manufacturability, and soft recovery - making it optimal for new 800–1000 V DC-link designs requiring EMI-sensitive, high-reliability rectification.

Availability

STTH310S is available at Aetrix Electronics and suitable for industrial SMPS, telecom power modules, and LED driver auxiliary supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for STTH310S 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, sensors, and analog ICs for automotive, industrial, and consumer markets.

STTH310S belongs to ST's ultrafast high-voltage rectifier product line, engineered specifically for high-frequency switching power conversion where low trr, soft recovery, and thermal robustness are essential - not general-purpose rectification.

FAQ

What is the maximum allowable PCB copper area for thermal relief of STTH310S in SMC package?

Per DS3069 Figure 6, Rth(j-a) drops from ~75 °C/W (no copper) to ~2.5 °C/W with 5 cm² total copper area (2.5 cm² per lead). For reliable 3 A operation at 75 °C ambient, ≥2 cm² of 35 µm-thick FR4 copper per lead is recommended - achieved using 8 mm × 8 mm thermal pads connected via ≥4 thermal vias per pad.

Does STTH310S support avalanche energy rating, and how is it validated?

STTH310S is not rated for repetitive avalanche operation. Its 1000 V VRRM is a non-repetitive blocking specification. Avalanche testing is not performed per ST's qualification flow; the device relies on proper circuit protection (e.g., clamping Zener, RC snubber) to avoid exceeding VRRM under transient conditions.

Can STTH310S replace STTH310 in existing DO-201AD designs?

No - STTH310S uses the SMC (DO-214AB) package, while STTH310 uses DO-201AD. Footprint, solder paste volume, reflow profile, and thermal path differ significantly. Mechanical redesign and layout revision are required; no drop-in replacement is possible without PCB modification and thermal validation.

How does the 0.98 V VF(typ.) at 150 °C impact conduction loss calculation?

Using ST's recommended equation P = 1.20 × IF(AV) + 0.075 × IF²(RMS), VF contributes directly to the linear term. At 3 A IF(AV), conduction loss is ~3.6 W - 15% lower than a diode with 1.15 V VF at same condition. This improves thermal margin in sealed enclosures and extends lifetime in high-ambient deployments.