STMicroelectronics STPS30SM120ST

Overview

STPS30SM120ST from STMicroelectronics is a 120 V, 30 A average forward current Schottky rectifier in TO-220AB package, featuring 0.47 V typical forward voltage at 125 °C and 5 A, avalanche-rated operation, and 2000 VRMS insulation (in FP variant). It serves as a high-efficiency output rectifier in notebook adapters and DC/DC converters where low conduction loss and high-frequency switching are critical.

For engineers reviewing the STPS30SM120ST datasheet, STPS30SM120ST pinout, STPS30SM120ST application, or STPS30SM120ST equivalent, key selection criteria include forward voltage drop at rated current, thermal resistance (Rth(j-c) = 1.35 °C/W), avalanche energy capability (1200 W peak), and insulated package compliance for safety-critical AC/DC power supplies.

Technical Context

This Schottky diode employs a planar silicon structure optimized for low VF and fast recovery, enabling efficient operation up to several hundred kHz in SMPS topologies. Its avalanche rating supports transient overvoltage robustness without external snubbers in flyback or LLC resonant converters.

The TO-220AB package provides direct heatsink mounting with 1.35 °C/W junction-to-case thermal resistance, while the related TO-220FPAB variant adds 2000 VRMS isolation-critical for reinforced insulation in Class II adapter designs meeting IEC 60950-1 or IEC 62368-1.

Key Specifications

Pinout & Package

STPS30SM120ST uses the TO-220AB package: three-terminal, through-hole, non-insulated plastic housing with metal tab (cathode-connected) for direct heatsink mounting. Mounting torque: 0.55 N·m (recommended), 0.70 N·m (max).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schottky rectifier applications.

Compared with VS-30CPH12 and SB3120, STPS30SM120ST delivers superior thermal performance (1.35 °C/W), lower VF at high temperature, and guaranteed avalanche capability-making it optimal for compact, high-efficiency, safety-certified AC/DC adapters.

Availability

STPS30SM120ST is available at Aetrix Electronics and suitable for notebook adapters, DC/DC converters, and LED lighting systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for STPS30SM120ST 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.

STPS30SM120ST belongs to ST's high-current Schottky rectifier product line, engineered specifically for high-efficiency, high-reliability secondary-side rectification in compact AC/DC and isolated DC/DC power supplies.

FAQ

What is the maximum allowable case temperature for continuous operation?

The device supports continuous operation with case temperature up to 100 °C when mounted on a heatsink providing ≤1.35 °C/W thermal resistance. At 100 °C case temperature and 30 A average current, junction temperature remains within the 150 °C limit assuming typical VF characteristics and derated conduction loss.

Is STPS30SM120ST suitable for synchronous rectification replacement?

No-it is a passive Schottky rectifier and cannot replace active synchronous rectifiers that require gate control. However, it serves as a high-performance alternative to standard silicon diodes in non-synchronous topologies like flyback or forward converters where simplicity and cost outweigh marginal efficiency gains from synchronous designs.

Does the TO-220AB package require electrical isolation from the heatsink?

Yes-the metal tab is electrically connected to the cathode. If the cathode node is not at chassis ground potential, an insulating washer and shoulder washer must be used between the tab and heatsink to prevent short circuits. Thermal grease must be applied over the insulator for effective heat transfer.

How does the avalanche rating impact design margin in adapter applications?

The 1200 W peak avalanche power rating (at 10 µs, Tj = 125 °C) allows the diode to absorb transient overvoltages-such as leakage inductance spikes in flyback transformers-without failure. This eliminates need for external TVS or RC snubbers, reducing BOM count and PCB area in space-constrained notebook adapters.