STMicroelectronics STPS40M120CT

Overview

STPS40M120CT from STMicroelectronics is a dual common-cathode 120 V, 2 × 20 A average forward current Schottky rectifier in TO-220AB package, featuring 0.61 V typical forward voltage at 125 °C and 150 °C max junction temperature, optimized for high-frequency SMPS in notebook adapters and DC/DC converters.

For engineers reviewing the STPS40M120CT datasheet, STPS40M120CT pinout, STPS40M120CT application, or STPS40M120CT equivalent, key selection criteria include avalanche-rated ruggedness (1600 W peak), low conduction loss profile, thermal coupling behavior between dual diodes, and ECOPACK®2-compliant packaging for industrial power supply design.

Technical Context

This dual-diode Schottky rectifier integrates two independent 120 V, 20 A per diode elements sharing a common cathode terminal, enabling synchronous half-wave or interleaved operation in high-density AC/DC front-ends. Its low VF–IR trade-off targets efficiency optimization across light-to-full load in compact adaptors.

Thermal design requires accounting for inter-diode coupling: junction-to-case resistance is 1.10 °C/W per diode, but total device Rth(j-c) is 0.80 °C/W due to shared case path; simultaneous conduction induces cross-heating modeled via Rth(c) = 0.50 °C/W coupling term.

Key Specifications

Pinout & Package

Delivered in TO-220AB package with insulated mounting hole, epoxy meeting UL 94 V0, and recommended torque of 0.55 N·m. Case serves as common cathode terminal; anodes are isolated pins.

Key Features

Applications

Equivalent & Alternatives

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

Compared with VS-40CPH12 and MBR40120CT, STPS40M120CT delivers superior thermal headroom (TC = 130 °C vs 110 °C/125 °C), lower conduction loss (0.61 V vs 0.65 V/0.67 V), and tighter IR control-critical for high-efficiency, fanless, or wide-temperature-range power supplies.

Availability

STPS40M120CT is available at Aetrix Electronics and suitable for notebook adapters, desktop PC power supplies, gaming console SMPS, and industrial DC/DC converters requiring stable component supply and long-term lifecycle support.

Supply support for STPS40M120CT 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, designing and manufacturing microcontrollers, power devices, sensors, and analog ICs for automotive, industrial, and consumer markets.

The STPS series targets high-efficiency, high-reliability power conversion in compact form factors-specifically engineered for next-generation AC/DC adapters, server PSUs, and industrial DC/DC modules demanding low VF, high Tj, and avalanche robustness.

FAQ

Is STPS40M120CT suitable for synchronous rectification circuits?

No-it is a passive Schottky rectifier, not a synchronous rectifier controller or MOSFET driver. It functions as a diode-only output rectifier. For synchronous rectification, a dedicated gate driver IC (e.g., STSR3) paired with low-RDS(on) MOSFETs is required; STPS40M120CT replaces traditional diodes in non-controlled rectification stages.

What is the maximum allowable case temperature for continuous operation?

The maximum case temperature for continuous operation is 130 °C per diode, as specified in the absolute ratings table for IF(AV) = 20 A. Exceeding this requires derating; at TC = 120 °C, the device supports 40 A total average current (2 × 20 A), confirmed in the product summary and Table 1.

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

Yes-the TO-220AB tab is electrically connected to the common cathode (K). If the heatsink is chassis-grounded or at a different potential, insulating hardware (e.g., mica washer + nylon screw) must be used to prevent short circuits. The datasheet specifies the tab as "electrically connected to cathode" in Section 2.1.

How does thermal coupling affect derating when both diodes conduct simultaneously?

When both diodes conduct, junction temperature rise of Diode 1 equals P₁ × 1.10 + P₂ × 0.50 °C, where P₁ and P₂ are respective power dissipations. This coupling term (Rth(c) = 0.50 °C/W) means simultaneous full-load operation raises each junction by ~10–15 °C more than independent operation-requiring conservative thermal design per AN5088.