STMicroelectronics FERD40M45CT

Overview

FERD40M45CT from STMicroelectronics is a dual-field-effect rectifier in TO-220AB package, rated for 45 V repetitive peak reverse voltage and 2 × 20 A average forward current per diode at Tc = 150 °C. It delivers low forward voltage drop (VF(typ) = 0.34 V at 10 A, 125 °C), stable leakage current up to 50 mA at 125 °C/45 V, and supports high-frequency switching in SMPS and automotive power converters.

For engineers reviewing the FERD40M45CT datasheet, FERD40M45CT pinout, FERD40M45CT application, or FERD40M45CT equivalent, key selection criteria include thermal resistance (Rth(j–c) = 1.6 °C/W per diode), junction-to-case coupling (0.5 °C/W), conduction loss modeling (P = 0.31×IF(AV) + 0.0095×IF²(RMS)), and ECOPACK®-compliant packaging for industrial and automotive-grade reliability.

Technical Context

This dual common-cathode rectifier uses ST's proprietary field-effect process to minimize VF/IR trade-off across temperature and voltage. Each diode operates independently with validated thermal coupling behavior-junction-to-case resistance is 1.6 °C/W per diode, and inter-diode thermal coupling adds 0.5 °C/W when both conduct simultaneously.

It is optimized for continuous conduction mode (δ = 0.5) in DC–DC converters and offline SMPS, where low forward voltage (0.34–0.50 V across 10–20 A, 25–125 °C) directly reduces conduction losses, and stable IR (<50 mA at 125 °C/45 V) ensures predictable reverse blocking under thermal stress.

Key Specifications

Pinout & Package

Packaged in TO-220AB with insulated tab, the FERD40M45CT features three terminals: two anodes (A1, A2) and one common cathode (K). The case is electrically connected to the cathode, requiring isolation when mounted to grounded heatsinks.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-field-effect rectifier applications.

Compared with STTH30L06CW and VS-80EQ040MN, FERD40M45CT uniquely balances 45 V rating, dual-anode integration, and ultra-low VF (0.34 V) for thermally constrained secondary-side SMPS-making it optimal for space-limited 12 V/20 A outputs where efficiency and footprint are co-prioritized.

Availability

FERD40M45CT is available at Aetrix Electronics and suitable for server power supplies, automotive DC–DC converters, industrial PLC power modules, and telecom rectifier bricks requiring stable component supply and long-term production continuity.

Supply support for FERD40M45CT 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 sensors for industrial, automotive, and consumer markets.

The FERD40M45CT belongs to ST's Field Effect Rectifier (FER) product line, engineered specifically to replace conventional Schottky and fast-recovery diodes in high-efficiency, high-temperature switch-mode power supplies.

FAQ

What is the maximum junction temperature and how is it enforced?

The absolute maximum operating junction temperature is 175 °C for TO-220AB packaging. This limit is enforced via thermal design using the specified Rth(j–c) = 1.6 °C/W per diode and Rth(c) = 0.5 °C/W coupling term. Derating curves in Figure 2 confirm 20 A IF(AV) is sustainable only when ambient temperature stays below 75 °C with adequate heatsinking.

Can FERD40M45CT be used in synchronous rectification topologies?

No-FERD40M45CT is a passive rectifier, not a synchronous MOSFET driver or controlled switch. It functions as a unidirectional, self-commutated diode. Its low VF and fast recovery enable high-efficiency operation in quasi-resonant and LLC topologies, but gate drive signals or external control logic cannot modulate its conduction.

Is the TO-220AB tab electrically isolated?

No-the metal tab is internally connected to the common cathode (K) terminal. Electrical isolation from the heatsink is mandatory unless the heatsink is floated or biased to the same potential as the cathode net. ST recommends using insulating shoulder washers and thermal pads rated for ≥500 V isolation.

How does thermal coupling affect dual-diode derating?

When both diodes conduct simultaneously, total junction temperature rise is ΔTj = P₁×Rth(j–c) + P₂×Rth(c), where Rth(c) = 0.5 °C/W represents inter-diode thermal coupling. This means simultaneous 20 A conduction in both diodes raises junction temperature by an additional 10 °C beyond single-diode operation-requiring 10 °C derating or reduced per-diode current to maintain 175 °C Tj max.