Freewheeling Diode / Synchronous MOSFET: Current Rating 5A-100A

Q: What is the difference between a freewheeling diode and a synchronous MOSFET?

A freewheeling diode is a passive component that conducts when forward-biased, while a synchronous MOSFET is an active switch that replaces the diode to reduce conduction losses through lower voltage drop.

Q: Why is this component essential in buck converters?

It provides a current path during the switch-off period, preventing high voltage spikes, enabling continuous inductor current, and improving efficiency by recirculating stored energy.

Component Specifications

Definition

In buck converter circuits, the freewheeling diode (or synchronous MOSFET in synchronous designs) provides a path for inductor current during the switch-off period, preventing voltage spikes and enabling continuous current flow. This component is critical for energy recirculation, reducing switching losses, and improving overall converter efficiency.

Working Principle

During the switch-off phase of the buck converter's main switch, the freewheeling diode becomes forward-biased (or the synchronous MOSFET is actively turned on in synchronous designs), allowing inductor current to circulate through the load. This maintains continuous current flow, stores and releases magnetic energy, and prevents destructive voltage transients across the switching elements.

Materials

Freewheeling diode: Silicon or Schottky semiconductor materials; Synchronous MOSFET: Silicon or gallium nitride (GaN) with copper or aluminum terminals, epoxy encapsulation.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Package Type	TO-220, D2PAK, SO-8
Current Rating	5A-100A
Voltage Rating	20V-100V
Switching Frequency	100kHz-2MHz
Forward Voltage Drop	0.3V-0.7V (diode), <0.1V (MOSFET)

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEC 60747, JEDEC JESD22

Parent Products

This component is used in the following industrial products

Buck Converter

A step-down DC-to-DC power converter that efficiently reduces a higher input voltage to a lower output voltage.

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Engineering Analysis

Risks & Mitigation

Thermal runaway due to excessive current
Reverse recovery issues in diodes
Gate driver failure in MOSFETs

FMEA Triads

Trigger: Overcurrent or overheating
Failure: Component thermal destruction or short circuit
Mitigation: Implement current limiting, thermal protection, and proper heatsinking

Trigger: Improper gate driving in synchronous MOSFET
Failure: Cross-conduction or shoot-through
Mitigation: Use dead-time control in gate drivers and ensure proper timing

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±5% for voltage ratings, ±10% for current ratings

Test Method

Dynamic switching tests, thermal cycling, HALT (Highly Accelerated Life Testing)

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

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Inspection readiness

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Manufacturers of Freewheeling Diode / Synchronous MOSFET

Manufacturer profiles associated with Freewheeling Diode / Synchronous MOSFET.

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Frequently Asked Questions

What is the difference between a freewheeling diode and a synchronous MOSFET?