SVF20N50F Power MOSFET 20A 500V TO-220F Power Supply repair

SVF20N50F 20A 500V N-Channel MOSFET – High-Power Switching for Mining PSU Repair

The SVF20N50F is a 20 A / 500 V N-channel power MOSFET in a TO-220F fully-insulated package, built on Silan Microelectronics' F-Cell VDMOS process. With a typical on-resistance of just 0.20 Ω, it minimises conduction losses in the primary-side switching stage of crypto miner power supplies. The TO-220F package provides full electrical insulation between the drain tab and the heatsink, eliminating the need for a mica washer and simplifying thermal management in dense PSU layouts.

Why This MOSFET Fails in Mining Power Supplies

Primary-side MOSFETs in mining PSUs switch the full DC bus voltage at frequencies typically between 65 kHz and 130 kHz, generating substantial switching and conduction losses. Under continuous 24/7 load, cumulative thermal stress degrades the gate oxide and the die-to-lead solder joint. Voltage spikes from transformer leakage inductance or mains transients can also exceed the drain-source breakdown rating if the snubber circuit has deteriorated. A failed MOSFET typically results in a blown input fuse, no output from the PSU, or in partial-failure cases, intermittent shutdowns under load as the damaged device oscillates between conduction and blocking states.

Replacement Procedure

Disconnect the PSU from mains and discharge the bulk capacitors — primary-side voltages can exceed 400 V DC and remain lethal for minutes after power-off. Locate the SVF20N50F on the primary switching board, typically bolted to a heatsink near the main transformer. Remove the mounting screw, desolder the three leads (gate, drain, source), and clean the pads. Install the new MOSFET with the correct pin orientation per the board silkscreen, apply thermal compound between the TO-220F tab and the heatsink, and torque the mounting screw to specification. After reassembly, power the PSU through a variac and monitor the output voltage under progressive load — a stable, ripple-free output confirms a good repair.

The SVF20N50F's low gate charge and fast switching characteristics make it suitable for both hard-switched and resonant (LLC) topologies commonly found in mining PSUs rated from 1,200 W to 3,600 W. If you are replacing multiple MOSFETs on the same half-bridge, always replace both devices as a matched pair to ensure balanced switching.

SVF20N50F MOSFET Specifications

Related Power MOSFETs for Mining PSU Repair

• MDF5N50F 500V N-Channel MOSFET – Avalon PSU Repair
• PTW40N50 500V 46A MOSFET – Crypto Miner PSU
• GPT13N50DG High-Voltage MOSFET – Whatsminer PSU
• NCE65TF130D 650V 28A Super Junction MOSFET – PSU Repair

Replacing MOSFETs across a fleet of mining PSUs? Contact us at contact@lys-sz.com for matched pairs and volume pricing.

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