FAN7930C FAN7930CMX Power Factor Correction PFC Critical Conduction Mode

FAN7930C PFC Controller – Critical Conduction Mode for Mining PSU Repair

The FAN7930C (FAN7930CMX) is a voltage-mode PWM controller for boost PFC applications operating in critical conduction mode (CRM), packaged in SOP-8. It eliminates the need for rectified AC line voltage sensing, reducing input network power loss. Key features include an internal THD optimiser, zero-current detector (ZCD), MOSFET overcurrent protection, internal soft-start without overshoot, adjustable output OVP and UVLO with 3.5V hysteresis. Peak gate drive +500/-800mA, switching frequency up to 300kHz, operating range -40°C to 125°C.

Role of the PFC Stage in Mining PSUs

The PFC boost stage shapes the AC input current to follow the voltage waveform, achieving power factor close to unity. This reduces harmonic distortion on the mains supply and is required for compliance in high-wattage mining PSUs. When the PFC controller fails, the PSU either shuts down entirely or produces an unstable DC bus voltage that causes downstream converter failure. The FAN7930C's PFC-Ready signal with hysteresis ensures clean handoff to the downstream LLC or half-bridge stage.

Replacement Procedure

Disconnect mains and discharge all capacitors including the PFC bulk cap. Locate the FAN7930C on the PFC control board — SOP-8 near the boost inductor and MOSFET gate drive. Desolder, clean pads, install with pin 1 aligned and reflow. Power through a variac and verify the PFC output voltage stabilises at the correct level before the downstream converter starts.

FAN7930C PFC Controller Specifications

Related PFC Controllers & PSU ICs

• ICE3PCS01G PFC Controller – Avalon PSU3300
• CM6800UX PFC Controller – SMPS
• L4981AD PFC – Lovecore / Aixin A1 PSU
• L6599D LLC Controller – Bitmain / Avalon PSU

Repairing mining PSU PFC stages? Contact us at contact@lys-sz.com for PFC controllers, boost MOSFETs and all PSU ICs.

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