FAN6756 is a new green-mode PWM controller from Fairchild Semiconductor Corporation. It incorporates innovative mWSaver™ technology, which dramatically reduces the standby and no-load power consumption of a power supply with minimum external components. This application note presents the step-by-step design with an example of applying FAN6756 to a flyback power supply. It covers designing of the transformer and selecting the external components.
The document introduces the FAN6756, a green-mode PWM controller featuring mWSaver™ technology to reduce standby and no-load power consumption. It explains how the controller utilizes AX-CAP™ and Standby Mode to minimize losses in the EMI filter and switching stages.
The core of the document is a detailed design example for a 65W/19V offline flyback SMPS. It provides a 11-step procedure covering input power estimation, component selection (capacitors, MOSFETs, transformers), and circuit design for feedback and protection.
| Nominal Output Power (Example) | 65W |
|---|---|
| Output Voltage (Example) | 19V |
| Input Voltage Range (Example) | 90 V RMS to 264 V RMS |
| Switching Frequency (Example) | 65kHz |
| Primary Turns (Example) | 38 turns |
| Secondary Turns (Example) | 11 turns |
It incorporates innovative mWSaver™ technology which dramatically reduces standby and no-load power consumption.
It uses AX-CAP™ technology to remove the X-capacitor bleeder resistor and its associated loss through intelligent detection and discharge methods.
The current density is typically 6-10A/mm2 when the wire is long, or 8-14A/mm2 when the wire is short with a small number of turns.