ON Semiconductor


Primary-Side-Regulation PWM Controller

Topology: Flyback
Switching Frequency (min.): 47.00 kHz
Switching Frequency (max.): 53.00 kHz

Original publication on 2014-01-01, revision 1.0.7


This third-generation Primary Side Regulation (PSR) and highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters. The proprietary topology, TRUECURRENT®, of FAN103 enables precise CC regulation and simplified circuit for battery charger applications. A low-cost, smaller and lighter charger results as compared to a conventional design or a linear transformer.To minimize standby power consumption, the proprietary green-mode function provides off-time modulation to linearly decrease PWM frequency under light-load conditions. This green mode assists the power supply in meeting the power conservation requirement. By using the FAN103, a charger can be implemented with few external components and minimized cost.


  • Low Standby Power Under 30mW
  • High-Voltage Startup
  • Fewest External Component Counts
  • Constant-Voltage (CV) and Constant-Current (CC) Control without Secondary-Feedback Circuitry
  • Green-Mode Function: Linearly-Decreasing PWM Frequency
  • Fixed PWM Frequency at 50kHz with Frequency Hopping to Solve EMI Problem
  • Cable Compensation in CV Mode
  • Peak-Current-Mode Control in CV Mode
  • Cycle-by-Cycle Current Limiting
  • VDD Over-Voltage Protection with Auto Restart
  • VDDUnder-Voltage Lockout (UVLO)
  • Gate Output Maximum Voltage Clamped at 15V
  • Fixed Over-Temperature Protection with Auto Restart
  • Available in the 8-Lead SOP PackageRemarks:Inductors 1mH , 4.7uH And Transformer Used


Order Code SPEC Product series Samples
750341797 PDF Flyback Transformer