ON Semiconductor


FSL336LR Green Mode Fairchild Buck Switch

Topology: Flyback
Input Voltage (min.): 85.00 V
Input Voltage (max.): 265.00 V
Switching Frequency (min.): 45.00 kHz
Switching Frequency (max.): 55.00 kHz
Output 1: 15.00 V / 0.450 A
Output 2: 3.30 V / 0.100 A

Original publication on 2015-01-01, revision 1.1


The FSL336LR integrated Pulse Width Modulator (PWM) and SenseFET is specifically designed for high-performance offline buck, buck-boost, and non-isolation flyback Switched Mode Power Supplies (SMPS) with minimal external components. This device integrates a high-voltage power regulator that enables operation without auxiliary bias winding. An internal transconductance amplifier reduces external components for the feedback compensation circuit.The integrated PWM controller includes: 10 V regulator for no external bias circuit, Under-Voltage Lockout (UVLO), Leading-Edge Blanking (LEB), an optimized gate turn-on / turn-off driver, EMI attenuator, Thermal Shutdown (TSD), temperature-compensated precision current sources for loop compensation, and fault-protection circuitry. Protections include: Overload Protection (OLP), Over-Voltage Protection (OVP), and Feedback Open Loop Protection (FB_OLP). FSL336LR offers good soft-start performance during startup.The internal high-voltage startup switch and the Burst-Mode operation with very low operating current reduce the power loss in Standby Mode. As the result, it is possible to reach power loss of 120 mW without external bias and 25 mW with external bias when input voltage is 230 VAC.


  • Built-in Avalanche-Rugged SenseFET: 650 V
  • Fixed Operating Frequency: 50 kHz
  • No-Load Power Consumption:
  • 25 mW at 230 VAC with External Bias;
  • 120 mW at 230 VAC without External Bias
  • No Need for Auxiliary Bias Winding
  • Frequency Modulation for Attenuating EMI
  • Pulse-by-Pulse Current Limiting
  • Ultra-Low Operating Current: 250 µA
  • Built-in Soft-Start and Startup Circuit
  • Adjustable Peak Current Limit
  • Built-in Transconductance (Error) Amplifier
  • Various Protections: Overload Protection (OLP), Over-Voltage Protection (OVP), Feedback Open-Loop Protection (FB_OLP), Thermal Shutdown (TSD)
  • Fixed 650 ms Restart Time for Safe Auto-Restart of All Protections


  Order Code SPEC Product series LBASE
∫Udt Base
LS Base
(V (AC))
749196521 PDF WE-FLEX Flexible Transformer for DC/DC Converter 12 1:1:1:1:1:1 1.7 1.73 71.1 98.4 0.24 500