Description
This user manual provides elementary information about an isolated
flyback with FSL518APG, it performs high efficiency and smaller
than 50 mW no−load power consumption. FSL518APG is an
integrated pulse width modulation (PWM) and 800 V power switch
with SENSEFET®, it can help to save external MOSFET and sense
resistor, increase power density and reliability. This application is
targeting auxiliary power supply for white goods and industrial
equipment, such as refrigerator, E−metering or similar types of
equipment.
The PWM controller includes an integrated variable frequency
oscillator, Under−Voltage Lockout (UVLO), Leading Edge Blanking
(LEB), optimized gate driver, internal soft−start, and temperature−
compensated precise current source for loop compensation and
self−protection circuitry. This design focuses mainly on the
FSL518APG current−mode PWM controller. Please refer to
FSL518APG’s materials to get more information about this device.
The FSL518APG is a current−mode PWM controller, it can have
better response to handle dynamic operation. Controller combines line
detection and burst−mode adjustment in one pin. It’s easy to achieve
these functionalities just need voltage divider and one Zener diode.
Line detection includes brown−in, brown−out and line OVP,
burst−mode adjustment is for fine tune audible noise and light load
efficiency. Of course, it also provides frequency reduction with
loading decreasing for gaining more design margin to improve light
load efficiency.

Key Features
• Integrated Rugged 800 V Super Junction
MOSFET with SENSEFET Technology
• Built−in HV Current Source for Start−up
• Peak−Current−Mode Control with Slope
Compensation
• Line Compensation for Maximum
Over−Power Limiting
• Advanced Soft−start for Low Electrical
Stress
• Peak−Current−Mode Control with Built−in
Slope Compensation
• Pulse−by−pulse Current Limit
• Line Brown−in, Brown−out,
and Over−Voltage Protection (LOVP)
• Adjustable Burst−mode Operation
• Frequency Hopping for Better EMI
• Various Protections:
♦ Auto Restart Mode: Brown−out, OLP,
OVP, AOCP and TSD
♦ Recovery Immediately by Triggering
Level: LOVP