Applying Fairchild Power Switch (FPS™) FSL1x7 to
Low- Power Supplies
The highly integrated FSL-series consists of an integrated
current-mode Pulse Width Modulator (PWM) and an
avalanche-rugged 700V SenseFET. It is specifically
designed for high-performance offline Switched Mode
Power Supplies (SMPS) with minimal external components.
The features of the integrated PWM controller include a
proprietary green-mode function providing off-time
modulation to linearly decrease the switching frequency at
light-load conditions to minimize standby power
consumption. The PWM controller is manufactured using
the BiCMOS process to further reduce power consumption.
The green mode and burst mode functions with a low
operating current (2mA in green mode) maximize light-load
efficiency so that the power supply can meet stringent
standby power regulations.
The FSL-series has a built-in synchronized slope
compensation to achieve stable peak-current-mode control.
The proprietary external line compensation ensures constant
output power limit over a wide AC input voltage range,
, and helps optimize the power stage.
Many protection functions; such as open–loop / overload
protection (OLP), over-voltage protection (OVP), and over-
temperature protection (OTP); are fully integrated into FSL-
series. These features improve the SMPS reliability without
increasing system cost.
Compared to a discrete MOSFET and controller or RCC
switching converter solution, the FSL-series reduces total
component count, converter size, and weight while
increasing efficiency, productivity, and system reliability.
These devices provide a basic platform for design of cost-
effective flyback converters.
Figure 1. Typical Application Circuit
© 2010 Fairchild Semiconductor Corporation
Rev. 1.0.0 • 11/2/10