Data Sheet

© 2008 Fairchild Semiconductor Corporation www.fairchildsemi.com
FSQ500L • Rev. 1.0.3 3
FSQ500L — Compact, Green Mode, Fairchild Power Switch (FPS™)
Pin Assignments
GND
V
CC VFBD
FSQ500L
Figure 3. Package / Pin Diagram
Pin Definitions
Pin # Name Description
1 D
High-voltage power senseFET drain connection. In addition, at startup, the internal high-voltage
current source supplies internal bias and charges the external capacitor connected to the V
CC
pin.
Once V
CC
reaches 6.0V, all internal blocks are activated. The internal high-voltage current source
is alive until V
CC
reaches 6.5V. After that, the internal high voltage current source turns on and off
irregularly to maintain V
CC
at 6.5V.
2 V
CC
This pin is connected to a storage capacitor. A high-voltage regulator connected between pin 1 (D)
and this pin provides the supply voltage to the FSQ500L at startup and when switching during
normal operation. The FSQ500L eliminates the need for auxiliary bias winding and associated
external components.
3 V
FB
This pin is internally connected to the non-inverting input of the PWM comparator. The collector of
an opto-coupler is typically tied to this pin. For stable operation, a capacitor should be placed
between this pin and GND. If the voltage of this pin reaches 4.5V, the overload protection triggers,
which shuts down the FPS.
4 GND This pin is the control ground and the senseFET source.