FSCQ-SERIES
Pin Definitions
Pin Number
Pin Name
Pin Function Description
High voltage power SenseFET drain connection.
This pin is the control ground and the SenseFET source.
1
2
Drain
GND
This pin is the positive supply input. This pin provides internal operating
current for both start-up and steady-state operation.
3
Vcc
This pin is internally connected to the 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 7.5V, the over load protection triggers, which
results in the FPS shutting down.
4
Vfb
This pin is internally connected to the sync detect comparator for quasi-
resonant switching. In normal quasi-resonant operation, the threshold of the
sync comparator is 4.6V/2.6V. Whereas, the sync threshold is changed to
3.0V/1.8V in an extended quasi-resonant operation.
5
Sync
Pin Configuration
TO-220F-5L
5.Sync
4.Vfb
3.Vcc
2.GND
1.Drain
TO-3PF-7L
5.Sync
4.Vfb
3.Vcc
2.GND
1.Drain
Figure 3. Pin Configuration (Top View)
3
FAIRCHILD [ FAIRCHILD SEMICONDUCTOR ]
