FSFM261 Fairchild Semiconductor, FSFM261 Datasheet - Page 4

• Manufacturer Part Number: FSFM261
• Description: The FSFM260N/261N/300N is an integrated Pulse Width Modulator (PWM) and SenseFET specifically designed for high-performance offline Switch Mode Power Supplies (SMPS) with minimal external components
• Manufacturer: Fairchild Semiconductor

FSFM260N / FSFM261N / FSFM300N • Rev. 1.0.1
© 2009 Fairchild Semiconductor Corporation
Pin Configuration
Pin Definitions
Pin #
6,7,8
1
2
3
4
5
Name
Drain
V
GND
V
I
FB
LIM
STR
CC
Ground. This pin is the control ground and the SenseFET source.
Power Supply. This pin is the positive supply input, providing internal operating current for
both startup and steady-state operation.
Feedback. 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 6V, the overload pro-
tection triggers, which shuts down the FPS.
Peak Current Limit. Adjusts the peak current limit of the Sense FET. The feedback 0.9mA
current source is diverted to the parallel combination of an internal 2.8kΩ resistor and any ex-
ternal resistor to GND on this pin to determine the peak current limit.
Startup. This pin is connected directly, or through a resistor, to the high-voltage DC link. At
startup, the internal high-voltage current source supplies internal bias and charges the exter-
nal capacitor connected to the V
disabled. It is not recommended to connect V
SenseFET Drain. High-voltage power SenseFET drain connection.
Figure 3. Pin Configuration (Top View)
GND
V
FB
I
LIM
CC
FSFM260 Rev.1.0.0
8-DIP
CC
4
pin. Once V
Description
Drain
Drain
Drain
V
STR
STR
CC
and drain together.
reaches 12V, the internal current source is
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