FSDL321 Fairchild Semiconductor, FSDL321 Datasheet - Page 13

• Manufacturer Part Number: FSDL321
• Description: IC SWIT PWM GREEN CM OVP HV 8DIP
• Manufacturer: Fairchild Semiconductor

Specifications of FSDL321

• Output Isolation: Isolated
• Frequency Range: 45 ~ 55kHz
• Voltage - Input: 8 ~ 20 V
• Voltage - Output: 650V
• Power (watts): 17W
• Operating Temperature: 25°C ~ 140°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Power Switch Family: FSDL321
• Power Switch On Resistance: 14Ohm
• Output Current: 2A
• Number Of Outputs: Single
• Mounting: Through Hole
• Supply Current: 3mA
• Package Type: PDIP
• Operating Temperature (min): -25C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Pin Count: 8
• Power Dissipation: 1.4W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FSDL321_NL; FSDL321_NL

8. Adjusting Current limit function: As shown in fig 12, a
combined 2.8kΩ internal resistance is connected into the
non-inverting lead on the PWM comparator. A external
resistance of A on the current limit pin forms a parallel resis-
tance with the 2.8kΩ when the internal diodes are biased by
the main current source of 900uA.
For example, FSDH321 has a typical Sense FET current
limit (I
to 0.5 by inserting a 7kΩ between the current limit pin and
ground which is derived from the following equations:
0.7: 0.5 = 2.8kΩ : XkΩ ,
X = 2kΩ,
Since X represents the resistance of the parallel network, A
can be calculated using the following equation:
A = X / (1 - (X/2.8kΩ))
Current
Limit
Feed
Back
LIM
AK
Ω
) of 0.7A. The Sense FET current can be limited
3
4
Figure 12. Peak current adjustment
5uA
900uA
0
8 .
2
K
K
Ω
Ω
Rsense
comparator
SenseFET
Sense
PWM
Layout Considerations
FSDH321, FSDL321
13