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FPF2123-FPF2125 Rev. F

This is more power than the package can dissipate, but the

thermal shutdown of the part will activate to protect the part from

damage due to excessive heating. When using the FPF2124,

attention must be given to the manual resetting of the part.

Continuously resetting the part when a short on the output is

present will cause the temperature of the part to increase. The

junction temperature will only be able to increase to the thermal

shutdown threshold. Once this temperature has been reached,

toggling ON will not turn-on the switch until the junction

temperature drops. For the FPF2125, a short on the output will

cause the part to operate in a constant current state dissipating

a worst case power of,

This large amount of power will activate the thermal shutdown

and the part will cycle in and out of thermal shutdown so long as

the ON pin is active and the short is present.

Board Layout

For best performance, all traces should be as short as possible.

To be most effective, the input and output capacitors should be

placed close to the device to minimize the effects that parasitic

trace inductances may have on normal and short-circuit

minimize parasitic electrical effects along with minimizing the

case to ambient thermal impedance.

5.5

1.5

×

=

8.25W

=

P max

(

)

V

IN

·

max

(

)

I

(

)

×

=

(5)