FPF2163_07 FAIRCHILD [Fairchild Semiconductor], FPF2163_07 Datasheet - Page 11

• Manufacturer Part Number: FPF2163_07
• Description: Full Function Load Switch with Adjustable Current Limit
• Manufacturer: FAIRCHILD [Fairchild Semiconductor]

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 FPF2164,
attention must be given to the manual resetting of the part. 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 FPF2165, a short on the output will
cause the part to operate in a constant current state dissipating
a worst case power of,
P(max) = V
(max) x I
(max)
(5)
IN
LIM
= 5.5 x 1.5 = 8.25W
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
operation. Using wide traces for V
, V
and GND will help
IN
OUT
minimize parasitic electrical effects along with minimizing the
case to ambient thermal impedance.
The middle pad (pin 7) should be connected to the GND plate
of PCB for improving thermal performance of the load switch.
An improper layout could result higher junction temperature and
triggering the thermal shutdown protection feature. This concern
applies when the switch is set at higher current limit value and
an overcurrent condition occurs. In this case power dissipation
of the switch (P
= (V
- V
) x I
(max)) could exceed the
D
IN
OUT
LIM
maximum absolute power dissipation of 1.2W.
11
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FPF2163/4/5 Rev. D