FPF2116 데이터 시트보기 (PDF) - Fairchild Semiconductor

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FPF2116

IntelliMAX™ Advanced Load Management Products

Fairchild Semiconductor 

Application Information

Typical Application

Battery

5.5V

OFF ON

5.5V MAX

C1 = 4.7µF

VIN

VOUT

FPF2116

ON

FLAGB

GND

R1 = 100KΩ

C2 = 0.1µF

R2 = 110Ω

Input Capacitor

To limit the voltage drop on the input supply caused by transient

in-rush currents when the switch turns-on into a discharged load

capacitor or a short-circuit, a capacitor needs to be placed

between VIN and GND. A 4.7µF ceramic capacitor, CIN, must be

placed close to the VIN pin. A higher value of CIN can be used to

further reduce the voltage drop experienced as the switch is

turned on into a large capacitive load.

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 VIN, VOUT and GND will help

minimize parasitic electrical effects along with minimizing the

case to ambient thermal impedance.

Output Capacitor

A 0.1uF capacitor COUT, should be placed between VOUT and

GND. This capacitor will prevent parasitic board inductances

from forcing VOUT below GND when the switch turns-off. The

total output capacitance needs to be kept below a maximum

value, COUT(max), to prevent the part from registering an

over-current condition and turning off the switch. The maximum

output capacitance can be determined from the following

formula,

COUT(max)

=

I--L---I--M----(---m-----i--n---)----×-----t--B---L---A----N---K----(--m------i-n----)

VIN

(1)

Power Dissipation

During normal operation as a switch, the power dissipation is

small and has little effect on the operating temperature of the

part. The parts with the higher current limits will dissipate the

most power and that will only be,

P = (ILIM)2 × RDS = (0.4)2 × 0.125 = 20mW

(2)

When in current limit the maximum power dissipation will occur

when the output is shorted to ground. The power dissipation will

scale by the Auto-Restart Time, tRSTRT, and the Over Current

Blanking Time, tBLANK, so that the maximum power dissipated

is typically,

P(max)

=

-------------t--B----L---A---N----K--------------

tRETRY + tBLANK

×

VIN(max)

×

ILIM(max)

=

---------6---0----------

60 + 960

×

5.5

×

0.4

=

130mW

(3)

FPF2116 Rev. D

10

www.fairchildsemi.com

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