FPF2123 데이터 시트보기 (PDF) - ON Semiconductor
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FPF2123 Datasheet PDF : 15 Pages
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Description of Operation
The FPF2123, FPF2124, and FPF2125 are current limited
switches that protect systems and loads which can be damaged
or disrupted by the application of high currents. The core of
each device is a 0.125 P-channel MOSFET and a controller
capable of functioning over a wide input operating range of
1.8-5.5V. The controller protects against system malfunctions
through current limiting under-voltage lockout and thermal
shutdown. The current limit is adjustable from 150mA to 1.5A
through the selection of an external resistor.
On/Off Control
The ON pin controls the state of the switch. When ON is high,
the switch is in the on state. Activating ON continuously holds
the switch in the on state so long as there is no fault. For all
versions, an under-voltage on VIN or a junction temperature in
excess of 140°C overrides the ON control to turn off the switch.
In addition, excessive currents will cause the switch to turn off in
the FPF2123 and FPF2124. The FPF2123 has an Auto-Restart
feature which will automatically turn the switch on again after
160ms. For the FPF2124, the ON pin must be toggled to turn-on
the switch again. The FPF2125 does not turn off in response to
an over current condition but instead remains operating in a
constant current mode so long as ON is active and the thermal
shutdown or under-voltage lockout have not activated.
The ON pin control voltage and VIN pin have independent
recommended operating ranges. The ON pin voltage can be
driven by a voltage level higher than the input voltage.
Current Limiting
The current limit ensures that the current through the switch
doesn't exceed a maximum value while not limiting at less than
a minimum value. The current at which the parts will limit is
adjustable through the selection of an external resistor
connected to ISET. Information for selecting the resistor is found
in the Application Info section. The FPF2123 and FPF2124
have a blanking time of 10ms, nominally, during which the
switch will act as a constant current source. At the end of the
blanking time, the switch will be turned-off. The FPF2125 has
no current limit blanking period so it will remain in a constant
current state until the ON pin is deactivated or the thermal
shutdown turns-off the switch.
Under-Voltage Lockout
The under-voltage lockout turns-off the switch if the input
voltage drops below the under-voltage lockout threshold. With
the ON pin active, the input voltage rising above the
under-voltage lockout threshold will cause a controlled turn-on
of the switch which limits current over-shoots.
Thermal Shutdown
The thermal shutdown protects the die from internally or
externally generated excessive temperatures. During an
over-temperature condition the switch is turned-off. The switch
automatically turns-on again if the temperature of the die drops
below the threshold temperature.
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FPF2123-FPF2125 Rev. F
www.fairchildsemi.com
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