FPF2172(2006) Ver la hoja de datos (PDF) - Fairchild Semiconductor
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FPF2172 Datasheet PDF : 11 Pages
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Description of Operation
The FPF2172 is a current limited switch that protects systems
and loads which can be damaged or disrupted by the
application of high currents. The core of the device is a 0.125Ω
P-channel MOSFET and a controller capable of functioning over
a wide input operating range of 1.8-5.5V paired with a low
forward voltage drop Schottky diode for reverse blocking. The
controller protects against system malfunctions through current
limiting, under-voltage lockout and thermal shutdown. The
current limit is preset for 200mA.
On/Off Control
The ON pin controls the state of the switch. Activating ON
continuously holds the switch in the on state so long as there is
no under-voltage on VIN or a junction temperature in excess of
150°C. ON is active HI and has a low threshold making it
capable of interfacing with low voltage signals. When the
MOSFET is off, the Schottky diode acts as a barrier so that no
reverse current can flow when VOUT is greater than VIN.
Fault Reporting
Upon the detection of an over-current, an input under-voltage,
or an over-temperature condition, the FLAGB signals the fault
mode by activating LO. The FLAGB goes LO at the end of the
blanking time and is latched LO and ON must be toggled to
release it. FLAGB is an open-drain MOSFET which requires a
pull-up resistor between VIN and FLAGB. During shutdown, the
pull-down on FLAGB is disabled to reduce current draw from
the supply.
Current Limiting
The current limit guarantees that the current through the switch
doesn't exceed a maximum value while not limiting at less than
a minimum value. The minimum current is 200mA and the
maximum current is 400mA. The device has 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 and the FLAGB pin will activate to indicate that
current limiting has occurred.
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 FLAGB is activated and the
switch is turned-off. The switch automatically turns-on again if
temperature of the die drops below the threshold temperature.
Ordering Information
Part
FPF2172
Current Limit
[mA]
200
Current Limit
Blanking Time
[ms]
10
Auto-Restart
Time
[ms]
NA
ON Pin
Activity
Active HI
Top Mark
2172
FPF2172 Rev. E
8
www.fairchildsemi.com
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