FPF2108 Fairchild Semiconductor, FPF2108 Datasheet - Page 9

• Manufacturer Part Number: FPF2108
• Description: IC LOAD SWITCH ADVANCED SOT23-5
• Manufacturer: Fairchild Semiconductor
• Series: IntelliMax™r
• Type: High Side Switchr

Specifications of FPF2108

• Number Of Outputs: 1
• Rds (on): 160 mOhm
• Internal Switch(s): Yes
• Current Limit: 400mA
• Voltage - Input: 1.8 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Switch Type: Low Side
• Power Switch Family: FPF2108
• Input Voltage: 1.8 to 5.5V
• Output Current: 400mA
• Mounting: Surface Mount
• Package Type: SOT-23
• Operating Temperature (min): -40C
• Operating Temperature Classification: Automotive
• Pin Count: 5
• Power Dissipation: 667mW
• On State Resistance: 0.125ohm
• On / Enable Input Polarity: Active Low
• Power Dissipation Pd: 667mW
• No. Of Outputs: 1
• Internal Switch: No
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

FPF2108-FPF2110 Rev. E
Description of Operation
The FPF2108-FPF2110 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. The controller protects
against system malfunctions through current limiting, under-
voltage lockout and thermal shutdown.
preset for either 200mA or 400mA.
On/OffControl
The ON pin controls the state of the switch. Active HI and LO
versions are available. Refer to the Ordering Information for
details. Activating ON continuously holds the switch in the on
state so long as there is no fault.
under-voltage on V
150°C overrides the ON control to turn off the switch. For
FPF2108, the ON pin must be toggled to turn on the switch
again. The FPF2109 and FPF2110 do not turn off in response
to a over current condition but instead remain operating in a
constant current mode so long as ON is active and the thermal
shutdown or under-voltage lockout have not activated. When
the MOSFET is off, the body diode is disabled so no current
can flow through it.
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. For the FPF2108, the FLAGB goes LO
at the end of the blanking time while FLAGB goes LO immedi-
ately for the FPF2109 and FPF2110. For the FPF2108, FLAGB
is latched LO and ON must be toggled to release it.With the
FPF2109 and FPF2110, FLAGB is LO during the faults and
immediately returns HI at the end of the fault condition. FLAGB
is an open-drain MOSFET which requires a pull-up resistor
between V
FLAGB is disabled to reduce current draw from the supply.
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. For the FPF2109 the minimum current is
200mA and the maximum current is 400mA and for the
FPF2108 and FPF2110 the minimum current is 400mA and the
maximum current is 800mA. The FPF2108 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. The FPF2109 and
FPF2110 have no current limit blanking period so immediately
upon a current limit condition FLAGB is activated. These parts
will remain in a constant current state until the ON pin is
deactivated or the thermal shutdown turns-off the switch.
IN
and FLAGB. During shutdown, the pull-down on
IN
or a junction temperature in excess of
For all versions, an
The current limit is
9
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 part from internally or
externally generated excessive temperatures. During an over-
temperature condition the FLAGB is activated and the switch is
turned-off.
temperature of the die drops below the threshold temperature.
The switch automatically turns-on again if the
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