FPF2225 Fairchild Semiconductor, FPF2225 Datasheet - Page 9

• Manufacturer Part Number: FPF2225
• Description: IC LOAD SWITCH MICROFET6
• Manufacturer: Fairchild Semiconductor
• Type: High Side Switchr

Specifications of FPF2225

• Number Of Outputs: 1
• Rds (on): 185 mOhm
• Internal Switch(s): Yes
• Current Limit: Adjustable
• Voltage - Input: 1.8 ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 6-MLP, 6-MicroFET™
• Input Voltage: 1.8 to 5.5V
• Power Switch On Resistance: 230mOhm
• Mounting: Surface Mount
• Package Type: MicroFET
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Pin Count: 6
• Power Dissipation: 1.2W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: FPF2225TR

FPF2223-FPF2225 Rev. C
Description of Operation
The FPF2223, FPF2224, and FPF2225 are state of the art
Adjustable High Precision Current Limit 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 0.16
P-channel MOSFET and a controller capable of functioning over
an input operating range of 1.8- 5.5V. The controller protects or
offers current limiting, UVLO(undervoltage lockout) and thermal
shutdown protection. The current limit is adjustable from 250mA
to 625mA through the selection of an external resistor.
On/Off Control
The ON pin is active high, and controls the state of the switch.
Applying a continuous high signal will hold the switch in the on
state. The switch will move into the OFF state when the active
high is removed, or if a fault is encountered. For all versions, an
undervoltage 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 FPF2223 and FPF2224. The FPF2223 has an Auto-Restart
feature which will automatically turn the switch on again after
450ms. For the FPF2224, the ON pin must be toggled to turn-on
the switch again. The FPF2225 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 UVLO have not activated.
Fault Reporting
Upon the detection of an over-current condition, an input UVLO,
or an over-temperature condition, the FLAGB signals the fault
mode by activating LO. In the event of an over-current condition
for the FPF2223 and FPF2224, the FLAGB goes LO at the end
of the blanking time while FLAGB goes LO immediately for the
FPF2225. If the over-current condition lasts longer than
blanking time, FLAGB remains LO through the Auto-Restart
Time for the FPF2223 while for the FPF2224, FLAGB is latched
LO and ON must be toggled to release it. With the FPF2225,
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 VIN and FLAGB.
During shutdown, the pull-down on FLAGB is disabled to reduce
current draw from the supply. A 100K
recommended to be used in the application.
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 the ISET pin. The FPF2223 and FPF2224 have a
blanking time of 30ms (nominal) 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 FPF2225 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.
pull up resistor is
9
Undervoltage Lockout (UVLO)
The undervoltage lockout turns-off the switch if the input voltage
drops below the undervoltage lockout threshold. With the ON
pin active the input voltage rising above the undervoltage
lockout threshold will cause a controlled turn-on of the switch
which limits current over-shoots.
Output Discharge Resistor
The FPF2223/4/5 family contains an 80
for quick output discharge when the switch is turned off. This
features become more attractive when application requires
large output capacitor to be discharge when the switch tunrs off.
However, V
battery source due to the discharge mechanism of the load
switch.
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.
temperature of the die drops below the threshold temperature.
OUT
The
pin should not be connected directly to the
switch
automatically
on-chip load resistor
turns-on
www.fairchildsemi.com
again
if