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FPF2000-FPF2007 Rev. C1

Typical Characteristics

Description of Operation

The FPF2000-FPF2007 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 0.7

Ω

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 pre-

set for either 50mA or 100mA.

On/Off Control

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. For all versions, an under-volt-

age on VIN or a junction temperature in excess of 150°C over-

rides the ON control to turn off the switch. In addition, excessive

currents will cause the switch to turn off in FPF2000-FPF2002

and FPF2004-FPF2007. The FPF2000, FPF2001, FPF2004

and FPF2005 have an Auto-Restart feature which will automati-

cally turn the switch on again after 80ms. For the FPF2002 and

FPF2006, the ON pin must be toggled to turn-on the switch

again. The FPF2003 and FPF2007 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.

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 FPF2000-FPF2002 and

FPF2004-FPF2006, the FLAGB goes LO at the end of the

blanking time while FLAGB goes LO immediately for the

FPF2003 and FPF2007. FLAGB remains LO through the Auto-

Restart Time for the FPF2000, FPF2001 FPF2004 and

FPF2005. For the FPF2002 and FPF2006, FLAGB is latched

LO and ON must be toggled to release it. With the FPF2003 and

FPF2007, FLAGB is LO during the faults and immediately

returns HI at the end of the fault condition. FLAGB is an open-

and FLAGB. During shutdown, the pull-down on FLAGB is dis-

abled 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 FPF2000-FPF2003 the minimum cur-

rent is 50mA and the maximum current is 100mA and for the

FPF2004-FPF2007 the minimum current is 100mA and the

maximum current is 200mA. The FPF2000-FPF2002 and the

FPF2004-FPF2006, 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 and

the FLAGB pin will activate to indicate that current limiting has

occurred. The FPF2003 and FPF2007 have no current limit

blanking period so immediately upon a current limit condition

FLAGB is activated. These parts will remain in a constant cur-

rent state until the ON pin is deactivated or the thermal shut-

down turns-off the switch.

Under-Voltage Lockout

The under-voltage lockout turns-off the switch if the input volt-

age 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 exter-

nally generated excessive temperatures. During an over-tem-

perature condition the FLAGB is activated and the switch is

turned-off. The switch automatically turns-on again if tempera-

ture of the die drops below the threshold temperature.

Figure 19. Current-Limit Response Time

(Output to GND)

Figure 20. Current-Limit Response

2V / DIV

100mA / DIV

2V / DIV

2V / DIV

100mA / DIV

(Shorted to

GND)

20uS/DIV

20uS/DIV