2174 Ver la hoja de datos (PDF) - Fairchild Semiconductor

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componentes Descripción

Fabricante

2174

IntelliMAX™ Advanced Load Management Products

Fairchild Semiconductor 

Description of Operation

The FPF2174 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 0.125

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 and a

16V zener diode for output clamp. The controller protects

against system malfunctions through current limiting, under-

voltage lockout and thermal shutdown. The current limit is

preset for 200mA.

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.

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.

FPF2174 Rev. D

9

www.fairchildsemi.com

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