Current Limited Load Switch
Functional Block Diagram
AAT4618
IN
Over-Temperature
Protection
OUT
Under-Voltage
Lockout
Current
Limit
ON (ON)
4ms Delay
FAULT
GND
Functional Description
The AAT4618 is a single channel current limited
load switch that protects against short circuits by
current limiting to a preset level. A patented fast-
acting current limit loop limits the current in a frac-
tion of a microsecond and instantly resets to low
impedance once the short-circuit condition is
removed. The AAT4618 is internally protected
from thermal damage by an over-temperature
detection circuit. If the die temperature reaches
the internal thermal limit, the power device is
switched off until the die temperature cools to a
level below the thermal limit threshold. The device
will thermal cycle indefinitely until the over-current
condition is removed. The AAT4618 operates with
input voltages ranging from 2.4V to 5.5V which,
along with its extremely low operating current,
makes it ideal for battery-powered applications. In
cases where the input voltage drops below 2.4V,
the AAT4618 MOSFET is protected from entering
the saturated region of operation by being auto-
matically shut down by an under-voltage lockout
circuit. A current limit condition is reported by the
open drain FAULT output. A 4ms blanking interval
prevents false reporting during the charging of a
capacitive load, which typically occurs during
device turn-on, but may also occur during a port
hot plug-in event.
The AAT4618 is ideally suited for protection of
peripheral ports such as USB, RS232, and parallel
ports.
4618.2006.05.1.2
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ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
