AAT4285 Datasheet, PDF (7/11 Pages) Advanced Analogic Technologies – 12V Slew Rate Controlled Load Switch

Functional Block Diagram
AAT4285
12V Slew Rate Controlled Load Switch
IN
ON/OFF
Under-
Voltage
Lockout
Level
Shift
Turn-On
Slew Rate
Control
OUT
GND GND GND GND
Functional Description
The AAT4285 is a slew rate controlled P-channel
MOSFET power switch designed for high-side load
switching applications. The device operates with
input voltages ranging from 3.0V to 13.2V, making
it ideal for single- or multi-cell battery-powered
applications. In cases where the input voltage
drops below 3.0V, the AAT4285 MOSFET is pro-
tected from entering the saturated region of opera-
tion by automatically shutting down. In addition, the
TTL compatible ON/OFF pin makes the AAT4285
an ideal level-shifted load switch. The slew rate
controlling feature eliminates inrush current when
the MOSFET is turned on, allowing the AAT4285 to
operate with a small input capacitor, or no input
capacitor at all. During slewing, the current ramps
linearly until it reaches the level required for the
output load condition. The proprietary control
method works by careful control and monitoring of
the MOSFET gate voltage. When the device is
switched ON, the gate voltage is quickly increased
to the threshold level of the MOSFET. Once at this
level, the current begins to slew as the gate voltage
is slowly increased until the MOSFET becomes
fully enhanced. Once it has reached this point, the
gate is quickly increased to the full input voltage
and R_DS(ON) is minimized.
4285.2007.04.1.0
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