AAT4280A_08 Datasheet, PDF (10/16 Pages) Advanced Analogic Technologies – Slew Rate Controlled Load Switch

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Functional Block Diagram
IN
PRODUCT DATASHEET
AAT4280A
Slew Rate Controlled Load Switch
OUT
ON/OFF
Level
Shift
Turn-On
Slew Rate
Control
*
GND
*AAT4280A-3 and -4 only
Functional Description
The AAT4280A is a family of flexible P-channel MOSFET
power switches designed for high-side load switching
applications. There are three versions of the AAT4280A
with different turn-on and turn-off characteristics to
choose from, depending upon the specific requirements
of an application. The first version, the AAT4280A-1, has
a moderate turn-on slew rate feature, which reduces
inrush current when the MOSFET is turned on. This
function allows the load switch to be implemented with
either a small input capacitor or no input capacitor at all.
During turn-on slewing, the current ramps linearly until
it reaches the level required for the output load condi-
tion. The proprietary turn-on current 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.
The second version, the AAT4280A-2, is a very fast
switch intended for high-speed switching applications.
This version has no turn-on slew rate control and no
special output discharge features.
The third switch version, the AAT4280A-3, has the addition
of a minimized slew rate limited turn-on function and a
shutdown output discharge circuit to rapidly turn off a load
when the load switch is disabled through the ON/OFF pin.
The final switch version, the AAT4280A-4, features a very
slow turn-on slew rate with a typical value of 4.5ms for
LCD panel applications.
All versions of the AAT4280A operate with input voltages
ranging from 1.5V to 5.5V. All versions of this device
have extremely low operating current, making them
ideal for battery-powered applications. The ON/OFF con-
trol pin is TTL compatible and will also function with 2.5V
to 5V logic systems, making the AAT4280A an ideal
level-shifting load switch.
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4280A.2008.04.1.5