AAT4252AITP-3-T1 AnalogicTech, AAT4252AITP-3-T1 Datasheet - Page 9

• Manufacturer Part Number: AAT4252AITP-3-T1
• Description: Dual Slew Rate Controlled Load Switch
• Manufacturer: AnalogicTech

SmartSwitch
Functional Description
The AAT4252A is a family of flexible dual P-channel
MOSFET power switches designed for high-side load
switching applications. There are three versions of the
AAT4252A with different turn-on and turn-off character-
istics to choose from, depending upon the specific
requirements of an application.
The first version, the AAT4252A-1, has a moderate turn-
on slew rate feature, which reduces in-rush 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 condition. The propri-
etary 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 the
R
The second version, the AAT4252A-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 final switch version, the AAT4252A-3, has the addi-
tion 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. Using the FAST input pin on the AAT4252A-3, the
device can be manually switched to a slower slew rate.
All versions of the AAT4252A operate with input voltages
ranging from 1.5V to 6.5V. All versions of this device
have extremely low operating current, making them
ideal for battery-powered applications.
The ON/OFF control pin is TTL compatible and will also
function with 2.5V to 5V logic systems, making the
AAT4252A an ideal level-shifting load switch.
4252A.2009.06.1.1
DS(ON)
is minimized.
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Applications Information
Input Capacitor
A 1μF or larger capacitor is typically recommended for
C
for basic operation; however, it is useful in preventing
load transients from affecting upstream circuits. C
should be located as close to the device VIN pin as prac-
tically possible. Ceramic, tantalum, or aluminum electro-
lytic capacitors may be selected for C
specific capacitor equivalent series resistance (ESR)
requirement for C
ceramic capacitors are recommended for CIN due to
their inherent capability over tantalum capacitors to
withstand input current surges from low-impedance
sources, such as batteries in portable devices.
Output Capacitor
For proper slew operation, a 0.1μF capacitor or greater
is required between V
output capacitor, there is no specific capacitor ESR
requirement. If desired, C
limit to accommodate any load transient condition with-
out adversely affecting the slew rate.
Enable Function
The AAT4252A features an enable / disable function. This
pin (ON) is active high and is compatible with TTL or
CMOS logic. To assure the load switch will turn on, the
ON control level must be greater than 2.0V. The load
switch will go into shutdown mode when the voltage on
the ON pin falls below 0.8V. When the load switch is in
shutdown mode, the OUT pin is tri-stated, and quiescent
current drops to leakage levels below 1μA.
Reverse Output-to-Input Voltage
Conditions and Protection
Under normal operating conditions, a parasitic diode
exists between the output and input of the load switch.
The input voltage should always remain greater than the
output load voltage, maintaining a reverse bias on the
internal parasitic diode. Conditions where V
exceed V
bias the internal parasitic diode and allow excessive cur-
rent flow into the V
switch. In applications where there is a possibility of V
exceeding V
operation, the use of a larger value C
IN
Dual Slew Rate Controlled Load Switch
in most applications. A C
IN
should be avoided since this would forward
IN
for brief periods of time during normal
IN
OUT
. However, for higher current C
PRODUCT DATASHEET
OUT
pin, possibly damaging the load
AAT4252A
and GND. Likewise, with the
OUT
IN
may be increased without
capacitor is not required
IN
IN
. There is no
capacitor is
OUT
might
OUT
IN
9
IN
,