The AAT4611 SmartSwitch™ is a member of
AnalogicTech's Application Specific Power
MOSFET™ (ASPM™) product family. It is a Current
Limited P-channel MOSFET power switch designed
for high-side load-switching applications. This switch
operates with inputs ranging from 2.7V to 5.5V, making it ideal for both 3V and 5V systems. An integrated current-limiting circuit protects the input supply against large currents which may cause the supply to fall out of regulation. The AAT4611 is also protected from thermal overload which limits power dissipation and junction temperatures. It can be used
to control loads that require up to 1 A. Current limit
threshold is programmed with a resistor from SET to
ground. The quiescent supply current is typically a
low 15µA max. In shutdown mode, the supply current decreases to less than 1µA.
The AAT4611 is available in a 5 pin SOT-23 and 8pin SC70JW specified over -40 to 85°C.
The AAT4600 Series is a family of adjustable and
fixed SmartSwitch™ with a range of current handling capabilities. Available are single versions in
adj. current limit (AAT4600, AAT4601) as well as in
fixed current limit (AAT4602, AAT4625). Dual versions (AAT4620, AAT4626) are also available.
SmartSwitch
Features
•2.7V to 5.5V Input voltage range
•Programmable over current threshold
•Fast transient response:
•<1µs response to short circuit
•Low quiescent current
•15µA typical
•1µA max with Switch off
• 160mΩ typical R
•Only 2.5V needed for ON/OFF Control
•Undervoltage Lockout
•Thermal shutdown
•Temp range -40 to 85°C
•4kV ESD Rating
•5 pin SOT-23 or SC70JW-8 package
Applications
•Peripheral ports
•Notebook computers
•Personal communication devices
•Hot swap supplies
DS(ON)
™
Preliminary Information
Typical Application
INPUT
5
IN
AAT4611
1
OUT
SOT-23
ON (ON)
1µF
GNDGND
4611.2001.8.0.91
4
ON/(ON)
GND
2
SET
3
R
SET
0.47µF
OUTPUT
Pin Configuration
AAT4611
Current Limited Load Switch in SOT-23 Package
5-Pin SOT-23
(Top View)
OUT
GND
SET
1
2
3
5
IN
4
ON
SC70JW-8
(Top View)
OUT
GND
GND
GND
1 2
1
2
3
4
8
7
6
5
IN
SET
GND
ON
Pin Descriptions
Pin #SymbolFunction
1OUTP-channel MOSFET drain. Connect 0.47µF capacitor from OUT to GND.
2GNDGround connection
3SETCurrent-Limit Set Input. A resistor from SET to ground sets the current limit for
the switch.
4ONEnable Input. Two versions are available, active-high and active-low. See order-
ing information for details.
5INP-channel MOSFET source. Connect 1µF capacitor from IN to GND.
24611.2001.8.0.9
AAT4611
Current Limited Load Switch in SOT-23 Package
4611.2001.8.0.93
Absolute Maximum Ratings (T
A
=25°C unless otherwise noted)
Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.
Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
In most applications, the variation in I
taken into account when determining R
variation is due to processing variations from part
to part, as well as variations in the voltages at IN
(pin 5) and OUT (pin 3), plus the operating temperature. See charts "Current Limit vs. Temperature",
and "Output Current vs. V
". Together these
OUT
three factors add up to a ±25% tolerance (see I
specification in Electrical Characteristics section).
In the figure below, a cold device with a statistically higher current limit, and a hot device with a statistically lower current limit, both with R
10.5kΩ are shown. While the chart, "R
indicates an I
of 0.7A with an R
LIM
this figure shows that the actual current limit will be
at least 0.525A, and no greater than 0.880A.
Current Limit Using10.5 k
1.2
0.88 A
1
0.8
(A)
0.6
LIM
I
0.525 A
0.4
0.2
Device with high current limit at -40 C
Device with low current limit at 85 C
LIM
SET.
SET
SET
of 10.5kΩ ,
SET
Ω
must be
The I
LIM
LIM
equal to
vs. I
LIM
that is less than or equal to it. For greater precision,
the value of R
I
LIMRSET
cient vs. I
product found in the chart "R
LIM
multiplying the typical current for the chosen R
may also be calculated using the
SET
SET
coeffi-
". The maximum current is derived by
SET
in the chart by 1.25. A few standard resistor values
are listed in the table "Current Limit R
Current Limit R
R
SET
Current Device will Device always
SET
Values
SET
Values".
(kΩ ) Limit typ not current current limits
(mA)limit below: below:
(mA)(mA)
40.2200150250
"
30.9250188313
24.9300225375
22.1350263438
19.6400300500
17.8450338563
16.2500375625
14.7550413688
13.0600450750
10.5700525875
8.878006001000
7.509006751125
6.8110007501250
6.0411008251375
5.4912009001500
4.9913009751625
4.64140010501750
0
012345
Vout ( V )
To determine R
start with the maximum current
SET,
drawn by the load, and multiply it by 1.33. (typical_I
current limit value. Next, refer to "R
find the R
= minimum_I
LIM
SET
/ 0.75) This is the typical
LIM
SET
vs. I
LIM
" and
that corresponds to the typical current
limit value. Choose the largest resistor available
Example: A USB port requires 0.5A. 0.5A multiplied
by 1.33 is 0.665A. From the chart named "R
I
LIM
", R
should be less than 11kΩ. 10.5 kΩ is a
SET
SET
vs.
standard value that is a little less than 11kΩ but
very close. The chart reads approximately 0.700A
as a typical I
value for 10.5kΩ. Multiplying
LIM
0.700A by 0.75 and 1.25 shows that the AAT4611
will limit the load current to greater than 0.525A but
less than 0.875A.
84611.2001.8.0.9
Current Limited Load Switch in SOT-23 Package
Overloa d Oper ation
1
0.75
0.5
0.25
0
5
4
Output ( V )
3
2
1
0
-0.050 0.050.10.150.20.250.3
1Ω load is turned on at time = 0
Tim e ( s )
Outp ut Curre nt
Outp ut Volta ge
AAT4611
Output (A)
Operation in Current Limit
When a heavy load is applied to the output of the
AAT4611, the load current is limited to the value of
I
determined by R
LIM
Operation". Since the load is demanding more current than I
, the voltage at the output drops. This
LIM
causes the AAT4611 to dissipate a larger than normal quantity of power, and its die temperature to
increase. When the die temperature exceeds an
over temperature limit, the AAT4611 will shut down
until is has cooled sufficiently, at which point it will
startup again. The AAT4611 will continue to cycle
on and off until the load is removed, power is
removed, or until a logic high level is applied to ON
(pin 4).
. See the figure "Overload
SET
Enable Input
In many systems, power planes are controlled by
integrated circuits which run at lower voltages than
the power plane itself. The enable input ON (pin 4)
of the AAT4611 has low and high threshold voltages that accommodate this condition. The threshold voltages are compatible with 5 volt TTL, and 2.5
volt to 5 volt CMOS.
Reverse Voltage
The AAT4611 is designed to control current flowing
from IN to OUT. If a voltage is applied to OUT which
is greater than the voltage on IN, large currents may
flow. This could cause damage to the AAT4611.