DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
General Description
Features
The AAT4702 SmartSwitch™ is a member of Skyworks'
Application Specific Power MOSFET™ (ASPM™) product
family. This device integrates a high side P-channel
MOSFET current limiting load switch with a nanopower
low dropout (LDO) linear voltage regulator, making the
AAT4702 ideal for use in load current protected applications that also require a system power supply. The load
switch operates with input voltages ranging from 2.4V to
5.5V, making it ideal for 2.5V, 3V, and 5V systems. A
fault flag is provided to alert the system to an overcurrent event. The fault flag has a 5ms blanking time to
prevent from reporting false events such as inrush currents during system startup.
Load Switch:
2.4V-5.5V Input Voltage Range
150mA Default Current Limit Level
270m Typical RDS(ON) at 2.4V
400ns Response to Short Circuit
Reverse Voltage Protection
Current Limit Shutdown with Output Pull Down
Auto Restart with 40ms Timer
5ms Fault Blanking Timeout
Under-Voltage Lockout Protection
LDO Regulator:
Output Current up to 100mA
1.8V Output Voltage with ±2% Accuracy
Thermal and Short Circuit Protection
Active Shutdown Output Pull-Down
Low Quiescent Current 15μA Typical for Switch and
LDO
Less than 1μA Shutdown Current
Only 1μF Ceramic Output Capacitor Required
Available in FTDFN22-8L Package.
The load switch current limit is 150mA by default or programmed up to 1A through an external set resistor.
The AAT4702 LDO linear regulator is designed to deliver
a regulated 1.8V supply voltage for load levels up to
100mA. The regulator section may be powered directly
from an input source supply or from the load switch output.
Applications
The AAT4702 is offered in a Pb-free, space-saving 8-pin
2x2mm FTDFN22 package, and is specified for operation
over the -40°C to +85°C ambient temperature range.
Cell Phones
Device Peripheral Ports
Fingerprint Sensors
Hot Swap Supplies
Media Players
Notebook Computers
Typical Application
INPUT
IN
N/C
FAULT FLAG
OUTPUT
AAT4702
1μF
ENABLE
OUT
IN_REG
SET
ON / ON
FLT
LDO REG OUTPUT
VREG
GND
1μF
1μF
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1
DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Pin Descriptions
Pin #
Symbol
1
OUT
2
IN_REG
3
4
VREG
GND
5
SET
6
FLT
7
ON (ON)
8
IN
Description
Current limited P-channel MOSFET load switch output. A 0.47μF to 1μF ceramic capacitor connected from
OUT to GND is recommended for best circuit response.
LDO regulator power input. Connect to IN to power from a common input supply with the load switch, in
which case, bypass with a 1μF ceramic capacitor connected between this pin and ground. Alternatively, this
pin may be powered from the load switch output by connecting IN_REG to OUT; a 1μF or greater ceramic
capacitor should be placed between the OUT pin and ground for this application
LDO regulator output. Connect a 1μF or larger capacitor from VREG to GND for best operating performance.
IC ground pin.
Current limit set input. Connect a resistor from SET to ground to program current limit set point for the load
switch. Or leave open for 150mA default current limit level.
Fault flag, open drain output. Pull to a logic high level through an external resistor for normal operation.
Pulled low when fault is present. Leave open if unused.
Enable input for load switch and LDO regulator.
AAT4702 -1: Active low; pull to a logic low level to enable.
AAT4702 -2: Active high; pull to a logic high level to enable.
Input to the P-channel MOSFET source. Connect a 1μF capacitor from IN to GND.
Pin Configuration
FTDFN22-8L
(Top View)
OUT
IN_REG
VREG
GND
2
1
8
2
7
3
6
4
5
IN
ON (ON)
FLT
SET
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Symbol
VIN, FAULT
VON
VOUT
IOUT
VESD
TJ
TLEAD
Description
IN, IN_REG, FAULT to GND
ON to GND
OUT to GND
Maximum Output Current2
ESD Rating, HBM
Maximum Junction Operating temperature
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
-0.3 to 6
-0.3 to VIN + 0.3
-0.3 to VIN + 0.3
Internally Limited
4000
-40 to +150
300
V
A
V
O
C
Thermal Information3
Symbol
JA
PD
Description
Thermal Resistance
Maximum Power Dissipation4 (TA = 25oC)
Value
116.3
860
Units
C/W
mW
O
1. 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.
2. Based on long-term current density limitations.
3. Mounted on 1oz. copper clad FR4 material printed circuit board.
4. Derate 8.6mW/°C above 25°C.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Electrical Characteristics1
VIN=3.6V;TA = -40oC to 85oC unless otherwise noted. Typical values are at TA = 25oC.
Symbol
Description
Conditions
General
VIN(SW)
Input Voltage Range
VIN(REG)
Input Voltage Range
Load Switch Section
Stable Output
For VOUT Within Regulation Tolerance
VIN = 5V, ON = 0V, IOUT = 0
ON = IN = 5.5V, VOUT = 0
IQ
Operation Quiescent Current
ISD(OFF)
Shutdown Supply Current
Load Switch
RDS(ON)
PMOS On-Resistance
ID(OFF)
Switch Off-Leakage
ILIM
Current Limit
RSET_INT Current Limit Internal Set Resistor
VUVLO
Under-Voltage Lockout Threshold
VUVLO_HYS
Under-Voltage Lockout Hysteresis
LDO Regulator
VOUT
DC Output Voltage
IOUT
Output Current
ISC
Short-Circuit Current
VOUT/
Line Regulation
VOUT*VIN
VOUT/VOUT
Load Regulation
VDO
RDS(REG)
PSRR
TC
Logic
VEN(L)
Dropout Voltage
Regulator Pass Element On-Resistance
Power Supply Rejection Ratio
Output Voltage Temperature Coefficient
VOUT = 5V, TA = 25°C
VOUT = 3.6V, TA = 25°C
VOUT = 2.4V, TA = 25°C
ON = VIN
Rising edge; RSET = open
Min
2.4
2.4
VOUT + VDO
15
180
220
270
100
Rising edge
VIN = 3.6V, IOUT = 10mA
VOUT = 1.8V
VOUT < 0.4V
Typ
1.764
150
50
1.8
0.2
1.8
ON Input High Voltage
IEN
tAUTO
tBLANK
tRESP
tON
tOFF
TSD
THYS
ON Input Leakage
Auto-Restart Time
Over-Current Blanking Time
Current Limit Response Time
Load Switch Turn On Time
Load Switch Turn Off Time
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
5.5
5.5
5.5
30
1
280
320
360
1
200
2.4
IOUT = 1mA to 100mA, VOUT = 1.8V,
TA = 25°C
IOUT = 100mA, VOUT = 1.8V
VIN_REG = 3.6V
100Hz
VIN = 5V
VIN = 5V; RO = 10; CO = 1μF
VIN = 5V; RO = 10; CO = 1μF
m
μA
mA
kΩ
V
V
0.4
%/V
1.0
1.65
%
300
3.0
50
80
mV
dB
PPM/°C
2.0
2.4
20
2
%
μA
μA
0.14
0.4
2.4V < VIN ≤ 4.2V
4.2V < VIN < 5.5V
VEN = 5.5V or 0V
V
V
mA
mA
350
VIN = 4.0 to 5.5V, TA = 25°C
Units
1.836
100
ON Input Low Voltage
VEN(H)
Max
V
V
0.5
40
5
0.4
18
3
140
20
2.0
80
10
35
10
μA
ms
ms
μs
μs
μs
°C
°C
1. The AAT4702 is guaranteed to meet performance over the -40oC to +85oC operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
4
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Typical Characteristics−General
Unless otherwise noted, VIN= 3.6V, CIN = 1μF, COUT = 1μF, COUT-LDO = 1μF ,TA = 25°C.
Quiescent Current vs. Temperature
Quiescent Current vs. Input Voltage
(Load Switch + LDO)
(Load Switch + LDO)
30
Quiescent Current (μA)
30
25
IQ (μA)
20
15
10
VIN = 5.5V
VIN = 4.2V
VIN = 3.3V
5
0
-40
-15
10
35
60
85
Temperature (°C)
25
20
15
10
5
0
0.5
1.5
2.5
3.5
4.5
5.5
Input Voltage (V)
VEN(H) and VEN(L) vs. Input Voltage
VEN(H) and VEN(L) (V)
2.4
1.9
1.4
0.9
VEN(H)
VEN(L)
0.4
2
2.5
3
3.5
4
4.5
5
5.5
Input Voltage (V)
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Typical Characteristics−Load Switch
Unless otherwise noted, VIN= 3.6V, CIN = 1μF, COUT = 1μF, COUT-LDO = 1μF ,TA = 25°C.
VUVLO vs. Temperature
Switch Off-Leakage Current
vs. Temperature
(Rising and Falling)
0.05
2
VIN = 5.5V
VIN = 3.6V
VIN = 2.4V
1.9
0.04
1.8
ID(OFF) (μA)
VUVLO (V)
1.7
1.6
1.5
1.4
0.03
0.02
1.3
1.2
0.01
Rising Edge
Falling Edge
1.1
1
-40
-15
10
35
60
0
-40
85
-15
10
Temperature (°C)
60
85
Temperature (°C)
RDS(ON) vs. Input Voltage
RDS(ON) vs. Temperature
280
380
IOUT = 100mA
IOUT = 50mA
340
RDS(ON) (mΩ)
260
RDS(ON) (mΩ)
35
240
220
200
180
300
260
220
180
VIN = 2.4V
VIN = 3.6V
VIN = 5.5V
140
160
2
2.5
3
3.5
4
4.5
5
100
-40
5.5
-15
10
Input Voltage (V)
35
60
85
Temperature (°C)
Current Limit vs. Output Voltage
RSET vs. ILIM
(RSET = Open)
200
1000
180
160
RSET (kΩ)
ILIM (mA)
140
120
100
80
60
100
10
40
20
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Output Voltage (V)
6
4.0
4.5
5.0
5.5
1
150
250
350
450
550
650
750
850
950
1050 1150 1250
ILIM (mA)
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Typical Characteristics−Load Switch
Unless otherwise noted, VIN= 3.6V, CIN = 1μF, COUT = 1μF, COUT-LDO = 1μF ,TA = 25°C.
TBLANK Response
TAUTO Response
(VIN = 4V; RSET = Open)
(VIN = 4V; RSET = Open)
VDRIVE
(5V/div)
VDRIVE
(5V/div)
VOUT
(5V/div)
VOUT
(5V/div)
IOUT
(200mA/div)
IOUT
(200mA/div)
FLT
(5V/div)
FLT
(5V/div)
Time (4ms/div)
Time (10ms/div)
TON Response
TOFF Response
(VIN = 5V; RL = 40Ω; CL = 0.1μF)
(VIN = 5V; RL = 40Ω; CL = 1μF)
ON
(5V/div)
ON
(5V/div)
VOUT
(2V/div)
VOUT
(2V/div)
IOUT
(50mA/div)
IOUT
(50mA/div)
Time (40μs/div)
Time (40μs/div)
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Typical Characteristics−LDO Regulator
Unless otherwise noted, VIN= 3.6V, CIN = 1μF, COUT = 1μF, COUT-LDO = 1μF ,TA = 25°C.
Output Voltage vs. Output Current
Output Voltage vs. Output Current
2
1.8
1.81
Output Voltage (V)
Output Voltage (V)
1.82
1.8
1.79
1.78
1.77
1.76
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
1.75
0
20
40
60
80
0
100
100
150
200
Output Current (mA)
1.8
1.81
1.7
1.6
IOUT = 1mA
IOUT = 10mA
IOUT = 40mA
IOUT = 100mA
1.3
1.9
2.1
2.3
2.5
Output Voltage (V)
Output Voltage (V)
1.82
1.7
350
400
450
1.8
1.79
1.78
IOUT = 1mA
IOUT = 10mA
IOUT = 40mA
IOUT = 100mA
1.77
1.76
1.75
2.5
Input Voltage (V)
3
3.5
4
4.5
5
Input Voltage (V)
Line Transient Response
Dropout Voltage vs. Output Current
(VIN = 4V->5V->4V; IOUT = 1mA)
Dropout Voltage (mV)
350
300
VIN
(2V/div)
250
200
VOUT
(AC Coupled)
(200mV/div)
150
100
IOUT
(10mA/div)
50
0
0
20
40
60
Output Current (mA)
8
500
Output Voltage vs. Input Voltage
1.9
1.4
300
Output Current (mA)
Output Voltage vs. Input Voltage
1.5
250
80
100
Time (1ms/div)
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5.5
DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Typical Characteristics−LDO Regulator
Unless otherwise noted, VIN= 3.6V, CIN = 1μF, COUT = 1μF, COUT-LDO = 1μF ,TA = 25°C.
Line Transient Response
Line Transient Response
(VIN = 4V->5V->4V; IOUT = 20mA)
(VIN = 4V->5V->4V; IOUT = 100mA)
VIN
(2V/div)
VIN
(2V/div)
VOUT
(AC Coupled)
(200mV/div)
VOUT
(AC Coupled)
(200mV/div)
IOUT
(20mA/div)
IOUT
(50mA/div)
Time (1ms/div)
Time (1ms/div)
Load Transient Response
Load Transient Response
(VIN = 4V; IOUT = 1mA-50mA)
(VIN = 4V; IOUT = 1mA-100mA)
VOUT
(AC Coupled)
(200mV/div)
VOUT
(AC Coupled)
(200mV/div)
IOUT
(50mA/div)
IOUT
(50mA/div)
Time (400μs/div)
Time (400μs/div)
Power-Up with 1mA Load
Power-Up with 100mA Load
ON
(2V/div)
ON
(2V/div)
VOUT
(1V/div)
VOUT
(1V/div)
Time (200μs/div)
Time (200μs/div)
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Functional Block Diagram
Reverse
Blocking
IN
OUT
Timer
ON / ON
Control
Current
Set
Over-Temperature
Protection
SET
FAULT
1.2V Reference
10ms
Delay
IN_REG
VREG
GND
Functional Description
The AAT4702 is an auto-restarting current limiting load
switch with an integrated low dropout linear voltage
regulator. The combined function of this device serves to
protect system loads or peripheral circuits from overcurrent conditions while simultaneously supplying an
independent regulated voltage for the system.
Current Limiting Load Switch
The AAT4702 load switch provides an auto-restarting,
reverse current blocking, programmable current limiting
and shutdown function. If an applied load exceeds the
programmed current limit level, the load switch pass element will be turned off to isolate the input source from
10
the output and discharge the applied load to ground via
an internal NMOS switch and a typical 100Ω resistor. The
default current limit (ILIM) set point is 150mA with a
50mA tolerance when the SET pin is left open (no external resistor connected). The device may be user programmed to a higher current limit level up to 1A via an
external resistor placed between the SET pin and
ground.
When under an output over-current shutdown event, the
AAT4702 has an auto-restart output polling function that
will wake up and re-enable the device every 40ms to
check for the continued existence of an over-current
condition. If the over-current fault condition remains,
the AAT4702 will remain in the shutdown state with both
the load switch and LDO regulator output pulled low to
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
ground. When the over-current condition is removed, the
AAT4702 will automatically resume normal operation.
The internal load switch controller provides a fault flag
function to alert a system controller to any over current
or temperature event. The fault flag output consists of
an open drain NMOS switch that should be pulled to a
logic high level externally through a 10k or greater
value resistor. The fault flag has a 5ms blanking time
feature to guard against reporting false fault conditions,
such events could happen during normal circuit start-up.
If the fault flag function is not required, the FLT pin may
be left unconnected.
When operating within the limits set by the default or
user programmed current limit level, the device overtemperature protection will monitor the internal die temperature. If the internal die temperature exceeds 140°C,
the thermal protection circuit will shut down the load
switch to protect the loaded device and the system supply source.
The AAT4702 load switch and LDO regulator are enabled
and disabled through common enable signal at the ON
(ON) pin. The AAT4702 provides options for both active
low (default) and/or active high operation; refer to the
Ordering Information table to select the desired enable
polarity. If the device is operated in an always-on state,
the enable function may be terminated to GND or IN
respective to which active low or high option is selected.
The AAT4702 load switch has an under-voltage lockout
(UVLO) function, which senses the voltage of the IN pin.
Once VIN > VUVLO rising edge (typical 1.8V), the AAT4702
will start to operate. For the LDO regulator input IN_REG
pin, there is no UVLO.
Low Dropout Linear Regulator
The AAT4702 LDO linear regulator section has an independent input pin allowing the regulator to be powered
by the load switch output or directly from an input supply. When the enable pin switches to an active state, the
LDO regulator output will typically start up and stabilize
regulation within 1ms after the load switch.
The LDO regulator output is designed and tested to
maintain voltage regulation accuracy within a 2% toler-
ance. Voltage regulation accuracy is maintained for input
voltage ranges from 5.5V down to a minimum input level
(VIN_MIN) which is defined by the factory trimmed output
voltage level (VOUT) plus the specified regulator dropout
voltage level (VDO), by following the formula:
VIN_MIN = VOUT + VDO
Where:
VIN_MIN = Minimum input voltage applied to the IN_REG
pin to maintain regulation
VOUT = Factory set LDO regulator output as measured at
the VREG pin
VDO = Specified LDO regulator dropout voltage
Should the LDO regulator input supply fall below the
required VIN_MIN level, the output is designed to track the
input supply minus a nominal voltage drop across the
regulator’s high-side P-channel MOSFET caused by the
device's on resistance. The regulator is designed to
maintain a stable linear output level of 1.8V for an input
supply level down to 2.4V at the specified load current
level of 100mA.
During LDO regulator shutdown, the VREG output is
internally connected to ground via a series resistor and
a low-side NMOS switch which have a combined impedance of 100. The LDO regulator has over-temperature
and short-circuit protection independent to the load
switch for comprehensive device protection.
Since the system enable is common to both the LDO
regulator and load switch, the LDO regulator will shut
down in the event of a fault occurring on the load switch
output. For the case of LDO regulator shut down via a
load switch fault, the LDO regulator automatically
restarts along with the load switch auto-restart system
with a 1ms delay. When the LDO regulator is shut down
by either the enable function or a fault on the load switch
output, the regulator output load will be discharged
through the internal active output pull-down circuit.
The AAT4702 LDO regulator has high power supply ripple
rejection (PSRR) in addition to fast load and line transient response characteristics. The LDO regulator output
has been specifically optimized to function with low cost,
low-ESR ceramic capacitors.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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11
DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Application Information
Setting the Load Switch Current Limit
With no external resistor at the SET pin, the default current limit is 150mA typically set by the internal 50kΩ
resister. The current limit function is triggered when the
load current reaches 150mA, the load switch and LDO
output voltages are shut down; the AAT4702 would
restart to check if the over-current condition is removed
every 40ms. As illustrated in the “Current Limit ILIM vs.
Output Voltage” curve, the current limit level is kept
lower when the output voltage drops; this is helpful to
minimize the power dissipation at the load switch to provide safer operation at over-current or output short-circuit condition.
If a higher current limit is desired, an external resistor
could be placed at the SET pin. To determine RSET, multiply the maximum current drawn by the load by 1.33
(typical ILIM = minimum ILIM/0.75); this is the typical current limit value. Next, refer to the “RSET vs. ILIM” curve
and find the RSET that corresponds to the typical current
limit value. The maximum current is derived by multiplying the typical current for the chosen RSET in the chart by
1.25. Some resistor values are listed in Table 1.
RSET
(kΩ)
Current
Limit Typ
(mA)
Current
Limit Min
(mA)
Current
Limit Max
(mA)
205.1
80.9
49.6
39.6
32.2
27.6
24
20.8
17.6
13.3
10.8
8.82
7.88
6.87
6.17
5.54
200
250
300
350
400
450
500
550
600
700
800
900
1000
1100
1200
1300
150
188
225
263
300
338
375
413
450
525
600
675
750
825
900
975
250
313
375
438
500
563
625
688
750
875
1000
1125
1250
1375
1500
1625
Table 1: Current Limit vs. RSET Values.
12
Example: A USB port requires 500mA. 500mA multiplied
by 1.33 is 665mA. From the “RSET vs. ILIM” curve, RSET
should be less than 16.5kΩ. 14.9kΩ is a standard value
that is a little less than 16.5kΩ but very close. The chart
reads approximately 700mA as a typical ILIM value for
14.9kΩ. Multiplying 700mA by 0.75 and 1.25 shows that
the AAT4702 load switch will limit the load current to
greater than 525mA but less than 875mA.
Load Switch Operation in Current
Limit and Thermal Protection
When a heavy load is applied to the output of the
AAT4702 load switch output, the current limit circuit is
triggered when the load current reaches the value of ILIM
determined by RSET. See Figure 1 for over-current operation and fault recovery. Since the load demands more
current than ILIM, the voltage at the output drops. When
the output voltage drops, the load current is folded back
to a lower level. When the overload condition continues
for a period longer than the over-current blanking time
tBLANK, the output will be turned off and discharged
through the internal N-channel MOSFET and resistor.
After TAUTO timeout 40ms, the AAT4702 turns on the load
switch output to check if the overload condition is
removed. If the overload still exists, the output turns off
again after tBLANK timeout. The AAT4702 load switch and
LDO will continue to cycle on and off until the overload
condition is removed. When the die temperature exceeds
the over-temperature limit, the AAT4702 will shutdown
until it has cooled sufficiently, at which point it will start
up again.
Enable Input
The AAT4702 features a load switch and LDO common
enable / disable function. This ON (ON) pin is compatible
with CMOS logic. Active high or active low options are
available (see Ordering Information).
In many systems, power planes are controlled by integrated circuits which run at lower voltages than the
power plane itself. The enable input ON (ON) of the
AAT4702 has low and high threshold voltages that
accommodate this condition, which could be found in
“VEN(H) and VEN(L) vs. Input Voltage” curve. The threshold
voltages are compatible with 5V TTL and 2.4V to 5V
CMOS. When enable is active, the load switch starts up,
and the LDO starts up after 1ms. When it is disabled, the
device shuts down and the LDO output capacitor is discharged through the internal N-channel MOSFET and
100Ω resistor; the load switch is also reverse blocked.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201964A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 17, 2012
DATA SHEET
AAT4702
Auto-Restarting Current Limiting Load Switch with LDO Regulator
Normal
Operation
Fault
Recovers
Over-Current Protection
ILIM
IOUT
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