Page 1
AAT4608
Current Limited Load Switch in SOT-23 Package
General Description
The AAT4608 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 AAT4608 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.
The AAT4608 is available in a 5 pin SOT-23 specified over -40 to 85°C.
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
• Undervoltage Lockout
• Thermal shutdown
• Temp range -40 to 85°C
• 4kV ESD Rating
• 5 pin SOT-23 package
Applications
• Peripheral ports
• Notebook computers
• Personal communication devices
• Hot swap supplies
DS(ON)
™
Preliminary Information
Typical Application
INPUT
1µF
GND GND
4608.2001.10.0.9 1
5
IN
AAT4608
SOT-23
GND
2
OUT
SET
1
3
R
SET
0.47µF
OUTPUT
Page 2
Pin Configuration
AAT4608
Current Limited Load Switch in SOT-23 Package
5-Pin SOT-23
(Top View)
OUT
GND
SET
1
2
3
5
IN
4
NC
Pin Descriptions
Pin # Symbol Function
1 OUT P-channel MOSFET drain. Connect 0.47µF capacitor from OUT to GND.
2 GND Ground connection
3 SET Current-Limit Set Input. A resistor from SET to ground sets the current limit for
the switch.
4 NC No internal connection.
5 IN P-channel MOSFET source. Connect 1µF capacitor from IN to GND.
2 4608.2001.10.0.9
Page 3
AAT4608
Current Limited Load Switch in SOT-23 Package
Absolute Maximum Ratings (T
=25°C unless otherwise noted)
A
Symbol Description Value Units
V
IN
V
SET,VOUT
I
MAX
T
J
T
LEAD
V
ESD
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 to GND -0.3 to 6 V
SET, OUT to GND -0.3 to VIN+0.3 V
Maximum Continuous Switch Current 2 A
Operating Junction Temperature Range -40 to 150 °C
Maximum Soldering Temperature (at Leads) 300 °C
ESD Rating1- HBM 4000 V
Thermal Characteristics
Symbol Description Value Units
Θ
JA
P
D
Note 2: Mounted on a demo board.
Thermal Resistance
Power Dissipation
Electrical Characteristics (V
are at TA=25°C)
2
2
= 5V, TA= -40 to 85°C unless otherwise noted. Typical values
IN
150 °C/W
667 mW
Symbol Description Conditions Min Typ Max Units
V
IN
I
Q
V
UVLO
R
DS(ON)
I
LIM
I
LIM(MIN)
T
RESP
Operation Voltage 2.7 5.5 V
Quiescent Current VIN= 5V, I
= 0 15 30 µA
OUT
Undervoltage Lockout Rising edge, 1% hysteresis, 2.0 2.3 2.7 V
VIN=5.0V 160 180 mΩ
On-Resistance VIN=4.5V 165 mΩ
VIN=3.0V 195 230 mΩ
Current Limit R
= 6.8kΩ 0.5 1 2.0 A
SET
Minimum Current Limit 150 mA
Current Limit Response Time VIN=5V 0.8 µs
4608.2001.10.0.9 3
Page 4
Current Limited Load Switch in SOT-23 Package
Typical Characteristics
(Unless otherwise noted, VIN= 5V, TA= 25°C)
AAT4608
Quiescent Current vs. Temperature
25
20
15
10
5
Quiescent Current (µA)
0
-40 -20 0 20 40 60 80 100 120
Temperature
Output Current vs
0.6
A)
(
0.4
R
=16 kΩ
0.2
Output Current
0
012345
SET
Vout ( V )
V
(C)
OUT
Quiescent Current
40
30
A )
µ
20
Input (
10
0
2.5 3 3.5 4 4.5 5 5.5
Input ( V )
R
250
Input = 3V
200
150
(mΩ)
100
DS(ON)
R
50
0
-40 -20 0 20 40 60 80 100
vs. Temperature
DS(ON)
Te
mperatur e (C)
Input = 5V
Short Circuit through 0.3Ω
8
(V)
6
4
2
Input and Output
0
0123
Input Voltage
Output Current
Output Voltage
Time (µs)
12
8
4
0
-4
Output (A)
8
(V)
6
4
2
Input and Output
0
0123
Short Circuit through 0.6Ω
Input Voltage
Output Current
Output Volt age
Time (µs)
9
6
3
0
-3
4 4608.2001.10.0.9
Output (A)
Page 5
Current Limited Load Switch in SOT-23 Package
(Unless otherwise noted, VIN= 5V, TA= 25°C)
R
vs I
SET
LIM
R
coefficent vs I
SET
AAT4608
LIM
100
)
Ω
(k
10
SET
R
1
0.1 101
I
(A)
LIM
Current Limit v. Temperature
6%
4%
2%
0%
-2%
-4%
Current Limit (%)
-6%
-50 - 25 0 25 50 75 100
Temperatur e (C)
R
SET
V
IN-VOUT
= 22.1k
=0.5V
10
9
8
Product ( kV )
7
LIM
I
6
SET
R
5
0 0.5 1 1.5 2
I
(A)
LIM
4608.2001.10.0.9 5
Page 6
Functional Block Diagram
AAT4608
Current Limited Load Switch in SOT-23 Package
IN
Undervoltage
Lockout
Over-Temp
1.2V
Reference
GND
Protection
Current
Limit
OUT
SET
R
SET
6 4608.2001.10.0.9
Page 7
AAT4608
Current Limited Load Switch in SOT-23 Package
Applications Information
Setting Current Limit
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 Using 10.5 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
Ω
LIM
SET.
SET
SET
of 10.5kΩ ,
SET
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)
40.2 200 150 250
"
30.9 250 188 313
24.9 300 225 375
22.1 350 263 438
19.6 400 300 500
17.8 450 338 563
16.2 500 375 625
14.7 550 413 688
13.0 600 450 750
10.5 700 525 875
8.87 800 600 1000
7.50 900 675 1125
6.81 1000 750 1250
6.04 1100 825 1375
5.49 1200 900 1500
4.99 1300 975 1625
4.64 1400 1050 1750
0
012345
V
(V)
OUT
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
4608.2001.10.0.9 7
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 AAT4608
will limit the load current to greater than 0.525A but
less than 0.875A.
Page 8
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 tur ned on at time = 0
Tim e ( s )
Outp ut Current
Outp ut Voltage
AAT4608
Output (A)
Operation in Current Limit
When a heavy load is applied to the output of the
AAT4608, 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 AAT4608 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 AAT4608 will shut down
until is has cooled sufficiently, at which point it will
startup again. The AAT4608 will continue to cycle
on and off until the load is removed or power is
removed.
. See the figure "Overload
SET
Reverse Voltage
The AAT4608 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 AAT4608.
8 4608.2001.10.0.9
Page 9
Ordering Information
c
AAT4608
Current Limited Load Switch in SOT-23 Package
Package Marking
SOT-23-5 N/A AAT4608IGV-T1
SOT-23-5 N/A AAT4608IGV-1-T1
Package Information
SOT-23-5
e
S1
H
E
D
A
A1
S
b
Part Number
Bulk Tape and Reel
Dim
Millimeters Inches
Min Max Min Max
A 0.95 1.45 0.037 0.057
A1 0.05 0.15 0.002 0.006
A2 0.90 1.30 0.035 0.051
b 0.35 0.50 0.014 0.019
c 0.08 0.20 0.003 0.078
D 2.84 3.00 0.112 0.112
E 1.50 1.70 0.059 0.067
e 1.90 0.0748
H 2.60 3.00 0.102 0.118
L 0.35 0.55 .0137 .0216
S 0.47 0.55 0.019 .0216
S1 .95 0.037
L
Θ 0° 10° 0° 10°
4608.2001.10.0.9 9
Page 10
AAT4608
Current Limited Load Switch in SOT-23 Package
This page intentionally left blank.
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
10 4608.2001.10.0.9
Loading...