ANALOGICTECH AAT4618IJS-1-T1

AAT4618
Current Limited Load Switch
General Description
Features
The AAT4618 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 operating
with inputs ranging from 2.4V to 5.5V which makes it
ideal for 2.5V, 3V and 5V systems. An integrated current-limiting circuit protects the input supply from large
currents which potentially cause the supply to fall out
of regulation. In addition, the AAT4618 thermal overload protection limits power dissipation and junction
temperatures associated with prolonged periods of
operation in current limit. Due to its low RDS(ON), the
AAT4618 can be used to control loads that require up
to 500mA even while operating at high ambient temperatures. The ultra fast current-limit response to a
sudden short circuit is a mere 400ns which reduces
the requirements of local supply bypassing. An open
drain FAULT flag signals an over current or over temperature condition after a 4ms timeout. Quiescent
current is a low 10µA and in shutdown mode, the supply current decreases to less than 1µA.
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•
•
•
•
•
•
•
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2.4V to 5.5V Input voltage range
500mA min current limit trip threshold
Fast transient response:
• 400ns response to short circuit
Low quiescent current
• 10µA typical
• < 1µA with Switch off
125mΩ typical R DS(ON)
FAULT flag with 4ms blanking
Undervoltage Lockout
Thermal shutdown
Temp range -40 to 85°C
4kV ESD Rating
5 pin SOT23 package
8 pin SC70JW package
Preliminary Information
The AAT4618 is available in a 5 pin SOT-23, and an
8 pin SC70JW specified over a -40 to 85°C temperature range.
•
SmartSwitch™
Applications
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Peripheral ports
USB Ports
Notebook computers
Personal communication devices
Hot swap supplies
The AAT4600 Series is a family of adjustable and
fixed SmartSwitch™ products with a range of current
handling capabilities. Available are single versions
with adjustable current limit (AAT4610, AAT4601) as
well as fixed current limit (AAT4625), and dual versions with fixed current limit (AAT4626, AAT4670).
Typical Application
OUTPUT
INPUT
IN
OUT
AAT4618
100k
FAULT
CIN
1µF
GND
4618.2002.2.0.9
ON
(ON)
FAULT
ON (ON)
GND
COUT
0.47µF
GND
1
AAT4618
Current Limited Load Switch
Pin Descriptions
Pin #
SOT23-5
SC70JW-8
Symbol
Function
1
5
OUT
P-channel MOSFET drain
2
6, 7, 8
GND
Ground connection
3
1
FAULT
4
2
ON (ON)
5
3, 4
IN
Open-drain FAULT output
Enable Input: 4618 active low, 4618-1 active high
P-channel MOSFET source
Pin Configuration
SOT23-5
5
IN
2
3
4
ON (ON)
FAULT
ON (ON)
IN
IN
1
8
7
2
2
2
1
1
OUT
GND
FAULT
SC70JW-8
3
6
4
5
GND
GND
GND
OUT
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Absolute Maximum Ratings
(TA=25°C unless otherwise noted)
Symbol
Description
VIN, FAULT
VON
VOUT
IOUT
TJ
VESD
TLEAD
IN, FAULT to GND
ON (ON) to GND
OUT to GND
Output Current
Operating Junction Temperature Range
ESD Rating1—HBM
Maximum Soldering Temperature (at Leads)
Value
Units
-0.3 to 6
-0.3 to VIN+1
-0.3 to VIN+0.3
Internally Limited
-40 to 150
4000
300
V
V
V
A
°C
V
°C
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.
Thermal Characteristics
Symbol
ΘJA
PD
Description
Maximum Thermal Resistance
Maximum Power Dissipation 2
2
Value
Units
150
667
°C/W
mW
Note 2: Mounted on a demo board.
Electrical Characteristics
(VIN = 5V, TA = -40 to 85°C unless otherwise noted. Typical values
are at TA=25°C; bold values denote full temperature range)
Symbol
VIN
IQ
Description
Conditions
VIN = 5V, ON (ON) = active, IOUT = 0
ON (ON) = inactive, VIN = 5.5V
ON (ON) = inactive, VIN = 5.5V, VOUT = 0
VIN falling
RDS(ON)
On-Resistance
VIN = 5.0V, TA = 25°C
VIN = 3.0V, TA = 25°C
TCRDS
ILIM
VON(L)
ON-Resistance Temp-co
Current Limit
ON (ON) Input Low Voltage
VON(H)
ON (ON) Input High Voltage
ION(SINK)
tRESP
TOFF
TON
VFAULTLOW
ISINK
ON (ON) Input leakage
Current Loop Response
Turn-Off Time
Turn-On Time
FAULT Logic Output Low
FAULT Logic Output High
Leakage Current
Fault Blanking Time
Over-temperature threshold
IQ(OFF)
ISD(OFF)
VUVLO
VUVLO(hys)
Tblank
TSD
Min
Typ
2.4
Operation Voltage
Quiescent Current
Off Supply Current
Off Switch Current
Undervoltage Lockout
Undervoltage Lockout Hysteresis
VOUT = VIN - 0.5V
VIN = 2.7V to 5.5V 3
VIN = 2.7V to ≤ 4.2V 3
VIN = > 4.2V to 5.0V 3
VON (ON) = 5.5V
VIN = 5V
VIN = 5V, RL = 20Ω
VIN = 5V, RL = 20Ω
ISINK = 1mA
VFAULT = 5.5V
VIN = 5V
10
500
0.1
1.9
0.3
125
155
2800
750
Max
Units
5.5
20
1
1
V
µA
µA
µA
V
V
175
225
1000
0.8
2.0
2.4
0.01
400
5
1
0.5
4
125
1
0.4
1
mΩ
ppm/°C
mA
V
V
V
µA
ns
µs
µs
V
µA
ms
°C
Note 3: For VIN outside this range consult Typical ON (ON) Threshold curve.
4618.2002.2.0.9
3
AAT4618
Current Limited Load Switch
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25ºC)
Quiescent Current vs. Temperature
Quiescent Current vs. Input Voltage
20
Quiescent Current (µA)
Quiescent Current (µA)
20
15
10
5
0
-20
0
20
40
60
80
100
10
5
0
0
120
1
2
4
5
IN (V)
Current Limit vs. VOUT
RDS(ON) vs. Temperature
220
200
180
160
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
3
Temperature (°C)
RDS(ON) (mΩ)
Current Limit (A)
-40
15
1
2
3
4
5
VOUT (V)
6
VIN=3V
140
120
100
80
60
40
20
0
VIN=5V
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Off-Switch Current vs. Temperature
1.00
1.00
Off-Switch Current (µA)
Off-Supply Current (µA)
Off-Supply Current vs. Temperature
0.10
0.01
0.00
-40
0.01
0.00
-20
0
20
40
60
Temperature (°C)
4
0.10
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25ºC)
Turn-Off
RL=20Ω, CL=0.47µF
6
6
5
5
4
ON
3
Voltage (V)
Voltage (V)
Turn-On
RL=20Ω, CL=0.47µF
OUT
2
1
4
2
0
0
-1
-10
0.5
1.0
1.5
2.0
OUT
1
-1
-0.5
0.0
ON
3
0
10
Short Circuit through 0.3 Ω
30
40
50
Thermal Shutdown Response
6
12
Input Voltage
5
10
Output Current
4
8
Output Voltage
3
6
2
4
1
2
0
Output Voltage (5V/div)
Output (A)
Input and Output (V)
20
Time (µs)
Time (µs)
Output Current (1A/div)
0
-1
0
1
2
3
4
5
Time (µs)
Time (50ms/div)
Fault Delay from Short Circuit
ON (ON) Threshold vs. VIN
Output Voltage (5V/div)
Output Current (1A/div)
FAULT (5V/div)
ON (ON) Threshold (V)
2.4
2.2
2
1.8
VON(H)
1.6
1.4
VON(L)
1.2
1
0.8
0.6
0.4
2
Time (1ms/div)
4618.2002.2.0.9
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
5
AAT4618
Current Limited Load Switch
Functional Block Diagram
IN
OUT
Under-Voltage
Lockout
Over-Temp
Protection
Current
Limit
FAULT
ON (ON)
4ms Delay
GND
Functional Description
The AAT4618 is a single channel current limited
load switch that protects against short circuits by
current limiting to a preset level. A patented fast
acting current limit loop limits the current in a fraction of a micro second and instantly resets to low
impedance once the short circuit condition is
removed.
The AAT4618 is internally protected
from thermal damage by an over temperature
detection circuit. If the die temperature reaches
the internal thermal limit, the power device is
switched off until the die temperature cools to a
level below the thermal limit threshold. The device
will thermal cycle indefinitely until the over current
condition is removed. The AAT4618 operates with
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input voltages ranging from 2.4V to 5.5V which,
along with its extremely low operating current,
makes it ideal for battery-powered applications. In
cases where the input voltage drops below 2.4V,
the AAT4618 MOSFET is protected from entering
the saturated region of operation by being automatically shut down by an under voltage lockout
circuit. A current limit condition is reported by the
open drain FAULT output. A four millisecond blanking interval prevents false reporting during the
charging of a capacitive load, which typically
occurs during device turn-on, but may also occur
during a port hot plug-in event.
The AAT4618 is ideally suited for protection of
peripheral ports such as USB, RS232 and parallel
ports.
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Applications Information
Input Capacitor
The input capacitor, CIN protects the power supply
from current transients generated by the load
attached to the AAT4618. When a short circuit is
suddenly applied to the output of the AAT4618, a
large current, limited only by the RDS(ON) of the
MOSFET, will flow for less than 1µs before the current limit circuitry activates. (See characteristic
curve "Short Circuit Through 0.3Ω.") In this event,
a moderately sized CIN will dramatically reduce the
voltage transient seen by the power supply and by
other circuitry upstream from the AAT4618. The
extremely fast short circuit response time of the
AAT4618 reduces the size requirement of CIN.
CIN should be located as close to the device VIN pin
as practically possible. Ceramic, tantalum or aluminum electrolytic capacitors are appropriate for
CIN. There is no specific capacitor ESR requirement
for CIN. However, for higher current operation,
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
In order to insure stability while current limit is
active, a small capacitance of approximately
0.47µF is required. No matter how large the output
capacitor however, output current is limited to the
value set by the AAT4618 current limiting circuitry,
so very large output capacitors can be used.
For example, USB ports are specified to have at
least 120µF of capacitance down stream from their
controlling power switch. The current limiting circuit
will allow an output capacitance of 1000µF or more
without disturbing the upstream power supply.
ON (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) of
the AAT4618 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 systems.
When switching the AAT4618 on into a capacitive
load, the AAT4618 will charge the output capacitive
load at a rate no greater than the current limit setting.
Attaching Loads
Capacitive loads attached to an enabled AAT4618
will charge at a rate no greater than the current limit
setting.
FAULT Output
The FAULT flag is provided to alert the system if an
AAT4618 load is not receiving sufficient voltage to
operate properly. If current limit or over temperature circuits in any combination are active for more
than approximately four milliseconds, the FAULT
flag is pulled to ground through approximately
100Ω. The filtering of voltage or current transients
of less than four milliseconds prevents capacitive
loads connected to the AAT4618 output from activating the FAULT flag when they are initially
attached. Pull up resistances of 1kΩ to 100kΩ are
recommended. Since FAULT is an open drain terminal, it may be pulled up to any unrelated voltage
less than the maximum operating voltage of 5.5V,
allowing for level shifting between circuits.
Thermal Considerations
Since the AAT4618 has internal current limit and
over temperature protection, junction temperature
is rarely a concern. However, if the application
requires large currents in a hot environment, it is
possible that temperature rather than current limit
will be the dominant regulating condition. In these
applications, the maximum current available without risk of an over temperature condition must be
calculated. The maximum internal temperature
while current limit is not active can be calculated
using Equation 1.
TJ(MAX) = IMAX2 × RDS(ON)(MAX) × RθJA + TA(MAX)
In Equation 1, IMAX is the maximum current
required by the load. RDS(ON)(MAX) is the maximum rated RDS(ON) of the AAT4618 at high temperature. RθJA is the thermal resistance between the
AAT4618 die and the board onto which it is mounted. TA(MAX) is the maximum temperature that the
PCB under the AAT4618 would be if the AAT4618
were not dissipating power. Equation 1 can be
rearranged to solve for IMAX; Equation 2.
IMAX=
4618.2002.2.0.9
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) × RθJA
7
AAT4618
Current Limited Load Switch
TSD(MIN) is the minimum temperature required to
activate the AAT4618 over temperature protection.
With typical specification of 125°C, 115°C is a safe
minimum value to use.
For example, if an application is specified to operate in 50°C environments, the PCB operates at
temperatures as high as 85°C. The application is
8
sealed and its PCB is small, causing RθJA to be
approximately 150 °C/W. Using Equation 2,
IMAX=
115 - 85
= 950 mA
220m × 150
The AAT4618 is safe to operate at the minimum
current limit level of 500mA at 85°C.
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Ordering Information
Part Number
Package
Enable
SOT23-5
Marking
Bulk
Tape and Reel
Active Low
N/A
AAT4618IGV-T1
SOT23-5
Active High
N/A
AAT4618IGV-1-T1
SC70JW-8
Active Low
N/A
AAT4618IJS-T1
SC70JW-8
Active High
N/A
AAT4618IJS-1-T1
Package Information
SOT23-5
e
Dim
S1
H
E
D
A
A1
S
b
c
I
A
A1
A2
b
c
D
E
e
H
L
S
S1
Θ
Millimeters
Min
Max
0.95
1.45
0.05
0.15
0.90
1.30
0.35
0.50
0.08
0.20
2.84
3.00
1.50
1.70
1.90
2.60
3.00
0.35
0.55
0.47
0.55
.95
0°
10°
Inches
Min
Max
0.037
0.057
0.002
0.006
0.035
0.051
0.014
0.019
0.003
0.078
0.112
0.112
0.059
0.067
0.0748
0.102
0.118
.0137
.0216
0.019
.0216
0.037
0°
10°
L
4618.2002.2.0.9
9
AAT4618
Current Limited Load Switch
SC70JW-8
e
e
e
Dim
E
b
D
0.048REF
c
A2 A
E
E1
L
A
A1
A2
D
e
b
c
Θ
Θ1
Millimeters
Min
Max
2.10 BSC
1.75
2.00
0.23
0.40
1.10
0
0.10
0.70
1.00
2.00 BSC
0.50 BSC
0.15
0.30
0.10
0.20
0
8º
4º
10º
Inches
Min
Max
0.083 BSC
0.069
0.079
0.009
0.016
0.043
0.004
0.028
0.039
0.079 BSC
0.020 BSC
0.006
0.012
0.004
0.008
0
8º
4º
10º
A1
Θ1
L
E1
Θ
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
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4618.2002.2.0.9