AAT4682 [ANALOGICTECH]
Dual Electronic Resettable Switches; 双电复位开关
| 型号： | AAT4682 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | Dual Electronic Resettable Switches |
| 文件： | 总8页 (文件大小：243K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT4682
Dual Electronic Resettable Switches
™
SmartSwitch
General Description
Features
The AAT4682 Dual Electronic Resettable fuse is
part of the AnalogicTech Application Specific Power
MOSFET (ASPM™) line of products. It has two 1A
current limited P-channel MOSFET power devices
that remain fully enhanced as long as the input
power supply is above an under voltage lockout
threshold, and the load is below the current limit
setting. If the load increases above the current limit
setting, as is the case during a short circuit, the
MOSFET effectively becomes a constant current
source equal to the current limit. If the current limit
condition persists long enough to heat the MOSFET
to an extreme temperature, both devices will ther-
mal cycle off and on until the current limit condition
is removed. Independent open drain FAULT flags
signal an over current or over temperature condi-
tion. Quiescent current typically is a low 10µA.
•
•
•
•
•
•
Dual P-Channel MOSFETS
500mA steady state load current
600mA minimum current limit trip point
Low quiescent current, typically 10µA.
Over temperature protection
Fast transient response:
•
< 1µs response to short circuit
•
•
•
•
•
400mΩ typical RDS(ON)
Undervoltage Lockout
Temp range -40 to 85°C
FAULT flag with 2ms blanking
6-pin SOT23 package
Applications
The AAT4682 is available in a 6 pin SOT-23, spec-
ified over a -40 to 85°C temperature range.
•
•
•
•
USB ports
Peripheral ports
Desktop PCs
Cell phone ports
Typical Application
AAT4682
5
6
IN
OUTA
OUTB
INPUT
OUTA
OUTB
4
1
3
FAULTA
FAULTB
FAULTA
FAULTB
GND
2
CIN
1µF
COUTA
1µF
COUTB
1µF
GND
GND
4682.2001.11.0.9
1
AAT4682
Dual Electronic Resettable Switches
Pin Descriptions
Pin # Symbol
Function
1
2
3
4
5
6
FAULTA
GND
Channel A open drain output signals over-current and over-temperature condition
Ground connection
FAULTB
OUTB
IN
Channel B open drain output signals over-current and over-temperature condition
Channel B P-channel MOSFET drain
Channel A and Channel B P-channel MOSFET sources
Channel A P-channel MOSFET drain
OUTA
Pin Configuration
SOT23-6
FAULTA
GND
OUTA
IN
1 6
2
5
3 4
OUTB
FAULTB
2
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AAT4682
Dual Electronic Resettable Switches
Absolute Maximum Ratings (TA=25°C unless otherwise noted)
Symbol
Description
Value
Units
VIN
VOUT
VFLG
IOUT
TJ
IN to GND
-0.3 to 6
-0.3 to 6
V
V
OUTA or OUTB to GND
FAULTA or FAULTB to GND
Output Current
-0.3 to 6
V
Internally Limited
-40 to 150
5000
A
Operating Junction Temperature Range
ESD Rating1 - HBM
°C
V
VESD
TLEAD
Maximum Soldering Temperature (at Leads)
300
°C
Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-
ditions 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
Description
Maximum Thermal Resistance2
Maximum Power Dissipation2
Value
Units
ΘJA
150
667
°C/W
mW
PD
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 designate full temperature range)
Symbol
Description
Conditions
Min
1.8
Typ
Max Units
VIN
IQ
Operation Voltage
5.5
20
V
µA
V
Quiescent Current
VIN = 5V, IOUT = 0
VIN falling
10
1.5
VUVLO
VUVLO(hys)
RDS(ON)
Undervoltage Lockout
Undervoltage Lockout Hysteresis
On-Resistance
0.3
V
VIN = 5.0V,TA = 25°C
VIN = 3.V,TA = 25°C
OUT < IN - 0.5V
VIN = 5V
400
525
0.875
500
500
650
1.25
mΩ
ILIM
tRESP
VFAULTLOW
ISINK
Current Limit
0.6
A
ns
V
Current Loop Response
FAULT Logic Output Low
FAULT Logic Output High
Leakage Current
ISINK = 1mA
0.4
1
VFAULT = 5.5V
0.5
µA
Tblank
TSD
FAULT Blanking Time
Over-temperature threshold
2
ms
°C
125
4682.2001.11.0.9
3
AAT4682
Dual Electronic Resettable Switches
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25°C)
Quiescent Current vs. Input Voltage
Quiescent Current vs. Temperature
12
20
18
16
14
12
10
8
10
8
6
4
6
2
0
4
2
0
1
2
3
4
5
6
0
-40
-20
0
20
40
60
80
100
120
Input (V)
Temperature (°C)
Current Limit vs. Output Voltage
RDS(ON) vs. Temperature
1.0
600
550
500
450
400
350
300
0.8
0.6
0.4
0.2
0.0
VIN=3V
VIN=5V
0
1
2
3
4
5
Output (V)
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Short Circuit Through 0.6Ω
Short Circuit Through 0.3Ω
6
4
2
0
5
6
4
7
Input Voltage
Input Voltage
5
3
2
3
Output Current
Output Voltage
Output Voltage
Output Current
1
0
1
-2
-1
-1
-0.5
0.0
0.5
1.0
1.5
2.0
-0.5
0.0
0.5
1.0
1.5
2.0
Time (µs)
Time (µs)
4
4682.2001.11.0.9
AAT4682
Dual Electronic Resettable Switches
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25°C)
Thermal Shutdown Response
Fault Delay
FAULTA (5V/div)
OUTA (5V/div)
FAULTA (5V/div)
OUTA (5V/div)
FAULTB
(5V/div)
FAULTB (5V/div)
OUTB (5V/div)
OUTB
(5V/div)
IIN (1A/div)
IIN (1A/div)
500µs/div
50ms/div
4682.2001.11.0.9
5
AAT4682
Dual Electronic Resettable Switches
Functional Block Diagram
INA
OUTB
ILIM
UVLO
OTMP
ILIM
OUTB
FAULTA
FAULTB
3ms Blanking
3ms Blanking
GND
will thermal cycle indefinitely until the over current
condition is removed. Due to the high thermal con-
ductivity of silicon and the size of the die, the tem-
perature across the die is relatively uniform at high
temperatures, and therefore, as a precaution, both
power devices are switched off when the thermal
threshold is reached. The AAT4682 operates with
input voltages ranging from 1.8V 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 1.8V,
the AAT4682 internal MOSFETS are protected
from entering the saturated region of operation by
being automatically shut down by an undervoltage
lockout circuit.
Functional Description
The AAT4682 is a dual channel electronic reset-
table fuse that protects against short circuit condi-
tions by current limiting to a preset level. A patent-
ed fast acting current limit loop limits load current in
a fraction of a microsecond, and instantly resets
back to a low impedance state once the short cir-
cuit condition is removed. A current limit condition
is reported by the open drain FAULT output after a
two millisecond blanking interval. The blanking
prevents false reporting during the charging of a
capacitive load, which typically occurs when a load
is connected. The AAT4682 is internally protected
from thermal damage by an over temperature
detection circuit. If the die temperature reaches the
internal thermal limit, both power devices are
switched off until the die temperature cools to a
level below the thermal limit threshold. The device
The AAT4682 is ideally suited for protection of
peripheral ports such as USB, RS232 and parallel
ports.
6
4682.2001.11.0.9
AAT4682
Dual Electronic Resettable Switches
tive loads connected to theAAT4682 output from acti-
vatingtheFAULT flagwhentheyareinitiallyattached.
Pull up resistances of 10kΩ to 100kΩ are recom-
mended. Since the FAULT outputs are open drain
terminals, they may be pulled up to any voltage rail
less than the maximum operating voltage of 5.5V,
allowing for level shifting between circuits.
Applications Information
Input Capacitor
The input capacitor protects the power supply from
current transients generated by the loads attached to
the AAT4682. If a short circuit is suddenly applied to
a AAT4682 output, there is a 500 nanosecond long
period during which a large current can flow before
current limit circuitry activates. (See characteristic
curve "Short Circuit Through 0.3Ω.") In this event, a
properly sized input capacitor can dramatically
reduce the voltage transient seen by the power sup-
ply and other circuitry upstream from the AAT4682.
Thermal Considerations
Since the AAT4682 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 tem-
perature rather than current limit will be the dominant
regulating condition. In these applications, the max-
imum combined current available without risk of an
over temperature condition can be calculated. The
maximum internal temperature while current limit is
not active can be calculated using Equation 1.
CIN should be located as close to the device VIN pin
as practically possible. Ceramic, tantalum or alu-
minum electrolytic capacitors may be selected 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.
2
T
J(MAX) = IMAX × RDS(ON)(MAX) × RθJA + TA(MAX)
In Equation 1, IMAX is the maximum current
required by the load. RDS(ON)(MAX) is the maxi-
mum rated RDS(ON) of the AAT4682 at high temper-
ature. RθJA is the thermal resistance between the
AAT4682 die and the board onto which it is mount-
ed. TA(MAX) is the maximum temperature that the
PCB under the AAT4682 would be if the AAT4682
were not dissipating power. Equation 1 can be
rearranged to solve for IMAX; Equation 2.
Output Capacitors
In order to insure stability while current limit is
active, a small output capacitance of approximately
1µF is required at each output. No matter how big
the output capacitor, output current is limited to the
value set by the AAT4682 current limiting circuitry,
allowing very large output capacitors to be used.
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) × RθJA
IMAX
=
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.
TSD(MIN) is the minimum temperature required to
activate the AAT4682 over temperature protection.
The typical over temperature threshold specifica-
tion is 125°C, therefore 115°C is a safe minimum
value to use.
Attaching Loads
Capacitive loads attached to the AAT4682 will charge
at a rate no greater than the current limit setting.
For example, if an application is specified to oper-
ate in 50°C environments, the PCB operates at
temperatures as high as 85°C. The application is
sealed and its PCB is small, causing RθJA to be
approximately 150°C/W. Using Equation 2,
FAULT Outputs
FAULT flags are provided to alert a system if a
AAT4682 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 two milliseconds, the corresponding
FAULT output is pulled to ground through approxi-
mately 100Ω. Removal of voltage or current tran-
sients of less than two milliseconds prevents capaci-
115 - 85
600 × 150
IMAX
=
= 575mA
To prevent thermal limiting, the combined operating
load current of each output in the application must
be less than 575mA.
4682.2001.11.0.9
7
AAT4682
Dual Electronic Resettable Switches
Ordering Information
Part Number
Package
SOT23-6
Marking
Bulk
N/A
Tape and Reel
AAT4682IGU-T1
Package Information
t
Millimeters
Inches
e1
e
Dim
Min
0.95
0.05
0.90
0.35
0.08
2.84
1.50
2.60
Max
1.45
0.15
1.30
0.50
0.20
3.00
1.70
3.00
Min
Max
A
A1
A2
b
c
D
E
E1
e
e1
f
L
0.037
0.002
0.035
0.057
0.006
0.051
L2
0.0137 0.019
0.0031 0.0078
0.1118 0.118
0.059 0.0669
E
0.102
0.118
L
0.95 BSC
1.90 BSC
0.50 BSC
0.0374 BSC
0.0748 BSC
0.0197 BSC
f
C
D
0.23
0.40
0.009
0.039 BSC
0.0236 BSC
0.016
L1
L2
t
0.10 BSC
0.60 BSC
0º
10º
0º
10º
A2
A1
A
b
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
8
4682.2001.11.0.9
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