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Dual-Input, Dual-Output Load Switch General Description
The AAT4670 SmartSwitch is a member of AnalogicTech's Application Specific Power MOSFETTM (ASPMTM) product family. The AAT4670 consists of dual, independent, 1A current limited, slew rate controlled P-channel MOSFET power switches with a dedicated source and drain pin assigned to each switch. The internal circuitry automatically derives power from the higher of the two input power source pins with a low operating quiescent current of 18A. In shutdown mode, the supply current decreases to less than 1A. The switches operate with inputs ranging from 2.2V to 5.5V, making them ideal for 2.5V, 3V, and 5V systems. The dual configuration permits integration of the load switch function for systems with two different power busses. Independent under-voltage lockout circuits will shut down the corresponding switch if its input voltage falls below the under-voltage lockout threshold. If the die temperature reaches the thermal limit, both switches thermal cycle off and on indefinitely without damage until the thermal condition is removed. An open drain FAULT output signals an over-current or over-temperature condition for each channel. Input logic levels are TTL compatible. The AAT4670 is available in a Pb-free, space-saving, thermally-enhanced TDFN 3x3x0.8mm 12-lead package. The device is also available in a Pb-free 8-pin SOP, TSSOP, or MSOP package and is specified over the -40C to +85C temperature range.
AAT4670
Features
* * * * * * * * * * * *
SmartSwitchTM
2.2V to 5.5V Input Voltage Range 1A Current Limit Per Channel 95m Typical RDS(ON) Fast Transient Response: -- <1s Response to Short Circuit Low 18A Quiescent Current 1A Max with Switches Off Slew Rate Controlled Thermal Shutdown Fault Flags with 3ms Blanking Under-Voltage Lockout Temperature Range: -40C to +85C Available in TDFN33-12, SOP-8, TSSOP-8, or MSOP-8 Package
Applications
* * * * * * Hot Swap Supplies Media Bay Notebook Computer PDA, Subnotebook Peripheral Ports USB Ports
Typical Application
AAT4670
INA INB EN
INA INB EN GND OUTA OUTB FAULTA FAULTB
OUTA OUTB FAULTA FAULTB
CINA 1F
GND
CINB 1F
COUTA 1F
COUTB 1F
GND
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1
Dual-Input, Dual-Output Load Switch Pin Descriptions
Pin #
TDFN Other Pkgs
AAT4670
Symbol
OUTA EN FAULTA FAULTB GND OUTB INB INA
Function
P-channel MOSFET drain channel A. Active-low enable input (logic low turns the switches on). Open drain output; signals over-current for OUTA and over-temperature condition. Open drain output; signals over-current for OUTB and over-temperature condition. Ground connection. P-channel MOSFET drain channel B. P-channel MOSFET source channel B. P-channel MOSFET source channel A. Exposed paddle (bottom); connect to ground as closely as possible to the device.
1, 12 2 3 4 5 6, 7 8, 9 10, 11 EP
8 1 2 3 4 5 6 7
Pin Configuration
TDFN33-12 SOP-8
OUTA EN FAULTA FAULTB GND OUTB
1 2 3 4 5 6
12 11 10 9 8 7
OUTA INA INA INB INB OUTB
EN FAULTA FAULTB GND
1
8
OUTA INA INB OUTB
1
2
7
2
3
6
4
5
TSSOP-8
MSOP-8
EN FAULTA FAULTB GND
1 2 3 4
8 7 6 5
OUTA INA INB OUTB
EN FAULTA FAULTB GND
1
8
OUTA INA INB OUTB
1
2
7
2
3
6
4
5
2
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Dual-Input, Dual-Output Load Switch Absolute Maximum Ratings1
TA = 25C, unless otherwise noted. Symbol
VINA,B VOUTA,B VFAULTA,B IOUT TJ VESD TLEAD
AAT4670
Description
INA or INB to GND OUTA or OUTB to GND FAULTA or FAULTB to GND Output Current Operating Junction Temperature Range ESD Rating2 - HBM Maximum Soldering Temperature (at Leads)
Value
-0.3 to 6 -0.3 to 6 -0.3 to 6 Internally Limited -40 to 150 4000 300
Units
V V V A C V C
Thermal Characteristics3
Symbol
JA PD
Description
Maximum Thermal Resistance Maximum Power Dissipation SOP-8 TDFN33-12 SOP-8 TDFN33-12
Value
100 50 1.25 2.0
Units
C/W W
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. Human body model is a 100pF capacitor discharged through a 1.5k resistor into each pin. 3. Mounted on a demo board. 4670.2006.09.1.4
3
Dual-Input, Dual-Output Load Switch Electrical Characteristics
VIN = 5V, TA = 25C, unless otherwise noted. Bold values designate -40C to +85C temperature range. Symbol Description
VIN IQ IQ(OFF) ISD(OFF) VUVLO RDS(ON) TCRDS ILIM t1 t2 t3 t4 VEN(L) VEN(H) IEN(SINK) tRESP VFAULTLOW ISINK Tblank TSD Operation Voltage Quiescent Current Off Supply Current Off Switch Current Under-Voltage Lockout On-Resistance Channel A or B Switch Resistance Temperature Coefficient Current Limit Channel A or B Output Turn-On Delay Time Output Rise Time Output Turn-Off Delay Time Output Fall Time EN Input Low Voltage EN Input High Voltage EN Input Leakage Current Loop Response FAULT Logic Output Low FAULT Logic Output High Leakage Current Fault Blanking Time Over-Temperature Threshold
AAT4670
Conditions
VINA or VINB = 5V IOUTA = IOUTB = 0 EN = VIN, VINA = VINB = 5V, OUTA, OUTB Open EN = VIN, VINA = VINB = 5V, VOUTA = VOUTB = 0V VIN = 5.0V VIN = 3.0V
Min
2.2
Typ
18 0.1 1.7 95 105 2800
Max Units
5.5 40 1 1 2.2 130 150 V A A A V m ppm/C 1.50 1000 1000 20 20 0.8 A s s s s V V
VOUT < VIN to 0.5V VIN = 5V, OUT = 0 to 10%, RLOAD = 20 VIN = 5V, OUT = 10% to 90%, RLOAD = 20 VIN = 5V, OUT = 100% to 90%, RLOAD = 20 VIN = 5V, OUT = 90% to 10%, RLOAD = 20 VIN = 2.7V to 5.5V1 VIN = 2.7V to < 3.6V VIN = 3.6V to 5.5V VEN = 5.5V VIN = 5V ISINK = 1mA VFAULT = 5.5V
1.0
1.25 100 100 10 5
2.0 2.4 0.01 750 0.5 3 125 1 0.4 1
A ns V A ms C
1. For VIN outside this range, consult typical EN threshold curve.
4
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Dual-Input, Dual-Output Load Switch Typical Characteristics
Quiescent Current vs. Temperature
30 20 18
AAT4670
Quiescent Current vs. Input Voltage
Quiescent Current (A)
Input Current (A)
-40 -20 0 20 40 60 80 100 120
25 20 15 10 5 0
16 14 12 10 8 6 4 2 0 0 1 2 3 4 5 6
Temperature (C)
Input Voltage (V)
Off-Supply Current vs. Temperature
1.0000
Off-Switch Current vs. Temperature
1.0000
Off-Supply Current (A)
0.1000 0.0100 0.0010 0.0001 0.0000 -40 -20 0 20 40 60 80 100 120
Off-Switch Current (A)
0.1000 0.0100 0.0010 0.0001 0.0000 -40 -20 0 20 40 60 80 100 120
Temperature (C)
Temperature (C)
Current Limit vs. Output Voltage
1.4 150 140
RDS(ON) vs. Temperature
Output Current (A)
1.2
RDS(ON) (m)
1.0 0.8 0.6 0.4 0.2 0.0 0 1 2 3 4 5
130 120 110 100 90 80 70 60 -40 -20 0 20 40 60 80 100 120
VIN = 3V
VIN = 5V
Output Voltage (V)
Temperature (C)
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Dual-Input, Dual-Output Load Switch Typical Characteristics
Turn-On/Off Response with 20 1F Loads
EN (5V/div) FAULT (5V/div) OUTB (5V/div) INB = 5V OUTA (5V/div) INA = 3V IINA + IINB (200mA/div)
AAT4670
FAULT Delay Start Into 0.6 Load
ON (5V/div) FAULT (5V/div) VOUT (1V/div)
IIN (500mA/div)
Time (100s/div)
Time (500s/div)
Short Circuit Through 0.6
Input and Output Voltage (V)
Input and Output Voltage (V)
8 9 8 6 4 2 0 -2 -1
Short Circuit Through 0.3
12
Output Current (A)
6
Input Voltage
Output Current (A)
6
Input Voltage
8
4
Output Current Output Voltage
-1 0 1 2 3 4
3
Output Current
4
2
0
0
0
-3
Output Voltage
-4 0 1 2 3 4
Time (s)
Time (s)
Thermal Shutdown Response
2.4
Typical EN Threshold vs. Input Voltage
ON (5V/div) FAULT (5V/div) VOUT (1V/div)
EN Threshold (V)
2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VEN(H) VEN(L)
IIN (500mA/div)
Time (200ms/div)
Input Voltage (V)
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Dual-Input, Dual-Output Load Switch Functional Block Diagram
INA
ILIM UVLO OTMP UVLO ILIM Slew Rate Slew Rate
AAT4670
OUTA
EN
INB
OUTB FAULTA FAULTB
GND
Functional Description
The AAT4670 dual channel load switch, implemented with isolated independent P-channel MOSFET devices, is ideal for applications where dual power supplies are in continuous use. Typical applications for this include products with multiple USB ports, or ports requiring protection that operate from separate power supplies. The input power supplies can be any voltage between 2.2V and 5.5V in any combination; one supply is not required to be the higher voltage. Internally, the power supply for the control circuitry will automatically switch to the higher of the two supplies. In the case where the supplies are equal, 30mV of hysteresis prevents the internal supply from oscillating between the two input supplies. The low impedance P-channel MOSFET devices are identical in size, allowing for layout flexibility. They are controlled by a patented fast acting current loop and respond to short circuits in a fraction of a microsecond, easing requirements on the input capacitors. With such fast transient response time, the upstream power supply rail is naturally isolated from the protected port. The AAT4670 is internally protected from thermal damage by an over-temperature detection circuit. If
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a high ambient temperature or an over-current condition causes the die temperature to reach 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 will thermal cycle indefinitely until the over-current or high temperature condition is removed. Due to the high thermal conductivity of silicon and the size of the die, the temperature across the die is relatively uniform at high temperatures; therefore, as a precaution, both power devices are switched off when the thermal threshold is reached. Since the power devices operate from independent power supplies, independent undervoltage lockout circuits are employed. If the power supply to one channel falls below the under-voltage lockout threshold, the other channel will remain active. A current limit condition is reported by the open drain FAULT output associated with the appropriate channel. A thermal limit condition is reported by both FAULT outputs. A three 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 AAT4670 is ideally suited for protection of peripheral ports such as USB, PS2, and parallel ports. 7
Dual-Input, Dual-Output Load Switch Applications Information
Input Capacitor
The input capacitors, CINA and CINB, protect the input power supplies from current transients generated by loads attached to the AAT4670. If a short circuit is suddenly applied to an output of the AAT4670, there is a 750 nanosecond period during which a large current flows before current limit circuitry activates. (See characteristic curve "Short Circuit Through 0.3.") In this event, a properly sized input capacitor can dramatically reduce the voltage transient seen by the power supply and other circuitry upstream from the AAT4670. CIN should be located as close to the device VIN pin as practically possible. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor equivalent series resistance (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. than approximately three milliseconds, the associated FAULT flag is pulled to ground through approximately 100. Removal of voltage or current transients of less than three milliseconds prevents capacitive loads connected to either AAT4670 output from activating the associated FAULT flag when they are initially attached. Pull-up resistances of 1k to 100k 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.
AAT4670
Thermal Considerations
Since the AAT4670 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.
Output Capacitor
In order to insure stability while the current limit is active, a small capacitance of approximately 1F is required on each output. No matter how big the output capacitor, output current is limited to the value set by the AAT4670 current limiting circuitry, allowing very large output capacitors to be used. For example, USB ports are specified to have at least 120F of capacitance downstream from their controlling power switch. The current limiting circuit will allow an output capacitance of 1000F or more without disturbing the upstream power supply. Eq. 1: TJ(MAX) = IMAX2 * RDS(ON)(MAX) * RJA + TA(MAX)
Attaching Loads
Capacitive loads attached to the AAT4670 will charge at a rate no greater than the current limit setting.
In Equation 1, IMAX is the maximum current required by the load. RDS(ON)(MAX) is the maximum rated RDS(ON) of the AAT4670 at high temperature. RJA is the thermal resistance between the AAT4670 die and the board onto which it is mounted. TA(MAX) is the maximum temperature that the PCB under the AAT4670 would be if the AAT4670 were not dissipating power. Equation 1 can be rearranged to solve for IMAX; Equation 2.
Eq. 2:
IMAX =
TSD(MIN) - TA(MAX) RDS(ON)(MAX) * RJA
FAULT Output
FAULT flags are provided to alert the system if an AAT4670 load is not receiving sufficient voltage to operate properly. If current limit or over-temperature circuits in any combination are active for more TSD(MIN) is the minimum temperature required to activate the AAT4670 over-temperature protection. With typical specification of 125C, 115C is a safe minimum value to use.
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4670.2006.09.1.4
Dual-Input, Dual-Output Load Switch
For example, if an application is specified to operate in 50C environments, the PCB operates at temperatures as high as 85C. The application is sealed and its PCB is small, causing RJA to be approximately 120C/W. Using Equation 2: To prevent thermal limiting, the operating load current in the application must be less than 1.25A which lies in the current limiting range. So, in this application, any operating current below the current limit threshold is allowed.
AAT4670
Eq. 3:
IMAX =
115 - 85 = 1.25A 160m * 120
Timing Diagram
EN
OUT
t1
t2
t3
t4
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Dual-Input, Dual-Output Load Switch Ordering Information
Package
SOP-8 TSSOP-8 MSOP-8 TDFN33-12
AAT4670
Marking1
4670 4670 BFXYY
Part Number (Tape and Reel)2
AAT4670IAS-T1 AAT4670IHS-T1 AAT4670IKS-T1 AAT4670IWP-T1
All AnalogicTech products are offered in Pb-free packaging. The term "Pb-free" means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree.
Package Information
SOP-8
3.90 0.10
4.90 0.10
6.00 0.20
0.375 0.125
45
1.55 0.20
0.175 0.075
4 4
0.235 0.045 0.825 0.445
0.42 0.09 x 8
1.27 BSC
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
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Dual-Input, Dual-Output Load Switch
TSSOP-8
AAT4670
4.40 0.10
6.40 0.20
3.00 0.10 0.65 BSC
12 REF x 4
1.05 MAX
1.20 MAX
0.145 0.055 4 4
0.245 0.055 x 8
0.10 0.05 12
0.60 0.15 1.00 REF
DETAIL A
All dimensions in millimeters.
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Dual-Input, Dual-Output Load Switch
MSOP-8
4 4 1.95 BSC
AAT4670
3.00 0.10
4.90 0.10
0.60 0.20 PIN 1 0.254 BSC
0.95 REF
3.00 0.10 10 5
0.95 0.15 0.85 0.10
0.075 0.075 0.65 BSC 0.30 0.08
All dimensions in millimeters.
12
GAUGE PLANE
0.155 0.075
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Dual-Input, Dual-Output Load Switch
TDFN33-12
Index Area (D/2 x E/2)
AAT4670
Detail "B"
3.00 0.05
2.40 0.05
0.3 0.10 0.16 0.375 0.125 0.075 0.075 0.1 REF
Top View
Bottom View
Pin 1 Indicator (optional)
7.5 7.5
+ 0.05 0.8 -0.20
0.229 0.051
0.05 0.05
Option A: C0.30 (4x) max Chamfered corner
Option B: R0.30 (4x) max Round corner
Detail "B"
Side View
Detail "A"
All dimensions in millimeters.
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech's standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611
4670.2006.09.1.4
0.23 0.05
0.45 0.05
Detail "A"
3.00 0.05
1.70 0.05
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