PRODUCT DATASHEET
AAT4672
SmartSwitchTM
General Description
The AAT4672 SmartSwitch™ is a member of AnalogicTech’s Application Specific Power Management IC™ family. This device is a dual input, single output power supply selector switch, designed to operate from USB ports, AC adapter inputs, batteries, or any other power supply with an input voltage up to 6V. The AAT4672 connects the supply on the MAIN pin to the OUT pin through a very low on-resistance power MOSFET when the device is enabled, the MAIN pin voltage is higher than the under voltage lockout (UVLO) threshold, and MAIN pin voltage is greater than the AUX pin voltage plus 200mV. The AUX pin connects to the OUT pin only when the MAIN pin voltage drops 0.2V below the AUX pin voltage and the AUX pin voltage is greater than the UVLO threshold. If both input supplies (MAIN/AUX) are below the UVLO threshold, then the OUT pin floats. The two internal power switches are current limited and the thresholds can be programmed through resistors on the IMAIN and IAUX pins respectively. A power level selection pin, PWRSEL, is provided to toggle the AUX current limit between 100% and 20% of the current limit setting programmed by the resistor on the IAUX pin. This is particularly useful for USB applications where the power supply can be powered by either a 500mA or a 100mA USB port. The AAT4672 is available in a thermally enhanced, space-saving, Pb-free 12-pin TSOPJW package and is specified for operation over the -40°C to +85°C temperature range.
Power Supply Selector Switch
Features
• Input Voltage Supply Range: 2.5V to 6V • High Level of Integration: ▪ Reverse Blocking Diode ▪ Current Sensing ▪ Programmable Current Limiting ▪ Automatic Power Supply Switching • Break-Before-Make Switch-Over ▪ Minimum Output Voltage Drop During Change-Over • Shutdown Current < 1µA • Thermal Protection • TSOPJW-12 Package
Applications
• • • • • Bluetooth™ Headsets Cell Phones Digital Still Cameras MP3 Players Personal Data Assistants (PDAs)
Typical Application
AC Adapter USB Port USB H/L select
MAIN OUT AUX IMAIN PWRSEL IAUX RIAUX RIMAIN System Load
Enable
EN GND
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Pin Descriptions
Pin Number
1, 2 3, 4 5 6, 7 8 9 10 11, 12
Power Supply Selector Switch
Name
MAIN AUX EN GND PWRSEL IAUX IMAIN OUT
Type
I I I I/O I I I O
Function
Power supply 1 input. Power supply 2 input. Enable pin, active low. Ground. Power level select input for AUX-OUT switch. Logic “0”: 20% of the current limit programmed by RIAUX Logic “1”: 100% of the current limit programmed by RIAUX AUX-OUT switch current limit set input. MAIN-OUT switch current limit set input. Output pin.
Pin Configuration
TSOPJW-12 (Top View)
MAIN MAIN AUX AUX EN GND
1 2 3 4 5 6
12 11 10 9 8 7
OUT OUT IMAIN IAUX PWRSEL GND
2
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Absolute Maximum Ratings1
Symbol
VN VX TLEAD IOUT
Power Supply Selector Switch
Description
[MAIN, AUX] to GND [OUT, EN, IMAIN, IAUX, PWRSEL] to GND Maximum Soldering Temperature (at Leads) Maximum Output Current
Value
-0.3 to 6.5 -0.3 to VN + 0.3 300 3
Units
V V °C A
Thermal Information2
Symbol
θJA PD TJ
Description
Maximum Thermal Resistance Maximum Power Dissipation Operating Junction Temperature Range
Value
160 625 -40 to 150
Units
°C/W mW °C
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. Mounted on a FR4 board.
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Electrical Characteristics1
Power Supply Selector Switch
VMAIN/AUX = 5V, TA = -40 to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Symbol
Operation VMAIN VAUX VMAIN-AUX VUVLO_MAIN VUVLO_AUX
Description
MAIN Operating Voltage Range AUX Operating Voltage Range MAIN Switch-Over Threshold (Input Voltage Difference) MAIN Under-Voltage Lockout AUX Under-Voltage Lockout
Conditions
Min
2.5 2.5 VAUX + 0.15
Typ
Max
6 6 VAUX +0.25 2.3 2.3
Units
V V V V V µA µA µA µA µA µA Ω Ω mV
MAIN, AUX > 2.5V Rising edge Hysteresis Rising edge Hysteresis VMAIN = 5V, VEN = 0V VMAIN = VEN = 5V, OUT open VMAIN = 2.5V, VAUX = 5V, VEN = 0V VAUX = 5V, VEN = 0V VAUX = VEN = 5V, OUT open VMAIN = 5V, VAUX = 2.5V, VEN = 0V VMAIN = 5.0V VMAIN = 3.5V VAUX = 5.0V VAUX = 3.5V IO(OUT) = 0.5A, CO(OUT) = 10µF
VAUX + 0.2 0.1 0.1 10 1 10 1 0.12 0.14 0.12 0.14 150
IMAIN_OP MAIN Normal Operating Current IMAIN_SHDN MAIN Shutdown Mode Current IMAIN_SLP MAIN Sleep Current AUX Normal Operating Current IAUX_OP IAUX_SHDN AUX Shutdown Mode Current IAUX_SLP AUX Sleep Current Power Switches RDS(ON) MAIN RDS(ON) AUX MAIN-to-OUT FET On-Resistance AUX-to-OUT FET On-Resistance
30 1 5 30 1 5
OUT Voltage Droop from the Lower Voltage of MAIN and AUX, When Switching Over Between MAIN and AUX Current Regulation tSOFT_START Soft-Start Delay ILIM_MAIN_range MAIN Current Limit Range VDROOP_OUT ILIM_AUX_range ILIM_MAIN ILIM_AUX AUX Current Limit Range MAIN Current Limit Accuracy AUX Current Limit Accuracy
Delay of start from EN , or UVLO PWRSEL = 5V PWRSEL = 0V RIAUX = 100kΩ RIMAIN = 100kΩ PWRSEL = 5V PWRSEL = 0V 0.2 0.2 0.04 0.8 0.8 0.18 1.6
100 2.0 2.0 0.4 1.2 1.2 0.22
µs A A A A V V °C
1 1 0.2
Logic Control / Protection VIH(EN) Logic High Threshold VIL(EN) Logic Low Threshold TSHDN Chip Thermal Shutdown Temperature Threshold Hysteresis
0.4 140 15
1. The output charge voltage accuracy is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C temperature range is guaranteed by design.
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
IMAIN Shutdown Current vs. Temperature
IMAIN Shutdown Current (µA) IAUX Shutdown Current (µA)
0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40
Power Supply Selector Switch
IAUX Shutdown Current vs. Temperature
VAUX = 6.5V VAUX = 5V
VMAIN = 6.5V VMAIN = 5V VMAIN = 3.6V VMAIN = 4.2V
-15 10 35 60 85
VAUX = 3.6V VAUX = 4.2V
-15 10 35 60 85
Temperature (°C)
Temperature (°C)
IMAIN Operation Current vs. Temperature
(IOUT = 0A) IMAIN Operation Current (µA) IAUX Operation Current (µA)
20 18 16 14 12 10 8 6 4 -40 -15 10 35 60 85 20 18 16 14 12 10 8 6 4
IAUX Operation Current vs. Temperature
(IOUT = 0A) VAUX = 6.5V VAUX = 5V
VMAIN = 6.5V VMAIN = 5V VMAIN = 4.2V VMAIN = 3.6V
VAUX = 3.6V
VAUX = 4.2V
-40
-15
10
35
60
85
Temperature (°C)
Temperature (°C)
RDS(ON) vs. Temperature
250 200 1.1
Enable Threshold vs. Input Voltage
Enable Threshold (V)
VMAIN/AUX = 3.5V VMAIN/AUX = 2.5V
1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 2.5 3 3.5 4 4.5 5 5.5 6 6.5
RDS(ON) (mΩ)
VIH(EN)
150 100 50 0
VMAIN/AUX = 5V
VMAIN/AUX = 6.5V
VIL(EN)
-40
-15
10
35
60
85
110
Temperature (°C)
Input Voltage (V)
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
IMAIN Sleep Current vs. VMAIN Voltage
(VAUX = 6.5V)
2.5 2.5
Power Supply Selector Switch
IAUX Sleep Current vs. VAUX Voltage
(VMAIN = 6.5V) IAUX Sleep Current (µA)
IMAIN Sleep Current (µA)
2 1.5 1 0.5 0 2.5 3 3.5 4
85°C 25°C -40°C
2 1.5 1 0.5 0 2.5 3 3.5 4
85°C 25°C
-40°C
4.5
5
5.5
6
4.5
5
5.5
6
VMAIN Voltage (V)
VAUX Voltage (V)
Current Limit vs. RIMAIN/IAUX
(VMAIN = 5V; VAUX = 3.3V; VOUT = VMAIN or VOUT = VAUX)
2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 50 100 150 200 250 300 350 400 450 500 2V
Turn-On/Off Response
(ROUT = 10Ω; VMAIN = 5V)
Current Limit (A)
VEN (2V/div)
0V
VOUT (5V/div) IOUT (500mA/div) RIMAIN/IAUX (kΩ)
0V
0A
Time (100µs/div)
Short Circuit Through 0.3Ω Response
VIN (2V/div)
Short Circuit Through 0.6Ω Response
VIN (2V/div)
5V
5V
IOUT (5A/div) VOUT (5V/div)
0A
2A
IOUT (5A/div) VOUT (5V/div)
0A
2A
5V
0.6V
5V
1.2V
Time (10µs/div)
Time (10µs/div)
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
Thermal Shutdown Response
(VMAIN = 5V)
2V 0V
Power Supply Selector Switch
VEN (2V/div)
VOUT (2V/div) IOUT (2A/div)
0V
0A
Time (40ms/div)
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Functional Block Diagram
Switch 1
Power Supply Selector Switch
MAIN
OUT
IMAIN
Thermal and Current Sense Logic Control
PWRSEL IAUX
EN
AUX
Switch 2
GND
Truth Table
Y = Yes, N = No, X = don’t care.
Input Conditions VMAIN > UVLO
N Y N Y Y
AAT4672 VMAIN > VAUX + 0.2V
X X X Y N
VAUX > UVLO
N N Y Y Y
VOUT
Floating VMAIN VAUX VMAIN VAUX
Functional Description
To power the OUT pin, at least one of the two input supplies (MAIN/AUX) must be greater than the UVLO threshold. If only one supply is greater than the UVLO threshold, the load will be connected to that particular supply when the device is enabled. If both supplies are above the UVLO threshold, the AAT4672 will connect the supply from the MAIN pin to the OUT pin when the device is enabled and the MAIN voltage is greater than the AUX voltage plus 0.2V (typical); otherwise, the AAT4672 will connect the supply from the AUX pin to the OUT pin. The two internal power switches are current limited; the current limits are programmed by the resistors on the IMAIN and IAUX pins respectively.
Applications Information
Input Capacitors
A 1µF or greater capacitor is generally recommended between MAIN and GND (CMAIN), and between AUX and GND (CAUX). An input capacitor is not required for basic operation; however, it is useful in preventing load transients from affecting up-stream circuits. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CMAIN/CAUX. There is no specific capacitor equivalent series resistance (ESR) requirement for CMAIN/CAUX. However, for higher current operation, ceramic capacitors are recommended for CMAIN/CAUX due to their inherent capability over tantalum capacitors to withstand
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
input current surges from low impedance sources such as batteries in portable devices.
Power Supply Selector Switch
For MAIN (power supply 1 input):
Output Capacitor
A 1µF or greater capacitor is required between OUT and GND (COUT). As with the input capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased to accommodate any load transient condition.
⎛ VIMAIN ⎞ RIMAIN = ⎝ I ⎠ · 200k
CLMAIN
⎛0.5V⎞ = ⎝ 2A ⎠ · 200k = 50kΩ (49.9kΩ standard value)
For AUX (power supply 2 input):
EN Input
The AAT4672 is enabled when VEN is ≤ 0.4V (logic ‘0’); conversely, the AAT4672 is disabled when VEN is ≥ 1.6V (logic ‘1’).
⎛ VIAUX ⎞ RIAUX = ⎝ I ⎠ · 200k
CLAUX
PWRSEL Input
When VPWRSEL is ≤ 0.4V (logic ‘0’) the AUX-OUT current limit is 20% of the current limit value programmed by RIAUX; when VPWRSEL is ≥ 1.6V (logic ‘1’), the AUX-OUT current limit is 100% of the current limit value programmed by RIAUX.
⎛0.5V⎞ = ⎝0.2A⎠ · 200k = 500kΩ (499.9kΩ standard value)
Thermal Considerations
Since the AAT4672 has an internal current limit and overtemperature protection(thermal shutdown), junction temperature is rarely a concern. However, if the application requires large currents in a high temperature 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 (Eq. 1). Eq. 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 AAT4672 at high temperatures (consult the “RDSON vs. Temperature” performance graph in the “Typical Characteristics” section of this datasheet). For estimating the RDS(ON)(MAX) use the data on the “RDSON vs Temperature” performance graph and increase the value from the performance graph by 50%. RθJA is the thermal resistance between the AAT4672 die and the printed circuit board (PCB) onto which it is mounted; RθJA is the thermal resistance of the TSOPJW-12 package. TA(MAX) is the maximum ambient temperature that the PCB under the AAT4672 would be if the AAT4672 were not dissipating power. Equation 1 can be rearranged to solve for IMAX, into Equation 2 (Eq. 2).
Current Limit Resistor Selection
The current limits for power supply 1 and power supply 2 inputs are set by resistors between IMAIN/IAUX and GND. The following equation can be used to select the appropriate resistor for a particular current limit:
⎛ VIMAIN/IAUX ⎞ ICLMAIN/AUX = ⎝ R · 200k IMAIN/IAUX ⎠
ICLIMAIN/AUX Current limit for MAIN and/or AUX pins respectively VIMAIN/IAUX Internally Regulated Voltage [0.5V ± 20%] on the IMAIN and IAUX pins respectively RIMAIN/IAUX IMAIN and/or IAUX Resistor 200k Internal Gain Factor
Design Example
A particular application requires that the current limit for MAIN be set to 2A and the current limit for AUX be set to 0.2A. What value of resistor is required for the IMAIN and IAUX pins respectively?
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Eq. 2: IMAX =
Power Supply Selector Switch
TSD(MIN) - TA(MAX) RDS(ON)(MAX) · RΘJA
PCB Layout Recommendations
For proper thermal management, to minimize PCB trace resistance, and to take advantage of the low RDS(ON) values of the two internal power switches in the AAT4672, certain circuit board layout rules should be followed: MAIN, AUX, and OUT should be routed using wider than normal traces. The two MAIN pins (1 and 2) and two AUX pins (3 and 4) should be connected to the same wide PCB trace; and GND should be connected to a ground plane. For best performance, input capacitors (CMAIN, CAUX) and output capacitor (COUT) should be placed as close to the package pins as possible. The AAT4672 evaluation board layout follows the printed circuit board layout recommendations and can be used as an example of an optimal board layout.
TSD(MIN) is the minimum temperature required to activate the AAT4672 over-temperature protection (thermal shutdown). With typical specification of 140°C, 125°C is a safe minimum value to use. For example, for a 2.5V input power supply application that is specified to operate in 50°C environments where the PCB operates at temperatures as high as 85°C. The application is sealed and its PCB is small, causing RθJA to be approximately 160°C/W. The RDS(ON)(MAX) is estimated to be 300mΩ (from the “RDS(ON) vs. Temperature” performance graph, where VIN = 2.5V at 85°C plus 50%). To find the maximum current (IMAX) for this application, use Equation 2:
IMAX =
125°C - 85°C 300mΩ · 160°C/W = 0.913A
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
C3 4.7µF IMAIN
SmartSwitchTM
Evaluation Board Schematic
Power Supply Selector Switch
C1 4.7µF
MAIN AUX J1 C2 4.7µF
2 1
U1
1 2 3 4 5 6
MAIN MAIN AUX AUX EN GND AAT4672
OUT OUT IMAIN IAUX SELECT GND
12 11 10 9 8 7
OUT
IAUX
EN R1 100K GND PWRSEL
R3 49.9K
Header 2
R2 49.9K
Figure 1: AAT4672 Evaluation Board Schematic.
Evaluation Board Layout
Figure 2: AAT4672 Evaluation Board Top Side Layout.
Figure 3: AAT4672 Evaluation Board Bottom Side Layout.
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Ordering Information
Package
TSOPJW-12
Power Supply Selector Switch
Marking1
ZWXYY
Part Number (Tape and Reel)2
AAT4672ITP-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/about/quality.aspx.
Package Information
TSOPJW-12
0.20 + 0.10 - 0.05
2.40 ± 0.10
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
2.85 ± 0.20
7° NOM 3.00 ± 0.10
0.9625 ± 0.0375 + 0.10 1.00 - 0.065
0.04 REF
0.15 ± 0.05
0.055 ± 0.045
4° ± 4°
0.010
0.45 ± 0.15 2.75 ± 0.25
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. 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.
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
General Description
The AAT4672 SmartSwitch™ is a member of AnalogicTech’s Application Specific Power Management IC™ family. This device is a dual input, single output power supply selector switch, designed to operate from USB ports, AC adapter inputs, batteries, or any other power supply with an input voltage up to 6V. The AAT4672 connects the supply on the MAIN pin to the OUT pin through a very low on-resistance power MOSFET when the device is enabled, the MAIN pin voltage is higher than the under voltage lockout (UVLO) threshold, and MAIN pin voltage is greater than the AUX pin voltage plus 200mV. The AUX pin connects to the OUT pin only when the MAIN pin voltage drops 0.2V below the AUX pin voltage and the AUX pin voltage is greater than the UVLO threshold. If both input supplies (MAIN/AUX) are below the UVLO threshold, then the OUT pin floats. The two internal power switches are current limited and the thresholds can be programmed through resistors on the IMAIN and IAUX pins respectively. A power level selection pin, PWRSEL, is provided to toggle the AUX current limit between 100% and 20% of the current limit setting programmed by the resistor on the IAUX pin. This is particularly useful for USB applications where the power supply can be powered by either a 500mA or a 100mA USB port. The AAT4672 is available in a thermally enhanced, space-saving, Pb-free 12-pin TSOPJW package and is specified for operation over the -40°C to +85°C temperature range.
Power Supply Selector Switch
Features
• Input Voltage Supply Range: 2.5V to 6V • High Level of Integration: ▪ Reverse Blocking Diode ▪ Current Sensing ▪ Programmable Current Limiting ▪ Automatic Power Supply Switching • Break-Before-Make Switch-Over ▪ Minimum Output Voltage Drop During Change-Over • Shutdown Current < 1µA • Thermal Protection • TSOPJW-12 Package
Applications
• • • • • Bluetooth™ Headsets Cell Phones Digital Still Cameras MP3 Players Personal Data Assistants (PDAs)
Typical Application
AC Adapter USB Port USB H/L select
MAIN OUT AUX IMAIN PWRSEL IAUX RIAUX RIMAIN System Load
Enable
EN GND
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Pin Descriptions
Pin Number
1, 2 3, 4 5 6, 7 8 9 10 11, 12
Power Supply Selector Switch
Name
MAIN AUX EN GND PWRSEL IAUX IMAIN OUT
Type
I I I I/O I I I O
Function
Power supply 1 input. Power supply 2 input. Enable pin, active low. Ground. Power level select input for AUX-OUT switch. Logic “0”: 20% of the current limit programmed by RIAUX Logic “1”: 100% of the current limit programmed by RIAUX AUX-OUT switch current limit set input. MAIN-OUT switch current limit set input. Output pin.
Pin Configuration
TSOPJW-12 (Top View)
MAIN MAIN AUX AUX EN GND
1 2 3 4 5 6
12 11 10 9 8 7
OUT OUT IMAIN IAUX PWRSEL GND
2
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Absolute Maximum Ratings1
Symbol
VN VX TLEAD IOUT
Power Supply Selector Switch
Description
[MAIN, AUX] to GND [OUT, EN, IMAIN, IAUX, PWRSEL] to GND Maximum Soldering Temperature (at Leads) Maximum Output Current
Value
-0.3 to 6.5 -0.3 to VN + 0.3 300 3
Units
V V °C A
Thermal Information2
Symbol
θJA PD TJ
Description
Maximum Thermal Resistance Maximum Power Dissipation Operating Junction Temperature Range
Value
160 625 -40 to 150
Units
°C/W mW °C
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. Mounted on a FR4 board.
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Electrical Characteristics1
Power Supply Selector Switch
VMAIN/AUX = 5V, TA = -40 to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Symbol
Operation VMAIN VAUX VMAIN-AUX VUVLO_MAIN VUVLO_AUX
Description
MAIN Operating Voltage Range AUX Operating Voltage Range MAIN Switch-Over Threshold (Input Voltage Difference) MAIN Under-Voltage Lockout AUX Under-Voltage Lockout
Conditions
Min
2.5 2.5 VAUX + 0.15
Typ
Max
6 6 VAUX +0.25 2.3 2.3
Units
V V V V V µA µA µA µA µA µA Ω Ω mV
MAIN, AUX > 2.5V Rising edge Hysteresis Rising edge Hysteresis VMAIN = 5V, VEN = 0V VMAIN = VEN = 5V, OUT open VMAIN = 2.5V, VAUX = 5V, VEN = 0V VAUX = 5V, VEN = 0V VAUX = VEN = 5V, OUT open VMAIN = 5V, VAUX = 2.5V, VEN = 0V VMAIN = 5.0V VMAIN = 3.5V VAUX = 5.0V VAUX = 3.5V IO(OUT) = 0.5A, CO(OUT) = 10µF
VAUX + 0.2 0.1 0.1 10 1 10 1 0.12 0.14 0.12 0.14 150
IMAIN_OP MAIN Normal Operating Current IMAIN_SHDN MAIN Shutdown Mode Current IMAIN_SLP MAIN Sleep Current AUX Normal Operating Current IAUX_OP IAUX_SHDN AUX Shutdown Mode Current IAUX_SLP AUX Sleep Current Power Switches RDS(ON) MAIN RDS(ON) AUX MAIN-to-OUT FET On-Resistance AUX-to-OUT FET On-Resistance
30 1 5 30 1 5
OUT Voltage Droop from the Lower Voltage of MAIN and AUX, When Switching Over Between MAIN and AUX Current Regulation tSOFT_START Soft-Start Delay ILIM_MAIN_range MAIN Current Limit Range VDROOP_OUT ILIM_AUX_range ILIM_MAIN ILIM_AUX AUX Current Limit Range MAIN Current Limit Accuracy AUX Current Limit Accuracy
Delay of start from EN , or UVLO PWRSEL = 5V PWRSEL = 0V RIAUX = 100kΩ RIMAIN = 100kΩ PWRSEL = 5V PWRSEL = 0V 0.2 0.2 0.04 0.8 0.8 0.18 1.6
100 2.0 2.0 0.4 1.2 1.2 0.22
µs A A A A V V °C
1 1 0.2
Logic Control / Protection VIH(EN) Logic High Threshold VIL(EN) Logic Low Threshold TSHDN Chip Thermal Shutdown Temperature Threshold Hysteresis
0.4 140 15
1. The output charge voltage accuracy is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C temperature range is guaranteed by design.
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
IMAIN Shutdown Current vs. Temperature
IMAIN Shutdown Current (µA) IAUX Shutdown Current (µA)
0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40
Power Supply Selector Switch
IAUX Shutdown Current vs. Temperature
VAUX = 6.5V VAUX = 5V
VMAIN = 6.5V VMAIN = 5V VMAIN = 3.6V VMAIN = 4.2V
-15 10 35 60 85
VAUX = 3.6V VAUX = 4.2V
-15 10 35 60 85
Temperature (°C)
Temperature (°C)
IMAIN Operation Current vs. Temperature
(IOUT = 0A) IMAIN Operation Current (µA) IAUX Operation Current (µA)
20 18 16 14 12 10 8 6 4 -40 -15 10 35 60 85 20 18 16 14 12 10 8 6 4
IAUX Operation Current vs. Temperature
(IOUT = 0A) VAUX = 6.5V VAUX = 5V
VMAIN = 6.5V VMAIN = 5V VMAIN = 4.2V VMAIN = 3.6V
VAUX = 3.6V
VAUX = 4.2V
-40
-15
10
35
60
85
Temperature (°C)
Temperature (°C)
RDS(ON) vs. Temperature
250 200 1.1
Enable Threshold vs. Input Voltage
Enable Threshold (V)
VMAIN/AUX = 3.5V VMAIN/AUX = 2.5V
1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 2.5 3 3.5 4 4.5 5 5.5 6 6.5
RDS(ON) (mΩ)
VIH(EN)
150 100 50 0
VMAIN/AUX = 5V
VMAIN/AUX = 6.5V
VIL(EN)
-40
-15
10
35
60
85
110
Temperature (°C)
Input Voltage (V)
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
IMAIN Sleep Current vs. VMAIN Voltage
(VAUX = 6.5V)
2.5 2.5
Power Supply Selector Switch
IAUX Sleep Current vs. VAUX Voltage
(VMAIN = 6.5V) IAUX Sleep Current (µA)
IMAIN Sleep Current (µA)
2 1.5 1 0.5 0 2.5 3 3.5 4
85°C 25°C -40°C
2 1.5 1 0.5 0 2.5 3 3.5 4
85°C 25°C
-40°C
4.5
5
5.5
6
4.5
5
5.5
6
VMAIN Voltage (V)
VAUX Voltage (V)
Current Limit vs. RIMAIN/IAUX
(VMAIN = 5V; VAUX = 3.3V; VOUT = VMAIN or VOUT = VAUX)
2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 50 100 150 200 250 300 350 400 450 500 2V
Turn-On/Off Response
(ROUT = 10Ω; VMAIN = 5V)
Current Limit (A)
VEN (2V/div)
0V
VOUT (5V/div) IOUT (500mA/div) RIMAIN/IAUX (kΩ)
0V
0A
Time (100µs/div)
Short Circuit Through 0.3Ω Response
VIN (2V/div)
Short Circuit Through 0.6Ω Response
VIN (2V/div)
5V
5V
IOUT (5A/div) VOUT (5V/div)
0A
2A
IOUT (5A/div) VOUT (5V/div)
0A
2A
5V
0.6V
5V
1.2V
Time (10µs/div)
Time (10µs/div)
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Typical Characteristics
Thermal Shutdown Response
(VMAIN = 5V)
2V 0V
Power Supply Selector Switch
VEN (2V/div)
VOUT (2V/div) IOUT (2A/div)
0V
0A
Time (40ms/div)
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Functional Block Diagram
Switch 1
Power Supply Selector Switch
MAIN
OUT
IMAIN
Thermal and Current Sense Logic Control
PWRSEL IAUX
EN
AUX
Switch 2
GND
Truth Table
Y = Yes, N = No, X = don’t care.
Input Conditions VMAIN > UVLO
N Y N Y Y
AAT4672 VMAIN > VAUX + 0.2V
X X X Y N
VAUX > UVLO
N N Y Y Y
VOUT
Floating VMAIN VAUX VMAIN VAUX
Functional Description
To power the OUT pin, at least one of the two input supplies (MAIN/AUX) must be greater than the UVLO threshold. If only one supply is greater than the UVLO threshold, the load will be connected to that particular supply when the device is enabled. If both supplies are above the UVLO threshold, the AAT4672 will connect the supply from the MAIN pin to the OUT pin when the device is enabled and the MAIN voltage is greater than the AUX voltage plus 0.2V (typical); otherwise, the AAT4672 will connect the supply from the AUX pin to the OUT pin. The two internal power switches are current limited; the current limits are programmed by the resistors on the IMAIN and IAUX pins respectively.
Applications Information
Input Capacitors
A 1µF or greater capacitor is generally recommended between MAIN and GND (CMAIN), and between AUX and GND (CAUX). An input capacitor is not required for basic operation; however, it is useful in preventing load transients from affecting up-stream circuits. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CMAIN/CAUX. There is no specific capacitor equivalent series resistance (ESR) requirement for CMAIN/CAUX. However, for higher current operation, ceramic capacitors are recommended for CMAIN/CAUX due to their inherent capability over tantalum capacitors to withstand
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
input current surges from low impedance sources such as batteries in portable devices.
Power Supply Selector Switch
For MAIN (power supply 1 input):
Output Capacitor
A 1µF or greater capacitor is required between OUT and GND (COUT). As with the input capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased to accommodate any load transient condition.
⎛ VIMAIN ⎞ RIMAIN = ⎝ I ⎠ · 200k
CLMAIN
⎛0.5V⎞ = ⎝ 2A ⎠ · 200k = 50kΩ (49.9kΩ standard value)
For AUX (power supply 2 input):
EN Input
The AAT4672 is enabled when VEN is ≤ 0.4V (logic ‘0’); conversely, the AAT4672 is disabled when VEN is ≥ 1.6V (logic ‘1’).
⎛ VIAUX ⎞ RIAUX = ⎝ I ⎠ · 200k
CLAUX
PWRSEL Input
When VPWRSEL is ≤ 0.4V (logic ‘0’) the AUX-OUT current limit is 20% of the current limit value programmed by RIAUX; when VPWRSEL is ≥ 1.6V (logic ‘1’), the AUX-OUT current limit is 100% of the current limit value programmed by RIAUX.
⎛0.5V⎞ = ⎝0.2A⎠ · 200k = 500kΩ (499.9kΩ standard value)
Thermal Considerations
Since the AAT4672 has an internal current limit and overtemperature protection(thermal shutdown), junction temperature is rarely a concern. However, if the application requires large currents in a high temperature 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 (Eq. 1). Eq. 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 AAT4672 at high temperatures (consult the “RDSON vs. Temperature” performance graph in the “Typical Characteristics” section of this datasheet). For estimating the RDS(ON)(MAX) use the data on the “RDSON vs Temperature” performance graph and increase the value from the performance graph by 50%. RθJA is the thermal resistance between the AAT4672 die and the printed circuit board (PCB) onto which it is mounted; RθJA is the thermal resistance of the TSOPJW-12 package. TA(MAX) is the maximum ambient temperature that the PCB under the AAT4672 would be if the AAT4672 were not dissipating power. Equation 1 can be rearranged to solve for IMAX, into Equation 2 (Eq. 2).
Current Limit Resistor Selection
The current limits for power supply 1 and power supply 2 inputs are set by resistors between IMAIN/IAUX and GND. The following equation can be used to select the appropriate resistor for a particular current limit:
⎛ VIMAIN/IAUX ⎞ ICLMAIN/AUX = ⎝ R · 200k IMAIN/IAUX ⎠
ICLIMAIN/AUX Current limit for MAIN and/or AUX pins respectively VIMAIN/IAUX Internally Regulated Voltage [0.5V ± 20%] on the IMAIN and IAUX pins respectively RIMAIN/IAUX IMAIN and/or IAUX Resistor 200k Internal Gain Factor
Design Example
A particular application requires that the current limit for MAIN be set to 2A and the current limit for AUX be set to 0.2A. What value of resistor is required for the IMAIN and IAUX pins respectively?
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Eq. 2: IMAX =
Power Supply Selector Switch
TSD(MIN) - TA(MAX) RDS(ON)(MAX) · RΘJA
PCB Layout Recommendations
For proper thermal management, to minimize PCB trace resistance, and to take advantage of the low RDS(ON) values of the two internal power switches in the AAT4672, certain circuit board layout rules should be followed: MAIN, AUX, and OUT should be routed using wider than normal traces. The two MAIN pins (1 and 2) and two AUX pins (3 and 4) should be connected to the same wide PCB trace; and GND should be connected to a ground plane. For best performance, input capacitors (CMAIN, CAUX) and output capacitor (COUT) should be placed as close to the package pins as possible. The AAT4672 evaluation board layout follows the printed circuit board layout recommendations and can be used as an example of an optimal board layout.
TSD(MIN) is the minimum temperature required to activate the AAT4672 over-temperature protection (thermal shutdown). With typical specification of 140°C, 125°C is a safe minimum value to use. For example, for a 2.5V input power supply application that is specified to operate in 50°C environments where the PCB operates at temperatures as high as 85°C. The application is sealed and its PCB is small, causing RθJA to be approximately 160°C/W. The RDS(ON)(MAX) is estimated to be 300mΩ (from the “RDS(ON) vs. Temperature” performance graph, where VIN = 2.5V at 85°C plus 50%). To find the maximum current (IMAX) for this application, use Equation 2:
IMAX =
125°C - 85°C 300mΩ · 160°C/W = 0.913A
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672 AAT4672
C3 4.7µF IMAIN
SmartSwitchTM
Evaluation Board Schematic
Power Supply Selector Switch
C1 4.7µF
MAIN AUX J1 C2 4.7µF
2 1
U1
1 2 3 4 5 6
MAIN MAIN AUX AUX EN GND AAT4672
OUT OUT IMAIN IAUX SELECT GND
12 11 10 9 8 7
OUT
IAUX
EN R1 100K GND PWRSEL
R3 49.9K
Header 2
R2 49.9K
Figure 1: AAT4672 Evaluation Board Schematic.
Evaluation Board Layout
Figure 2: AAT4672 Evaluation Board Top Side Layout.
Figure 3: AAT4672 Evaluation Board Bottom Side Layout.
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PRODUCT DATASHEET
AAT4672 AAT4672
SmartSwitchTM
Ordering Information
Package
TSOPJW-12
Power Supply Selector Switch
Marking1
ZWXYY
Part Number (Tape and Reel)2
AAT4672ITP-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/about/quality.aspx.
Package Information
TSOPJW-12
0.20 + 0.10 - 0.05
2.40 ± 0.10
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
2.85 ± 0.20
7° NOM 3.00 ± 0.10
0.9625 ± 0.0375 + 0.10 1.00 - 0.065
0.04 REF
0.15 ± 0.05
0.055 ± 0.045
4° ± 4°
0.010
0.45 ± 0.15 2.75 ± 0.25
All dimensions in millimeters.
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. 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.
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