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5V/3V PC Card Power Switch General Description
The AAT4650 SmartSwitch is a single channel PC card (PCMCIA) power switch. It is used to select between two different voltage inputs, each between 2.7V and 5.5V. An internal switch powers the circuitry from whichever input voltage is higher. The device's output, VCC, is slew rate controlled and current limited, in compliance with PC card specifications. The current limit response time to a short circuit is typically 1s. The internal P-channel MOSFET switches are configured to break before make; that is, both switches cannot be closed at the same time. Controlled by a 2-bit parallel interface, the four states for VCC are VCC5, VCC3, high impedance, or ground. When in the ground state, VCC is pulled to ground by a 5k resistor. An open drain FAULT output is asserted during over-current conditions. During power-up slewing, FAULT also signals that VCC is out of tolerance. An internal over-temperature sensor forces VCC to a high impedance state when an overtemperature condition exists. Quiescent current is typically a low 15A, as long as ICC is less than approximately 500mA. Above this load current, the quiescent current increases to 200A. The AAT4650 is available in a Pb-free, 8-pin SOP or TSSOP package and is specified over the -40C to +85C temperature range.
AAT4650
Features
* * * * * * * * *
SmartSwitchTM
2.7V to 5.5V Input Voltage Range 80m (5V) Typical RDS(ON) Low Quiescent Current 15A (typ) Reverse-Blocking Switches Short-Circuit Protection Over-Temperature Protection FAULT Flag Output Temperature Range: -40C to +85C 8-Pin SOP or TSSOP Package
Applications
* * * Notebook Computer PDA, Subnotebook Power Supply Multiplexer Circuit
Typical Application
VCC5 VCC3 CTL1 CTL0 FAULT
CIN5 1F CIN3 1F
8 5 3 2 4 1
VCC5 VCC3 CTL1 AAT4650 VCC CTL0 FAULT GND
6,7
V CC
COUT 0.1F
GND
GND
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1
5V/3V PC Card Power Switch Pin Descriptions
Pin #
1 2 3 4 5 6, 7 8
AAT4650
Symbol
GND CTL0 CTL1 FAULT VCC3 VCC VCC5
Function
Ground connection. Control input (see Control Logic Table below). Control input (see Control Logic Table below). Open drain output; signals over-current condition. 3V supply. Output (see Control Logic Table below). 5V supply.
Pin Configuration
SOP-8 / TSSOP-8 (Top View)
GND CTL0 CTL1 FAULT
1 2
8 7
3 4
6 5
VCC5 VCC VCC VCC3
1 2
Control Logic Table
CTL1
0 0 1 1
CTL0
0 1 0 1
Function
OFF 5V 3V HiZ
Result
5k VCC to GND VCC = VCC5 VCC = VCC3 Both FETs OFF
2
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5V/3V PC Card Power Switch Absolute Maximum Ratings1
TA = 25C, unless otherwise noted. Symbol
VCC3, VCC5 VCC IMAX TJ TLEAD VESD
AAT4650
Description
IN to GND OUT to GND Maximum Continuous Switch Current Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) ESD Rating2 -- HBM
Value
-0.3 to 6 -0.3 to 6 Current Limited -40 to 150 300 4000
Units
V V A C C V
Thermal Characteristics3
Symbol
JA PD
Description
Thermal Resistance Power Dissipation SOP-8 TSSOP-8 SOP-8 TSSOP-8
Value
120 150 1.0 833
Units
C/W W mW
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 an FR4 board. 4650.2006.05.1.2
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5V/3V PC Card Power Switch Electrical Characteristics
VIN = 5V, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = 25C; bold values designate full temperature range. Symbol
VCC Output ICC Hi-Z Iccsc RDS(ON) Tcrds High Impedance Output Leakage Current Short-Circuit Current Limit On Resistance Off Mode, VCC = 0V VCC = VCCIN -0.5V, On Mode VCC3 or VCC5 Selected, TA = 25C VCC = 3.0V, TA = 25C VCC = 5.0V, TA = 25C 1.0 85 80 2800 VCC VCC VCC VCC VCC VCC VCC VCC VCC VCC = = = = = = = = = = 0V to 10% of 3.3V, ROUT = 10 0V to 10% of 5.0V, ROUT = 10 10% to 90% of 3.3V, RLOAD = 10 10% to 90% of 5.0V, RLOAD = 10 3.3V to 90% of 3.3V, RLOAD = 10 5.0V to 90% of 5.0V, RLOAD = 10 90% to 10% of 3.3V, RLOAD = 10 90% to 10% of 5.0V, RLOAD = 10 90% to 10% of 3.3V, RLOAD = 10 90% to 10% of 5.0V, RLOAD = 10 500 500 1000 1000 2000 1500 3000 3000 400 400 200 200 1500 2000 5.5 5.5 1 5 10 10 15 20 1 40 40 40 0.8 VCC3 or VCC5 = 2.7V to 3.6V VCC3 or VCC5 = 4.5V to 5.5V VCTL = 5.5V ISINK = 1mA VFAULT = 5.5V 0.05 125 2.0 2.4 0.01 1 0.4 1 1 2.5 110 100 A A m ppm/C
AAT4650
Description
Conditions
Min
Typ
Max
Units
Switch Resistance Temperature Coefficient VCC Switching Time (Refer to Figure 1) t1 Output Turn-On Delay Time t2 Output Turn-On Delay Time t3 Output Rise Time t4 Output Rise Time t5 Output Turn-Off Delay Time t6 Output Turn-Off Delay Time t7 Output Fall Time to Off State t8 Output Fall Time to Off State t9 Output Fall Time to HiZ State t10 Output Fall Time to HiZ State Power Supply VCC3 VCC3 Operation Voltage VCC5 VCC5 Operation Voltage ICC3 VCC3 Supply Current
300 300
s
2.7 2.7 VCC = 5V or HiZ or Off, VCC3 < VCC5, ICC Out = 0 VCC = 3.3V, VCC3 < VCC5, ICC Out = 0 VCC = Off, VCC5 > VCC3, ICC Out = 0 VCC = HiZ, VCC5 > VCC3, ICC Out = 0 VCC = 3.3V, VCC5 > VCC3, ICC Out = 0 VCC = 5V, VCC5 > VCC3, ICC Out = 0
V V A
ICC5
VCC5 Supply Current
A
Parallel Interface VCTLLOW CTL Input Low Voltage VCTLHI ISINKCTL VFAULTLOW ISINKFAULT Other OTMP CTL Input High Voltage CTL Input Leakage FAULT Logic Output Low Voltage FAULT Logic Output High Leakage Current Over-Temperature Shutdown
V V A V A C
4
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5V/3V PC Card Power Switch Typical Characteristics
Unless otherwise noted, TA = 25C.
Quiescent Current vs. Temperature
(ICC5)
30
2
AAT4650
Current Limit
(VCC = VCC3)
Quiescent Current (A)
25 20 15 10
VCC3 = 3V CTL0 = 5V VCC5 = 5V CTL1 = 0V
1.5
1
0.5
5 0 -40 -20 0 20 40 60 80 100 120
0 0 0.5 1 1.5 2 2.5 3
Temperature (C)
Output Voltage (V)
Current Limit
(VCC = VCC5)
Off-Switch Current vs. Temperature
(ICC3)
Off-Switch Current (A)
2
1.0000 0.1000 0.0100 0.0010 0.0001 0.0000 -40 -20 0 20 40 60 80 100 120
1.5
VCC3 = 3V VCC5 = 5V
CTL1 = 0V CTL0 = 0V
1
0.5
0 0 1 2 3 4 5 6
Output Voltage (V)
Temperature (C)
Off-Switch Current vs. Temperature
(ICC5)
RDS(ON) vs. Temperature
120.0
Off-Switch Current (A)
1.0000 0.1000 0.0100 0.0010 0.0001 0.0000
-40
RDS(ON) (m)
VCC5 = 5V CTL1 = 0V VCC3 = 3V CTL0 = 0V
110.0 100.0 90.0 80.0 70.0 60.0
VCC = VCC3 = 3.0V VCC = VCC5 = 5.0V
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (C)
Temperature (C)
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5V/3V PC Card Power Switch Typical Characteristics
Unless otherwise noted, TA = 25C.
AAT4650
Turn-On/Off Response
(10, 1F Load)
Turn-On/Off Response
(15, 1F Load)
CTL1 (5V/div)
FAULT (5V/div)
CTL0 (5V/div) FAULT (5V/div) VCC (2V/div) IVCC5 (200mA/div)
Time (500s/div)
VCC (2V/div) IVCC3 (200mA/div)
Time (500s/div)
Thermal Shutdown Response
CTL1 (5V/div) FAULT (5V/div)
8
Short Circuit Through 0.3
11
Input and Output (V)
6
Input Voltage
8
Output (A)
4
5
VCC (1V/div)
Output Current
2 2
Output Voltage
0 -2 0 2 4 6 8 10 -1
IVCC5 (500mA/div)
Time (100ms/div)
Time (s)
Short Circuit Through 0.6
8 9
Input and Output (V)
6
Input Voltage Output Current Output Voltage
6
Output (A)
4
3
2
0
0 -2 0 2 4 6 8 10
-3
Time (s)
6
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5V/3V PC Card Power Switch Functional Block Diagram
VCC3 VCC5
AAT4650
Body Control
VCC
OverCurrent
OverCurrent
OverTemperature
Slew Rate
Slew Rate
5k FAULT
CTL1 CTL0
Control Logic
GND
Functional Description
The AAT4650 is a single channel power switch that can be used in any application where dual power supply multiplexing is required. Typical applications include PC card applications not requiring a 12V power supply, or applications where power is switched, for example, between 5V for operation and 3.3V for standby mode. The AAT4650 operates with input voltages ranging from 2.7V to 5.5V in any combination and automatically powers its internal circuitry off of whichever input voltage is higher. Two identical low RDS(ON) P-channel MOSFETs serve as the power multiplexing circuit with a common drain as the VCC output and independent sources as the two VCC3 and VCC5 inputs. A 2-bit parallel interface determines the state of the multiplexer: VCC = VCC3, VCC = VCC5, VCC with resistive pull down to ground, or VCC high impedance. When the state is set to either of the two inputs, the multiplexing circuit will
slowly slew the VCC output to the new voltage level which protects the upstream power supply from sudden load transients. When the resistive pull down is chosen for VCC, the VCC output is quickly discharged by the resistive pull down. The AAT4650 always serves as an electronic fuse by limiting the load current if it exceeds the current limit threshold. During power-up into a short, the current will gradually increase until the current limit is reached. During a sudden short circuit on the output, the current limit will respond in 1s to isolate and protect the upstream power supply from the load short circuit. In most applications, because the response time is so fast, a short circuit to VCC will not affect the upstream supply, so system functionality will not be affected. In the case of an over-current condition, an open drain FAULT flag output will signal the event. The FAULT output is also active during output voltage slew, and becomes inactive once the output is within regulation.
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5V/3V PC Card Power Switch Applications Information
Input Capacitor
A 1F or larger capacitor is typically recommended for CIN. A CIN capacitor is not required for basic operation; however, it is useful in preventing load transients from affecting up-stream circuits. 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.
AAT4650
Voltage Regulation
The PC card specification calls for a regulated 5V supply tolerance of 5%. Of this, a typical power supply will drop less than 2% and the PCB traces will drop another 1%. This leaves 2% for the AAT4650 as the PC card switch. In the PC card application, the maximum allowable current for the AAT4650 is dominated by voltage regulation, rather than by thermal considerations, and is set by either the current limit or the maximum RDS(ON) of the Pchannel MOSFET. The maximum RDS(ON) at 85C is calculated by applying the RDS temperature coefficient to the maximum room temperature RDS(ON):
RDS(ON)(MAX) = RDS(ON)25 (1 + [TC T])
Output Capacitor
A 0.1F or greater capacitor is generally required between VCC and GND. Likewise, with the output capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased to accommodate any load transient condition.
-or-
RDS(ON)(MAX) = 100m (1 + [0.0028 60]) = 116.8m
Parallel Interface / Break Before Make
A 2-bit parallel interface determines the state of the VCC output. The logic levels are compatible with CMOS or TTL logic. A logic low value must be less than 0.8V, and a logic high value must be greater than 2.4V. In cases where the interface pins rapidly change state directly from 3V to 5V (or vice versa), internal break-before-make circuitry prevents any back flow of current from one input power supply to the other. In addition, the body connections of the internal P-channel MOSFET switches are always set to the highest potential of VCC3, VCC5, or VCC, which prevents any body diode conduction, power supply backflow, or possible device damage.
The maximum current is equal to the 2% tolerance of the 5V supply (100mV) across the AAT4650 divided by RDS(ON)(MAX). Or:
IMAX5 =
100mV = 856.2mA 116.8m
For the 3.3V supply in the PC card application, the conditions are a bit relaxed, with the allowable voltage regulation drop equal to 300mV. With a 2% supply and 1% PCB trace regulation, the PC card switch can have a 200mV drop. So:
IMAX3 =
200mV = 1.5A 134m
FAULT Output
The FAULT output is pulled to ground by an open drain N-channel MOSFET during an over-current or output slew condition. It should be pulled up to the reference power supply of the controller IC via a nominal 100k resistor. Since 1.5A is the nominal current limit value, the AAT4650 will current limit before IMAX3 is reached.
8
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5V/3V PC Card Power Switch
Thermal issues are not a problem in the SOP-8 package since JA, the package thermal resistance, is only 120C/W. At any given ambient temperature (TA) the maximum package power dissipation can be determined by the following equation:
TJ(MAX) -TA JA
AAT4650
PD(MAX) =
Constants for the AAT4650 are maximum junction temperature, TJ(MAX) = 125C, and package thermal resistance, JA = 120C/W. Worst case conditions are calculated at the maximum operating temperature where TA = 85C. Typical conditions are calculated under normal ambient conditions where TA = 25C. At TA = 85C, PD(MAX) = 333mW. At TA = 25C, PD(MAX) = 833mW. Maximum current is given by the following equation:
over-current threshold. This results in a voltage drop across the AAT4650 which causes excess power dissipation and a package temperature increase. As the die begins to heat up, the over-temperature circuit is activated. If the temperature reaches the maximum level, the AAT4650 automatically switches off the P-channel MOSFETs. While they are off, the over-temperature circuit remains active. Once the temperature has cooled by approximately 10C, the P-channel MOSFETs are switched back on. In this manner, the AAT4650 is thermally cycled on and off until the short circuit is removed. Once the short is removed, normal operation automatically resumes. To save power, the full high-speed over-current circuit is not activated until a lower threshold of current (approximately 500mA) is exceeded in the power device. When the load current exceeds this crude threshold, the AAT4650 quiescent current increases from 15A to 200A. The high-speed over-current circuit works by linearly limiting the current when the current limit is reached. As the voltage begins to drop on VCC due to current limiting, the current limit magnitude varies and generally decreases as the VCC voltage drops to 0V.
IOUT(MAX) =
PD(MAX) RDS(ON)
For the AAT4650 at 85C, IOUT(MAX) = 1.65A, a value greater than the internal minimum current limit specification.
Switching VCC Voltage
The AAT4650 meets PC card standards for switching the VCC output by providing a ground path for VCC, as well as a high impedance state. The PC card protocol for determining low voltage operations is to first power the peripheral with 5V and poll for 3.3V operation. When transitioning from 5V to 3.3V, VCC must be discharged to less than 0.8V to provide a hard reset. The resistive ground state (CTL1 = 0, CTL0 = 0) will accommodate this. The ground state will also guarantee the VCC voltage to be discharged within the specified amount of time (100ms).
Over-Current and Over-Temperature Protection
Because many AAT4650 applications provide power to external devices, it is designed to protect its host device from malfunctions in those peripherals through slew rate control, current limiting, and thermal limiting. The AAT4650 current limit and thermal limit serve as an immediate and reliable electronic fuse without any increase in RDS(ON) for this function. Other solutions, such as a poly fuse, do not protect the host power supply and system from mishandling or short circuiting peripherals; they will only prevent a fire. The AAT4650 high-speed current limit and thermal limit not only prevent fires, they also isolate the power supply and entire system from any activity at the external port and report a mishap by means of a FAULT signal. Over-current and over-temperature go hand in hand. Once an over-current condition exists, the current supplied to the load by the AAT4650 is limited to the
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Printed Circuit Board Layout Recommendations
For proper thermal management, to minimize PCB trace resistance, and to take advantage of the low RDS(ON) of the AAT4650, a few circuit board layout rules should be followed: VCC3, VCC5, and VCC should be routed using wider than normal traces; the two VCC pins (Pins 6 and 7) should be connected to the same wide PCB trace; and GND should be connected to a ground plane. For best performance, CIN and COUT should be placed close to the package pins. 9
5V/3V PC Card Power Switch Timing Diagram
5 0 5 Vcc t1, t2 t3, t4 t5, t6 t7, t8 t9, t10 CTL0,1
AAT4650
0
Figure 1: VCC Switching Time Diagram.
Refer to VCC Switching Time specifications in the Electrical Characteristics section for definitions of t1 to t10.
Typical PC Card Application Circuit
Power 5V Supply 3.3V
CIN5 1F
100k
8 5 3
PC Card Controller
VCC
CIN3 1F
2 4 1
VCC5 VCC3 CTL1 AAT4650 VCC CTL0 FAULT GND
6,7
PC Card Slot
VCC COUT 0.1F
FAULT CTL1 CTL0
10
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5V/3V PC Card Power Switch Evaluation Board Layout
The AAT4650 evaluation board layout follows the printed circuit board layout recommendations and can be used for good applications layout. Note: Board layout shown is not to scale.
AAT4650
Figure 2: Evaluation Board Top Side Silk Screen Layout / Assembly Drawing.
Figure 3: Evaluation Board Component Side Layout.
Figure 4: Evaluation Board Solder Side Layout.
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5V/3V PC Card Power Switch Ordering Information
Package
SOP-8 TSSOP-8
AAT4650
Marking
4650 4650
Part Number (Tape and Reel)1
AAT4650IAS-T1 AAT4650IHS-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. Sample stock is generally held on all part numbers listed in BOLD.
12
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5V/3V PC Card Power Switch
TSSOP-8
AAT4650
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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5V/3V PC Card Power Switch
AAT4650
(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 14
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