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AAT4252A
Dual Slew Rate Controlled Load Switch General Description
The AAT4252A SmartSwitchTM is a dual P-channel MOSFET power switch designed for high-side loadswitching applications. Each MOSFET has a typical RDS(ON) of 105m, allowing increased load switch current handling capacity with a low forward voltage drop. The device is available in three different versions with flexible turn-on and turn-off characteristics-from very fast to slew-rate limited. The standard 4252A (-1) version has a slew-rate limited turn-on load switch. The AAT4252A (-2) version features a fast turn-on capabilities, typically less than 500ns turn-on and 3s turn-off times. The AAT4252A (-3) variation offers a shutdown load discharge circuit to rapidly turn-off a load circuit when the switch is disabled. An additional feature is a slew-rate selector pin which can switch between fast and slow slew rate. All the AAT4252A load switch versions are designed to operate from 1.5V up to 6.5V, making then ideal for both 3V and 5V systems. Input logic levels are TTL and 2.5V to 5V CMOS compatible. The quiescent supply current is a very low 500nA. The AAT4252A is available in the Pb-free TSOPJW12 package and is specified over the -40C to +85C temperature range.
Features
* *
SmartSwitchTM
*
* * * * *
VIN Range: 1.5V to 6.5V Low RDS(ON) -- 87m Typical @ 5V -- 196m Typical @ 1.5V Slew Rate Turn-On Time Options -- 1ms -- 0.5s -- 100s Fast Shutdown Load Discharge Option Low Quiescent Current -- Typically 500nA TTL/CMOS Input Logic Level Temperature Range: -40C to +85C Available in TSOPJW-12 package
Applications
* * * * * * * Cellular Telephones Digital Still Cameras Notebook Computers PDA Phones PDAs PMPs Smartphones
Typical Application
INA
2
INA
OUTA
12
OUTA
INB
ON/OFF
5
INB
OUTB
7
OUTB
3
ENA
AAT4252A
C3 0.1F
C4 0.1F
C1 1F
C2 1F
ON/OFF
4
ENB FAST GND
8,9,10,11 6
FAST/SLOW
1
N/C
4252A.2007.06.1.0
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AAT4252A
Dual Slew Rate Controlled Load Switch Pin Descriptions
Pin #
1 2 3 4 5 6 7 8, 9, 10, 11 12
Symbol
FAST INA ENA ENB INB N/C OUTB GND OUTA
Function
Active-high input switches between FAST (Logic H) and SLOW (Logic L) slew rate. This is the pin to the P-channel MOSFET source for Switch A. Bypass to ground through a 1F capacitor. INA is independent of INB. Active-High Enable Input A. A logic low turns the switch off and the device consumes less than 1A of current. Logic high resumes normal operation. Active-High Enable Input B. A logic low turns the switch off and the device consumes less than 1A of current. Logic high resumes normal operation. This is the pin to the P-channel MOSFET source for Switch B. Bypass to ground through a 1F capacitor. INB is independent of INA. Not connected. This is the pin to the P-channel MOSFET drain connection. Bypass to ground through a 0.1F capacitor. Ground connection. This is the pin to the P-channel MOSFET drain connection. Bypass to ground through a 0.1F capacitor.
Pin Configuration
TSOPJW-12 (Top View)
FAST INA ENA ENB INB N/C
1 2 3 4 5 6
12 11 10 9 8 7
OUTA GND GND GND GND OUTB
2
4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch Selector Guide
Part Number
AAT4252A-1 AAT4252A-21 AAT4252A-3
1
Slew Rate (Typ) FAST (H) SLOW (L)
1ms 0.5s 100s 1ms
Active Pull-Down
NO NO YES
Enable
Active High Active High Active High
Absolute Maximum Ratings2
Symbol
VIN VEN, FAST VOUT IMAX IDM TJ TLEAD VESD
Description
IN to GND EN, FAST to GND OUT to GND Maximum Continuous Switch Current IN 2.5V Maximum Pulsed Current IN 2.5V Operating Junction Temperature Range Maximum Soldering Temperature (at leads) ESD Rating3 - HBM
Value
-0.3 to 7 -0.3 to 7 -0.3 to VIN + 0.3 1.8 5.5 2.0 -40 to 150 300 4000
Units
V V V A A C C V
Thermal Characteristics4
Symbol
JA PD
Description
Thermal Resistance Maximum Power Dissipation
Value
160 625
Units
C/W mW
1. Contact Sales for product availability 2. 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. 3. Human body model is a 100pF capacitor discharged through a 1.5k resistor into each pin. 4. Mounted on an AAT4252A demo board in still 25C air. 4252A.2007.06.1.0
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AAT4252A
Dual Slew Rate Controlled Load Switch Electrical Characteristics1
VIN = 5V, TA = -40C to +85C unless otherwise noted. Typical values are at TA = 25C. Per channel. Symbol Description Conditions Min
1.5 ON/OFF = ACTIVE, FAST = VIN, IOUT = 0 ON/OFF = Inactive, OUT = Open ON/OFF = GND, VOUT = 0 VIN = 5V VIN = 4.2V VIN = 3.0V VIN = 1.8V VIN = 1.5V
Typ
Max
6.5 1.0 1.0 1.0 155
Units
V A A A
AAT4252A All Versions VIN Operation Voltage IQ IQ(OFF) ISD(OFF) Quiescent Current Off Supply Current Off Switch Current2
RDS(ON)
On-Resistance
TCRRDS VIL VIH ISINK AAT4252A-12 TD(ON) TON TD(OFF) AAT4252A-22 TD(ON) TON TD(OFF) AAT4252A-3 TD(ON) TON TON TD(OFF) RPD
On Resistance Temp Co ON/OFF Input Logic Low Voltage VIN = 1.5V to 5.5V ON/OFF Input Logic High Voltage VIN = 1.5V to 5.5V ON/OFF Input Leakage VON/OFF = 5.5V Output Turn-On Delay Time Turn-On Rise Time Output Turn-OFF Delay Time Output Turn-On Delay Time Turn-On Rise Time Output Turn-OFF Delay Time Output Turn-On Delay Time Turn-On Rise Time Turn-On Rise Time Output Turn-OFF Delay Time Output Pull-Down Resistance During OFF VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD =10, TA =25C VIN = 5V, RLOAD VIN = 5V, RLOAD TA =25C VIN = 5V, RLOAD TA =25C VIN = 5V, RLOAD =10, TA =25C =10, FAST = 5V, =10, FAST = 0V, =10 , TA =25C
87 92 103 145 196 2800 1.4
m
0.4 1.0 10 600 2.0 0.5 0.5 4.0 10 65 600 2.0 10 40 1500 10 2 1.0 10 40 150 1500 10 50
ppm/C V V A s s s s s s s s s s
ON/OFF = Inactive, TA =25C
1. The AAT4252A is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. Contact Sales for product availability.
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4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch Typical Characteristics
VIN = 5V, TA = 25C unless otherwise noted.
Quiescent Current vs. Temperature
(No Load; Single Switch)
5 0.7
Quiescent Current vs. Input Voltage
(No Load; Single Switch)
Quiescent Current (A)
Quiescent Current (A)
4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 -40 -15 10 35 60 85
0.6 0.5 0.4 0.3 0.2 0.1 0 0 1 2 3 4 5 6
VIN = 5V VIN = 3V
Temperature (C)
Input Voltage (V)
Off Supply Current vs. Temperature
(No Load; EN = GND; VIN = 5V)
9
Typical ON/OFF Threshold vs. Input Voltage
1.3
Off Supply Current (A)
ON/OFF Threshold (V)
8 7 6 5 4 3 2 1 0 -40 -15 10 35 60 85
1.2 1.1 1 0.9 0.8 0.7 0.6 1.5 2 2.5 3 3.5
VIH VIL
4
4.5
5
5.5
Temperature (C)
Input Voltage (V)
On-Resistance vs. Temperature
140 250
On-Resistance vs. Input Voltage
On-Resistance (m)
On-Resistance (m)
120 100 80 60 40 20 0 -40 -15 10 35 60 85
230 210 190 170 150 130 110 90 70 50 1.5
VIN = 3V VIN = 5V
ISW = 2A
ISW = 100mA
2 2.5 3 3.5 4 4.5 5 5.5
Temperature (C)
Input Voltage (V)
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AAT4252A
Dual Slew Rate Controlled Load Switch Typical Characteristics
VIN = 5V, TA = 25C unless otherwise noted.
(VINA/VENA = 5V; VINB/VENB = 3V; RLA = 10; RLB = 20)
Enable Voltage (top) (V) Output Voltage (bottom) (V)
Enable Voltage (top) (V) Output Voltage (bottom) (V)
6 4 2 0
6 4 2 0
Output Turn-On
(VINA/VINB/VEN = 5V; RL = 10)
Output Turn-On
Switch A
Switch A
4 2 0
4 2 0
Switch B
Switch B
Time (500s/div)
Time (500s/div)
Output Turn-On
(VIN = 5V; RL = 10)
Output Turn-On
(VIN = 3V; RL = 20)
Enable Voltage (top) (V) Output Voltage (middle) (V)
Enable Voltage (top) (V) Output Voltage (middle) (V)
6 5 4 3 2 1 0
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
3.5 3 2.5 2 1.5 1 0.5 0
0.35 0.3 0.25 0.2 0.15 0.1 0.05 0
Input Current (bottom) (A)
Input Current (bottom) (A)
Time (500s/div)
Time (500s/div)
Output Turn-On
Enable Voltage (top) (V) Output Voltage FAST (middle) (V) Output Voltage SLOW (bottom) (V)
(RL = 10)
Output Turn-Off
(VIN = 5V; RL = 10)
Enable Voltage (top) (V) Output Voltage (middle) (V)
7 6 5 4 3 2 1 0 -1
6 5 4 3 2 1 0
0.7 0.6 0.5 0.4 0.3 0.2 0.1 0
Input Current (bottom) (A)
Time (500s/div)
Time (5s/div)
6
4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch Typical Characteristics
VIN = 5V, TA = 25C unless otherwise noted.
Output Turn-Off
(VIN = 3V; RL = 20)
Enable Voltage (top) (V) Output Voltage (middle) (V)
3.5 3 2.5 2 1.5 1 0.5 0
0.35 0.3 0.25 0.2 0.15 0.1 0.05 0
Input Current (bottom) (A)
Time (5s/div)
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AAT4252A
Dual Slew Rate Controlled Load Switch Functional Block Diagram
INA
OUTA
Turn-On Slew Rate Control
Level Shift
* ENA
FAST INB OUTB
Turn-On Slew Rate Control
Level Shift
* ENB
GND
*AAT4252A-3 version only
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4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch Functional Description
The AAT4252A is a family of flexible dual P-channel MOSFET power switches designed for highside load switching applications. There are three versions of the AAT4252A with different turn-on and turn-off characteristics to choose from, depending upon the specific requirements of an application. The first version, the AAT4252A-1, has a moderate turn-on slew rate feature, which reduces in-rush current when the MOSFET is turned on. This function allows the load switch to be implemented with either a small input capacitor or no input capacitor at all. During turn-on slewing, the current ramps linearly until it reaches the level required for the output load condition. The proprietary turn-on current control method works by careful control and monitoring of the MOSFET gate voltage. When the device is switched ON, the gate voltage is quickly increased to the threshold level of the MOSFET. Once at this level, the current begins to slew as the gate voltage is slowly increased until the MOSFET becomes fully enhanced. Once it has reached this point the gate is quickly increased to the full input voltage and the RDS(ON) is minimized. The second version, the AAT4252A-2, is a very fast switch intended for high-speed switching applications. This version has no turn-on slew rate control and no special output discharge features. The final switch version, the AAT4252A-3, has the addition of a minimized slew rate limited turn-on function and a shutdown output discharge circuit to rapidly turn off a load when the load switch is disabled through the ON/OFF pin. Using the FAST input pin on the AAT4252A-3, the device can be manually switched to a slower slew rate. All versions of the AAT4252A operate with input voltages ranging from 1.5V to 6.5V. All versions of this device have extremely low operating current, making them ideal for battery-powered applications. The ON/OFF control pin is TTL compatible and will also function with 2.5V to 5V logic systems, making the AAT4252A an ideal level-shifting load switch.
Applications Information
Input Capacitor
A 1F or larger capacitor is typically recommended for CIN in most applications. A CIN capacitor is not required for basic operation; however, it is useful in preventing load transients from affecting upstream 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 CIN, 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
For proper slew operation, a 0.1F capacitor or greater is required between VOUT and GND. Likewise, with the output capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased without limit to accommodate any load transient condition without adversely affecting the slew rate.
Enable Function
The AAT4252A features an enable / disable function. This pin (ON) is active high and is compatible with TTL or CMOS logic. To assure the load switch will turn on, the ON control level must be greater than 2.0V. The load switch will go into shutdown mode when the voltage on the ON pin falls below 0.8V. When the load switch is in shutdown mode, the OUT pin is tri-stated, and quiescent current drops to leakage levels below 1A.
Reverse Output-to-Input Voltage Conditions and Protection
Under normal operating conditions, a parasitic diode exists between the output and input of the load switch. The input voltage should always remain greater than the output load voltage, maintaining a reverse bias on the internal parasitic diode. Conditions where VOUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into 9
4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch
the VOUT pin, possibly damaging the load switch. In applications where there is a possibility of VOUT exceeding VIN for brief periods of time during normal operation, the use of a larger value CIN capacitor is highly recommended. A larger value of CIN with respect to COUT will effect a slower CIN decay rate during shutdown, thus preventing VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode from VIN to VOUT (connecting the cathode to VIN and anode to VOUT). The Schottky diode forward voltage should be less than 0.45V. The maximum continuous output current for the AAT4252A is a function of the package power dissipation and the RDS of the MOSFET at TJ(MAX). The maximum RDS of the MOSFET at TJ(MAX) is calculated by increasing the maximum room temperature RDS by the RDS temperature coefficient. The temperature coefficient (TC) is 2800ppm/C. Therefore, at 125C: RDS(MAX) = RDS(25C) * (1 + TC T) RDS(MAX) = 155m * (1 + 0.002800 * (125C - 25C)) RDS(MAX) = 198m For maximum current, refer to the following equation:
Thermal Considerations and High Output Current Applications
The AAT4252A is designed to deliver a continuous output load current. The limiting characteristic for maximum safe operating output load current is package power dissipation. In order to obtain high operating currents, careful device layout and circuit operating conditions must be taken into account. The following discussions will assume the load switch is mounted on a printed circuit board utilizing the minimum recommended footprint as stated in the Printed Circuit Board Layout Recommendations section of this datasheet. At any given ambient temperature (TA), the maximum package power dissipation can be determined by the following equation:
TJ(MAX) - TA PD(MAX) = JA
IOUT(MAX) <
PD(MAX) RDS
For example, if VIN = 5V, RDS(MAX) = 198m, and TA = 25C, IOUT(MAX) = 1.8A. If the output load current were to exceed 1.8A or if the ambient temperature were to increase, the internal die temperature would increase and the device would be damaged. Higher peak currents can be obtained with the AAT4252A. To accomplish this, the device thermal resistance must be reduced by increasing the heat sink area or by operating the load switch in a duty cycle manner. Duty cycles with peaks less than 2ms in duration can be considered using the method below.
High Peak Output Current Applications
Some applications require the load switch to operate at a continuous nominal current level with short duration, high-current peaks. Refer to the IDM specification in the Absolute Maximum Ratings table to ensure the AAT4252A's maximum pulsed current rating is not exceeded. The duty cycle for both output current levels must be taken into account. To do so, first calculate the power dissipation at the nominal continuous current level, and then add the additional power dissipation due to the short duration, high-current peak scaled by the duty factor. For example, a 4V system using an AAT4252A operates at a continuous 100mA load current level and has short 2A current peaks, as in a GSM application. The current peak occurs for 576s out of a 4.61ms period.
Constants for the AAT4252A are maximum junction temperature (TJ(MAX) = 125C1) and package thermal resistance (JA = 160C/W). Worst case conditions are calculated at the maximum operating temperature, TA = 85C. Typical conditions are calculated under normal ambient conditions where TA = 25C. At TA = 85C, PD(MAX) = 250mW. At TA = 25C, PD(MAX) = 625mW.
1. The actual maximum junction temperature of AAT4252A is 150C. However,good design practice is to derate the maximum die temperature down to 125C to prevent the possibility of over temperature damage.
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4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch
First, the current duty cycle is calculated:
x 576s % Peak Duty Cycle = 100 = 4.61ms % Peak Duty Cycle = 12.5%
The power dissipation for 2A load at 12.5% duty cycle is 102.6mW. Finally, the two power figures are summed to determine the total true power dissipation under the varied load. PD(total) = PD(100mA) + PD(2A) PD(total) = 1.8mW + 102.6mW PD(total) = 104.4mW The maximum power dissipation for the AAT4252A operating at an ambient temperature of 85C is 250mW. The device in this example will have a total power dissipation of 104.4mW. This is well within the thermal limits for safe operation of the device; in fact, at 85C, the AAT4252A will handle a 2A pulse for up to 30% duty cycle. At lower ambient temperatures, the duty cycle can be further increased.
The load current is 100mA for 87.5% of the 4.61ms period and 2A for 12.5% of the period. Since the Electrical Characteristics do not report RDS(MAX) for 4V operation, it must be approximated by consulting the chart of RDS(ON) vs. VIN. The RDS reported for 5V at 100mA and 2A can be scaled by the ratio seen in the chart to derive the RDS for 4V VIN at 25C : 155m * 90m/87m = 160.3m. De-rated for temperature: 160.3m * (1 + 0.002800 x (125C -25C)) = 205m. The power dissipation for a 100mA load is calculated as follows: PD(MAX) = IOUT2 * RDS PD(100mA) = (100mA)2 * 205m PD(100mA) = 2.05mW PD(87.5%D/C) = %DC * PD(100mA) PD(87.5%D/C) = 0.875 * 2.05mW PD(87.5%D/C) = 1.8mW The power dissipation for 100mA load at 87.5% duty cycle is 1.97mW. Now the power dissipation for the remaining 12.5% of the duty cycle at 2A is calculated: PD(MAX) = IOUT2 * RDS PD(2A) = (2A)2 * 205m PD(2A) = 820.97mW PD(12.5%D/C) = %DC * PD(2A) PD(12.5%D/C) = 0.125 * 820.97mW PD(12.5%D/C) = 102.6mW
Printed Circuit Board Layout Recommendations
For proper thermal management, and to take advantage of the low RDS(ON) of the AAT4252A, a few circuit board layout rules should be followed: VIN and VOUT should be routed using wider than normal traces, and GND should be connected to a ground plane. For best performance, CIN and COUT should be placed close to the package pins.
Evaluation Board Layout
The AAT4252A evaluation layout follows the printed circuit board layout recommendations and can be used for good applications layout. Refer to Figures 1 and 2. Note: Board layout shown is not to scale.
4252A.2007.06.1.0
11
AAT4252A
Dual Slew Rate Controlled Load Switch
Figure 1: Evaluation Board Top Side Layout.
Figure 2: Evaluation Board Bottom Side Layout.
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4252A.2007.06.1.0
AAT4252A
Dual Slew Rate Controlled Load Switch Ordering Information
Device Option
AAT4252A-3
Package
TSOPJW-12
Marking1
WSXYY
Part Number (Tape and Reel)2
AAT4252AITP-3-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
TSOPJW-12
0.10 0.20 + 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. 4252A.2007.06.1.0
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AAT4252A
Dual Slew Rate Controlled Load Switch
(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. 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.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737- 4600 Fax (408) 737- 4611 14
4252A.2007.06.1.0

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