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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator General Description
The AAT3221 and AAT3222 PowerLinearTM NanoPower Low Dropout Linear Regulators are ideal for portable applications where extended battery life is critical. This device features extremely low quiescent current which is typically 1.1A. Dropout voltage is also very low, typically less than 200mV at the maximum output current of 150mA. The AAT3221/2 has an Enable pin feature, which when asserted will enter the LDO regulator into a shutdown mode removing power from its load and offering extended power conservation capabilities for portable battery powered applications. The AAT3221/2 has output short circuit and over current protection. In addition, the device also has an over temperature protection circuit, which will shutdown the LDO regulator during extended overcurrent events. It is available with active high or active low enable input. The AAT3221 and AAT3222 are available in space saving 5-pin SOT23 packages. The AAT3221 is also available in the 8-pin SC70JW package. The device is rated over a -40C to 85C temperature range. Since only a small, 1F ceramic output capacitor is recommended, often the only space used is that occupied by the AAT3221/2 itself. The AAT3221/2 is truly a compact and cost effective voltage conversion solution. The AAT3221/2 is similar to the AAT3220 with the exception that it offers further power savings with its enable pin.
Features
* * * * * * * * * * * * *
PowerLinearTM
1.1 A Quiescent Current Low Dropout: 200 mV (typical) Guaranteed 150 mA Output High accuracy: 2% Current limit protection Over-Temperature protection Extremely Low power shutdown mode Low Temperature Coefficient Factory programmed output voltages * 1.8V to 3.5V Stable operation with virtually any output capacitor type Active high or low Enable pin 5-pin SOT23 or 8-pin SC70JW packages 4kV ESD
Preliminary Information
Applications
* * * * * * * Cellular Phones Notebook Computers Portable Communication Devices Handheld Electronics Remote Controls Digital Cameras PDAs
Typical Application
INPUT IN OUT OUTPUT
AAT3221/2
CIN 1F ENABLE (ENABLE) EN (EN) GND COUT 1F
GND
GND
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Pin Descriptions
Pin # AAT3221
SOT23-5 SC70JW-8
AAT3222
2 1 5
Symbol
IN GND EN (EN)
Function
Input pin Ground connection pin Enable Input. Logic compatible enable with active high or active low option available; see Ordering Information and Applications Information for details. Not Connected Output pin - should be decoupled with 1F or greater capacitor
1 2 3
2 5, 6, 7, 8 4
4 5
3 1
4 3
NC OUT
Pin Configuration
AAT3221 SOT23-5 (Top View) AAT3221 SC70JW-8 (Top View) AAT3222 SOT23-5 (Top View)
IN GND (EN) EN
1 2 3
5
OUT NC
4
OUT IN NC (EN) EN
1 2
8 7
3 4
6 5
GND GND GND GND
GND IN OUT
1 2 3
5
EN (EN) NC
1 2
4
2
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Absolute Maximum Ratings
Symbol
VIN VEN VENIN(MAX) IOUT TJ TLEAD
(TA=25C unless otherwise noted) Value
-0.3 to 6 -0.3 to 6 0.3 PD/(VIN-VO) -40 to 150 300
Description
Input Voltage EN (EN) to GND Voltage Maximum EN (EN) to Input Voltage Maximum DC Output Current Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Units
V V V mA C C
Note: 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.
Thermal Information
Symbol
JA PD
Description
Thermal Resistance (SOT23-5 or SC70JW-8)1 Power Dissipation (SOT23-5 or SC70JW-8)1
Rating
150 667
Units
C/W mW
Note 1: Mounted on a demo board.
Recommended Operating Conditions
Symbol
VIN T
Description
Input Voltage Ambient Temperature Range
Rating
(VOUT+0.34) to 5.5 -40 to +85
Units
V C
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Electrical Characteristics (VIN=VOUT(NOM)+1V, IOUT=1mA, COUT=1F, TA=25C unless otherwise noted)
Symbol
VOUT IOUT ISC IQ ISD VOUT/VOUT
Description
DC Output Voltage Tolerance Output Current Short Circuit Current Ground Current Shutdown Current Line Regulation
Conditions
VOUT=2.8V VOUT > 1.2 V VOUT < 0.4 V VIN = 5 V, no load EN = inactive VIN = 4.0-5.5 V VOUT = VOUT = VOUT = VOUT = VOUT = IL=1 to 100mA VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = IOUT = 100mA VOUT = VOUT = VOUT = VOUT = VOUT = VOUT = VIN = 2.7 V to 3.6 V VIN = 5 V VON = 5.5 V 100 Hz
Min
-2.0 -1.4 150
Typ
Max
2.0 1.4
Units
% mA mA A nA %/V
VOUT/VOUT
Load Regulation
VDO
Dropout Voltage1
1.8 2.0 2.3 2.4 2.5 2.7 2.8 2.85 3.0 3.3 3.5 1.8 2.0 2.3 2.4 2.5 2.7 2.8 2.85 3.0 3.3 3.5 2.0 2.4
350 1.1 20 0.15 1.0 0.9 0.8 0.8 0.8 0.7 0.7 0.7 0.6 0.5 0.5 290 265 230 220 210 200 190 190 190 180 180
2.5 0.4 1.65 1.58 1.45 1.40 1.35 1.25 1.20 1.20 1.15 1.00 1.00 340 315 275 265 255 240 235 230 225 220 220 0.8
%
mV
VEN(L) VEN(H) IEN(SINK) PSRR TSD THYS eN TC
EN Input Low Voltage EN Input High Voltage EN Input leakage Power Supply Rejection Ratio Over Temp Shutdown Threshold Over Temp Shutdown Hysteresis Output Noise Output Voltage Temp. Coefficient
0.01 50 140 20 350 80
1
V V V A dB C C VRMS PPM/C
Note 1: VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
4
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AAT3221/2
150mA NanoPower Typical Characteristics
(Unless otherwise noted, VIN = VOUT + 1V, TA = 25 C, COUT = 5.6 F ceramic, IOUT = 100mA) Output Voltage vs. Output Current
3.03 3.02
3.1 3 2.9 2.8 2.7
LDO Linear Regulator
Output Voltage v. Input Voltage
Output (V)
Output (V)
3.01
1mA 40mA
-30C
3
25C
2.99
80C
2.98 2.97 0 20 40 60 80 100
10mA
2.6 2.5 2.7 2.9 3.1 3.3 3.5
Output (mA)
Input (V)
Output Voltage vs. Input Voltage
3.03
Drop-out Voltage vs. Output Current
40 0
Drop-out (mV )
3.02
1mA 10mA
300
Output (V)
80C
200
3.01
25C -30C
40mA
3
100
2.99 3.5 4 4.5 5 5.5
0 0 25 50 75 100 125 150
Input ( V )
Output (mA)
Supply Current vs. Input Voltage
5
PSRR with 10mA Load
60
Input (A) with No Load
4 3
25C PSRR (dB)
3 4 5 6
80C
40
2
-30C
1 0 0 1 2
20
0 1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
Input ( V )
Frequency (Hz)
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
(Unless otherwise noted, VIN = VOUT + 1V, TA = 25C, COUT = 5.6F ceramic, IOUT = 100mA) Noise Spectrum
30 3.8 3.6
Line Response with 1mA Load
6 5 4 3 2
Noise (dB V/rt Hz )
20
Output Voltage ( V )
10 0 -10 -20 -30 1.E+01
3.4 3.2 3
Output
2.8 2.6 -200 1 0 800
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
0
200
400
600
Freque ncy (Hz)
Time (s)
Line Response with 10mA Load
3.8 6 5 3.8 3.6
Line Response with 100mA Load
6 5 4 3 2
Output Voltage ( V )
Input Voltage ( V )
3.4 3.2 3
4 3 2
3.4 3.2 3
Output
2.8 2.6 -200 1 0 800
Output
2.8 2.6 -200 1 0 800
0
200
400
600
0
200
400
600
Time (s)
Time (s)
Load Transient - 1 mA / 40 mA
4 320 4
Load Transient - 1 mA / 80 mA
320
240
240
Output (m A)
Output
3 160
Output
3 160
80
80
2 -1 0 1 2 3
0
2 -1 0 1 2 3
0
Time (ms)
Time (ms)
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Output (mA)
Output (V)
Output (V)
Input Voltage ( V )
Input
Output Voltage ( V )
3.6
Input
Input Voltage ( V )
Input
AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
(Unless otherwise noted, VIN = VOUT + 1V, TA = 25C, COUT = 5.6F ceramic, IOUT = 100mA) Power Up with 1mA Load
4 5 4 3 3 3 2 4
Turn On with 1mA Load
3
Output (V)
Input (V )
Output (V)
2 2
Enable
Enable
2 1
1 0
1
-1
1
0
Output
0 -1 0 1 2
-2 -3 0 -1
Output
-1 0 1 2
Time (ms)
Time (ms)
Power Up with 10mA Load
4 5 4 3 3 3 4
Turn On with 10mA Load
3
2
Output (V)
Input (V)
Output (V)
2 2
Enable
1 0
Enable
2 1
1
-1
1
0
Output
0 -1 0 1 2
-2 -3 0 -1
Output
-1 0 1 2
Time (ms)
Time (ms)
Power Up with 100mA Load
4 5 4 3 3 3 4
Turn On with 100mA Load
3
2
Output (V)
Input ( V )
Output (V)
2 2
Enable
1 0
2
Enable
1
1
-1
1
0
Output
0 -1 0 1 2
-2 -3 0 -1
Output
-1 0 1 2
Time (ms)
Time (ms)
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Enable ( V )
Enable ( V )
Enable ( V )
7
AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Functional Block Diagram
IN
Over-Current Protection Over-Temp Protection
OUT
EN
VREF
GND
Functional Description
The AAT3221 and AAT3222 are intended for LDO regulator applications where output current load requirements range from No Load to 150mA. The advanced circuit design of the AAT3221/2 has been optimized for very low quiescent or ground current consumption making it ideal for use in power management systems for small battery operated devices. The typical quiescent current level is just 1.1A. The AAT3221/2 also contains an enable circuit, which has been provided to shutdown the LDO regulator for additional power conservation in portable products. In the shutdown state the LDO draws less than 1A from input supply. The LDO also demonstrates excellent power supply ripple rejection (PSRR), and load and line transient response characteristics. The AAT3221/2 is a
truly high performance LDO regulator especially well suited for circuit applications which are sensitive to load circuit power consumption and extended battery life. The LDO regulator output has been specifically optimized to function with low cost, low ESR ceramic capacitors. However, the design will allow for operation with a wide range of capacitor types. The AAT3221/2 has complete short circuit and thermal protection. The integral combination of these two internal protection circuits give the AAT3221/2 a comprehensive safety system to guard against extreme adverse operating conditions. Device power dissipation is limited to the package type and thermal dissipation properties. Refer to the thermal considerations section for details on device operation at maximum output load levels.
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Applications Information
To assure the maximum possible performance is obtained from the AAT3221/2, please refer to the following application recommendations. The total output capacitance required can be calculated using the following formula: COUT = Where: I = maximum step in output current V = maximum excursion in voltage that the load can tolerate Note that use of this equation results in capacitor values approximately two to four times the typical value needed for an AAT3221/2 at room temperature. The increased capacitor value is recommended if tight output tolerances must be maintained over extreme operating conditions and maximum operational temperature excursions. If tantalum or aluminum electrolytic capacitors are used, the capacitor value should be increased to compensate for the substantial ESR inherent to these capacitor types. I x 15F V
Input Capacitor
Typically a 1F or larger capacitor is recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation. However, if the AAT3221/2 is physically located any distance more than a centimeter or two from the input power source, a CIN capacitor will be needed for stable operation. CIN should be located as close to the device VIN pin as practically possible. CIN values greater than 1F will offer superior input line transient response and will assist in maximizing the power supply ripple rejection. Ceramic, tantalum or aluminum electrolytic capacitors may be selected for CIN as there is no specific capacitor ESR requirement. For 150mA LDO regulator output 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.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3221/2. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint and is non-polarized. Line and load transient response of the LDO regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are less prone to damage if connected incorrectly. Equivalent Series Resistance (ESR): ESR is a very important characteristic to consider when selecting a capacitor. ESR is the internal series resistance associated with a capacitor, which includes lead resistance, internal connections, capacitor size and area, material composition and ambient temperature. Typically capacitor ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. Ceramic Capacitor Materials: Ceramic capacitors less than 0.1F are typically made from NPO or COG materials. NPO and COG materials are typically tight tolerance and very stable over temperature. Larger capacitor values are typically composed of X7R, X5R, Z5U and Y5V dielectric materials.
Output Capacitor
For proper load voltage regulation and operational stability, a capacitor is required between pins VOUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT3221/2 has been specifically designed to function with very low ESR ceramic capacitors. Although the device is intended to operate with these low ESR capacitors, it is stable over a very wide range of capacitor ESR, thus it will also work with some higher ESR tantalum or aluminum electrolytic capacitors. However, for best performance, ceramic capacitors are recommended. The value of COUT typically ranges from 0.47F to 10F, however 1F is sufficient for most operating conditions. If large output current steps are required by an application, then an increased value for COUT should be considered. The amount of capacitance needed can be calculated from the step size of the change in output load current expected and the voltage excursion that the load can tolerate.
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
Large ceramic capacitors, typically greater than 2.2F are often available in the low cost Y5V and Z5U dielectrics. These two material types are not recommended for use with LDO regulators since the capacitor tolerance can vary more than 50% over the operating temperature range of the device. A 2.2F Y5V capacitor could be reduced to 1F over the full operating temperature range. This can cause problems for circuit operation and stability. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than 15%. Capacitor area is another contributor to ESR. Capacitors, which are physically large in size will have a lower ESR when compared to a smaller sized capacitor of equivalent material and capacitance value. These larger devices can also improve circuit transient response when compared to an equal value capacitor in a smaller package size. Consult capacitor vendor data sheets carefully when selecting capacitors for use with LDO regulators. dissipation capacity has been exceeded and the internal die temperature reaches approximately 140C the system thermal protection circuit will become active. The internal thermal protection circuit will actively turn off the LDO regulator output pass device to prevent the possibility of over temperature damage. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back below the 140C trip point. The interaction between the short circuit and thermal protection systems allow the LDO regulator to withstand indefinite short circuit conditions without sustaining permanent damage.
No-Load Stability
The AAT3221/2 is designed to maintain output voltage regulation and stability under operational noload conditions. This is an important characteristic for applications where the output current may drop to zero. An output capacitor is required for stability under no load operating conditions. Refer to the output capacitor considerations section for recommended typical output capacitor values.
Enable Function
The AAT3221/2 features an LDO regulator enable / disable function. This pin (EN) is compatible with CMOS logic. Active high or active low options are available (see Ordering Information). For a logic high signal, the EN control level must be greater then 2.4 volts. A logic low signal is asserted when the voltage on the EN pin falls below 0.6 volts. For example, the active high version 3221/2 will turn on when a logic high is applied to the EN pin. If the enable function is not needed in a specific application, it may be tied to the respective voltage level to keep the LDO regulator in a continuously on state; e.g. the active high version 3221/2 will tie VIN to EN to remain on.
Thermal Considerations and High Output Current Applications
The AAT3221/2 is designed to deliver a continuous output load current of 150mA under normal operating conditions. The limiting characteristic for the maximum output load safe operating area is essentially package power dissipation and the internal preset thermal limit of the device. In order to obtain high operating currents, careful device layout and circuit operating conditions need to be taken into account. The following discussions will assume the LDO regulator is mounted on a printed circuit board utilizing the minimum recommended footprint and the printed circuit board is 0.062inch thick FR4 material with one ounce copper. At any given ambient temperature (TA) the maximum package power dissipation can be determined by the following equation: PD(MAX) = [TJ(MAX) - TA] / JA Constants for the AAT3221/2 are TJ(MAX), the maximum junction temperature for the device which is 125C and JA = 150C/W, the package thermal resistance. Typically, maximum conditions are calculated at the maximum operating temperature where TA = 85C, under normal ambient conditions
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Short Circuit Protection and Thermal Protection
The AAT3221/2 is protected by both current limit and over temperature protection circuitry. The internal short circuit current limit is designed to activate when the output load demand exceeds the maximum rated output. If a short circuit condition were to continually draw more than the current limit threshold, the LDO regulator's output voltage will drop to a level necessary to supply the current demanded by the load. Under short circuit or other over current operating conditions, the output voltage will drop and the AAT3221/2's die temperature will increase rapidly. Once the regulator's power
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
TA = 25C. Given TA = 85, the maximum package power dissipation is 267mW. At TA = 25C, the maximum package power dissipation is 667mW. The maximum continuous output current for the AAT3221/2 is a function of the package power dissipation and the input to output voltage drop across the LDO regulator. Refer to the following simple equation: IOUT(MAX) < PD(MAX) / (VIN - VOUT) For example, if VIN = 5V, VOUT = 2.5V and TA = 25, IOUT(MAX) < 267mA. The output short circuit protection threshold is set between 150mA and 300mA. If the output load current were to exceed 267mA or if the ambient temperature were to increase, the internal die temperature will increase. If the condition remained constant and the short circuit protection did not activate, there would be a potential damage hazard to LDO regulator since the thermal protection circuit will only activate after a short circuit event occurs on the LDO regulator output. To figure what the maximum input voltage would be for a given load current refer to the following equation. This calculation accounts for the total power dissipation of the LDO Regulator, including that caused by ground current. PD(MAX) = (VIN - VOUT)IOUT + (VIN x IGND) This formula can be solved for VIN to determine the maximum input voltage. VIN(MAX) = (PD(MAX) + (VOUT x IOUT)) / (IOUT + IGND) The following is an example for an AAT3221/2 set for a 2.5 volt output: From the discussion above, PD(MAX) was determined to equal 667mW at TA = 25C. VOUT = 2.5 volts IOUT = 150mA IGND = 1.1A VIN(MAX)=(667mW+(2.5Vx150mA))/(150mA +1.1A) VIN(MAX) = 6.95V Thus, the AAT3221/2 can sustain a constant 2.5V output at a 150mA load current as long as VIN is 6.95V at an ambient temperature of 25C. 5.5V is the maximum input operating voltage for the AAT3221/2, thus at 25C, the device would not have any thermal concerns or operational VIN(MAX) limits. This situation can be different at 85C. The following is an example for an AAT3221/2 set for a 2.5 volt output at 85C: From the discussion above, PD(MAX) was determined to equal 267mW at TA = 85C. VOUT = 2.5 volts IOUT = 150mA IGND = 1.1A VIN(MAX)=(267mW+(2.5Vx150mA))/(150mA +1.1A) VIN(MAX) = 4.28V Higher input to output voltage differentials can be obtained with the AAT3221/2, while maintaining device functions in the thermal safe operating area. To accomplish this, the device thermal resistance must be reduced by increasing the heat sink area or by operating the LDO regulator in a duty cycled mode. For example, an application requires VIN = 5.0V while VOUT = 2.5V at a 150mA load and TA = 85C. VIN is greater than 4.28V, which is the maximum safe continuous input level for VOUT = 2.5V at 150mA for TA = 85C. To maintain this high input voltage and output current level, the LDO regulator must be operated in a duty cycled mode. Refer to the following calculation for duty cycle operation: PD(MAX) is assumed to be 267mW IGND = 1.1A IOUT = 150mA VIN = 5.0 volts VOUT = 2.5 volts %DC = 100(PD(MAX) / ((VIN - VOUT)IOUT + (VIN x IGND)) %DC=100(267mW/((5.0V-2.5V)150mA+(5.0Vx1.1A)) %DC = 71.2% For a 150mA output current and a 2.5 volt drop across the AAT3221/2 at an ambient temperature of 85C, the maximum on time duty cycle for the device would be 71.2%. The following family of curves shows the safe operating area for duty cycled operation from ambient room temperature to the maximum operating level.
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
High Peak Output Current Applications
Some applications require the LDO regulator to operate at continuous nominal levels with short duration high current peaks. The duty cycles for both output current levels must be taken into account. To do so, one would first need to calculate the power dissipation at the nominal continuous level, then factor in the addition power dissipation due to the short duration high current peaks. For example, a 2.5V system using a AAT3221/ 2IGV-2.5-T1 operates at a continuous 100mA load current level and has short 150mA current peaks. The current peak occurs for 378s out of a 4.61ms period. It will be assumed the input voltage is 5.0V. First, the current duty cycle percentage must be calculated: Device Duty Cycle vs. VDROP VOUT = 2.5V @ 50 degrees C
3.5
Device Duty Cycle vs. VDROP VOUT = 2.5V @ 25 degrees C
3.5
Voltage Drop (V)
3 2.5 2 1.5 1 0.5 0 0 10 20 30 40 50 60 70 80 90 100
200mA
Duty Cycle (%)
% Peak Duty Cycle: X/100 = 378ms/4.61ms % Peak Duty Cycle = 8.2% The LDO Regulator will be under the 100mA load for 91.8% of the 4.61ms period and have 150mA peaks occurring for 8.2% of the time. Next, the continuous nominal power dissipation for the 100mA load should be determined then multiplied by the duty cycle to conclude the actual power dissipation over time.
100
Voltage Drop (V)
3 2.5 2 1.5 1 0.5 0 0 10 20 30 40 50 60 70 80 90
200mA 150mA
Duty Cycle (%)
PD(MAX) = (VIN - VOUT)IOUT + (VIN x IGND) PD(100mA) = (5.0V - 2.5V)100mA + (5.0V x 1.1mA) PD(100mA) = 250mW PD(91.8%D/C) = %DC x PD(100mA) PD(91.8%D/C) = 0.918 x 250mW PD(91.8%D/C) = 229.5mW
Device Duty Cycle vs. VDROP VOUT = 2.5V @ 85 degrees C
3.5
Voltage Drop (V)
3 2.5 2 1.5 1 0.5 0 0 10 20 30 40 50 60
100mA 200mA 150mA
70
80
90
100
Duty Cycle (%)
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
The power dissipation for a 100mA load occurring for 91.8% of the duty cycle will be 229.5mW. Now the power dissipation for the remaining 8.2% of the duty cycle at the 150mA load can be calculated: PD(MAX) = (VIN - VOUT)IOUT + (VIN x IGND) PD(150mA) = (5.0V - 2.5V)150mA + (5.0V x 1.1mA) PD(150mA) = 375mW PD(8.2%D/C) = %DC x PD(150mA) PD(8.2%D/C) = 0.082 x 375mW PD(8.2%D/C) = 30.75mW The power dissipation for a 150mA load occurring for 8.2% of the duty cycle will be 20.9mW. Finally, the two power dissipation levels can summed to determine the total true power dissipation under the varied load. PD(total) = PD(100mA) + PD(150mA) PD(total) = 229.5mW + 30.75mW PD(total) = 260.25mW The maximum power dissipation for the AAT3221/2 operating at an ambient temperature of 85C is 267mW. The device in this example will have a total power dissipation of 260.25mW. This is within the thermal limits for safe operation of the device.
Printed Circuit Board Layout Recommendations
In order to obtain the maximum performance from the AAT3221/2 LDO regulator, very careful attention must be considered in regard to the printed circuit board layout. If grounding connections are not properly made, power supply ripple rejection and LDO regulator transient response can be compromised. The LDO Regulator external capacitors CIN and COUT should be connected as directly as possible to the ground pin of the LDO Regulator. For maximum performance with the AAT3221/2, the ground pin connection should then be made directly back to the ground or common of the source power supply. If a direct ground return path is not possible due to printed circuit board layout limitations, the LDO ground pin should then be connected to the common ground plane in the application layout.
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Ordering Information
Output Voltage 1.8V 2.0V 2.3V 2.4V 2.5V 2.7V 2.8V 2.85V 3.0V 3.3V 3.5V 1.8V 2.0V 2.3V 2.4V 2.5V 2.7V 2.8V 2.85V 3.0V 3.3V 3.5V 1.8V 1.8V 2.0V 2.3V 2.4V 2.5V 2.7V 2.8V 2.85V 3.0V 3.3V 3.5V 2.8V Enable Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active high Active low Package SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SC70JW-8 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 SOT23-5 Marking Bulk N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A Part Number Tape and Reel AAT3221IGV-1.8-T1 AAT3221IGV-2.0-T1 AAT3221IGV-2.3-T1 AAT3221IGV-2.4-T1 AAT3221IGV-2.5-T1 AAT3221IGV-2.7-T1 AAT3221IGV-2.8-T1 AAT3221IGV-2.85-T1 AAT3221IGV-3.0-T1 AAT3221IGV-3.3-T1 AAT3221IGV-3.5-T1 AAT3221IJS-1.8-T1 AAT3221IJS-2.0-T1 AAT3221IJS-2.3-T1 AAT3221IJS-2.4-T1 AAT3221IJS-2.5-T1 AAT3221IJS-2.7-T1 AAT3221IJS-2.8-T1 AAT3221IJS-2.85-T1 AAT3221IJS-3.0-T1 AAT3221IJS-3.3-T1 AAT3221IJS-3.5-T1 AAT3222IGV-1.8-T1 AAT3222IGV-1.8-T1 AAT3222IGV-2.0-T1 AAT3222IGV-2.3-T1 AAT3222IGV-2.4-T1 AAT3222IGV-2.5-T1 AAT3222IGV-2.7-T1 AAT3222IGV-2.8-T1 AAT3222IGV-2.85-T1 AAT3222IGV-3.0-T1 AAT3222IGV-3.3-T1 AAT3222IGV-3.5-T1 AAT3221IGV-2.8-2 T1
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3221.2002.03.0.94
AAT3221/2
150mA NanoPowerTM LDO Linear Regulator Package Information
SOT23-5
e
Dim
S1
E
H
D
A A1 S b
I
c L
A A1 A2 b c D E e H L S S1
Millimeters Min Max 0.95 1.45 0.05 0.15 0.90 1.30 0.35 0.50 0.08 0.20 2.84 3.00 1.50 1.70 1.90 2.60 3.00 0.35 0.55 0.47 0.55 .95 0 10
Inches Min Max 0.037 0.057 0.002 0.006 0.035 0.051 0.014 0.019 0.003 0.078 0.112 0.112 0.059 0.067 0.0748 0.102 0.118 .0137 .0216 0.019 .0216 0.037 0 10
SC70JW-8
e e e
Dim E E1 L A A1 A2 D e b c 1
E
b D 0.048REF c A2 A
Millimeters Min Max 2.10 BSC 1.75 2.00 0.23 0.40 1.10 0 0.10 0.70 1.00 2.00 BSC 0.50 BSC 0.15 0.30 0.10 0.20 0 8 4 10
Inches Min Max 0.083 BSC 0.069 0.079 0.009 0.016 0.043 0.004 0.028 0.039 0.079 BSC 0.020 BSC 0.006 0.012 0.004 0.008 0 8 4 10
A1 1 L E1
3221.2002.03.0.94
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AAT3221/2
150mA NanoPowerTM LDO Linear Regulator
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Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 16
3221.2002.03.0.94

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