AMXYY [ANALOGICTECH]
150mA NanoPower™ LDO Linear Regulator; 150毫安纳安级™ LDO线性稳压器
| 型号： | AMXYY |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | 150mA NanoPower™ LDO Linear Regulator |
| 文件： | 总16页 (文件大小：222K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
General Description
Features
The AAT3221 and AAT3222 PowerLinear NanoPower low
dropout (LDO) linear regulators are ideal for portable
applications where extended battery life is critical.
These devices feature extremely low quiescent current,
typically 1.1μA. Dropout voltage is also very low, typi-
cally less than 200mV at the maximum output current of
150mA. The AAT3221/2 have an enable pin feature
which, when asserted, will enter the LDO regulator into
shutdown mode, removing power from its load and offer-
ing extended power conservation capabilities for portable
battery-powered applications.
• 1.1μA Quiescent Current
• Low Dropout: 200mV (typical)
• Guaranteed 150mA Output
• High Accuracy: ±2%
• Current Limit Protection
• Over-Temperature Protection
• Extremely Low Power Shutdown Mode
• Low Temperature Coefficient
• Factory-Programmed Output Voltages
▪ 1.5V to 3.5V
• Stable Operation With Virtually Any Output Capacitor
Type
• Active High or Low Enable Pin
• 4kV ESD
The AAT3221/2 have output short-circuit and over-cur-
rent protection. In addition, the devices also have an
over-temperature protection circuit, which will shut
down the LDO regulator during extended over-current
events. The devices are available with active high or
active low enable input.
• 5-Pin SOT23 or 8-Pin SC70JW Package
• -40°C to +85°C Temperature Range
Applications
• Cellular Phones
The AAT3221 and AAT3222 are available in Pb-free,
space-saving 5-pin SOT23 packages. The AAT3221 is
also available in a Pb-free, 8-pin SC70JW package. The
device is rated over the -40°C to +85°C temperature
range. Since only a small, 1μF ceramic output capacitor
is recommended, often the only space used is that occu-
pied by the AAT3221/2 itself. The AAT3221/2 provide a
compact and cost-effective voltage conversion solution.
• Digital Cameras
• Handheld Electronics
• Notebook Computers
• PDAs
• Portable Communication Devices
• Remote Controls
The AAT3221 and AAT3122 are similar to the AAT3220,
with the exception that they offer further power savings
with an enable pin.
Typical Application
INPUT
OUTPUT
ENABLE
(ENABLE)
(EN)
CIN
1μF
COUT
1μF
GND
GND
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PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Pin Descriptions
Pin #
AAT3221
SOT23-5
SC70JW-8
AAT3222 Symbol Function
1
2
2
2
1
IN
GND
Input pin.
Ground connection pin.
5, 6, 7, 8
Enable input. Logic compatible enable with active high or active low option
available; see Ordering Information and Applications Information for details.
3
4
5
EN (EN)
4
5
3
1
4
3
NC
OUT
Not connected.
Output pin; should be decoupled with 1μF or greater capacitor.
Pin Configuration
AAT3221
SOT23-5
(Top View)
AAT3221
SC70JW-8
(Top View)
AAT3222
SOT23-5
(Top View)
5
5
1
1
OUT
EN (EN)
NC
IN
GND
8
GND
IN
1
GND
GND
GND
GND
OUT
IN
2
3
4
7
6
5
2
3
2
3
NC
(EN) EN
4
4
NC
(EN) EN
OUT
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3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
Symbol
Description
Value
Units
VIN
Input Voltage, <30ms, 10% DC (continuous max = 6.0V)
-0.3 to 7
V
VEN
VENIN(MAX)
IOUT
EN (EN) to GND Voltage
-0.3 to 6
0.3
PD/(VIN-VO)
-40 to 150
V
V
mA
°C
Maximum EN (EN) to Input Voltage
Maximum DC Output Current
Operating Junction Temperature Range
TJ
Thermal Information2
Symbol
Description
Value
Units
ΘJA
PD
Thermal Resistance
Power Dissipation
150
667
°C/W
mW
Recommended Operating Conditions
Symbol
Description
Input Voltage3
Ambient Temperature Range
Rating
Units
VIN
T
(VOUT + VDO) to 5.5
-40 to +85
V
°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 demo board.
3. To calculate minimum input voltage, use the following equation: VIN(MIN) = VOUT(MAX) + VDO(MAX) as long as VIN ≥ 2.5V.
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PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Electrical Characteristics
VIN = VOUT(NOM) + 1V, IOUT = 1mA, COUT = 1μF, TA = 25°C, unless otherwise noted.
Symbol
Description
Conditions
Min
Typ
Max
Units
VOUT
IOUT
ISC
IQ
ISD
DC Output Voltage Tolerance
Output Current
Short-Circuit Current
Ground Current
-2.0
150
2.0
%
mA
mA
μA
nA
%/V
VOUT > 1.2V
VOUT < 0.4V
VIN = 5V, No Load
EN = Inactive
VIN = 4.0V to 5.5V
350
1.1
20
2.5
Shutdown Current
ΔVOUT/VOUT*ΔVIN Line Regulation
0.15
1.3
1.2
1.1
1.0
1.0
0.9
0.8
0.8
0.8
0.8
0.7
0.7
0.7
0.7
0.6
0.6
0.5
0.5
230
220
210
205
200
190
190
190
190
188
180
180
0.4
1.72
1.69
1.67
1.65
1.62
1.58
1.45
1.40
1.35
1.30
1.25
1.20
1.20
1.18
1.15
1.06
1.00
1.00
275
VOUT = 1.5
VOUT = 1.6
VOUT = 1.7
VOUT = 1.8
VOUT = 1.9
VOUT = 2.0
VOUT = 2.3
VOUT = 2.4
VOUT = 2.5
VOUT = 2.6
VOUT = 2.7
VOUT = 2.8
VOUT = 2.85
VOUT = 2.9
VOUT = 3.0
VOUT = 3.1
VOUT = 3.3
VOUT = 3.5
VOUT = 2.3
VOUT = 2.4
VOUT = 2.5
VOUT = 2.6
VOUT = 2.7
VOUT = 2.8
VOUT = 2.85
VOUT = 2.9
VOUT = 3.0
VOUT = 3.1
VOUT = 3.3
VOUT = 3.5
ΔVOUT/VOUT
Load Regulation
IL = 1 to 100mA
%
265
255
247
240
235
230
228
225
VDO
Dropout Voltage1, 2
IOUT = 100mA
mV
222
220
220
VEN(L)
VEN(H)
EN Input Low Voltage
EN Input High Voltage
0.8
V
V
VIN = 2.7V to 3.6V
VIN = 5V
2.0
2.4
IEN(SINK)
PSRR
TSD
THYS
eN
EN Input Leakage
VON = 5.5V
100Hz
0.01
50
140
20
350
80
1
μA
dB
°C
Power Supply Rejection Ratio
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Output Noise
°C
μVRMS
PPM/°C
TC
Output Voltage Temperature Coefficient
1. VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
2. For VOUT < 2.3V, VDO = 2.5V - VOUT
.
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3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Typical Characteristics
Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.
Output Voltage vs. Output Current
Output Voltage vs. Input Voltage
3.03
3.02
3.01
3
3.1
3
1mA
2.9
2.8
2.7
2.6
2.5
-30°C
40mA
25°C
80°C
2.99
2.98
2.97
10mA
2.7
2.9
3.1
3.3
3.5
0
20
40
60
80
100
Input Voltage (V)
Output Current (mA)
Output Voltage vs. Input Voltage
Dropout Voltage vs. Output Current
3.03
3.02
3.01
3
400
300
200
100
0
1mA
80°C
10mA
25°C
40mA
-30°C
2.99
3.5
4
4.5
5
5.5
0
25
50
75
100
125
150
Input Voltage (V)
Output Current (mA)
Supply Current vs. Input Voltage
PSRR with 10mA Load
2.0
60
40
20
0
1.6
25°C
80°C
1.2
0.8
0.4
0
-30°C
0
1
2
3
4
5
6
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
Input Voltage (V)
Frequency (Hz)
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PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Typical Characteristics
Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.
Noise Spectrum
Line Response with 1mA Load
30
20
10
0
3.8
3.6
3.4
3.2
3
6
5
4
3
2
1
0
Input
-10
-20
-30
Output
2.8
2.6
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
-200
0
200
400
600
800
Frequency (Hz)
Time (µs)
Line Response with 10mA Load
Line Response with 100mA Load
3.8
3.6
3.4
3.2
3
6
5
4
3
2
1
3.8
3.6
3.4
3.2
3
6
5
4
3
2
1
0
Input
Input
Output
Output
2.8
2.6
2.8
2.6
0
-200
0
200
400
600
800
-200
0
200
400
600
800
Time (µs)
Time (µs)
Load Transient - 1mA / 40mA
Load Transient - 1mA / 80mA
4
3
2
320
240
160
80
4
3
2
320
240
160
80
Output
Output
0
0
-1
0
1
2
3
-1
0
1
2
3
Time (ms)
Time (ms)
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3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Typical Characteristics
Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.
Power-Up with 1mA Load
Turn-On with 1mA Load
4
3
2
1
0
5
4
4
3
2
1
0
3
3
2
2
Enable
Output
Enable
1
1
0
-1
-2
-3
0
Output
-1
-1
0
1
2
-1
-1
-1
0
1
2
2
2
Time (ms)
Time (ms)
Turn-On with 10mA Load
Power-Up with 10mA Load
4
3
2
1
0
5
4
4
3
2
1
0
3
2
3
2
Enable
Enable
1
1
0
-1
-2
-3
0
Output
Output
-1
-1
0
1
2
0
1
Time (ms)
Time (ms)
Power-Up with 100mA Load
Turn-On with 100mA Load
4
3
2
5
4
4
3
2
3
3
2
2
Enable
1
1
Enable
Output
0
1
-1
-2
-3
1
0
Output
0
0
-1
-1
0
1
2
0
1
Time (ms)
Time (ms)
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PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Functional Block Diagram
IN
OUT
Over-Current
Protection
Over-Temperature
Protection
EN
VREF
GND
regulator is especially well suited for circuit applications
that are sensitive to load circuit power consumption and
extended battery life.
Functional Description
The AAT3221 and AAT3222 are intended for LDO regula-
tor 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 1.1μA. AAT3221/2 devices also contain an
enable circuit which has been provided to shut down the
LDO regulator for additional power conservation in por-
table products. In the shutdown state, the LDO draws
less than 1μA from input supply.
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 inter-
nal protection circuits gives the AAT3221/2 a compre-
hensive 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 of this docu-
ment for details on device operation at maximum output
load levels.
The LDO also demonstrates excellent power supply rip-
ple rejection (PSRR) and load and line transient response
characteristics. The AAT3221/2 high performance LDO
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3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
The total output capacitance required can be calculated
using the following formula:
Applications Information
To ensure that the maximum possible performance is
obtained from the AAT3221/2, please refer to the follow-
ing application recommendations.
ΔI
COUT
=
· 15µF
ΔV
Where:
Input Capacitor
ΔI = maximum step in output current
ΔV = maximum excursion in voltage that the load can
tolerate
A 1μF or larger capacitor is typically 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
one or two centimeters from the input power source, a
CIN capacitor will be needed for stable operation. CIN
should be located as closely to the device VIN pin as
practically possible. CIN values greater than 1μF will
offer superior input line transient response and will
assist in maximizing the power supply ripple rejection.
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 toler-
ances must be maintained over extreme operating con-
ditions and maximum operational temperature excur-
sions. 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.
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 recommend-
ed over all other types of capacitors for use with the
AAT3221/2. Ceramic capacitors offer many advantages
over their tantalum and aluminum electrolytic counter-
parts. 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 capaci-
tors. Since ceramic capacitors are non-polarized, they
are less prone to damage if incorrectly connected.
Output Capacitor
For proper load voltage regulation and operational sta-
bility, 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 pos-
sible 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 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.
Equivalent Series Resistance (ESR)
ESR is a very important characteristic to consider when
selecting a capacitor. ESR is the internal series resis-
tance 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.
The value of COUT typically ranges from 0.47μF to 10μF;
however, 1μF is sufficient for most operating conditions.
If large output current steps are required by an applica-
tion, then an increased value for COUT should be consid-
ered. The amount of capacitance needed can be calcu-
lated from the step size of the change in output load
current expected and the voltage excursion that the load
can tolerate.
Ceramic Capacitor Materials
Ceramic capacitors less than 0.1μF are typically made
from NPO or C0G materials. NPO and C0G materials are
typically tight tolerance and very stable over tempera-
ture. Larger capacitor values are typically composed of
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3221.2007.11.1.12
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PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
X7R, X5R, Z5U, and Y5V dielectric materials. Large
ceramic capacitors, typically greater than 2.2μF, are often
available in 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 2.2μF Y5V capacitor could be reduced to 1μF
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%.
rapidly increase. Once the regulator’s power dissipation
capacity has been exceeded and the internal die tem-
perature reaches approximately 140°C, the system ther-
mal 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 tem-
perature falls back below the 140°C trip point.
The interaction between the short-circuit and thermal
protection systems allows the LDO regulator to with-
stand indefinite short-circuit conditions without sustain-
ing permanent damage.
Capacitor area is another contributor to ESR. Capacitors
that are physically large in size will have a lower ESR
when compared to a smaller sized capacitor of equiva-
lent material and capacitance value. These larger devic-
es can also improve circuit transient response when
compared to an equal value capacitor in a smaller pack-
age size.
No-Load Stability
The AAT3221/2 is designed to maintain output voltage
regulation and stability under operational no-load condi-
tions. 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 of this document for recommended typical out-
put capacitor values.
Consult capacitor vendor datasheets carefully when
selecting capacitors for use with LDO regulators.
Enable Function
The AAT3221/2 features an LDO regulator enable / dis-
able 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 than 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
AAT3221/2 will turn on when a logic high is applied to
the EN pin. If the enable function is not needed in a spe-
cific 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 AAT3221/2 will tie VIN
to EN to remain on.
Thermal Considerations and High Output
Current Applications
The AAT3221/2 is designed to deliver a continuous out-
put load current of 150mA under normal operating con-
ditions. 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 foot-
print and the printed circuit board is 0.062-inch thick
FR4 material with one ounce copper.
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 out-
put 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 volt-
age will drop and the AAT3221/2 die temperature will
At any given ambient temperature (TA), the maximum
package power dissipation can be determined by the fol-
lowing equation:
TJ(MAX) - TA
θJA
PD(MAX)
=
Constants for the AAT3221/2 are TJ(MAX), the maximum
junction temperature for the device which is 125°C and
ΘJA = 150°C/W, the package thermal resistance. Typically,
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3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
maximum conditions are calculated at the maximum
operating temperature where TA = 85°C, under normal
ambient conditions TA = 25°C. Given TA = 85°C, the
maximum package power dissipation is 267mW. At TA =
25°C, the maximum package power dissipation is
667mW.
From the discussion above, PD(MAX) was determined to
equal 667mW at TA = 25°C. 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
25°C. 5.5V is the maximum input operating voltage for
the AAT3221/2, thus at 25°C the device would not have
any thermal concerns or operational VIN(MAX) limits.
The maximum continuous output current for the
AAT3221/2 is a function of the package power dissipa-
tion and the input-to-output voltage drop across the
LDO regulator. Refer to the following simple equation:
This situation can be different at 85°C. The following is
an example for an AAT3221/2 set for a 2.5 volt output
at 85°C:
VOUT = 2.5 volts
IOUT = 150mA
IGND = 1.1μA
PD(MAX)
IOUT(MAX)
=
(VIN - VOUT
)
(267mW + [2.5V · 150mA])
(150mA + 1.1µA)
For example, if VIN = 5V, VOUT = 2.5V and TA = 25°C,
IOUT(MAX) < 267mA. The output short-circuit protection
threshold is set between 150mA and 300mA. If the out-
put load current were to exceed 267mA or if the ambient
temperature were to increase, the internal die tempera-
ture would increase. If the condition remained constant
and the short-circuit protection did not activate, there
would be a potential damage hazard to the LDO regula-
tor since the thermal protection circuit would only acti-
vate after a short-circuit event occured on the LDO
regulator output.
VIN(MAX)
=
VIN(MAX) = 4.28V
From the discussion above, PD(MAX) was determined to
equal 267mW at TA = 85°C.
Higher input-to-output voltage differentials can be
obtained with the AAT3221/2, while maintaining device
functions in the thermal safe operating area. To accom-
plish 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.
To determine the maximum input voltage for a given
load current, refer to the following equation. This calcu-
lation accounts for the total power dissipation of the LDO
regulator, including that caused by ground current.
For example, an application requires VIN = 5.0V while
VOUT = 2.5V at a 150mA load and TA = 85°C. VIN is
greater than 4.28V, which is the maximum safe continu-
ous input level for VOUT = 2.5V at 150mA for TA = 85°C.
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) = (VIN - VOUT)IOUT + (VIN · IGND
)
This formula can be solved for VIN to determine the
maximum input voltage.
IGND = 1.1μA
(PD(MAX) + [VOUT · IOUT])
)
IOUT = 150mA
VIN = 5.0 volts
VOUT = 2.5 volts
VIN(MAX)
=
(IOUT + IGND
The following is an example for an AAT3221/2 set for a
2.5 volt output:
PD(MAX)
([VIN - VOUT]IOUT + [VIN · IGND])
%DC = 100
VOUT = 2.5 volts
IOUT = 150mA
IGND = 1.1μA
267mW
([5.0V - 2.5V]150mA + [5.0V · 1.1µA])
%DC = 100
(667mW + [2.5V · 150mA])
(150mA + 1.1µA)
%DC = 71.2%
VIN(MAX)
=
PD(MAX) is assumed to be 267mW.
VIN(MAX) = 6.95V
w w w . a n a l o g i c t e c h . c o m
3221.2007.11.1.12
11
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
For a 150mA output current and a 2.5 volt drop across
the AAT3221/2 at an ambient temperature of 85°C, the
maximum on-time duty cycle for the device would be
71.2%.
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 nom-
inal continuous level, then factor in the addition power
dissipation due to the short duration, high-current
peaks.
The following family of curves shows the safe operating
area for duty-cycled operation from ambient room tem-
perature to the maximum operating level.
Device Duty Cycle vs. VDROP
(VOUT = 2.5V @ 25°C)
For example, a 2.5V system using an AAT3221/
2IGV-2.5-T1 operates at a continuous 100mA load cur-
rent level and has short 150mA current peaks. The cur-
rent peak occurs for 378μs out of a 4.61ms period. It
will be assumed the input voltage is 5.0V.
3.5
3
200mA
2.5
2
1.5
1
First, the current duty cycle percentage must be
calculated:
0.5
0
% Peak Duty Cycle: X/100 = 378ms/4.61ms
% Peak Duty Cycle = 8.2%
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
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.
Device Duty Cycle vs. VDROP
(VOUT = 2.5V @ 50°C)
3.5
3
200mA
2.5
2
150mA
PD(MAX) = (VIN - VOUT)IOUT + (VIN · IGND
)
1.5
1
PD(100mA) = (5.0V - 2.5V)100mA + (5.0V · 1.1mA)
PD(100mA) = 250mW
0.5
0
PD(91.8%D/C) = %DC · PD(100mA)
PD(91.8%D/C) = 0.918 · 250mW
PD(91.8%D/C) = 229.5mW
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
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:
Device Duty Cycle vs. VDROP
(VOUT = 2.5V @ 85°C)
3.5
3
2.5
2
100mA
PD(MAX) = (VIN - VOUT)IOUT + (VIN · IGND
PD(150mA) = (5.0V - 2.5V)150mA + (5.0V · 1.1mA)
PD(150mA) = 375mW
)
200mA
150mA
1.5
1
0.5
0
PD(8.2%D/C) = %DC · PD(150mA)
PD(8.2%D/C) = 0.082 · 375mW
PD(8.2%D/C) = 30.75mW
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
w w w . a n a l o g i c t e c h . c o m
12
3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
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:
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 lay-
out. If grounding connections are not properly made,
power supply ripple rejection and LDO regulator tran-
sient response can be compromised.
PD(total) = PD(100mA) + PD(150mA)
PD(total) = 229.5mW + 30.75mW
PD(total) = 260.25mW
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 limita-
tions, the LDO ground pin should then be connected to
the common ground plane in the application layout.
The maximum power dissipation for the AAT3221/2
operating at an ambient temperature of 85°C is 267mW.
The device in this example will have a total power dis-
sipation of 260.25mW. This is within the thermal limits
for safe operation of the device.
w w w . a n a l o g i c t e c h . c o m
3221.2007.11.1.12
13
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
Ordering Information
Output Voltage
Enable
Package
Marking1
Part Number (Tape and Reel)2
1.6V
1.7V
1.8V
1.9V
2.0V
2.3V
2.4V
2.5V
2.6V
2.7V
2.8V
2.85V
2.9V
3.0V
3.1V
3.3V
3.5V
1.5V
1.6V
1.7V
1.8V
1.9V
2.0V
2.3V
2.4V
2.5V
2.6V
2.7V
2.8V
2.85V
2.9V
3.0V
3.1V
3.2V
3.3V
3.5V
1.8V
2.0V
2.3V
2.4V
2.5V
2.7V
2.8V
2.85V
2.9V
3.0V
3.3V
3.5V
2.8V
3.3V
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 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
Active low
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
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
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
SOT23-5
GYXYY
GBXYY
BBXYY
CGXYY
BLXYY
FLXYY
FMXYY
AKXYY
GPXYY
GDXYY
AQXYY
BYXYY
JCXYY
ALXYY
GVXYY
AMXYY
BMXYY
CFXYY
AAT3221IGV-1.6-T1
AAT3221IGV-1.7-T1
AAT3221IGV-1.8-T1
AAT3221IGV-1.9-T1
AAT3221IGV-2.0-T1
AAT3221IGV-2.3-T1
AAT3221IGV-2.4-T1
AAT3221IGV-2.5-T1
AAT3221IGV-2.6-T1
AAT3221IGV-2.7-T1
AAT3221IGV-2.8-T1
AAT3221IGV-2.85-T1
AAT3221IGV-2.9-T1
AAT3221IGV-3.0-T1
AAT3221IGV-3.1-T1
AAT3221IGV-3.3-T1
AAT3221IGV-3.5-T1
AAT3221IJS-1.5-T1
AAT3221IJS-1.6-T1
AAT3221IJS-1.7-T1
BBXYY
CGXYY
BLXYY
FLXYY
FMXYY
AKXYY
GPXYY
GDXYY
AQXYY
BYXYY
JCXYY
ALXYY
GVXYY
LEXYY
AMXYY
BMXYY
BCXYY
AAT3221IJS-1.8-T1
AAT3221IJS-1.9-T1
AAT3221IJS-2.0-T1
AAT3221IJS-2.3-T1
AAT3221IJS-2.4-T1
AAT3221IJS-2.5-T1
AAT3221IJS-2.6-T1
AAT3221IJS-2.7-T1
AAT3221IJS-2.8-T1
AAT3221IJS-2.85-T1
AAT3221IJS-2.9-T1
AAT3221IJS-3.0-T1
AAT3221IJS-3.1-T1
AAT3221IJS-3.2-T1
AAT3221IJS-3.3-T1
AAT3221IJS-3.5-T1
AAT3222IGV-1.8-T1
AAT3222IGV-2.0-T1
AAT3222IGV-2.3-T1
AAT3222IGV-2.4-T1
ANXYY
AOXYY
BIXYY
FYXYY
AAT3222IGV-2.5-T1
AAT3222IGV-2.7-T1
AAT3222IGV-2.8-T1
AAT3222IGV-2.85-T1
AAT3222IGV-2.9-T1
AAT3222IGV-3.0-T1
AAT3222IGV-3.3-T1
AAT3222IGV-3.5-T1
AAT3221IGV-2.8-2 T1
AAT3221IGV-3.3-2-T1
BHXYY
APXYY
FTXYY
CXXYY
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
w w w . a n a l o g i c t e c h . c o m
14
3221.2007.11.1.12
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
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
SOT23-5
2.85 0.15
1.90 BSC
0.95
BSC
0.60 REF
0.15 0.07
GAUGE PLANE
0.075 0.075
0.45 0.15
0.10 BSC
0.60 REF
10° 5°
0.40 0.10
All measurements in millimeters.
w w w . a n a l o g i c t e c h . c o m
3221.2007.11.1.12
15
PRODUCT DATASHEET
AAT3221/2
PowerLinearTM
150mA NanoPower™ LDO Linear Regulator
SC70JW-8
0.50 BSC 0.50 BSC 0.50 BSC
0.225 0.075
2.00 0.20
0.048REF
0.100
0.45 0.10
4° 4°
7° 3°
2.10 0.30
All measurements in millimeters.
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.
w w w . a n a l o g i c t e c h . c o m
16
3221.2007.11.1.12
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