AAT3221IGV-20-T1 [ANALOGICTECH]
150mA NanoPower⑩ LDO Linear Regulator; 150毫安纳安级™ LDO线性稳压器
| 型号： | AAT3221IGV-20-T1 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | 150mA NanoPower⑩ LDO Linear Regulator |
| 文件： | 总16页 (文件大小：392K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
™
PowerLinear
General Description
Features
The AAT3221 and AAT3222 PowerLinear™
NanoPower Low Dropout Linear Regulators are
ideal for portable applications where extended bat-
tery life is critical. This device features extremely
low quiescent current which is typically 1.1µA.
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.
•
•
•
•
•
•
•
•
•
1.1 µA Quiescent Current
Low Dropout: 200 mV (typical)
Guaranteed 150 mA Output
High accuracy: 2ꢀ
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
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 over-
current events. It is available with active high or
active low enable input.
Applications
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 -40°C to 85°C temperature
range. Since only a small, 1µF 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 volt-
age conversion solution.
•
•
•
•
•
•
•
Cellular Phones
Notebook Computers
Portable Communication Devices
Handheld Electronics
Remote Controls
Digital Cameras
PDAs
The AAT3221/2 is similar to the AAT3220 with the
exception that it offers further power savings with
its enable pin.
Typical Application
INPUT
OUTPUT
ENABLE
(ENABLE)
(EN)
CIN
1µF
COUT
1µF
GND
GND
3221.2002.03.0.94
1
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Pin Descriptions
Pin #
AAT3221
AAT3222
Symbol
IN
Function
SOT23-5
SC70JW-8
1
2
3
2
5, 6, 7, 8
4
2
1
5
Input pin
GND
Ground connection pin
EN (EN)
Enable Input. Logic compatible enable with
active high or active low option available; see
Ordering Information and Applications
Information for details.
4
5
3
1
4
3
NC
Not Connected
OUT
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)
1
2
3
5
1
2
3
5
1
8
OUT
NC
EN (EN)
NC
IN
GND
(EN) EN
GND
IN
OUT
GND
GND
GND
GND
OUT
IN
NC
2
3
4
7
6
5
4
4
(EN) EN
2
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Absolute Maximum Ratings (TA=25°C unless otherwise noted)
Symbol
Description
Value
Units
VIN
VEN
Input Voltage
-0.3 to 6
-0.3 to 6
0.3
V
V
EN (EN) to GND Voltage
VENIN(MAX)
IOUT
Maximum EN (EN) to Input Voltage
Maximum DC Output Current
V
PD/(VIN-VO)
-40 to 150
300
mA
°C
°C
TJ
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
TLEAD
Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-
ditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.
Thermal Information
Symbol
Description
Thermal Resistance (SOT23-5 or SC70JW-8)1
Power Dissipation (SOT23-5 or SC70JW-8)1
Rating
Units
ΘJA
150
667
°C/W
mW
PD
Note 1: Mounted on a demo board.
Recommended Operating Conditions
Symbol
Description
Rating
Units
VIN
T
Input Voltage
(VOUT+0.34) to 5.5
-40 to +85
V
Ambient Temperature Range
°C
3221.2002.03.0.94
3
AAT3221/2
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
-2.0
-1.4
150
2.0
ꢀ
VOUT
DC Output Voltage Tolerance
VOUT=2.8V
VOUT > 1.2 V
1.4
IOUT
Output Current
mA
mA
ISC
Short Circuit Current
Ground Current
Shutdown Current
Line Regulation
VOUT < 0.4 V
350
1.1
IQ
ISD
VIN = 5 V, no load
EN = inactive
VIN = 4.0-5.5 V
2.5
µA
nA
20
∆VOUT/VOUT
0.15
1.0
0.4
ꢀ/V
VOUT = 1.8
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
VOUT = 2.0
VOUT = 2.3
VOUT = 2.4
VOUT = 2.5
VOUT = 2.7
VOUT = 2.8
VOUT = 2.85
VOUT = 3.0
VOUT = 3.3
VOUT = 3.5
VOUT = 1.8
VOUT = 2.0
VOUT = 2.3
VOUT = 2.4
VOUT = 2.5
VOUT = 2.7
VOUT = 2.8
VOUT = 2.85
VOUT = 3.0
VOUT = 3.3
VOUT = 3.5
0.9
0.8
0.8
0.8
∆VOUT/VOUT
Load Regulation
IL=1 to 100mA
0.7
ꢀ
0.7
0.7
0.6
0.5
0.5
290
265
230
220
210
200
190
190
190
180
180
VDO
Dropout Voltage1
IOUT = 100mA
mV
VEN(L)
VEN(H)
EN Input Low Voltage
EN Input High Voltage
V
V
V
IN = 2.7 V to 3.6 V
2.0
2.4
VIN = 5 V
V
IEN(SINK)
PSRR
TSD
EN Input leakage
VON = 5.5 V
100 Hz
0.01
50
1
µA
Power Supply Rejection Ratio
Over Temp Shutdown Threshold
Over Temp Shutdown Hysteresis
Output Noise
dB
140
20
°C
THYS
eN
°C
350
80
µVRMS
PPM/°C
TC
Output Voltage Temp. Coefficient
Note 1: VDO is defined as VIN - VOUT when VOUT is 98ꢀ of nominal.
4
3221.2002.03.0.94
AAT3221/2
150mA NanoPower LDO Linear Regulator
Typical Characteristics
(Unless otherwise noted, VIN = VOUT + 1V, TA = 25 C, COUT = 5.6 F ceramic, IOUT = 100mA)
Output Voltage v. Input Voltage
Output Voltage vs. Output Current
3.1
3
3.03
3.02
3.01
3
1mA
2.9
2.8
2.7
2.6
2.5
40mA
-30°C
25°C
2.99
2.98
2.97
80°C
10mA
2.7
2.9
3.1
3.3
3.5
0
20
40
60
80
100
Input (V)
Output (mA)
Output Voltage vs. Input Voltage
Drop-out 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 (V)
Output (mA)
Supply Current vs. Input Voltage
PSRR with 10mA Load
5
4
3
2
1
0
60
40
20
0
25°C
80°C
-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 (V)
Frequency (Hz)
3221.2002.03.0.94
5
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
(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 100mA Load
Line Response with 10mA Load
3.8
3.6
3.4
3.2
3
6
5
4
3
2
1
0
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
-200
0
200
400
600
800
-200
0
200
400
600
800
Time (µs)
Time (µs)
Load Transient - 1 mA / 40 mA
Load Transient - 1 mA / 80 mA
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)
6
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
(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
Enable
1
1
0
-1
-2
-3
0
Output
Output
-1
-
1
0
1
2
-
-
-
1
0
1
1
1
2
2
2
Time (ms)
Time (ms)
Power Up with 10mA Load
Turn On 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
1
0
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
1
0
Time (ms)
Time (ms)
3221.2002.03.0.94
7
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Functional Block Diagram
IN
OUT
Over-Current
Protection
Over-Temp
Protection
EN
VREF
GND
truly high performance LDO regulator especially
well suited for circuit applications which are sensi-
tive to load circuit power consumption and extend-
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 man-
agement systems for small battery operated
devices. The typical quiescent current level is just
1.1µA. The AAT3221/2 also contains an enable cir-
cuit, 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 1µA from input supply.
ed 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 condi-
tions. 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.
The LDO also demonstrates excellent power sup-
ply ripple rejection (PSRR), and load and line tran-
sient response characteristics. The AAT3221/2 is a
8
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
The total output capacitance required can be cal-
culated using the following formula:
Applications Information
To assure the maximum possible performance is
obtained from the AAT3221/2, please refer to the
following application recommendations.
∆I
∆V
COUT
=
× 15µF
Where:
Input Capacitor
∆I = maximum step in output current
Typically a 1µF 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 val-
ues greater than 1µF will offer superior input line
transient response and will assist in maximizing the
power supply ripple rejection.
∆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 tempera-
ture. The increased capacitor value is recommend-
ed if tight output tolerances must be maintained over
extreme operating conditions and maximum opera-
tional temperature excursions. If tantalum or alu-
minum 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 capaci-
tors may be selected for CIN as there is no specific
capacitor ESR requirement. For 150mA LDO reg-
ulator output operation, ceramic capacitors are rec-
ommended for CIN due to their inherent capability
over tantalum capacitors to withstand input current
surges from low impedance sources such as bat-
teries in portable devices.
Capacitor Characteristics
Ceramic composition capacitors are highly recom-
mended over all other types of capacitors for use
with the AAT3221/2. Ceramic capacitors offer
many advantages over their tantalum and alu-
minum electrolytic counterparts. A ceramic capac-
itor 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.
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 per-
formance. The AAT3221/2 has been specifically
designed to function with very low ESR ceramic
capacitors. Although the device is intended to oper-
ate 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 perform-
ance, 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
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.
The value of COUT typically ranges from 0.47µF to
10µF, however 1µF is sufficient for most operating
conditions.
Ceramic Capacitor Materials: Ceramic capacitors
less than 0.1µF are typically made from NPO or
COG materials. NPO and COG materials are typi-
cally tight tolerance and very stable over tempera-
ture. Larger capacitor values are typically composed
of X7R, X5R, Z5U and Y5V dielectric materials.
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.
3221.2002.03.0.94
9
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Large ceramic capacitors, typically greater than
dissipation capacity has been exceeded and the
internal die temperature reaches approximately
140°C the system thermal protection circuit will
become active. The internal thermal protection cir-
cuit will actively turn off the LDO regulator output
pass device to prevent the possibility of over tem-
perature damage. The LDO regulator output will
remain in a shutdown state until the internal die
temperature falls back below the 140°C trip point.
2.2µF are often available in the low cost Y5V and Z5U
dielectrics. These two material types are not recom-
mended for use with LDO regulators since the capac-
itor tolerance can vary more than 50ꢀ 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 prob-
lems for circuit operation and stability. X7R and X5R
dielectrics are much more desirable. The tempera-
ture tolerance of X7R dielectric is better than 15ꢀ.
The interaction between the short circuit and ther-
mal protection systems allow the LDO regulator to
withstand indefinite short circuit conditions without
sustaining permanent damage.
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 capaci-
tance value. These larger devices can also improve
circuit transient response when compared to an
equal value capacitor in a smaller package size.
No-Load Stability
The AAT3221/2 is designed to maintain output volt-
age regulation and stability under operational no-
load 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 recom-
mended typical output capacitor values.
Consult capacitor vendor data sheets carefully when
selecting capacitors for use with LDO regulators.
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 regula-
tor in a continuously on state; e.g. the active high ver-
sion 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 operat-
ing conditions. The limiting characteristic for the
maximum output load safe operating area is essen-
tially package power dissipation and the internal pre-
set 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 reg-
ulator is mounted on a printed circuit board utilizing
the minimum recommended footprint and the print-
ed circuit board is 0.062inch 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 acti-
vate 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 volt-
age will drop and the AAT3221/2's die temperature
will increase rapidly. Once the regulator's power
At any given ambient temperature (TA) the maxi-
mum package power dissipation can be deter-
mined by the following equation:
PD(MAX) = [TJ(MAX) - TA] / Θ JA
Constants for the AAT3221/2 are TJ(MAX), the maxi-
mum junction temperature for the device which is
125°C and ΘJA = 150°C/W, the package thermal
resistance. Typically, maximum conditions are cal-
culated at the maximum operating temperature
where TA = 85°C, under normal ambient conditions
10
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
TA = 25°C. Given TA = 85°, the maximum package
power dissipation is 267mW. At TA = 25°C°, the
maximum package power dissipation is 667mW.
AAT3221/2, thus at 25°C, the device would not have
any thermal concerns or operational VIN(MAX) limits.
This situation can be different at 85°C. The follow-
ing is an example for an AAT3221/2 set for a 2.5
volt output at 85°C:
The maximum continuous output current for the
AAT3221/2 is a function of the package power dis-
sipation and the input to output voltage drop across
the LDO regulator. Refer to the following simple
equation:
From the discussion above, PD(MAX) was deter-
mined to equal 267mW at TA = 85°C.
VOUT = 2.5 volts
IOUT = 150mA
IGND = 1.1µA
IOUT(MAX) < PD(MAX) / (VIN - VOUT
)
For example, if VIN = 5V, VOUT = 2.5V and TA = 25°,
IOUT(MAX) < 267mA. The output short circuit protec-
tion 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 inter-
nal 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.
VIN(MAX)=(267mW+(2.5Vx150mA))/(150mA +1.1µA)
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.
To figure what the maximum input voltage would be
for a given load current refer to the following equa-
tion. This calculation 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 continuous 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:
P
D(MAX) = (VIN - VOUT)IOUT + (VIN x IGND)
This formula can be solved for VIN to determine
the maximum input voltage.
PD(MAX) is assumed to be 267mW
VIN(MAX) = (PD(MAX) + (VOUT x IOUT)) / (IOUT + IGND
)
IGND = 1.1µA
IOUT = 150mA
VIN = 5.0 volts
VOUT = 2.5 volts
The following is an example for an AAT3221/2 set
for a 2.5 volt output:
From the discussion above, PD(MAX) was deter-
mined to equal 667mW at TA = 25°C.
ꢀDC = 100(PD(MAX) / ((VIN - VOUT)IOUT + (VIN x IGND))
ꢀDC=100(267mW/((5.0V-2.5V)150mA+(5.0Vx1.1µA))
ꢀDC = 71.2ꢀ
VOUT = 2.5 volts
IOUT = 150mA
IGND = 1.1µA
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 71.2ꢀ.
VIN(MAX)=(667mW+(2.5Vx150mA))/(150mA +1.1µA)
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 25°C. 5.5V is
the maximum input operating voltage for the
The following family of curves shows the safe oper-
ating area for duty cycled operation from ambient
room temperature to the maximum operating level.
3221.2002.03.0.94
11
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
High Peak Output Current Applications
Device Duty Cycle vs. VDROP
VOUT = 2.5V @ 25 degrees C
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 calcu-
late the power dissipation at the nominal continu-
ous level, then factor in the addition power dissipa-
tion due to the short duration high current peaks.
3.5
3
200mA
2.5
2
1.5
1
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 378µs out of a 4.61ms
period. It will be assumed the input voltage is 5.0V.
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
First, the current duty cycle percentage must be
calculated:
ꢀ Peak Duty Cycle: X/100 = 378ms/4.61ms
ꢀ Peak Duty Cycle = 8.2ꢀ
Device Duty Cycle vs. VDROP
VOUT = 2.5V @ 50 degrees C
The LDO Regulator will be under the 100mA load
for 91.8ꢀ of the 4.61ms period and have 150mA
peaks occurring for 8.2ꢀ 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 dis-
sipation over time.
3.5
3
200mA
2.5
2
150mA
1.5
1
0.5
0
PD(MAX) = (VIN - VOUT)IOUT + (VIN x IGND
)
0
10
20
30
40
50
60
70
80
90
100
PD(100mA) = (5.0V - 2.5V)100mA + (5.0V x 1.1mA)
PD(100mA) = 250mW
Duty Cycle (%)
PD(91.8ꢀD/C) = ꢀDC x PD(100mA)
PD(91.8ꢀD/C) = 0.918 x 250mW
PD(91.8ꢀD/C) = 229.5mW
Device Duty Cycle vs. VDROP
VOUT = 2.5V @ 85 degrees C
3.5
3
100mA
2.5
2
200mA
150mA
1.5
1
0.5
0
0
10
20
30
40
50
60
70
80
90
100
Duty Cycle (%)
12
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
The power dissipation for a 100mA load occurring
Printed Circuit Board Layout
Recommendations
for 91.8ꢀ of the duty cycle will be 229.5mW. Now
the power dissipation for the remaining 8.2ꢀ of the
duty cycle at the 150mA load can be calculated:
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 prop-
erly made, power supply ripple rejection and LDO
regulator transient response can be compromised.
PD(MAX) = (VIN - VOUT)IOUT + (VIN x IGND)
PD(150mA) = (5.0V - 2.5V)150mA + (5.0V x 1.1mA)
PD(150mA) = 375mW
PD(8.2ꢀD/C) = ꢀDC x PD(150mA)
PD(8.2ꢀD/C) = 0.082 x 375mW
PD(8.2ꢀD/C) = 30.75mW
The LDO Regulator external capacitors CIN and
COUT should be connected as directly as possible
to the ground pin of the LDO Regulator. For maxi-
mum performance with the AAT3221/2, the ground
pin connection should then be made directly back
to the ground or common of the source power sup-
ply. 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.
The power dissipation for a 150mA load occurring
for 8.2ꢀ 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.
P
D(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 85°C 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.
3221.2002.03.0.94
13
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Ordering Information
Part Number
Output Voltage
Enable
Package
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
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
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
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
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
14
3221.2002.03.0.94
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
Package Information
SOT23-5
e
Millimeters
Inches
Dim
S1
Min
Max
1.45
0.15
1.30
0.50
0.20
3.00
1.70
Min
Max
A
A1
A2
b
c
D
E
0.95
0.05
0.90
0.35
0.08
2.84
1.50
0.037
0.002
0.035
0.014
0.003
0.112
0.059
0.057
0.006
0.051
0.019
0.078
0.112
0.067
H
E
e
1.90
0.0748
D
H
L
S
S1
Θ
2.60
0.35
0.47
.95
3.00
0.55
0.55
0.102
.0137
0.019
0.037
0°
0.118
.0216
.0216
A
A1
c
I
S
b
0°
10°
10°
L
SC70JW-8
e
e
e
Millimeters
Min Max
2.10 BSC
Inches
Dim
Min
Max
E
E1
L
0.083 BSC
1.75
0.23
2.00
0.40
1.10
0.10
1.00
0.069
0.009
0.079
0.016
0.043
0.004
0.039
E
A
A1
A2
D
0
0.70
0.028
2.00 BSC
0.50 BSC
0.079 BSC
0.020 BSC
b
e
D
b
c
Θ
Θ 1
0.15
0.10
0
0.30
0.20
8º
0.006
0.004
0
0.012
0.008
8º
0.048REF
c
A2
A
4º
10º
4º
10º
A1
L
Θ
Θ1
E1
3221.2002.03.0.94
15
AAT3221/2
150mA NanoPower™ LDO Linear Regulator
This page intentionally left blank
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
相关型号：
AAT3221IGV-3.1-T1
Fixed Positive LDO Regulator, 3.1V, 0.222V Dropout, CMOS, PDSO5, GREEN, SOT-23, 5 PIN
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