AAT3221IGV-2.8-2-T1 - AnalogicTech

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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General Description

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.

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.

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.

The AAT3221 and AAT3122 are similar to the AAT3220,

with the exception that they offer further power savings

with an enable pin.

Features

• 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

• 5-Pin SOT23 or 8-Pin SC70JW Package

• -40°C to +85°C Temperature Range

Applications

• Cellular Phones

• Digital Cameras

• Handheld Electronics

• Notebook Computers

• PDAs

• Portable Communication Devices

• Remote Controls

Typical Application

AAT3221/2

INPUT

GND

OUT

OUTPUT

GNDGND

ENABLE

(ENABLE)

CIN

1μF

COUT

1μF

(EN)

AAT3221/2

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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Pin Descriptions

Pin #

Symbol Function

AAT3221

AAT3222

SOT23-5 SC70JW-8

1 2 2 IN Input pin.

2 5, 6, 7, 8 1 GND Ground connection pin.

34 5

EN (EN) Enable input. Logic compatible enable with active high or active low option

available; see Ordering Information and Applications Information for details.

4 3 4 NC Not connected.

5 1 3 OUT Output pin; should be decoupled with 1μF or greater capacitor.

Pin Configuration

AAT3221 AAT3221 AAT3222

SOT23-5 SC70JW-8 SOT23-5

(Top View) (Top View) (Top View)

GND

OUT

(EN) EN

GND

OUT 1

EN (EN)

OUT

GND

AAT3221/2

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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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 EN (EN) to GND Voltage -0.3 to 6 V

VENIN(MAX) Maximum EN (EN) to Input Voltage 0.3 V

IOUT Maximum DC Output Current PD/(VIN-VO)mA

TJOperating Junction Temperature Range -40 to 150 °C

Thermal Information2

Symbol Description Value Units

ΘJA Thermal Resistance 150 °C/W

PDPower Dissipation 667 mW

Recommended Operating Conditions

Symbol Description Rating Units

VIN Input Voltage3(VOUT + VDO) to 5.5 V

T Ambient Temperature Range -40 to +85 °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.

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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Electrical Characteristics

VIN = VOUT(NOM) + 1V, IOUT = 1mA, COUT = 1μF, TA = 25°C, unless otherwise noted.

Symbol Description Conditions Min Typ Max Units

VOUT DC Output Voltage Tolerance -2.0 2.0 %

IOUT Output Current VOUT > 1.2V 150 mA

ISC Short-Circuit Current VOUT < 0.4V 350 mA

IQGround Current VIN = 5V, No Load 1.1 2.5 μA

ISD Shutdown Current EN = Inactive 20 nA

ΔVOUT/VOUT*ΔVIN Line Regulation VIN = 4.0V to 5.5V 0.15 0.4 %/V

ΔVOUT/VOUT Load Regulation IL = 1 to 100mA

VOUT = 1.5 1.3 1.72

VOUT = 1.6 1.2 1.69

VOUT = 1.7 1.1 1.67

VOUT = 1.8 1.0 1.65

VOUT = 1.9 1.0 1.62

VOUT = 2.0 0.9 1.58

VOUT = 2.3 0.8 1.45

VOUT = 2.4 0.8 1.40

VOUT = 2.5 0.8 1.35

VOUT = 2.6 0.8 1.30

VOUT = 2.7 0.7 1.25

VOUT = 2.8 0.7 1.20

VOUT = 2.85 0.7 1.20

VOUT = 2.9 0.7 1.18

VOUT = 3.0 0.6 1.15

VOUT = 3.1 0.6 1.06

VOUT = 3.3 0.5 1.00

VOUT = 3.5 0.5 1.00

VDO Dropout Voltage1, 2 IOUT = 100mA

VOUT = 2.3 230 275

VOUT = 2.4 220 265

VOUT = 2.5 210 255

VOUT = 2.6 205 247

VOUT = 2.7 200 240

VOUT = 2.8 190 235

VOUT = 2.85 190 230

VOUT = 2.9 190 228

VOUT = 3.0 190 225

VOUT = 3.1 188 222

VOUT = 3.3 180 220

VOUT = 3.5 180 220

VEN(L) EN Input Low Voltage 0.8 V

VEN(H) EN Input High Voltage VIN = 2.7V to 3.6V 2.0 V

VIN = 5V 2.4

IEN(SINK) EN Input Leakage VON = 5.5V 0.01 1 μA

PSRR Power Supply Rejection Ratio 100Hz 50 dB

TSD Over-Temperature Shutdown Threshold 140 °C

THYS Over-Temperature Shutdown Hysteresis 20 °C

eNOutput Noise 350 μVRMS

TCOutput Voltage Temperature Coefﬁ cient 80 PPM/°C

1. VDO is defined as VIN - VOUT when VOUT is 98% of nominal.

2. For VOUT < 2.3V, VDO = 2.5V - VOUT

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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Typical Characteristics

Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.

Output Voltage vs. Output Current

2.97

2.98

2.99

3.01

3.02

3.03

020406080100

Output Current (mA)

Output Voltage (V)

80°C

25°C

-30°C

Output Voltage vs. Input Voltage

2.5

2.6

2.7

2.8

2.9

3.1

2.7 2.9 3.1 3.3 3.5

Input Voltage (V)

Output Voltage (V)

1mA

10mA

40mA

Output Voltage vs. Input Voltage

2.99

3.01

3.02

3.03

3.5 4 4.5 5 5.5

Input Voltage (V)

Output Voltage (V)

1mA

10mA

40mA

Dropout Voltage vs. Output Current

100

200

300

400

0255075100125150

Output Current (mA)

Dropout Voltage (mV)

80°C

-30°C

25°C

Supply Current vs. Input Voltage

2.0

1.6

1.2

0.8

0.4

0123456

Input Voltage (V)

Input Current (µA) with No Load

25°C

80°C

-30°C

PSRR with 10mA Load

1.E+01 1.E+02 1.E+03 1.E+04 1.E+05

Frequency (Hz)

PSRR (dB)

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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Typical Characteristics

Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.

Noise Spectrum

-30

-20

-10

1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Frequency (Hz)

Noise (dB

V/rt Hz)

Line Response with 1mA Load

2.6

2.8

3.2

3.4

3.6

3.8

-200 0 200 400 600 800

Time (µs)

Output Voltage (V)

Input Voltage (V)

Input

Output

Line Response with 10mA Load

2.6

2.8

3.2

3.4

3.6

3.8

-200 0 200 400 600 800

Time (µs)

Output Voltage (V)

Input

Output

Input Voltage (V)

Line Response with 100mA Load

2.6

2.8

3.2

3.4

3.6

3.8

-200 0 200 400 600 800

Time (µs)

Output Voltage (V)

Input

Output

Input Voltage (V)

Load Transient - 1mA / 40mA

-1 0 1 2 3

Time (ms)

Output Voltage (V)

160

240

320

Output Current (mA)

Output

Load Transient - 1mA / 80mA

-1 0 1 2 3

Time (ms)

Output Voltage (V)

160

240

320

Output Current (mA)

Output

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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Typical Characteristics

Unless otherwise noted, VIN = VOUT + 1V, TA = 25°C, COUT = 5.6μF Ceramic, IOUT = 100mA.

Power-Up with 1mA Load

-1 0 1 2

Time (ms)

Output Voltage (V)

-3

-2

-1

Input Voltage (V)

Output

Enable

Turn-On with 1mA Load

-1 0 1 2

Time (ms)

-1

Enable (V)

Output

Enable

Output Voltage (V)

Power-Up with 10mA Load

-1 0 1 2

Time (ms)

-3

-2

-1

Output

Enable

Output Voltage (V)

Input Voltage (V)

Turn-On with 10mA Load

-1 0 1 2

Time (ms)

-1

Enable (V)

Output

Enable

Output Voltage (V)

Power-Up with 100mA Load

-1 0 1 2

Time (ms)

-3

-2

-1

Output

Enable

Output Voltage (V)

Input Voltage (V)

Turn-On with 100mA Load

-1 0 1 2

Time (ms)

-1

Enable (V)

Output

Enable

Output Voltage (V)

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

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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 also demonstrates excellent power supply rip-

ple rejection (PSRR) and load and line transient response

characteristics. The AAT3221/2 high performance LDO

regulator is especially well suited for circuit applications

that 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 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.

Functional Block Diagram

Over-Current

Protection

Over-Temperature

Protection

VREF

OUT

GND

AAT3221/2

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Applications Information

To ensure that the maximum possible performance is

obtained from the AAT3221/2, please refer to the follow-

ing application recommendations.

Input Capacitor

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.

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.

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.

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.

The total output capacitance required can be calculated

using the following formula:

COUT = · 15µF

ΔI

ΔV

Where:

ΔI = maximum step in output current

ΔV = 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 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.

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.

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.

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

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

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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%.

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.

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.

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

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.

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.

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.

At any given ambient temperature (TA), the maximum

package power dissipation can be determined by the fol-

lowing equation:

PD(MAX) = TJ(MAX) - TA

θJA

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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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.

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:

IOUT(MAX) = PD(MAX)

(VIN - VOUT)

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.

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.

PD(MAX) = (VIN - VOUT)IOUT + (VIN · IGND)

This formula can be solved for VIN to determine the

maximum input voltage.

VIN(MAX) = (PD(MAX) + [VOUT · IOUT])

(IOUT + IGND)

The following is an example for an AAT3221/2 set for a

2.5 volt output:

VOUT = 2.5 volts

IOUT = 150mA

IGND = 1.1μA

VIN(MAX) =

VIN(MAX) = 6.95V

(667mW + [2.5V · 150mA])

(150mA + 1.1µA)

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.

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

VIN(MAX) =

VIN(MAX) = 4.28V

(267mW + [2.5V · 150mA])

(150mA + 1.1µA)

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.

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:

IGND = 1.1μA

IOUT = 150mA

VIN = 5.0 volts

VOUT = 2.5 volts

%DC = 100 PD(MAX)

([VIN - VOUT]IOUT + [VIN · IGND])

%DC = 100

%DC = 71.2%

267mW

([5.0V - 2.5V]150mA + [5.0V · 1.1µA]

)

PD(MAX) is assumed to be 267mW.

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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%.

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

0.5

1.5

2.5

3.5

0 102030405060708090100

Duty Cycle (%)

Voltage Drop (V)

200mA

(VOUT = 2.5V @ 25

Device Duty Cycle vs. VDROP

(VOUT = 2.5V @ 50

0.5

1.5

2.5

3.5

0 102030405060708090100

Duty Cycle (%)

Voltage Drop (V)

200mA

150mA

Device Duty Cycle vs. VDROP

(VOUT = 2.5V @ 85

0.5

1.5

2.5

3.5

0 10 2030 405060 7080 90100

Duty Cycle (%)

Voltage Drop (V)

200mA

150mA

100mA

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.

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.

First, the current duty cycle percentage must be

calculated:

% 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.

PD(MAX) = (VIN - VOUT)IOUT + (VIN · IGND)

PD(100mA) = (5.0V - 2.5V)100mA + (5.0V · 1.1mA)

PD(100mA) = 250mW

PD(91.8%D/C) = %DC · PD(100mA)

PD(91.8%D/C) = 0.918 · 250mW

PD(91.8%D/C) = 229.5mW

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 · IGND)

PD(150mA) = (5.0V - 2.5V)150mA + (5.0V · 1.1mA)

PD(150mA) = 375mW

PD(8.2%D/C) = %DC · PD(150mA)

PD(8.2%D/C) = 0.082 · 375mW

PD(8.2%D/C) = 30.75mW

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

3221.2007.11.1.12 13

www.analogictech.com

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 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.

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.

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.

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

14 3221.2007.11.1.12

www.analogictech.com

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

14 3221.2007.11.1.12

www.analogictech.com

Ordering Information

Output Voltage Enable Package Marking1Part Number (Tape and Reel)2

1.6V Active high SOT23-5 GYXYY AAT3221IGV-1.6-T1

1.7V Active high SOT23-5 GBXYY AAT3221IGV-1.7-T1

1.8V Active high SOT23-5 BBXYY AAT3221IGV-1.8-T1

1.9V Active high SOT23-5 CGXYY AAT3221IGV-1.9-T1

2.0V Active high SOT23-5 BLXYY AAT3221IGV-2.0-T1

2.3V Active high SOT23-5 FLXYY AAT3221IGV-2.3-T1

2.4V Active high SOT23-5 FMXYY AAT3221IGV-2.4-T1

2.5V Active high SOT23-5 AKXYY AAT3221IGV-2.5-T1

2.6V Active high SOT23-5 GPXYY AAT3221IGV-2.6-T1

2.7V Active high SOT23-5 GDXYY AAT3221IGV-2.7-T1

2.8V Active high SOT23-5 AQXYY AAT3221IGV-2.8-T1

2.85V Active high SOT23-5 BYXYY AAT3221IGV-2.85-T1

2.9V Active high SOT23-5 JCXYY AAT3221IGV-2.9-T1

3.0V Active high SOT23-5 ALXYY AAT3221IGV-3.0-T1

3.1V Active high SOT23-5 GVXYY AAT3221IGV-3.1-T1

3.3V Active high SOT23-5 AMXYY AAT3221IGV-3.3-T1

3.5V Active high SOT23-5 BMXYY AAT3221IGV-3.5-T1

1.5V Active high SC70JW-8 CFXYY AAT3221IJS-1.5-T1

1.6V Active high SC70JW-8 AAT3221IJS-1.6-T1

1.7V Active high SC70JW-8 AAT3221IJS-1.7-T1

1.8V Active high SC70JW-8 BBXYY AAT3221IJS-1.8-T1

1.9V Active high SC70JW-8 CGXYY AAT3221IJS-1.9-T1

2.0V Active high SC70JW-8 BLXYY AAT3221IJS-2.0-T1

2.3V Active high SC70JW-8 FLXYY AAT3221IJS-2.3-T1

2.4V Active high SC70JW-8 FMXYY AAT3221IJS-2.4-T1

2.5V Active high SC70JW-8 AKXYY AAT3221IJS-2.5-T1

2.6V Active high SC70JW-8 GPXYY AAT3221IJS-2.6-T1

2.7V Active high SC70JW-8 GDXYY AAT3221IJS-2.7-T1

2.8V Active high SC70JW-8 AQXYY AAT3221IJS-2.8-T1

2.85V Active high SC70JW-8 BYXYY AAT3221IJS-2.85-T1

2.9V Active high SC70JW-8 JCXYY AAT3221IJS-2.9-T1

3.0V Active high SC70JW-8 ALXYY AAT3221IJS-3.0-T1

3.1V Active high SC70JW-8 GVXYY AAT3221IJS-3.1-T1

3.2V Active high SC70JW-8 LEXYY AAT3221IJS-3.2-T1

3.3V Active high SC70JW-8 AMXYY AAT3221IJS-3.3-T1

3.5V Active high SC70JW-8 BMXYY AAT3221IJS-3.5-T1

1.8V Active high SOT23-5 BCXYY AAT3222IGV-1.8-T1

2.0V Active high SOT23-5 AAT3222IGV-2.0-T1

2.3V Active high SOT23-5 AAT3222IGV-2.3-T1

2.4V Active high SOT23-5 AAT3222IGV-2.4-T1

2.5V Active high SOT23-5 ANXYY AAT3222IGV-2.5-T1

2.7V Active high SOT23-5 AOXYY AAT3222IGV-2.7-T1

2.8V Active high SOT23-5 BIXYY AAT3222IGV-2.8-T1

2.85V Active high SOT23-5 FYXYY AAT3222IGV-2.85-T1

2.9V Active high SOT23-5 AAT3222IGV-2.9-T1

3.0V Active high SOT23-5 BHXYY AAT3222IGV-3.0-T1

3.3V Active high SOT23-5 APXYY AAT3222IGV-3.3-T1

3.5V Active high SOT23-5 FTXYY AAT3222IGV-3.5-T1

2.8V Active low SOT23-5 CXXYY AAT3221IGV-2.8-2 T1

3.3V Active low SOT23-5 AAT3221IGV-3.3-2-T1

1. XYY = assembly and date code.

2. Sample stock is generally held on part numbers listed in BOLD.

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

3221.2007.11.1.12 15

www.analogictech.com

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

3221.2007.11.1.12 15

www.analogictech.com

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

0.15

0.07

0.45

0.15 0.10 BSC

1.20

0.25

1.575

0.125

2.80

0.20

0.40

0.10

0.60 REF

2.85

0.15

1.90 BSC

0.95

BSC

1.10

0.20

GAUGE PLANE

0.075

0.60 REF

All measurements in millimeters.

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

16 3221.2007.11.1.12

www.analogictech.com

AAT3221/2

150mA NanoPower™ LDO Linear RegulatorPowerLinearTM

PRODUCT DATASHEET

16 3221.2007.11.1.12

www.analogictech.com

Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

Phone (408) 737-4600

Fax (408) 737-4611

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 speciﬁ cations 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 ﬁ tness 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. Speciﬁ c 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.

SC70JW-8

0.225

0.075

0.45

0.10

0.05

2.10

0.30

2.00

0.20

1.75

0.10

0.85

0.15

0.05

1.10 MAX

0.100

2.20

0.20

0.048REF

0.50 BSC 0.50 BSC 0.50 BSC

All measurements in millimeters.