Datasheet ADP3338 Datasheet (Analog Devices)

Page 1

High Accuracy, Ultralow IQ, 1 A,

FEATURES

High accuracy over line and load: ±0.8% @ 25°C,

±1.4% over temperature Ultralow dropout voltage: 190 mV (typ) @ 1 A Requires only C anyCAP = stable with any type of capacitor (including MLCC) Current and thermal limiting Low noise

2.7 V to 8 V supply range

−40°C to +85°C ambient temperature range SOT-223 package

APPLICATIONS

Notebook, palmtop computers SCSI terminators Battery-powered systems Bar code scanners Camcorders, cameras Home entertainment systems Networking systems DSP/ASIC supplies

GENERAL DESCRIPTION

The ADP3338 is a member of the ADP33xx family of precision, low dropout, anyCAP voltage regulators. The ADP3338 operates with an input voltage range of 2.7 V to 8 V and delivers a load current up to 1 A. The ADP3338 stands out from conventional LDOs with a novel architecture and an enhanced process that allows it to offer performance advantages and higher output current than its competition. Its patented design requires only a 1 µF output capacitor for stability. This device is insensitive to output capacitor equivalent series resistance (ESR), and is stable with any good quality capacitor, including ceramic (MLCC) types for space-restricted applications. The ADP3338 achieves exceptional accuracy of ±0.8% at room temperature and ±1.4% over temperature, line, and load variations. The dropout voltage of the ADP3338 is only 190 mV (typical) at 1 A. The device also includes a safety current limit and thermal overload protection. The ADP3338 has ultralow quiescent current: 110 µA (typical) in light load situations.

= 1.0 µF for stability

anyCAP

THERMAL

PROTECTION

1µF

Low Dropout Regulator

ADP3338

FUNCTIONAL BLOCK DIAGRAM

ADP3338

DRIVER

GND

Figure 1.

ADP3338

GND

Figure 2. Typical Application Circuit

BANDGAP

OUT

REF

1µF

OUT

02050-0-002

OUT

02050-0-001

Rev. A

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

www.analog.com

Page 2

ADP3338

TABLE OF CONTENTS

Specifications..................................................................................... 3

Capacitor Selection.................................................................... 10

Absolute Maximum Ratings............................................................ 4

ESD Caution.................................................................................. 4

Pin Configuration and Function Descriptions............................. 5

Typical Performance Characteristics ............................................. 6

Theory of Operation ........................................................................ 9

Application Information................................................................ 10

REVISION HISTORY

6/04—Data Sheet Changed from Rev. 0 to Rev. A

Updated Format..............................................................Universal

Changes to Figures 5, 11, 12, 13, 14, 15 ...................................... 6

Updated Outline Dimensions................................................... 12

Changes to Ordering Guide...................................................... 12

6/01—Rev. 0: Initial Version

Output Current Limit................................................................ 10

Thermal Overload Protection .................................................. 10

Calculating Power Dissipation ................................................. 10

Printed Circuit Board Layout Considerations........................ 10

Outline Dimensions....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. A | Page 2 of 12

Page 3

ADP3338

SPECIFICATIONS

VIN = 6.0 V, CIN = C

Table 1.

Parameter Symbol Conditions Min Typ Max Unit

OUTPUT

Voltage Accuracy V V V Line Regulation VIN = V Load Regulation IL = 0.1 mA to 1 A, TJ = 25°C 0.006 mV/mA Dropout Voltage V I I I Peak Load Current I Output Noise V

GROUND CURRENT

In Regulation I I I I In Dropout I

All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC) methods.

Application stable with no load.

VIN = 2.7 V for models with V

1, , 2 3

= 1 µF, TJ = −40°C to +125°C, unless otherwise noted.

OUT

DROP

LDPK

NOISE

GND

OUTNOM

VIN = V

= V

= 98% of V

OUT

= 1 A 190 400 mV

= 500 mA 125 200 mV

= 100 mA 70 150 mV

VIN = V f = 10 Hz–100 kHz, CL = 10 µF, IL = 1 A 95 µV rms

IL = 1 A 9 30 mA

= 500 mA 4.5 15 mA

= 100 mA 0.9 3 mA

= 0.1 mA 110 190 µA

VIN = V

≤ 2.2 V.

+ 0.4 V to 8 V, IL = 0.1 mA to 1 A, TJ = 25°C −0.8 +0.8 %

OUTNOM

+ 0.4 V to 8 V, IL = 0.1 mA to 1 A, TJ = −40°C to +125°C −1.4 +1.4 %

OUTNOM

+ 0.4 V to 8 V, IL = 50 mA to 1 A, TJ = 150°C −1.6 +1.6 %

OUTNOM

+ 0.4 V to 8 V, TJ = 25°C 0.04 mV/V

OUTNOM

+ 1 V 1.6 A

OUTNOM

– 100 mV, IL = 0.1 mA 190 600 µA

OUTNOM

Rev. A | Page 3 of 12

Page 4

ADP3338

ABSOLUTE MAXIMUM RATINGS

Unless otherwise specified, all voltages are referenced to GND.

Table 2.

Parameter Rating

Input Supply Voltage −0.3 V to +8.5 V Power Dissipation Internally Limited Operating Ambient Temperature Range −40°C to +85°C Operating Junction Temperature Range −40°C to +150°C θ

Storage Temperature Range −65°C to +150°C Lead Temperature Range (Soldering 10 sec) 300°C Vapor Phase (60 sec) 215°C Infrared (15 sec) 220°C

62.3°C/W

26.8°C/W

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Only one absolute maximum rating may be applied at any one time.

Rev. A | Page 4 of 12

Page 5

ADP3338

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

ADP3338

OUT

TOP VIEW

(Not to Scale)

NOTE: PIN 2 AND TAB ARE INTERNALLY CONNECTED

Figure 3. 3-Lead SOT-223 Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Function

1 GND Ground Pin. 2 OUT Output of the Regulator. Bypass to Ground with a 1 µF or larger capacitor. 3 IN Regulator Input. Bypass to Ground with a 1 µF or larger capacitor.

IN OUT

GND

02050-0-003

Rev. A | Page 5 of 12

Page 6

ADP3338

TYPICAL PERFORMANCE CHARACTERISTICS

TA = 25°C unless otherwise noted.

2.515 V

= 2.5V

OUT

2.510

2.505

2.500

OUTPUT VOLTAGE (V)

2.495

IL = 0A

= 1A

IL = 0.5A

GROUND CURRENT (mA)

= 2.5V

OUT

= 6V

2.490

2.5 4.5 6.5 8.0 INPUT VOLTAGE (V)

Figure 4. Line Regulation Output Voltage vs. Input Voltage

2.504

2.503

2.502

2.501

2.500

2.499

2.498

OUTPUT VOLTAGE (V)

2.497

2.496

2.495 0 0.8 1.00.60.40.2

LOAD CURRENT (A)

Figure 5. Output Voltage vs. Load Current

300

250

200

150

100

GROUND CURRENT (

INPUT VOLTAGE (V)

OUT

LOAD

= 6V

= 2.5V

= 0A

02050-0-004

02050-0-005

02050-0-006

0 0.2

0.4 0.6 0.8

OUTPUT LOAD (A)

Figure 7. Ground Current vs. Load Current

0.4 V

= 2.5V

OUT

= 6V

0.3

0.2

0.1

OUTPUT VOLTAGE (%)

–0.05

–40 –20

0 20 40 60 80 100 120

JUNCTION TEMPERATURE (°C)

IL = 1A

IL = 0.7A

IL = 0.5A

IL = 0.3A

IL = 0A

Figure 8. Output Voltage Variation % vs. Junction Temperature

GROUND CURRENT (mA)

–40

= 1A

LOAD

= 700mA

LOAD

= 500mA

LOAD

= 300mA

LOAD

–20 0 20 40 60 80 100 120 140 160

JUNCTION TEMPERATURE (°C)

1.0

02050-0-007

02050-0-008

02050-0-009

Figure 6. Ground Current vs. Supply Voltage

Figure 9. Ground Current vs. Junction Temperature

Rev. A | Page 6 of 12

Page 7

ADP3338

250

200

= 2.5V

OUT

2.51

2.50

= 2.5V

OUT

= 10µF

OUT

LOAD = 1A

150

100

DROPOUT (mV)

0 0.2 1.0

0.4 0.6 0.8

LOAD CURRENT (A)

Figure 10. Dropout Voltage vs. Load Current

= 2.5V

OUT

= 1A

LOAD

INPUT/OUTPUT VOLTAGE (V)

02050-0-010

2.49

VOLTS

4.5

3.5

2.6

2.5

VOLTS

2.4

8040

120 140 180 220

TIME (µs)

Figure 13. Line Transient Response

VIN = 6V

= 1µF

OUT

02050-0-013

0 56789

TIME (sec)

Figure 11. Power-Up/Power-Down

= 2.5V

OUT

= 1µF

OUT

2.51 I

= 1A

LOAD

2.50

2.49

VOLTS

4.5

3.5

8040

120 140 180 220

TIME (µs)

Figure 12. Line Transient Response

02050-0-011

02050-0-012

2.6

2.5

VOLTS

2.4

2000

400 600 800 1000

TIME (µs)

Figure 14. Load Transient Response

VIN = 6V

= 10µF

OUT

2000

400 600 800 1000

TIME (µs)

Figure 15. Load Transient Response

02050-0-014

02050-0-015

Rev. A | Page 7 of 12

Page 8

ADP3338

2.5

VOLTS

1.5

1.0

0.5

0.4

400mΩ SHORT

0.6 0.8 1.0

TIME (s)

FULL SHORT

VIN = 6V

02050-0-016

300

250

200

150

RMS NOISE (

100

010

= 1A

= 0A

CL(µF)

5020 30 40

02050-0-018

–10

–20

–30

–40

–50

–60

–70

RIPPLE REJECTION (dB)

–80

–90

–100

Figure 16. Short-Circuit Current

= 2.5V

OUT

CL = 1µF

CL = 10µF

= 1A

CL = 1µF

= 0

100 1k 10k 100k 1M

FREQUENCY (Hz)

IL = 1A

CL = 10µF

= 0

Figure 17. Power Supply Ripple Rejection

02050-0-017

100

0.1

0.01

VOLTAGE NOISE SPECTRAL DENSITY (µV/ Hz)

0.001 10 100

Figure 18. RMS Noise vs. C

CL = 10µF

FREQUENCY (Hz)

Figure 19. Output Noise Density

(10 Hz to 100 kHz)

CL = 1µF

10k

100k

02050-0-019

Rev. A | Page 8 of 12

Page 9

ADP3338

THEORY OF OPERATION

The ADP3338 anyCAP LDO uses a single control loop for regulation and reference functions. The output voltage is sensed by a resistive voltage divider, consisting of R1 and R2, which is varied to provide the available output voltage option. Feedback is taken from this network by way of a series diode (D1) and a second resistor divider (R3 and R4) to the input of an amplifier.

A very high gain error amplifier is used to control this loop. The amplifier is constructed in such a way that equilibrium produces a large, temperature-proportional input offset voltage that is repeatable and very well controlled. The temperatureproportional offset voltage is combined with the complementary diode voltage to form a virtual band gap voltage that is implicit in the network, although it never appears explicitly in the circuit. Ultimately, this patented design makes it possible to control the loop with only one amplifier. This technique also improves the noise characteristics of the amplifier by providing more flexibility on the trade-off of noise sources that leads to a low noise design.

The R1, R2 divider is chosen in the same ratio as the band gap voltage to the output voltage. Although the R1, R2 resistor divider is loaded by diode D1 and a second divider consisting of R3 and R4, the values can be chosen to produce a temperaturestable output. This unique arrangement specifically corrects for the loading of the divider, thus avoiding the error resulting from base current loading in conventional circuits.

Most LDOs place very strict requirements on the range of ESR values for the output capacitor because they are difficult to stabilize due to the uncertainty of load capacitance and resistance. Moreover, the ESR value required to keep conventional LDOs stable changes depending on load and temperature. These ESR limitations make designing with LDOs more difficult because of their unclear specifications and extreme variations over temperature.

With the ADP3338 anyCAP LDO, this is no longer true. It can be used with virtually any good quality capacitor, with no constraint on the minimum ESR. This innovative design allows the circuit to be stable with just a small 1 µF capacitor on the output. Additional advantages of the pole-splitting scheme include superior line noise rejection and very high regulator gain, which lead to excellent line and load regulation. An impressive ±1.4% accuracy is guaranteed over line, load, and temperature.

Additional features of the circuit include current limit and thermal shutdown.

OUT

GNDIN

ADP3338

OUT

C2 1

The patented amplifier controls a new and unique noninverting driver that drives the pass transistor, Q1. The use of this special noninverting driver enables the frequency compensation to include the load capacitor in a pole-splitting arrangement to achieve reduced sensitivity to the value, type, and ESR of the load capacitance.

INPUT

NONINVERTING

WIDEBAND

DRIVER

COMPENSATION CAPACITOR

ADP3338

Figure 21. Functional Block Diagram

02050-0-021

Figure 20. Typical Application Circuit

OUTPUT

ATTENUATION (V

BANDGAP/VOUT

GND

PTAT

CURRENT

PTAT

)

LOAD

(a)

LOAD

02050-0-020

Rev. A | Page 9 of 12

Page 10

ADP3338

−

APPLICATION INFORMATION

CAPACITOR SELECTION

Output Capacitor

The stability and transient response of the LDO is a function of the output capacitor. The ADP3338 is stable with a wide range of capacitor values, types, and ESR (anyCAP). A capacitor as low as 1 µF is all that is needed for stability. A higher capacitance may be necessary if high output current surges are anticipated, or if the output capacitor cannot be located near the output and ground pins. The ADP3338 is stable with extremely low ESR capacitors (ESR ≈ 0) such as multilayer ceramic capacitors (MLCC) or OSCON. Note that the effective capacitance of some capacitor types falls below the minimum over temperature or with dc voltage.

Input Capacitor

An input bypass capacitor is not strictly required but is recommended in any application involving long input wires or high source impedance. Connecting a 1 µF capacitor from the input to ground reduces the circuit’s sensitivity to PC board layout and input transients. If a larger output capacitor is necessary, a larger value input capacitor is also recommended.

OUTPUT CURRENT LIMIT

The ADP3338 is short-circuit protected by limiting the pass transistor’s base drive current. The maximum output current is limited to about 2 A. See Figure 16.

THERMAL OVERLOAD PROTECTION

The ADP3338 is protected against damage due to excessive power dissipation by its thermal overload protection circuit. Thermal protection limits the die temperature to a maximum of 160°C. Under extreme conditions (i.e., high ambient temperature and power dissipation) where the die temperature starts to rise above 160°C, the output current is reduced until the die temperature has dropped to a safe level.

CALCULATING POWER DISSIPATION

Device power dissipation is calculated as follows:

= (VIN – V

Where I and V

OUT

and I

LOAD

are the input and output voltages respectively.

are load current and ground current, VIN

GND

Assuming the worst-case operating conditions are I

= 10 mA, VIN = 3.3 V, and V

GND

OUT

) × I

+ (VIN × I

LOAD

= 2.5 V, the device power

OUT

GND

)

LOAD

= 1.0 A,

dissipation is

= (3.3 V – 2.5 V) × 1000 mA + (3.3 V × 10 mA) = 833 mW

So, for a junction temperature of 125°C and a maximum ambient temperature of 85°C, the required thermal resistance from junction to ambient is

C85C125

=θ

W833.0

°=

C/W48

PRINTED CIRCUIT BOARD LAYOUT CONSIDERATIONS

The SOT-223’s thermal resistance, θJA, is determined by the sum of the junction-to-case and the case-to-ambient thermal resistances. The junction-to-case thermal resistance, θ determined by the package design and is specified at 26.8°C/W. However, the case-to-ambient thermal resistance is determined by the printed circuit board design.

As shown in Figure 22, the amount of copper to which the ADP3338 is mounted affects thermal performance. When mounted to the minimal pads of 2 oz. copper (Figure 22a), θ

126.6°C/W. Adding a small copper pad under the ADP3338 (Figure 22b) reduces the θ

to 102.9°C/W. Increasing the

copper pad to 1 square inch (Figure 22c) reduces the θ further to 52.8°C/W.

, is

even

Current and thermal limit protections are intended to protect the device against accidental overload conditions. For normal operation, the device’s power dissipation should be externally limited so the junction temperature does not exceed 150°C.

02050-0-0-022

cab

Figure 22. PCB Layouts

Rev. A | Page 10 of 12

Page 11

ADP3338

Use the following general guidelines when designing printed circuit boards:

1. Keep the output capacitor as close to the output and

ground pins as possible.

5. If possible, utilize the adjacent area to add more copper

around the ADP3338. Connecting the copper area to the output of the ADP3338, as shown in Figure 22c, is best, but thermal performance will be improved even if it is connected to other signals.

2. Keep the input capacitor as close to the input and ground

pins as possible.

3. PC board traces with larger cross sectional areas remove

more heat from the ADP3338. For optimum heat transfer, specify thick copper and use wide traces.

4. The thermal resistance can be decreased by adding a

copper pad under the ADP3338, as shown in Figure 22b.

6. Use additional copper layers or planes to reduce the

thermal resistance. Again, connecting the other layers to the output of the ADP3338 is best, but is not necessary. When connecting the output pad to other layers, use multiple vias.

Rev. A | Page 11 of 12

Page 12

ADP3338

OUTLINE DIMENSIONS

3.15

3.00

2.90

3.50 BSC

0.85

0.70

0.60

1.70

1.50

0.10

0.02

132

2.30

BSC

6.50 BSC

4.60 BSC

COMPLIANT TO JEDEC STANDARDS TO-261-AA

7.00 BSC

1.05

0.85

SEATING PLANE

1.30

1.10

10° MAX

16° 10°

0.35

0.26

0.24

Figure 23. 3-Lead Small Outline Transistor Package [SOT-223]

(KC-3)

Dimensions shown in millimeters

ORDERING GUIDE

Model Temperature Range Output Voltage(V) Package Option Package Description

ADP3338AKC-1.5-RL –40°C to +85°C 1.5 KC-3 3-Lead SOT-223 ADP3338AKC-1.5-RL7 –40°C to +85°C 1.5 KC-3 3-Lead SOT-223 ADP3338AKC-1.8-RL –40°C to +85°C 1.8 KC-3 3-Lead SOT-223 ADP3338AKC-1.8-RL7 –40°C to +85°C 1.8 KC-3 3-Lead SOT-223 ADP3338AKC-2.5-RL –40°C to +85°C 2.5 KC-3 3-Lead SOT-223 ADP3338AKC-2.5-RL7 –40°C to +85°C 2.5 KC-3 3-Lead SOT-223 ADP3338AKC-2.85-RL –40°C to +85°C 2.85 KC-3 3-Lead SOT-223 ADP3338AKC-2.85-RL7 –40°C to +85°C 2.85 KC-3 3-Lead SOT-223 ADP3338AKC-3-RL –40°C to +85°C 3.0 KC-3 3-Lead SOT-223 ADP3338AKC-3-RL7 –40°C to +85°C 3.0 KC-3 3-Lead SOT-223 ADP3338AKC-3.3-RL –40°C to +85°C 3.3 KC-3 3-Lead SOT-223 ADP3338AKC-3.3-RL7 –40°C to +85°C 3.3 KC-3 3-Lead SOT-223 ADP3338AKC-5-RL –40°C to +85°C 5 KC-3 3-Lead SOT-223 ADP3338AKC-5-RL7 –40°C to +85°C 5 KC-3 3-Lead SOT-223

C02050–0–6/04(A)

Rev. A | Page 12 of 12