Analog Devices ADP1611 Datasheet

20 V,1.2 MHz Step-Up

FEATURES

Fully integrated 1.2 A , 0.23 Ω power switch
Pin-selectable 700 kHz or 1.2 MHz PWM frequency
90% efficiency
Adjustable output voltage up to 20 V
3% output regulation accuracy
Adjustable soft start
Input undervoltage lockout
MSOP 8-lead package

APPLICATIONS

TFT LC bias supplies
Portable applications
Industrial/instrumentation equipment

FUNCTIONAL BLOCK DIAGRAM

REF

FB

2

RAMP

GEN

7

RT

OSC

ERROR

g

m

COMP

1 6

AMP

COMPARATOR

DC-to-DC Switching Converter

ADP1611

GENERAL DESCRIPTION

The ADP1611 is a step-up dc-to-dc switching converter with an
integrated 1.2 A, 0.23 Ω power switch capable of providing an
output voltage as high as 20 V. With a package height of less
than 1.1 mm, the ADP1611 is optimal for space-constrained
applications such as portable devices or thin film transistor
(TFT) liquid crystal displays (LCDs).

The ADP1611 operates in pulse-width modulation (PWM)
current mode with up to 90% efficiency. Adjustable soft start
prevents inrush currents at startup. The pin-selectable switching
frequency and PWM current-mode architecture allow excellent
transient response, easy noise filtering, and the use of small,
cost-saving external inductors and capacitors.

The ADP1611 is offered in the Pb-free 8-lead MSOP and
operates over the temperature range of −40°C to +85°C.

IN

ADP1611

BIAS

SW

F/F

QSR

DRIVER

5

8

SOFT START

SS

3

SD

Rev. 0

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.

Figure 1.

CURRENT-

SENSE

AMPLIFIER

4

GND

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone]
Fax: [phone] © 2005 Analog Devices, Inc. All rights reserved.

www.analog.com

04906-001

ADP1611

TABLE OF CONTENTS

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

Choosing the Input and Output Capacitors ........................... 11

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

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

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

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

Theory of Operation ...................................................................... 10

Current-Mode PWM Operation.............................................. 10

Frequency Selection ................................................................... 10

Soft Start ......................................................................................10

On/Off Control........................................................................... 10

Setting the Output Voltage........................................................ 10

REVISION HISTORY

2/05—Revision 0: Initial Version

Diode Selection........................................................................... 12

Loop Compensation .................................................................. 12

Soft-Start Capacitor ................................................................... 13

Application Circuits ................................................................... 14

Step-Up DC-to-DC Converter with True Shutdown............ 14

TFT LCD Bias Supply ................................................................ 14

SEPIC Power Supply .................................................................. 15

Layout Procedure ........................................................................... 16

Outline Dimensions ....................................................................... 18

Ordering Guide .......................................................................... 18

Rev. 0 | Page 2 of 20

ADP1611

SPECIFICATIONS

VIN = 3.3 V, TA = −40°C to +85°C, unless otherwise noted. All limits at temperature extremes are guaranteed by correlation and
characterization using standard statistical quality control (SQC), unless otherwise noted.

Table 1.

Parameter Symbol Conditions Min Typ Max Unit
SUPPLY

Input Voltage V

IN

Quiescent Current

Nonswitching State I
Shutdown I

Switching State

1

Q

SD

Q

IQ

SW

OUTPUT

Output Voltage V

OUT

Load Regulation I
Overall Regulation Line, load, temperature ±3 %

REFERENCE

Feedback Voltage V

FB

Line Regulation VIN = 2.5 V to 5.5 V −0.15 +0.15 %/V

ERROR AMPLIFIER

Transconductance g
Voltage Gain A

m

V

FB Input Bias Current V

SWITCH

SW On Resistance R

ON

SW Leakage Current VSW = 20 V 0.01 20 µA
Peak Current Limit

2

I

CLSET

OSCILLATOR

Oscillator Frequency f

RT = GND 0.49 0.7 0.885 MHz

OSC

RT = IN 0.89 1.23 1.6 MHz
Maximum Duty Cycle D

MAX

SHUTDOWN

Shutdown Input Voltage Low V
Shutdown Input Voltage High V
Shutdown Input Bias Current I

IL

IH

SD

SOFT START

SS Charging Current VSS = 0 V 3 µA

UNDERVOLTAGE LOCKOUT

3

UVLO Threshold VIN rising 2.2 2.4 2.5 V
UVLO Hysteresis 220 mV

1

This parameter specifies the average current while switching internally and with SW (Pin 5) floating.

2

Guaranteed by design and not fully production tested.

3

Guaranteed by characterization.

2.5 5.5 V

VFB = 1.3 V, RT = V

IN

390 600 µA

VSD = 0 V 0.01 10 µA

fSW = 1.23 MHz, no load 1 2 mA

V

= 10 mA to 150 mA, V

LOAD

= 10 V 0.05 mV/mA

OUT

IN

20 V

1.212 1.230 1.248 V

∆I = 1 µA

100 µA/V

60 dB

= 1.23 V

FB

10 nA

ISW = 1.0 A 230 600 mΩ

2.0 A

COMP = open, VFB = 1 V, RT = GND 78 83 90 %

0.6 V

2.2 V
VSD = 3.3 V 0.01 1 µA

Rev. 0 | Page 3 of 20

ADP1611

7

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

IN, COMP, SD, SS, RT, FB to GND
SW to GND 22 V
RMS SW Pin Current 1.2 A
Operating Ambient Temperature Range −40°C to +85°C
Operating Junction Temperature Range −40°C to +125°C
Storage Temperature Range −65°C to +150°C
θJA, Two Layers 206°C/W
θJA, Four Layers 142°C/W
Lead Temperature Range (Soldering, 60 sec) 300°C

−0.3 V to +6 V

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 indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability. Absolute maximum ratings apply individually
only, not in combination. Unless otherwise specified, all other
voltages are referenced to GND.

F/F

QSR

IN

IN

BIAS

CURRENT-

SENSE

AMPLIFIER

ADP1611

DRIVER

C

IN

L1

D1

SW

5

4

GND

V

OUT

C

OUT

04906-002

R1

1.2MHz

00kHz

C

SS

R

C

C

C

V

OUT

FB

R2

V

IN

SD
SS

REF

2

RAMP

GEN

RT

7

OSC

3

SOFT START

8

COMP

1 6

ERROR

AMP

g

m

COMPARATOR

Figure 2. Block Diagram and Typical Application Circuit

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.

Rev. 0 | Page 4 of 20

ADP1611

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

COMP

FB
SD

GND

1

ADP1611

2

TOP VIEW

3

(Not to Scale)

4

8

SS
RT

7
6

IN
SW

5

04906-0-003

Figure 3. Pin Configuration

Table 3. Pin Function Descriptions

Pin No. Mnemonic Description

1 COMP

Compensation Input. Connect a series resistor-capacitor network from COMP to GND to compensate the
regulator.

2 FB

Output Voltage Feedback Input. Connect a resistive voltage divider from the output voltage to FB to set the
regulator output voltage.

3

SD Shutdown Input. Drive SD low to shut down the regulator; drive SD high to turn it on.
4 GND Ground.
5 SW

Switching Output. Connect the power inductor from the input voltage to SW and connect the external rectifier
from SW to the output voltage to complete the step-up converter.

6 IN

Main Power Supply Input. IN powers the ADP1611 internal circuitry. Connect IN to the input source voltage.
Bypass IN to GND with a 10 µF or greater capacitor as close to the ADP1611 as possible.

7 RT

Frequency Setting Input. RT controls the switching frequency. Connect RT to GND to program the oscillator to
700 kHz, or connect RT to IN to program it to 1.2 MHz.

8 SS Soft-Start Timing Capacitor Input. A capacitor from SS to GND brings up the output slowly at power-up.

Rev. 0 | Page 5 of 20

ADP1611

TYPICAL PERFORMANCE CHARACTERISTICS

100

EFFICIENCY (%)

90

80

70

60

VIN = 5V
F

= 700kHz

SW

L = 10µH

V

OUT

V

OUT

= 15V

= 20V

V

= 10V

OUT

EFFICIENCY (%)

100

90

80

70

60

50

VIN = 3.3V
F

= 1.2MHz

SW

L = 4.7µH

V

= 5V

OUT

V

= 13V

OUT

V

= 8.5V

OUT

50

40

1 10 100 1000

LOAD CURRENT (mA)

Figure 4. Output Efficiency vs. Load Current

100

VIN = 5V

= 1.2MHz

F

SW

L = 6.8µH

90

80

70

60

EFFICIENCY (%)

50

40

30

1 10 100 1000

LOAD CURRENT (mA)

V

V

= 20V

OUT

V

OUT

Figure 5. Output Efficiency vs. Load Current

OUT

= 15V

= 10V

04906-004

04906-005

40

30

1 10 100 1000

LOAD CURRENT (mA)

Figure 7. Output Efficiency vs. Load Current

2.8
V

= 10V

OUT

2.6

2.4

2.2

2.0

1.8

CURRENT LIMIT (A)

1.6

1.4

1.2

–40 –15 10 35 60 85

AMBIENT TEMPERATURE (°C)

= 5.5V

V

IN

V

IN

VIN = 2.5V

Figure 8. Current Limit vs. Ambient Temperature, V

= 3.3V

OUT

04906-007

04906-008

= 10 V

95

VIN = 3.3V

= 700kHz

F

SW

90

L = 10µH

85

80

75

70

EFFICIENCY (%)

65

60

55

50

1 10 100 1000

LOAD CURRENT (mA)

V

= 13V

OUT

V

= 8.5V

OUT

Figure 6. Output Efficiency vs. Load Current

V

= 5V

OUT

04906-006

1.4

1.2

1.0

0.8

0.6

0.4

OSCILLATORY FREQUENCY (MHz)

0.2
V

= 10V

OUT

= 3.3V

V

IN

0

–40 –15 10 35 60 85

AMBIENT TEMPERATURE (°C)

RT = V

RT = GND

IN

04906-009

Figure 9. Oscillatory Frequency vs. Ambient Temperature

Rev. 0 | Page 6 of 20