ANALOG DEVICES ADP2102 Service Manual

Low Duty Cycle, 600 mA, 3 MHz Synchronous

www.BDTIC.com/ADI

FEATURES

Input voltage range: 2.7 V to 5.5 V
600 mA maximum load current
95% efficiency
Low duty cycle operation
Only 3 tiny external ceramic components
3 MHz typical operating frequency
Fixed output voltage from 0.8 V to 1.875 V
Adjustable output voltage up to 3.3 V

0.01 μA shutdown supply current
Automatic power save mode
Internal synchronous rectifier
Internal soft start
Internal compensation
Enable/shutdown logic input
Undervoltage lockout
Current limit protection
Thermal shutdown
Small 8-lead, 3 mm × 3 mm LFCSP package

APPLICATIONS

USB powered devices
WLAN and gateways
Point of loads
Processor core power from 5 V
Digital cameras
PDAs and palmtop computers
Portable media players, GPS

Step-Down DC-to-DC Converter

ADP2102

GENERAL DESCRIPTION

The ADP2102 is a synchronous step-down dc-to-dc converter
that converts a 2.7 V to 5.5 V unregulated input voltage to a lower
regulated output voltage with up to 95% efficiency and 1%
accuracy. The low duty cycle capability of the ADP2102 is ideal for
USB applications or 5 V systems that power up submicron subvolt
processor cores. Its 3 MHz typical operating frequency and excel­lent transient response allow the use of small, low cost 1 µH
inductors and 2.2 µF ceramic capacitors. At medium-to-high
load currents, it uses a current mode, pseudofixed frequency pulse­width modulation to extend battery life. To ensure the longest
batter y life in portable applications, the ADP2102 has a power save
mode (PSM) that reduces the switching frequency under light
load conditions to significantly reduce quiescent current.

The ADP2102 is available in both fixed and adjustable output
v

oltage options with 600 mA maximum output current. The preset

output voltage options voltage are 1.875 V, 1.8 V, 1.5 V, 1.375 V,

1.25 V, 1.2 V, 1.0 V, and 0.8 V. The adjustable voltage option is
available from 0.8 V to 3.3 V. The ADP2102 requires only three
external components and consumes 0.01 µA in shutdown mode.

The ADP2102 is available in an 8-lead LFCSP package and is
s

pecified for the −40 °C to +85 °C temperature range.

TYPICAL PERFORMANCE CHARACTERISTICS

100

95

90

85

80

75

EFFICIENCY (%)

70

65

60

10 100 1000

Rev. B

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
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.

VIN = 3.6V

VIN = 2.7V

VIN = 3V

VIN = 4.2V

LOAD CURRENT (mA)

Figure 1.

V

OUT

T

A

= 1.375V

= 25°C

06631-052

TYPICAL APPLICATIONS CIRCUIT

INPUT VOLTAGE

2.7V TO 5. 5V

2.2µF

FORCED

DCM/

CCM

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2007 Analog Devices, Inc. All rights reserved.

C

IN

CCM

V

IN

MODE

OFF

ADP2102

EN GND

ON

LX

FB/OUT

Figure 2.

OUTPUT VO LTAGE

L

0.8V TO 1. 875V

1µH

C

2.2µF

OUT

06631-001

ADP2102

www.BDTIC.com/ADI

TABLE OF CONTENTS

Features .............................................................................................. 1

Applications....................................................................................... 1

General Description......................................................................... 1

Typical Performance Characteristics ............................................. 1

Typical Applicat i o n s C i rc uit............................................................ 1

Revision History ............................................................................... 2

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

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

Thermal Resistance ...................................................................... 4

Boundary Condition .................................................................... 4

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

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

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

Theory of Operation ...................................................................... 13

Control Scheme .......................................................................... 13

Constant On-Time Timer......................................................... 13

Forced Continuous Conduction Mode ...................................13

Power Save Mode........................................................................ 13

Synchronous Rectification ........................................................14

Current Limit .............................................................................. 14

Soft Start...................................................................................... 15

Enable........................................................................................... 15

Undervoltage L ockout ............................................................... 15

Thermal Shutdown .................................................................... 15

Applications Information.............................................................. 16

Inductor Selection...................................................................... 16

Input Capacitor Selection.......................................................... 16

Output Capacitor Selection....................................................... 16

Typical Applicat i o n s C i rc uits .................................................... 17

Setting the Output Voltage........................................................ 19

Efficiency Considerations ......................................................... 19

Thermal Considerations............................................................ 20

Design Example.......................................................................... 20

Circuit Board Layout Recommendations ................................... 22

Recommended Layout............................................................... 22

Outline Dimensions ....................................................................... 24

Ordering Guide .......................................................................... 24

REVISION HISTORY

9/07—Rev. A to Rev. B

Changes to Features, Applications, and General Description .... 1

Changes to Table 4............................................................................ 5

Changes to Table 6.......................................................................... 17

Changes to Table 7.......................................................................... 19

Changes to Circuit Board Layout Recommendations Section.... 21

Updated Outline Dimensions....................................................... 23

Changes to Ordering Guide.......................................................... 23

6/07—Rev. 0 to Rev. A

Changes to Ordering Guide.......................................................... 23

6/07—Revision 0: Initial Version

Rev. B | Page 2 of 24

ADP2102

www.BDTIC.com/ADI

SPECIFICATIONS

VIN = 3.6 V, EN = VIN, MODE = VIN, TA = 25°C, unless otherwise noted. Bold values indicate −40°C ≤ TA ≤ +85°C.

Table 1.

Parameter Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Input Voltage Range

2

2.7 5.5 V
Undervoltage Lockout Threshold VIN rising 2.2 2.4 2.5 V
Undervoltage Lockout Hysteresis 220 mV

OUTPUT CHARACTERISTICS

Output Voltage Range ADP2102-xx 0.8 1.875 V
Output Voltage Range ADP2102-ADJ 0.8 3.3 V
Output Voltage Initial Accuracy ADP2102-xx, TA= 25°C, I
ADP2102-xx, −40°C ≤TA ≤ 85°C, I
Load Regulation V

= 0.8 V to 1.875 V, I

OUT

Line Regulation VIN = 2.7 V to 5.5 V, I

= 0 mA

LOAD

= 0 mA

LOAD

= 0 mA to 600 mA 0.5 %

LOAD

= 10 mA 0.3 %

LOAD

−1

−2

FEEDBACK CHARACTERISTICS

FB Regulation Voltage ADP2102-ADJ

784

800
FB Bias Current ADP2102-ADJ, ADP2102-0.8
FB Impedance ADP2102-xx 375 kΩ

CURRENT CHARACTERISTICS

Operating Current ADP2102 PSM mode, I

= 0 mA 70

LOAD

Shutdown Current EN = 0 V 0.01
Output Current ADP2102, VIN = 2.7 V to 5.5 V 600 mA

LX (SWITCH NODE) CHARACTERISTICS

LX On Resistance P-channel switch, ILX = 100 mA
N-channel synchronous rectifier, ILX = 100 mA

325

200
LX Leakage Current VIN = 5.5 V, VLX = 0 V, 5.5 V
LX Minimum Off-Time ADP2102-xx, ADP2102-ADJ 100 ns
LX On-Time ADP2102-0.8

ADP2102-1.0
ADP2102-1.2
ADP2102-1.25
ADP2102-1.375
ADP2102-1.5
ADP2102-1.8
ADP2102-1.875
ADP2102-ADJ-1.2
ADP2102-ADJ-1.5
ADP2102-ADJ-1.875
ADP2102-ADJ-3.3 (VIN = 5 V)

55
70
100
103
135
150
180
190
80
155
200
198

87

107

131

133

165

182

220

237

131

177

226

238
Valley Current Limit 1 A

ENABLE, MODE CHARACTERISTICS

EN, MODE Input High Threshold

1.3

V
EN, MODE Input Low Threshold
EN, MODE Input Leakage Current VIN = 5.5 V, EN = MODE = 0 V, 5.5 V

SOFT START PERIOD

250

500

THERMAL CHARACTERISTICS

Thermal Shutdown Threshold 150 °C
Thermal Shutdown Hysteresis 15 °C

1

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

2

The input voltage (VIN) range over which the rest of the specifications are valid. The part operates as expected until VIN goes below the UVLO threshold.

1

+1
+2

816
50

99
1

600
400
1

105
135
160
169
195
210
260
270
170
210
275
270

0.4
1
800

%
%

mV
nA

µA
µA

mΩ
mΩ
µA

ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns

V
µA
µs

Rev. B | Page 3 of 24

ADP2102

www.BDTIC.com/ADI

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

AVIN, EN, MODE, FB/OUT to AGND −0.3 V to +6 V
LX to PGND −0.3 V to (VIN + 0.3 V)
PVIN to PGND −0.3 V to +6 V
PGND to AGND −0.3 V to +0.3 V
AVIN to PVIN −0.3 V to +0.3 V
Operating Ambient Temperature Range −40°C to +85°C

1

Junction Temperature Range −40°C to +125°C
Storage Temperature Range −65°C to +150°C
Soldering Conditions JEDEC J-STD-020

1

The ADP2102 can be damaged when junction temperature limits are exceeded.
Monitoring ambient temperature does not guarantee that T is within the

specified temperature limits. In applications where high power dissipation
and poor thermal resistance are present, the maximum ambient temperature
may have to be derated. In applications with moderate power dissipation
and low PCB thermal resistance, the maximum ambient temperature can
exceed the maximum limit as long as the junction temperature is within
specification limits. The junction temperature (T ) of the device is dependent
on the ambient temperature (T ), the power dissipation of the device (PD),
and the junction-to-ambient thermal resistance of the package (θ ). Maximum
junction temperature (T ) is calculated from the ambient temperature (T )
and power dissipation (PD) using the formula T = T + (θ × PD).
otherwise specified, all other voltages are referenced to AGND.

A

J A

J

J A JA

J

JA

Unless

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.

THERMAL RESISTANCE

Junction-to-ambient thermal resistance (θJA) of the package is
based on modeling and calculation using a 4-layer board. The
junction-to-ambient thermal resistance is highly dependent on
the application and board layout. In applications where high
maximum power dissipation exists, attention to thermal board
design is required. The value of θ

may vary, depending on PCB

JA

material, layout, and environmental conditions. Specified value
of θ

is based on a 4-layer, 4 in × 3 in, 2 1/2 oz copper board,

JA

as per JEDEC standards. For more information, see Application
Note

AN-772, A

Design and Manufacturing Guide for the Lead

Frame Chip Scale Package (LFCSP).

Table 3. Thermal Resistance

Package Type θ

JA

Unit

8-Lead LFCSP 54 °C/W
Maximum Power Dissipation 0.74 W

BOUNDARY CONDITION

Natural convection, 4-layer board, exposed pad soldered to PCB.

ESD CAUTION

Rev. B | Page 4 of 24

ADP2102

www.BDTIC.com/ADI

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

1MODE

2EN

ADP2102

TOP VIEW

3FB/OUT

(Not to Scale)

4AGND

Figure 3. Pin Configuration

Table 4. Pin Function Descriptions

Pin
No. Mnemonic Description

1 MODE

2 EN

3 FB/OUT

4 AGND

5 PGND Power Ground.
6 LX

7 PVIN

8 AVIN Power Source Input. AVIN is the supply for the ADP2102 internal circuitry. This pin can be connected in three different ways.

For light-to-medium loads up to 300 mA, the AVIN pin and the PVIN pin can be shorted together.

Mode Input. To set the ADP2102 to forced continuous conduc
to power save mode/auto mode (PSM), drive MODE low.

Enable Input. Drive EN high to turn on the ADP2102. Drive EN lo
This pin cannot be left floating.

Output Sense Input or Feedback Input. F
divider. Connect OUT to the output voltage. For adjustable (no suffix) versions, FB is the input to the error amplifier.
Drive FB through a resistive voltage divider to set the output voltage. The FB regulation threshold is 0.8 V.

Analog Ground. Connect AGND to PGND at a single point as clo
electrically common with the analog ground pin.

Switch Output. LX is the drain of the P-channel MOSFET switch and
output LC filter between LX and the output voltage.

Power Source Input. Drive PVIN with a 2.7 V to 5.5 V power source. A ceramic bypass capacitor of 2.2 µF or greater is

equired on this pin to the nearest PGND plane.

r

For noise reduction, place an external RC filter bet
external RC filter are 10 Ω and 0.1 µF, respectively. This configuration can be used for all loads.

For light-to-heavy loads (greater than 300 mA), bypass the AVIN pin with a 1 pF to 0.01 µF capacitor to the

est PGND plane. Do not short the AVIN and PVIN pins when using only a bypass capacitor.

near

or fixed output versions, OUT is the top of the internal resistive voltage

8AVIN

7PVIN

6LX

5PGND

ween PVIN and AVIN. The recommended values for the

06631-003

tion mode (CCM), drive MODE high. To set the ADP2102

w to turn it off and reduce the input current to 0.1 µA.

se to the ADP2102 as possible. The exposed paddle is

the N-channel synchronous rectifier. Connect the

Rev. B | Page 5 of 24

ADP2102

www.BDTIC.com/ADI

TYPICAL PERFORMANCE CHARACTERISTICS

VIN = 3.6 V, L = 2.2 µH, CIN = 2.2 µF, C

100

95

90

85

VIN = 2.7V

= 4.7 µF, unless otherwise noted.

OUT

TA = 25°C

1.22
TA = 25°C

1.21

VIN = 2.7V

80

75

EFFICIENCY (%)

70

65

60

1 10 100 1000

Figure 4. Efficiency vs. Load Current (V

100

95

90

VIN = 3.6V

85

80

75

EFFICIENCY (%)

70

65

60

1 10 100 1000

Figure 5. Efficiency vs. Load Current (V

VIN = 3.6V

LOAD CURRENT (mA)

VIN = 2.7V

LOAD CURRENT (mA)

VIN = 4.5V

OUT

VIN = 4.5V

OUT

MODE = PSM
L = 2.2µH
C

= 2.2µF

IN

C

= 10µF

OUT

= 1.2 V)

TA = 25°C

MODE = PSM
L = 2.2µH
C

= 2.2µF

IN

C

= 10µF

OUT

= 1.5 V)

1.20

OUTPUT VOLTAGE (V)

1.19

1.18

06631-004

0 100 200 300 400 500 600

Figure 7. Output Voltage Accuracy (V

1.52

1.51

1.50

OUTPUT VOLTAGE (V)

1.49

1.48

06631-005

0 100 200 300 400 500 600

Figure 8. Output Voltage Accuracy (V

VIN = 3.6V

LOAD CURRENT (mA)

VIN = 2.7V

VIN = 4.5V

LOAD CURRENT (mA)

VIN = 4.5V

OUT

VIN = 3.6V

OUT

= 1.2 V)

TA = 25°C

= 1.5 V)

06631-007

06631-020

100

95

90

VIN = 2.7V

85

80

VIN = 3.6V

75

EFFICIENCY (%)

70

65

60

1 10 100 1000

LOAD CURRENT (mA)

VIN = 4.5V

Figure 6. Efficiency vs. Load Current (V

TA = 25°C

MODE = PSM
L = 2.2µH
C

= 2.2µF

IN

C

OUT

= 1.8 V)

OUT

= 10µF

06631-006

Rev. B | Page 6 of 24

1.82

1.81

VIN = 2.7V

1.80

OUTPUT VOLTAGE (V)

1.79

1.78
0 100 200 300 400 500 600

VIN = 3.6V

VIN = 4.5V

LOAD CURRENT (mA)

Figure 9. Output Voltage Accuracy (V

= 1.8 V)

OUT

TA = 25°C

06631-009

ADP2102

www.BDTIC.com/ADI

100

EFFICIENCY (%)

TA = 25°C
C

= 6.8pF

FF

95

90

85

VIN = 4.5V

VIN = 5.0V

VIN = 5.5V

1.53

1.52

PSM

1.51

1.50

CCM

OUTPUT VOLTAGE (V)

1.49

TA = 25°C

80

1 10 100 1000

LOAD CURRENT (mA)

Figure 10. Efficiency vs. Load Current (V

95

90

85

80

75

70

EFFICIENCY (%)

65

60

55

50

PSM

CCM

10 100 1k

LOAD CURRENT (mA)

Figure 11. PSM vs. CCM Efficiency (V

1.22

1.21

PSM

1.20
CCM

OUTPUT VOLTAGE (V)

1.19

MODE = PSM

= 3.3 V)

OUT

= 1.8 V)

OUT

TA = 25°C

TA = 25°C

1.48

06631-050

0 100 200 300 400 500 600

Figure 13. Output Voltage vs. Load Current (V

1.84

1.83

1.82

PSM

1.81

CCM

1.80

OUTPUT VOLTAGE (V)

1.79

1.78

06631-026

0 100 200 300 400 500 600

Figure 14. Output Voltage vs. Load Current (V

1.23

1.22

1.21

1.20

OUTPUT VOL TAGE (V)

1.19

LOAD CURRENT (mA)

LOAD CURRENT (mA)

I

= 300mA

LOAD

I

= 600mA

LOAD

I

LOAD

= 0mA

= 1.5 V)

OUT

TA = 25°C

= 1.8 V)

OUT

06631-013

06631-017

1.18

0 100 200 300 400 500 600

Figure 12. Output Voltage vs. Load Current (V

LOAD CURRENT (mA)

= 1.2 V)

OUT

06631-011

Rev. B | Page 7 of 24

1.18
–45 –25 –5 15 35 55 75

Figure 15. Output Voltag

TEMPERATURE ( °C)

e vs. Temperature (V

OUT

= 1.2 V)

06631-046

ADP2102

www.BDTIC.com/ADI

1.52

1.51

1.50
I

= 0mA

LOAD

I

= 300mA

1.49

1.48

OUTPUT VOLTAGE (V)

1.47

1.46

–40 –15 10 35 60 85

Figure 16. Output Voltag

1.81

1.80

1.79

1.78

OUTPUT VOLTAGE (V)

1.77

LOAD

I

= 600mA

LOAD

TEMPERATURE ( °C)

e vs. Temperature (V

I

= 0mA

LOAD

I

= 300mA

LOAD

I

= 600mA

LOAD

= 1.5 V)

OUT

06631-047

85

80

75

70

QUIESCENT CURRENT (µA)

65

60

2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4
INPUT VOLTAGE (V)

+85°C

+25°C

–40°C

Figure 19. Quiescent Current vs. Input Voltage

77

76

75

74

73

72

QUIESCENT CURRENT (µA)

71

06631-045

1.76
–40 –15 10 35 60 85

Figure 17. Output Voltag

3.40

3.36

3.32

3.28

OUTPUT VOLTAGE (V)

3.24

3.20
0 100 200 300 400 500 600

Figure 18. Output Voltage Accuracy (V

TEMPERATURE (° C)

e vs. Temperature (V

LOAD CURRENT (mA)

+85°C

+25°C

–40°C

= 3.3 V)

OUT

OUT

= 1.8 V)

70

06631-048

–40 –20 0 20 40 60 80 100 120

TEMPERATURE (° C)

06631-053

Figure 20. Quiescent Current vs. Temperature

0.8005

0.8000

0.7995

0.7990

0.7985

0.7980

FEEDBACK VOLT AGE (V)

0.7975

0.7970

0.7965

06631-049

–50 0 50 100

TEMPERATURE ( °C)

V

= 3.6V

IN

06631-021

Figure 21. Feedback Voltage vs. Temperature

Rev. B | Page 8 of 24