EVAL-ADP2107 Datasheet by Analog Devices Inc.

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Evaluation Board for Step-Down DC-to-DC
Converter Solution
EVAL-ADP2107
Rev. 0
Evaluation boards are only intended for device evaluation and not for production purposes.
Evaluation boards as supplied “as is” and without warranties of any kind, express, implied, or
statutory including, but not limited to, any implied warranty of merchantability or fitness for a
particular purpose. No license is granted by implication or otherwise under any patents or other
intellectual property by application or use of evaluation boards. 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. Analog Devices reserves the right to change devices or specifications at any time
without notice. Trademarks and registered trademarks are the property of their respective owners.
Evaluation boards are not authorized to be used in life support devices or systems.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved.
FEATURES
Efficiency > 95%
Input voltage range: 2.7 V to 5.5 V
Output voltage range: 0.8 V to VIN
Maximum output current: 2.0 A
Switching frequency: 1.2 MHz
Quiescent current: 20 μA
Shutdown current: 0.1 μA
Enable/shutdown logic input
Optimized for small ferrite core inductors
Optimized for tiny ceramic input and output capacitors
Programmable soft start with single capacitor
Programmable compensation for optimizing transient
performance
GENERAL DESCRIPTION
The ADP2107 evaluation board is a complete step-down dc-to-dc
converter solution using the ADP2107 step-down dc-to-dc
converter. It provides a ±1% accurate (±3% over all conditions),
regulated output voltage with load currents up to 2 A. It comes
in two versions: the ADP2107-1.8-EVAL with fixed output
voltage of 1.8 V, and the ADP2107-EVAL with adjustable output
voltage initially set to 2.5 V.
The ADP2107 is a synchronous, step-down dc-to-dc converter
that uses a current-mode pulse width modulation (PWM)
control scheme at medium-to-heavy load currents for high
efficiency, but smoothly transitions to a pulse frequency
modulation (PFM) scheme at light loads to conserve power.
The power switch and synchronous rectifier are integrated for
minimal external part count and high efficiency. The ADP2107
has been optimized for operation with small ferrite core
inductors and tiny ceramic capacitors to deliver the maximum
output power per square inch of the PCB board area.
For more details, see the ADP2107 data sheet.
FUNCTIONAL BLOCK DIAGRAM
06314-001
GND
GND
ADP2107
V
OUT
C2C5
C6
R1
R4
R3
R5
C7
C3
L1
C4
ENB
R2 J1 V
IN
C1
ANALOG DEVICES, POWER MANAGEMENT (STP)
ADP2107
EVALUATION BOARD
V
OUT
:
Figure 1.
EVAL-ADP2107
Rev. 0 | Page 2 of 12
TABLE OF CONTENTS
Features .............................................................................................. 1
General Description......................................................................... 1
Functional Block Diagram .............................................................. 1
Using the Evaluation Board............................................................. 3
Powering Up the Evaluation Board............................................ 3
Measuring Evaluation Board Performance............................... 3
Modifying the Evaluation Board .................................................... 4
Changing the Output Voltage ..................................................... 4
Changing the Load Transient Response.....................................4
Measurement Setup...........................................................................5
Typical Performance Characteristics ..............................................6
Ordering Information.......................................................................7
Bill of Materials..............................................................................7
Ordering Guide .............................................................................9
ESD Caution...................................................................................9
REVISION HISTORY
12/06—Revision 0: Initial Version
EVAL-ADP2107
Rev. 0 | Page 3 of 12
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2107 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures in this section.
Jumper J1
Before turning on the ADP2107 evaluation board, make sure
that all the components are present, but Jumper J1 is removed.
Input Power Source
Before connecting the power source to the ADP2107 evaluation
board, make sure that it is turned off. If the input power source
includes a current meter, use that meter to monitor the input
current. Connect the positive terminal of the power source to
the VIN terminal on the evaluation board and the negative terminal
of the power source to the GND terminal of the evaluation board.
If the power source does not include a current meter, connect
a current meter in series with the input source voltage. Connect
the positive lead (+) of the power source to the ammeter positive
(+) connection, the negative lead (−) of the power source to the
GND terminal on the evaluation board, and the negative lead (−) of
the ammeter to the VIN terminal on the board.
Output Load
Although the ADP2107 evaluation board can sustain the sudden
connection of the load, it is possible to damage the load if it is not
properly connected. Make sure that the board is turned off before
connecting the load. If the load includes an ammeter, or if the
current is not measured, connect the load directly to the
evaluation board with the positive (+) load connection to the
VOUT terminal and the negative (−) load connection to the GND
terminal. If an ammeter is used, connect it in series with the
load; that is, connect the positive (+) ammeter terminal to the
evaluation board VOUT terminal, the negative (−) ammeter
terminal to the positive (+) load terminal, and the negative (−)
load terminal to the evaluation board GND terminal. Once the
load is connected, make sure that it is set to the proper current
before powering the ADP2107 evaluation board.
Input and Output Voltmeters
Measure the input and output voltages with voltmeters. Make
sure that the voltmeters are connected to the appropriate
evaluation board terminals, not the load or power source. If the
voltmeters are not connected directly to the evaluation board,
the measured voltages are incorrect due to the voltage drop
across the leads and/or connections between the evaluation
board, the power source, and/or the load.
Connect the input voltage measuring the voltmeter positive
terminal (+) to the evaluation board VIN terminal and the
negative (−) terminal to the evaluation board GND terminal.
Connect the output voltage measuring voltmeter positive (+)
terminal to the evaluation board VOUT terminal and the negative
(−) terminal to the evaluation board GND terminal.
Turning on the Evaluation Board
Once the power source and the load are connected to the
ADP2107 evaluation board, it can be powered up for operation.
Slowly increase the input power source voltage until the input
voltage exceeds the minimum input operating voltage of 2.7 V.
Insert Jumper J1, and check to see if the output voltage rises to
the regulated output voltage (1.8 V for the ADP2107-1.8-EVAL and
2.5 V for the ADP2107-EVAL). If the load is not already enabled,
enable the load, and check that it is drawing the proper current and
that the output voltage maintains voltage regulation.
MEASURING EVALUATION BOARD
PERFORMANCE
Measuring Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope
probe across the output capacitor (C3/C4) with the probe
ground lead at the negative (−) capacitor terminal and the probe
tip at the positive (+) capacitor terminal. Set the oscilloscope to ac,
20 mV/division, and 2 μs/division time base. In the PWM mode of
operation, the output voltage ripple is small (< 20 mV), but in PFM
mode, the output voltage ripple can be as large as 50 mV.
Measuring the Switching Waveform
To observe the switching waveform with an oscilloscope, place
the oscilloscope probe tip at the end of the inductor that is
connected to the LX pins with the probe ground at GND.
Set the scope to dc, 2 V/division, and 2 μs/division time base.
The switching waveform should alternate between 0 V and the
approximate input voltage.
Measuring Load Regulation
Load regulation must be tested by increasing the load at the output
and looking at the change in output voltage. To minimize voltage
drop, use short, low-resistance wires, especially for heavy loads.
Measuring Line Regulation
Vary the input voltage and examine the change in the output voltage.
Measuring Efficiency
The efficiency, η, is measured by comparing the input power
with the output power.
ININ
OUTOUT
IV
IV
×
×
=η
Measure the input and output voltages as close as possible to the
input and output capacitors to reduce the effect of IR drops.
Measuring Inductor Current
The inductor current can be measured by removing one end of
the inductor from its pad and connecting a current loop in
series with it. A current probe can then be used to measure the
current flowing through the current loop, as shown in Figure 2.
EVAL-ADP2107
Rev. 0 | Page 4 of 12
MODIFYING THE EVALUATION BOARD
The ADP2107 evaluation board is supplied fully assembled and
tested for proper operation. It comes in two versions: the
ADP2107-1.8-EVAL with fixed output voltage of 1.8 V and the
ADP2107-EVAL with adjustable output voltage initially set to 2.5 V.
The two most common modifications that can be done to the
evaluation boards are changing the output voltage and changing
the load transient response.
CHANGING THE OUTPUT VOLTAGE
The ADP2107-EVAL output regulation voltage can be changed
by altering its external components. The ADP2107-1.8-EVAL
output regulation voltage is fixed at 1.8 V and cannot be changed.
The ADP2107-EVAL output regulation voltage is set by a
resistive voltage divider consisting of Resistor R4 and Resistor R5.
Resistor R4 corresponds to the RTOP resistor in the ADP2107
data sheet, and Resistor R5 corresponds to the RBOT resistor in
the ADP2107 data sheet. The output regulation voltage is
determined by the equation
⎥
⎦
⎤
⎢
⎣
⎡+
×=
BOT
BOTTOP
OUT R
RR
VV8.0
where:
RTOP is the value of the top resistor of the voltage divider (R4).
RBOT is the value of the bottom resistor of the voltage divider (R5).
VOUT is the output regulation voltage in volts.
To set the output regulation voltage to the desired value, first
determine the value of the bottom resistor, RBOT, by
STRING
FB
BOT I
V
R=
where:
VFB is 0.8 V, the internal reference.
ISTRING is the resistor divider string current (20 μA nominally).
Once RBOT is determined, calculate the value of the top resistor,
RTOP, from
⎥
⎦
⎤
⎢
⎣
⎡−
=
FB
FBOUT
BOTTOP V
VV
RR
For example, to set the output regulation voltage of ADP2107-
EVAL to 2.0 V, calculate the value of Resistor R4 and Resistor
R5 as shown below.
Ω=== k40
μA20
V8.0
STRING
FB
I
V
R5
Ω=
⎥
⎦
⎤
⎢
⎣
⎡−
×Ω=
⎥
⎦
⎤
⎢
⎣
⎡−
×= k60
V8.0
V8.0V2
k40
FB
FBOUT
V
VV
R5R4
Note that when the output voltage of the ADP2107-EVAL is
changed, the output capacitors (C3 and C4), the inductor (L1),
and the compensation components (R1 and C6) must be
recalculated and changed according to the Application
Information section in the ADP2107 data sheet to ensure stable
operation.
CHANGING THE LOAD TRANSIENT RESPONSE
The ADP2107 evaluation board load transient response can be
altered by changing the output capacitors (C3 and C4) and the
compensation components (R1 and C6) as explained in the
Output Capacitor section and Loop Compensation section of
the ADP2107 data sheet. By default, the load transient response
of both ADP2107 evaluation boards is set to 5% of the output
voltage for a 1 A load transient.
Consider an example where the load transient response of
ADP2107-1.8-EVAL is changed to 10% of the output voltage for
a 1 A load transient.
First, choose the output capacitors (C3 and C4) based on the load
transient response requirements. The desired load transient
response is 10% overshoot for a 1 A load transient. For this
condition, the % Overshoot for a 1 A Load Transient Response vs.
Output Capacitor × Output Voltage figure in the Output
Capacitor Selection section of the ADP2107 data sheet gives
Output Capacitor × Output Voltage = 25 μC
μF14
V8.1
μC25 ≈=⇒ CapacitorOutput
Next, taking into account the loss of capacitance due to dc bias
as shown in the % Drop-In Capacitance vs. DC Bias for Ceramic
Capacitors figure in the Output Capacitor Selection section of
the ADP2107 data sheet, let C3 and C4 be two 10 μF X5R MLCC
capacitors (GRM21BR61A106KE19L).
Finally, calculate the compensation resistor and compensation
capacitor as follows:
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
×
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
=
REF
OUTOUT
CSm
CROSS
COMP V
VC
GG
F
R)π2(
8.0
Ω=
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛×
×
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
×
×
=k70
V8.0
V8.1μF14
V/A625.3V/μA50
kHz80)π2(
8.0
pF120
kΩ70kHz80π
2
π
2=
××
==
COMPCROSS
COMP RF
C
Therefore, choose the compensation resistor to be 70 kΩ and
the compensation capacitor to be 120 pF.
EVAL-ADP2107
Rev. 0 | Page 5 of 12
MEASUREMENT SETUP
GND
GND
PROBE OUTPUT
VOLTAGE ACROSS
OUTPUT CAPACITOR
ADP2107
V
OUT
C2C5
C6
R1
R4
R3
R5
C7
C3
C4
L1
ENABLE
R2 J1 V
IN
C1
06314-010
VD 1S DI V
mVVCH
VPOS
NVER T
DVADVA ADD
VD 1S DI V
mVV
1V SEP
OFF
0V H
0V V
OFF
0V H
0V V
1V SEP AT N ORW
EVE
OSCILLOSCOPE
INDUCTOR
CURRENT
WAVEFORM
LX NODE
WAVEFORM
OUTPUT
VOLTAGE
WAVEFORM
3A VOLTAGE SOURCE
V
IN
I
IN
ELECTRONIC LOAD
VOLTMETER
V
OUT
I
OUT
CURRENT
PROBE
INDUCTOR
Figure 2. Typical Measurement Setup
->-H- u VWN h—b- [‘l AAA/vaA \ ‘ \ l
EVAL-ADP2107
Rev. 0 | Page 6 of 12
TYPICAL PERFORMANCE CHARACTERISTICS
100
50
1 10000
06314-004
LOAD CURRENT (mA)
EFFICIENCY (%)
95
90
85
80
75
70
65
60
55
10 100 1000
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 4.2V
V
IN
= 5.5V
INDUCTOR: D62LCB, 1.5µH
DCR: 21m
T
A
= 25°C
Figure 3. Efficiency—ADP2107-1.8-EVAL (1.8 V Output)
06314-005
CH1 50mV
6%CH4 200mACH3 2V
M 2µs A CH3 3.88V
T
3
4
1
INDUCTOR CURRENT
OUTPUT VOLTAGE (AC-COUPLED)
LX NODE
(SWITCH NODE)
Figure 4. PFM Mode of Operation at Light Load (10 mA)
06314-006
3
1
2
CH1 2V
10.4%
CH2 100mV
CH3 1A
M 10µs A CH2 100mV
T
CH2 LOW
–108mV
LX (SWITCH) NODE VOLTAGE
OUTPUT CURRENT
OUTPUT VOLTAGE (AC-COUPLED)
Figure 5. 1 A Load Transient Response for ADP2107-1.8-EVAL
06314-007
100
50 1 10000
LOAD CURRENT (mA)
EFFICIENCY (%)
95
90
85
80
75
70
65
60
55
10 100 1000
V
IN
= 3.0V
V
IN
= 3.6V
V
IN
= 4.2V V
IN
= 5.5V
INDUCTOR: D62LCB, 2.0H
DCR: 28m
T
A
= 25°C
Figure 6. Efficiency—ADP2107-EVAL (2.5 V Output)
06314-008
CH1 20mV
17.4%CH4 1ACH3 2V
M 1µs A CH3 3.88V
T
3
4
1
LX NODE (SWITCH NODE)
OUTPUT VOLTAGE (AC-COUPLED)
INDUCTOR CURRENT
Figure 7. PWM Mode of Operation at Medium/Heavy Load (1.5 A)
06314-009
3
1
2
CH1 2V
20.20%
CH2 100mV
CH3 1A
M 10µs A CH2 100mV
T
CH2 LOW
–140mV
LX (SWITCH) NODE VOLTAGE
OUTPUT CURRENT
OUTPUT VOLTAGE
(AC-COUPLED)
Figure 8. 1 A Load Transient Response for ADP2107-EVAL
with VOUT Set to 2.5 V
EVAL-ADP2107
Rev. 0 | Page 7 of 12
ORDERING INFORMATION
BILL OF MATERIALS
Table 1. Bill of Materials for ADP2107-1.8-EVAL with VOUT Set to 1.8 V
Description Ref. Des. Ref. Name1Quantity Manufacturer Mfg. Part Number
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
C1, C2 CIN1, CIN2 2 Murata GRM21BR61A106KE19L
Capacitor, MLCC, 22 μF, 6.3 V,
0805, X5R, SMD
C3, C4 COUT 2 Murata GRM21BR60J226ME39L
Capacitor, MLCC, 1 nF, 16 V,
0603, X7R, SMD
C5 CSS 1 Vishay Vitramon or
equivalent
VJ0603Y102KXJA
Capacitor, MLCC, 68 pF, 50 V,
0603, NPO
C6 CCOMP 1 Vishay Vitramon or
equivalent
VJ0603Y680KXJA
Capacitor, MLCC, 0.1 μF, 25 V,
0603, X7R, SMD
C7 IN (filter
capacitor)
1 Vishay Vitramon or
equivalent
VJ0603Y104KXXA
Resistor, 140 kΩ, 1%, 0603, SMD R1 RCOMP 1 Vishay Dale or equivalent CRCW06031403FRT1
Resistor, 100 kΩ, 1%, 0603, SMD R2 EN (pull
down)
1 Vishay Dale or equivalent CRCW06031003FRT1
Resistor, 10 Ω, 1%, 0603, SMD R3 IN (filter
resistor)
1 Vishay Dale or equivalent CRCW060310R0FRT1
Resistor, 0 Ω, 1%, 0603, SMD R4 1 Vishay Dale or equivalent CRCW06030000ZSSF
Bottom Resistor of Voltage
Divider
R5 No stuff
Inductor 1.5 μH, 6.3 mm ×
6.2 mm × 2.0 mm
L1 L 1 Toko D62LCB—1R5M
1.8 V, 2 A, Step-Down DC-to-DC
Converter
U1 1 Analog Devices, Inc. ADP2107-1.8
Headers, 0.100, Single, Straight VOUT, VIN,
GND, GND,
J1, EN
6 Sullins Electric or
equivalent
S1012-36-ND PTC36SAAN
1 Refer to the Typical Applications Circuit for Fixed Output Voltage Options figure in the ADP2107 data sheet.
OUTPUT VOLTAGE: 1.8V
V
OU
T
R2
100k
R1
140k
R5
NS
R4
0k
C6
68pF C5
1nF
EN
OUT
L1
1.5µH
2
GND
J1
C3
22µF
C4
22µF
V
IN
INPUT VOLTAGE: 2.7V TO 5.5V
R3
10
C7
0.1µF
C1
10µF
V
IN
GND
V
IN
U1
ADP2107
EN
SS
LX2
FB PWIN1
AGND PADDLE
OUTPUT VOLTAGE = 2.5V
COMP
PGND
IN
GND3
GND2
GND1
NC
GND
LX1
PWIN2
FB
1
2
3
4
12
11
10
9
16 15 14 13
567 17 8
NC = NO CONNECT
C2
10µF
V
IN
1
06314-002
Figure 9. Evaluation Board Schematic of ADP2107-1.8-EVAL with VOUT = 1.8 V
EVAL-ADP2107
Rev. 0 | Page 8 of 12
Table 2. Bill of Materials for ADP2107-EVAL with VOUT Set to 2.5 V
Description Ref. Des. Ref. Name1QTY Manufacturer Mfg. Part Number
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
C1, C2 CIN1, CIN2 2 Murata GRM21BR61A106KE19L
Capacitor, MLCC, 22 μF, 6.3 V,
0805, X5R, SMD
C3 COUT 1 Murata GRM21BR60J226ME39L
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
C4 COUT 1 Murata GRM21BR61A106KE19L
Capacitor, MLCC, 1 nF, 16 V,
0603, X7R, SMD
C5 CSS 1 Vishay Vitramon or
equivalent
VJ0603Y102KXJA
Capacitor, MLCC, 68 pF, 50 V,
0603, NPO
C6 CCOMP 1 Vishay Vitramon or
equivalent
VJ0603Y680KXJA
Capacitor, MLCC, 0.1 μF, 25 V,
0603, X7R, SMD
C7 IN (filter
capacitor)
1 Vishay Vitramon or
equivalent
VJ0603Y104KXXA
Resistor, 140 kΩ, 1%, 0603, SMD R1 RCOMP 1 Vishay Dale or equivalent CRCW06031403FRT1
Resistor, 100 kΩ, 1%, 0603, SMD R2 EN (pull down) 1 Vishay Dale or equivalent CRCW06031003FRT1
Resistor, 10 Ω, 1%, 0603, SMD R3 IN (filter
resistor)
1 Vishay Dale or equivalent CRCW060310R0FRT1
Resistor, 87.6 kΩ, 0.5%, 0603,
SMD
R4 RTOP 1 Vishay Dale or equivalent TNPW060387K6DHTA
Resistor, 41.2 kΩ, 0.1%, 0603,
SMD
R5 RBOT 1 Vishay Dale or equivalent TNPW060341K2BEEN
Inductor 2.0 μH, 6.3 mm x
6.2 mm x 2.0 mm
L1 L 1 Toko D62LCB-2R0M
2 A Step-Down DC-to-DC
Converter with Adjustable
Output
U1 1 Analog Devices, Inc. ADP2107-ADJ
Headers, 0.100, Single, Straight VOUT, VIN, GND,
GND, J1, EN
6 Sullins Electric or equivalent S1012-36-ND PTC36SAAN
1 Refer to the Typical Applications Circuit for Adjustable Output Voltage Option figure in the ADP2107 data sheet.
R5
41.2k
R4
87.6k
OUTPUT VOLTAGE: 2.5V
V
OU
T
R2
100k
R1
140k
C6
68pF C5
1nF
EN
FB
L1
2.0µH
2
GND
J1
C3
22µF
C4
10µF
V
IN
INPUT VOLTAGE: 2.7V TO 5.5V
R3
10
C7
0.1µF
C1
10µF
V
IN
GND
V
IN
U1
ADP2107
EN
SS
LX2
FB PWIN1
AGND PADDLECOMP
PGND
IN
GND3
GND2
GND1
NC
GND
LX1
PWIN2
FB
1
2
3
4
12
11
10
9
16 15 14 13
5 6 7 17 8
NC = NO CONNECT
C2
10µF
V
IN
1
0
6314-003
Figure 10. Evaluation Board Schematic for ADP2107-EVAL with Adjustable VOUT Initially Set to 2.5 V
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EVAL-ADP2107
Rev. 0 | Page 9 of 12
ORDERING GUIDE
Model Description
ADP2107-1.8-EVAL Evaluation Board
ADP2107-EVAL Evaluation Board
ESD CAUTION
EVAL-ADP2107
Rev. 0 | Page 10 of 12
NOTES
EVAL-ADP2107
Rev. 0 | Page 11 of 12
NOTES
ANALOG DEVICES www.ana|ng.nnm
EVAL-ADP2107
Rev. 0 | Page 12 of 12
T
NOTES
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
EB06314-0-12/06(0)
TTT