EVAL-ADP2106:降压DC/DC转换器解决方案评估板 PDF

Evaluation Board for Step-Down DC-to-DC
Converter Solution
EVAL-ADP2106
FEATURES
GENERAL DESCRIPTION
Efficiency >95%
Input voltage range: 2.7 V to 5.5 V
Output voltage range: 0.8 V to VIN
Maximum output current: 1.5 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 with a resistor and a capacitor
The ADP2106 evaluation board is a complete step-down dc-to-dc
converter solution using the ADP2106 step-down dc-to-dc
converter. It provides a ±1% accurate (±3% over all conditions)
regulated output voltage with load currents up to 1.5 A. It comes
in two versions: the ADP2106-1.8-EVAL with fixed output
voltage of 1.8 V, and the ADP2106-EVAL with adjustable output
voltage initially set to 2.5 V.
The ADP2106 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 ADP2106 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 ADP2106 data sheet.
FUNCTIONAL BLOCK DIAGRAM
ADP2106
EVALUATION BOARD
VIN
J1
R2
GND
ENB
GND
R3
C4
C7
C1
L1
R4 R5
R1
ADP2106
VOUT
C6
C2
C3
VOUT:
ANALOG DEVICES, POWER MANAGEMENT (STP)
06313-001
C5
Figure 1.
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
©2007 Analog Devices, Inc. All rights reserved.
EVAL-ADP2106
TABLE OF CONTENTS
Features .............................................................................................. 1
Modifying the Evaluation Board .....................................................4
General Description ......................................................................... 1
Measurement Setup...........................................................................5
Functional Block Diagram .............................................................. 1
Typical Performance Characteristics ..............................................6
Revision History ............................................................................... 2
Ordering Information.......................................................................7
Using the Evaluation Board............................................................. 3
Bill of Materials..............................................................................7
Powering Up the Evaluation Board............................................ 3
Ordering Guide .............................................................................9
Measuring Evaluation Board Performance .................................. 3
ESD Caution...................................................................................9
REVISION HISTORY
1/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 12
EVAL-ADP2106
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
Turning On the Evaluation Board
The ADP2106 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures outlined in this section.
Once the power source and load are connected to the
ADP2106 evaluation board, it can be powered 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 ADP2106-1.8-EVAL
and 2.5 V for the ADP2106-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.
Jumper J1
Before turning on the ADP2106 evaluation board, make sure that
all the components are present, but that Jumper J1 is removed.
Input Power Source
Before connecting the power source to the ADP2106 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.
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 must
be small (<20 mV), but in PFM mode, the output voltage ripple
can be as large as 50 mV.
Output Load
Measuring the Switching Waveform
Although the ADP2106 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; 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 ADP2106 evaluation board.
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.
Input and Output Voltmeters
Measuring Efficiency
Measure the input and output voltages with voltmeters. Make
sure that the voltmeters are connected to the appropriate
evaluation board terminals and not to the load or power source
themselves. 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.
The efficiency, η, is measured by comparing the input power
with the output power.
Connect the input voltage measuring 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.
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.
η=
VOUT × I OUT
VIN × I IN
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. Then a current probe can be used to measure the
current flowing through the current loop, as shown in Figure 2.
Rev. 0 | Page 3 of 12
EVAL-ADP2106
MODIFYING THE EVALUATION BOARD
The ADP2106 evaluation board is supplied fully assembled and
tested for proper operation. It comes in two versions: the
ADP2106-1.8-EVAL with fixed output voltage of 1.8 V and the
ADP2106-EVAL with adjustable output voltage initially set to 2.5 V.
⎡V
⎡ 2 V − 0.8 V ⎤
− VFB ⎤
R4 = R5 × ⎢ OUT
⎥ = 40 kΩ × ⎢
⎥ = 60 kΩ
⎣ 0.8 V ⎦
⎣ VFB
⎦
The two most common modifications that can be done to the
evaluation boards are changing the output voltage and changing
the load transient response.
Note that when the output voltage of ADP2106-EVAL is
changed, the output capacitors (C3 and C4), inductor (L1), and
compensation components (R1 and C6) are recalculated and
changed according to the Application Information section in
the ADP2106 data sheet to ensure stable operation.
Changing the Output Voltage
Changing the Load Transient Response
The ADP2106-EVAL output regulation voltage can be changed
by altering its external components. The ADP2106-1.8-EVAL
output regulation voltage is fixed at 1.8 V and cannot be
changed.
The ADP2106 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 Selection and Loop Compensation sections of
the ADP2106 data sheet. By default, the load transient response
of both ADP2106 evaluation boards is set to 5% of the output
voltage for a 1 A load transient.
The ADP2106-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 ADP2106
data sheet, and Resistor R5 corresponds to the RBOT resistor in
the ADP2106 data sheet. The output regulation voltage is
determined by the equation
⎡ R + RBOT ⎤
VOUT = 0.8 V × ⎢ TOP
⎥
RBOT
⎣
⎦
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.
Consider an example where the load transient response of the
ADP2106-1.8-EVAL is changed to 10% of the output voltage for
a 1 A load transient.
First, select 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 ADP2106 data
sheet gives
Output Capacitor × Output Voltage = 25 μC
To set the output regulation voltage to the desired value, first
determine the value of the bottom resistor, RBOT, by
R BOT =
⇒ Output Capacitor =
V FB
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 ADP2106 data sheet, let C3 and C4 be two
10 μF X5R MLCC capacitors (GRM21BR61A106KE19L).
I STRING
where:
VFB = 0.8 V, the internal reference.
ISTRING is the resistor divider string current (20 μA nominally)
Finally, calculate the compensation resistor and compensation
capacitor as follows:
Once RBOT is determined, calculate the value of the top resistor,
RTOP, from
⎛ ( 2 π ) FCROSS
RCOMP = 0.8 ⎜⎜
⎝ GmGCS
⎡V − VFB ⎤
RTOP = RBOT ⎢ OUT
⎥
⎦
⎣ VFB
V FB
I STRING
=
0.8 V
= 40 kΩ
20 μA
⎞ ⎛ COUT VOUT
⎟×⎜
⎟ ⎜ V
REF
⎠ ⎝
⎞
⎟
⎟
⎠
⎞ ⎛ 14 μF × 1.8 V ⎞
⎛
( 2 π ) × 80 kHz
⎟⎟ = 90 kΩ
⎟⎟ × ⎜⎜
= 0.8 ⎜⎜
0 .8 V
⎠
⎝ 50 μA / V × 2.8125 A / V ⎠ ⎝
For example, to set the output regulation voltage of ADP2106EVAL to 2.0 V, calculate the value of Resistor R4 and Resistor R5 as
shown below.
R5 =
25 μC
≈ 14 μF
1 .8 V
CCOMP =
2
2
=
= 90 pF
πFCROSS RCOMP π × 80 kHz × 90 kΩ
Therefore, choose the compensation resistor to be 90 kΩ and
the compensation capacitor to be 100 pF.
Rev. 0 | Page 4 of 12
EVAL-ADP2106
MEASUREMENT SETUP
ELECTRONIC LOAD
VOLTMETER
3A VOLTAGE SOURCE
VIN
IIN
VOUT
IOUT
J1
R2
GND
ENABLE
VIN
GND
PROBE OUTPUT
VOLTAGE ACROSS
OUTPUT CAPACITOR
R3
C4
C7
C1
R4
ADP2106
L1
R5
VOUT
R1
C6
C5
C2
CURRENT
PROBE
C3
INDUCTOR
OSCILLOSCOPE
1V SEP
1V SEP AT NORW
OFF
0V H
0V V
EVE
OFF
0V H
0V V
VD 1S DIV
VD 1S DIV
VPOS
NVERT
OUTPUT
VOLTAGE
WAVEFORM
mV
V
mV
DVA DVA ADD
LX NODE
WAVEFORM
Figure 2. Typical Measurement Setup
Rev. 0 | Page 5 of 12
CH
INDUCTOR
CURRENT
WAVEFORM
06313-010
V
EVAL-ADP2106
TYPICAL PERFORMANCE CHARACTERISTICS
100
100
VIN = 3.6V
95
90
85
EFFICIENCY (%)
VIN = 4.2V
80
75
VIN = 5.5V
70
VIN = 5.5V
VIN = 4.2V
80
75
70
65
65
60
60
55
1
10
100
06313-004
INDUCTOR: D62LCB, 2µH
DCR: 28mΩ
TA = 25°C
50
10000
1000
INDUCTOR: LPS4012-222, 2.2µH
DCR: 90mΩ
TA = 25°C
55
1
10
100
06313-007
EFFICIENCY (%)
VIN = 3.6V
90
VIN = 2.7V
85
50
VIN = 3.0V
95
10000
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
Figure 6. Efficiency—ADP2106-EVAL (2.5 V Output)
Figure 3. Efficiency—ADP2106-1.8-EVAL (1.8 V Output)
LX NODE (SWITCH NODE)
LX NODE
(SWITCH NODE)
3
3
1
1
OUTPUT VOLTAGE (AC-COUPLED)
OUTPUT VOLTAGE (AC-COUPLED)
CH4 200mAΩ
M 2µs
T 6%
A CH3
4
CH1 20mV
CH3 2V
3.88V
CH4 1AΩ
M 1µs
T 17.4%
A CH3
3.88V
Figure 7. PWM Mode of Operation at Medium/Heavy Load (1 A)
Figure 4. PFM Mode of Operation at Light Load (10 mA)
3
OUTPUT CURRENT
OUTPUT CURRENT
2
2
CH2 LOW
–108mV
LX (SWITCH) NODE VOLTAGE
CH2 100mV
M 10µs
T 10.4%
A CH2
OUTPUT VOLTAGE
(AC-COUPLED)
1
06313-006
1
CH1 2V
CH3 1A
CH2 LOW
–140mV
OUTPUT VOLTAGE (AC-COUPLED)
06313-009
3
06313-008
INDUCTOR CURRENT
CH1 50mV
CH3 2V
INDUCTOR CURRENT
06313-005
4
LX (SWITCH) NODE VOLTAGE
CH1 2V
CH3 1A
100mV
CH2 100mV
M 10µs
T 20.20%
A CH2
100mV
Figure 8. 1 A Load Transient Response for ADP2106-EVAL
with VOUT Set to 2.5 V
Figure 5. 1 A Load Transient Response for ADP2106-1.8-EVAL
Rev. 0 | Page 6 of 12
EVAL-ADP2106
ORDERING INFORMATION
BILL OF MATERIALS
Table 1. Bill of Materials for ADP2106-1.8-EVAL with VOUT Set to 2.5 V
Reference
Designator
C1
Reference
Name 1
CIN1
Qty.
1
Manufacturer
Murata
Part Number
GRM21BR61A475KA73L
C2
CIN2
1
Murata
GRM21BR61A106KE19L
C3, C4
COUT
2
Murata
GRM21BR60J226ME39L
C5
CSS
1
Vishay Vitramon or
equivalent
VJ0603Y102KXJA
Capacitor, MLCC, 56 pF, 50 V,
0603, NPO
Capacitor, MLCC, 0.1 μF, 25 V,
0603, X7R, SMD
Resistor, 182 kΩ, 1%, 0603, SMD
C6
CCOMP
1
VJ0603Y560KXJA
C7
1
R1
IN (filter
capacitor)
RCOMP
1
Resistor, 100 kΩ, 1%, 0603, SMD
R2
EN (pull down)
1
Resistor, 10 Ω, 1%, 0603, SMD
R3
IN (filter
resistor)
1
Resistor, 0 Ω, 1%, 0603, SMD
R4
Vishay Vitramon or
equivalent
Vishay Vitramon or
equivalent
Vishay Dale or
equivalent
Vishay Dale or
equivalent
Vishay Dale or
equivalent
Vishay Dale or
equivalent
Bottom Resistor of Voltage
Divider 2
Inductor 2.2 μH, 3.9 mm x
3.9 mm x 1.1 mm
1.8 V, 1.5 A Step Down DC-toDC Converter
R5
Headers, 0.100, Single, Straight
Description
Capacitor, MLCC, 4.7 μF, 10 V,
0805, X5R, SMD
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
Capacitor, MLCC, 22 μF, 6.3 V,
0805, X5R, SMD
Capacitor, MLCC, 1 nF, 16 V,
0603, X7R, SMD
2
L1
L
CRCW06031823FRT1
CRCW06031003FRT1
CRCW060310R0FRT1
CRCW06030000ZSSF
1
Coilcraft®
LPS4012-222
U1
1
Analog Devices, Inc.
ADP2106-1.8
VOUT, VIN,
GND, GND,
J1, EN
6
Sullins Electronics
or equivalent
S1012-36-NDPTC36SAAN
Refer to the Typical Applications Circuit for Fixed Output Voltage Options figure in the ADP2106 data sheet.
Do not solder this component onto the board.
VCC
C7
R3
0.1µF 10Ω
VCC
C1
4.7µF
OUT
J1
16
15
14
OUT_SENSE GND4
1
EN
2
GND3
EN
R2
100kΩ
3
4
INPUT VOLTAGE: 2.7V TO 5.5V
VIN
GND
13
IN1 PWIN1
LX2 12
U1
ADP2106-1.8
PWIN2 9
GND1
5
1
LX1 10
GND2
COMP
PGND 11
SS
AGND PADDLE NC
6
7
17
C5
1nF
2
VCC
OUT
C2
10µF
8
OUTPUT VOLTAGE: 1.8V
C3
22µF
C4
22µF
R4
0kΩ
VOUT
GND
R5
NS
R1
182kΩ
C6
56pF
L1
2.2µH
NC = NO CONNECT
Figure 9. Evaluation Board Schematic of ADP2106-1.8-EVAL with VOUT = 1.8 V
Rev. 0 | Page 7 of 12
06313-002
1
1
VJ0603Y104KXXA
EVAL-ADP2106
Table 2. Bill of Materials for ADP2106-EVAL with VOUT Set to 2.5 V
Reference
Designator
C1
Reference
Name 1
CIN1
Qty.
1
Manufacturer
Murata
Part Number
GRM21BR61A475KA73L
C2
CIN2
1
Murata
GRM21BR61A106KE19L
C3
COUT
1
Murata
GRM21BR60J226ME39L
C4
COUT
1
Murata
GRM21BR61A106KE19L
Capacitor, MLCC, 1 nF, 16 V,
0603, X7R, SMD
Capacitor, MLCC, 56 pF, 50 V,
0603, NPO
Capacitor, MLCC, 0.1 μF, 25 V,
0603, X7R, SMD
Resistor, 182 kΩ, 1%, 0603, SMD
Resistor, 100 kΩ, 1%, 0603, SMD
C5
CSS
1
VJ0603Y102KXJA
C6
CCOMP
1
C7
1
1
1
Resistor, 10 Ω, 1%, 0603, SMD
R3
1
Vishay Dale or equivalent
CRCW060310R0FRT1
Resistor, 87.6 kΩ, 0.5%, 0603, SMD
Resistor, 41.2 kΩ, 0.1%, 0603, SMD
Inductor 2.5 μH, 5.2 mm x
5.2 mm x 1.4 mm
R4
R5
L1
IN (filter
capacitor)
RCOMP
EN (pull
down)
IN (filter
resistor)
RTOP
RBOT
L
Vishay Vitramon or
equivalent
Vishay Vitramon or
equivalent
Vishay Vitramon or
equivalent
Vishay Dale or equivalent
Vishay Dale or equivalent
1
1
1
Vishay Dale or equivalent
Vishay Dale or equivalent
Cooper Bussmann
(Coiltronics)
TNPW060387K6DHTA
TNPW060341K2BEEN
SD14-2R5
Analog Devices
ADP2106-ADJ
Sullins Electronics or
equivalent
S1012-36-NDPTC36SAAN
Description
Capacitor, MLCC, 4.7 μF, 10 V,
0805, X5R, SMD
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
Capacitor, MLCC, 22 μF, 6.3 V,
0805, X5R, SMD
Capacitor, MLCC, 10 μF, 10 V,
0805, X5R, SMD
R1
R2
1.5 A Step Down DC-to-DC
Converter with Adjustable
Output
Headers, 0.100, Single, Straight
1
6
VJ0603Y104KXXA
CRCW06031823FRT1
CRCW06031003FRT1
Refer to the Typical Applications Circuit for Adjustable Output Voltage Option figure in the ADP2106 data sheet.
V
C7
R3 CC
0.1µF 10Ω
VCC
FB
J1
16
C1
4.7µF
15
FB
EN
R2
100kΩ
14
GND4
INPUT VOLTAGE: 2.7V TO 5.5V
VIN
GND
13
IN1 PWIN1
LX2 12
1 EN
U1
PGND
ADP2106-ADJ
2 GND3
11
1
LX1 10
3 GND2
L1
2.5µH
2
VCC
PWIN2 9
4 GND1
COMP SS AGND PADDLE NC
5
6
7
17
C2
10µF
8
C5
1nF
C3
22µF
R4
87.6kΩ
C4
10µF
VOUT
GND
R5
41.2kΩ
R1
182kΩ
C6
56pF
FB
OUTPUT VOLTAGE: 2.5V
NC = NO CONNECT
06313-003
1
U1
VOUT, VIN, GND,
GND, J1, EN
VJ0603Y560KXJA
Figure 10. Evaluation Board Schematic for ADP2106-EVAL with Adjustable VOUT Initially Set to 2.5 V
Rev. 0 | Page 8 of 12
EVAL-ADP2106
ORDERING GUIDE
Model
ADP2106-1.8-EVAL
ADP2106-EVAL
Description
Evaluation board with fixed output voltage
Evaluation board with adjustable output voltage
ESD CAUTION
Rev. 0 | Page 9 of 12
EVAL-ADP2106
NOTES
Rev. 0 | Page 10 of 12
EVAL-ADP2106
NOTES
Rev. 0 | Page 11 of 12
EVAL-ADP2106
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
EB06313-0-1/07(0)
Rev. 0 | Page 12 of 12