ADP2441-EVALZ User Guide
UG-407
10694-101
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
ADP2441 Evaluation Board
FEATURES
Full-featured evaluation board for the ADP2441
Configurable synchronous step down dc-dc switching
regulator
Operating voltage range of board: V
Output voltage is set to 5 V or can be adjusted
Maximum load 1 A
Switching frequency set to 500 kHz or adjustable switching
frequency of 300 kHz to 1 MHz
Power saving mode at light load
Precision enable input pin
Current limit protection
Power good output
External soft start set to 6 ms or external tracking available
Board size: 53 mm × 53 mm
DOCUMENTS NEEDED
ADP2441 data sheet
UG-407
= 6 V to 36 V
IN
GENERAL DESCRIPTION
The ADP2441 evaluation board is a complete, dc-to-dc switching regulator design based on the ADP2441, a configurable, 1 A,
synchronous step-down, dc-to-dc regulator.
The ADP2441 is a synchronous, step-down dc-to-dc switching
regulator that uses a current mode pulse-width modulation
(PWM) control scheme at medium-to-heavy load currents for
high efficiency and smoothly transitions to a pulse skip mode
at light loads to conserve power. The power switch and
synchronous rectifier are integrated for minimal external part
count and high efficiency. The ADP2441 is optimized for
operation with small ferrite core inductors and ceramic
capacitors to deliver the maximum output power per square
millimeter of the PCB board area.
The ADP2441-EVALZ is available with 5 V at 1 A output,
switching frequency set to 500 kHz. If needed, the ADP2441
evaluation board configuration can be modified by changing
the values of the appropriate passive components.
Complete specifications for the ADP2441 device can be found
in the ADP2441 data sheet, which is available from Analog
Devices, Inc., and should be consulted in conjunction with this
user guide when using the evaluation board.
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
ADP2441-EVALZ
Figure 1.
Rev. 0 | Page 1 of 12
UG-407 ADP2441-EVALZ User Guide
TABLE OF CONTENTS
Features .............................................................................................. 1
Documents Needed .......................................................................... 1
General Description ......................................................................... 1
ADP2441-E VALZ ............................................................................. 1
Revision History ............................................................................... 2
Using the Evaluation Board ............................................................. 3
Powering Up the Evaluation Board ............................................ 3
Measuring Evaluation Board Performance ............................... 4
REVISION HISTORY
6/12—Initial Version: Revision 0
Modifying the Evaluation Board .....................................................5
Changing the Output Voltage ......................................................5
Changing the Switching Frequency ............................................5
Changing the Soft Start Time ......................................................5
Typical Performance Characteristics ..............................................6
Evaluation Board Schematics and Artwork ...................................8
Ordering Information .................................................................... 10
Bill of Materials ........................................................................... 10
Rev. 0 | Page 2 of 12
ADP2441-EVALZ User Guide UG-407
PGOOD
TP2: EXTERNAL
SUPPLY: 5V
JP1
10694-001
R7
50kΩ
R10
OPEN
R11
OPEN
C11
10nF
SS
SS/TRK
TRK
10694-002
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2441 evaluation board is provided fully assembled
and tested. Before applying power to the evaluation board,
follow the procedures in this section.
Input Power Source
The power source voltage must not exceed 36 V, the maximum
operation input voltage of the ADP2441.
Make sure the power source is switched off before connecting it
to the ADP2441 evaluation board. Connect the positive
terminal of the power source to the evaluation board V
terminal (T1), and the negative terminal of the power source to
the evaluation board GND terminal (T2). If the power source
includes an ammeter, connect the ammeter 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 ammeter to the evaluation board V
(T1), and the negative lead (−) of the power source to the
evaluation board GND terminal (T2).
Output Load
Make sure the evaluation board is switched off before connecting the load. Connect the load directly to the evaluation board,
with the positive (+) load connection to the V
OUT
(T3) and the negative (−) load connection to the GND terminal
(T4). If an ammeter is used, connect it in series with the load:
connect the positive (+) ammeter terminal to the evaluation
board V
terminal (T3), the negative (−) ammeter terminal
OUT
to the positive (+) load terminal, and the negative (−) load
terminal to the evaluation board GND terminal (T4).
Once the load is connected, make sure it is set to the proper
current before powering the ADP2441 evaluation board. Before
connecting a load to the output of the evaluation board, make
sure that the output voltage does not exceed the maximum
operating voltage range of the load.
Enabling and Disabling the DC-to-DC Switching Regulator
In the evaluation board, a voltage divider is used to generate
an enable signal for the IC. As soon as voltage is applied to
V
(24 V), IC is enabled.
IN
Alternatively, header TP1 (EN) is available to enable and disable
the evaluation board. To enable the output, connect the header
TP1 to the V
supply or to an external voltage source. To disable
IN
the output connect the header TP1 to the GND.
IN
terminal
IN
terminal
PGOOD Signals
When the output is enabled and the output voltage, VOUT, is in
regulation, the logic signal at the PGOOD test point is high. In
a typical application, a pull-up resistor from the PGOOD pin to
the external supply is used to generate this logic signal.
On the evaluation board, the pull-up resistor (R7) is available to
connect to the external supply through the jumper (JP1). Test
Point TP2 is available to connect the external supply of 5 V.
Figure 2 PGOOD Signal
External SS/Track Signal
The SS/TRK pin is multipurpose. It can be used either for
tracking the external supply or for soft start.
A header, TRK, is available on the board for connecting an
external signal to be tracked by the regulator output voltage.
Before applying a signal to the TRK header, make sure the
voltage divider resistor values (R10, R11) connected on the
evaluation board are the correct values (see the ADP2441
data sheet).
Alternatively, to program soft start time, a capacitor can be
connected to SS/TRK pin. On the evaluation board, a 10 nF
capacitor, C11, is connected for a soft start time of 6 ms.
Figure 3. Soft Start Signal
Rev. 0 | Page 3 of 12
UG-407 ADP2441-EVALZ User Guide
ININ
OUTOUT
IVIV×
×
=
η
10694-104
MEASURING EVALUATION BOARD PERFORMANCE
Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope
probe tip at Terminal T3 and connect the probe ground lead at
the negative (−) Terminal T4. Set the oscilloscope to an accoupled, 100 mV/division and 2 μs/division time base.
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 SW pin with the probe ground at Terminal T4,
GND. Set the scope to dc, 5 V/division, and 2 µs/division time
base. The switching waveform should alternate between 0 V
and approximately the input voltage.
Figure 4. Switch Node Measurement
Measuring Load Regulation
The load regulation should be measured 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. In PWM mode, the output voltage ripple should be
small (<50 mV) but in pulse skip mode, the output voltage
ripple can be as large as 100 mV.
Measuring Efficiency
The efficiency, η, is measured by comparing the input power
with the output power.
Measure the input and output voltages as close as possible to the
input and output capacitors to reduce the effect of IR drops.
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.
Line Transient Response
Generate a step input voltage (VIN) and observe the behavior
of the output voltage, with an oscilloscope.
Load Transient Response
Generate a load current transient at the output, V
OUT
, and
observe the output voltage response with an oscilloscope.
Use a current probe attached to the wire between the output
and the load to visualize the current transient.
Loop Stability Measurement
Closed-loop response can be measured using a network
analyzer. To measure the loop response, Header IN and
Header OUT are available.
Rev. 0 | Page 4 of 12
ADP2441-EVALZ User Guide UG-407
+
×=3V6.0
R
R3R2
V
OUT
STRING
FB
I
V
R3 =
−
=
FB
FB
OUT
V
VV
R3R2
kΩ10
μA60
V0.6
===
STRING
I
FB
V
R3
ΩΩ
k3.45
V6.0
V6.0V3.3
k10 =
−
×=
−
×=
FB
FB
OUT
V
VV
R3R2
1.2
10
10
SW
f
R
500,92
9 =
SS
REF
SS
t
V
I
C11 ×=
MODIFYING THE EVALUATION BOARD
The ADP2441 evaluation board is provided fully assembled
and tested for proper operation. The ADP2441-EVALZ has a
fixed 5 V output voltage.
CHANGING THE OUTPUT VOLTAGE
The ADP2441-EVALZ output regulation voltage is set by a
resistive voltage divider consisting of Resistors R2 and R3.
Resistor R2 corresponds to the R
and Resistor R3 corresponds to the R
sheet. The output regulation voltage is determined by the
equation
resistor in the data sheet
TOP
resistor in the data
BOTTOM
Note that when the output voltage of ADP2441-EVALZ is
changed, the output capacitors (C7 and C8), inductor (L1), and
compensation components (R5 and C10) should be recalculated
and changed according to the Application Information section
in the ADP2441 data sheet to ensure stable operation.
Table 1. Programming Output Voltage
Voltage (V) R2 (kΩ) R3 (kΩ)
12 190 10
5 73 10
3.3 45 10
where:
R2 is the value of the top resistor of the voltage divider (R
TOP
R3 is the value of the bottom resistor of the voltage divider
(R
V
).
BOTTOM
is the output regulation voltage in volts.
OUT
To set the output regulation voltage to the desired value, first
determine the value of the bottom resistor, R3, by
where:
= 0.6 V, the internal reference.
V
FB
I
is the resistor divider string current (greater than 20 μA
STRING
nominally).
Once R3 is determined, calculate the value of the top resistor,
R2, by
For example, to set the output regulation voltage of ADP2441-
EVAL Z to 3.3 V, calculate the value of Resistors R2 and R3 as
shown in the following equations:
CHANGING THE SWITCHING FREQUENCY
The switching frequency (fSW) set point can be changed by
).
replacing Resistor R9 with a different value using following
equation:
where:
R9 is the frequency resistor in kΩ.
f
is the switching frequency in kHz.
sw
Table 2. Programming Frequency
R9 (kΩ) Frequency (kHz)
308 300
132 700
92.5 1000
Note that when the switching frequency (fSW) is changed,
to ensure stable operation, the values of Inductor L1, C7, C8
(output capacitors), and R5, C10 (compensation components)
must be recalculated and changed (see the ADP2441 data sheet
for details on external component selection).
CHANGING THE SOFT START TIME
The soft start time of the ADP2441 on the evaluation board is
programmed to 6 ms. To change the soft start time, t
Capacitor C11 with a different capacitor value using the
following equation:
, replace
SS
where:
V
is the internal reference voltage and equals 0.6 V.
REF
I
is the soft start current and equals 1 μA.
SS
C11 is the soft start capacitor value.
t
is the soft start time
SS
Rev. 0 | Page 5 of 12
UG-407 ADP2441-EVALZ User Guide
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1
EFFICIENCY (%)
LOAD (A)
10694-004
VIN = 12V
V
IN
= 24V
V
IN
= 36V
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1
EFFICIENCY (%)
LOAD (A)
10694-005
VIN = 5V
V
IN
= 12V
V
IN
= 24V
V
OUT
(V)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
LOAD (A)
10694-006
5.001
5.003
5.005
5.007
5.009
5.011
5.013
5.015
VIN = 12V
V
IN
= 24V
V
IN
= 36V
V
OUT
(V)
VIN(V)
10694-007
4.985
4.990
4.995
5.000
5.005
5.010
5.015
5.020
8 13 18 23 28 33 38
NO LOAD
LOAD 1A
CH1 100mV CH2 10V M20µs A CH4 150mA
1
4
2
T 46.8%
B
W
CH4 500mA Ω
VOUT
SWSW
10694-008
INDUCTOR CURRENT
CH1 50mV CH2 10V M2µs A CH2 7.6V
1
4
2
T 46.8%
B
W
CH4 500mA Ω
VOUT
INDUCTOR CURRENT
SWSW
10694-009
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 5. Efficiency vs. Load Current, V
= 5 V, fSW = 500 kHz
OUT
Figure 8. Line Regulation, V
= 5 V, fSW = 500 kHz
OUT
Figure 6. Efficiency vs. Load Current, V
Figure 7. Load Regulation, V
OUT
= 3.3 V, fSW = 500 kHz
OUT
= 5 V, fSW = 500 kHz
Rev. 0 | Page 6 of 12
Figure 9. Pulse Skip Waveform
V
= 24 V; V
IN
Figure 10. PWM Waveform, V
= 5 V, fSW = 500 kHz, No Load
OUT
= 24 V, V
IN
= 5 V, fSW = 500K, Load = 1 A
OUT
ADP2441-EVALZ User Guide UG-407
CH1 100mV CH2 10V M200µs A CH4 720mA
1
4
2
T 71.2%
B
W
CH4 500mA Ω
VOUT
LOAD STE P 500mA
SWSW
10694-010
CH1 100mV
CH4 500mA
M200µs A CH4 800mA
1
4
2
T 71.4%
B
W
CH2 5V
Ω
VOUT
LOAD STE P 500mA
SW
10694-011
CH2 2VCH1 2V
CH3 2V
M2ms A CH2 1.92V
2
1
4
3
T 10.6%
B
W
CH4 500mV
ENABLE
VOUT
SS
PGOOD
10694-012
CH2 5VCH1 2V
CH3 2V
M400µs A CH2 1.90V
T 50.2%
B
W
CH4 1V
1
4
2
4
ENABLE
VOUT
SS
PGOOD
10694-013
200
–200
160
–160
120
–120
80
–80
40
–40
0
110
1k 10k 100k
–90
90
–70
70
–50
50
–30
30
–10
10
PHASE (Degrees)
MAGNITUDE ( dB)
FREQUENCY (Hz)
10694-014
Figure 11. Load Transient, V
Figure 12. Load Transient, V
= 24 V, V
IN
= 12 V, V
IN
= 5 V, 500 mA Step
OUT
= 5 V, 500 mA
OUT
Figure 14. Shutdown; V
= 24 V, V
IN
= 5 V, Load 5 Ω
OUT
Figure 15. Bode Plot; V
= 24 V, V
IN
f
= 37 kHz, Phase Margin = 55°
co
= 5 V, fSW = 500 kHz, Load = 1 A
OUT
Figure 13. Startup; V
= 24 V, V
IN
= 5 V, Load 5 Ω
OUT
Rev. 0 | Page 7 of 12
UG-407 ADP2441-EVALZ User Guide
EVALUATION BOARD SCHEMATICS AND ARTWORK
10694-015
Figure 16.
Rev. 0 | Page 8 of 12
ADP2441-EVALZ User Guide UG-407
10694-016
10694-018
10694-017
10694-019
Figure 17. Top Layer
Figure 18. Third layer
Figure 19. Second layer
Figure 20. Bottom Layer
Rev. 0 | Page 9 of 12
UG-407 ADP2441-EVALZ User Guide
2
R3, R8
Resistor, 10 kΩ, 1/10 W, 1% 0603 SMD
Determined by user
4
T1, T2, T3, T4
Terminal, double turret, brass, 0.078”
Keystone 1502-1
ORDERING INFORMATION
BILL OF MATERIALS
Table 3.
Qty Reference Designator Description Manufacturer/Part Number
2 C1, C2 Capacitor MLCC, 4.7 µF, 50 V,1206, X7R Murata GRM31CR71H475KA12L
2 C3, C4 Capacitor MLCC, 1 µF,25 V,0603, X7R Murata GRM188R71E105KA12D
1 C5 Capacitor, MLCC, 10 nF, 50 V,0603, X7R Murata GRM188R71H103KA01D
2 C7, C8 Capacitor, MLCC, 22 µF, 25 V 1210, X7R Murata GRM32ER71E226K
1 C11 Capacitor 10 nF, 50 V ceramic X7R Panasonic ECJ-1VB1H103K
1 L1 MSS1038T-273 Coilcraft Coilcraft
1 C6 Capacitor MLCC, 0.1 µF, 50 V, 0603, X7R Murata GRM188R71H104KA93D
1 C10 Capacitor MLCC 270 pF, 50 V,0603, X7R Murata
1 R1 Resistor, 49.9 Ω, 1/10 W, 1% 0603 SMD Determined by user
1 R7 Resistor, 50 kΩ, 1/10 W, 1% 0603 SMD Determined by user
1 R2 Resistor, 73.2 kΩ, 1/10 W, 1% 0603 SMD Determined by user
1 R5 Resistor, 118 kΩ, 1/10 W, 1% 0603 SMD Determined by user
1 R6 Resistor, 182 kΩ, 1/10 W, 1% 0603 SMD Determined by user
1 R9 Resistor, 185 kΩ, 1/10 W, 1% 0603 SMD Determined by user
1 R10 Resistor, 0 Ω, 1/10 W, 1% 0603 SMD Determined by user
1 R11 Resistor, open, 1/10 W, 1% 0603 SMD Determined by user
4 TRACK, SS, IN, OUT Headers Sullins PBC01SAAN
4 TP1, TP2, TP3, TP4 Headers Sullins PBC01SAAN
1 JP1 PGOOD Jumper Sullins PBC03SAAN
1 U1 ADP2441 Analog Devices ADP2441
Rev. 0 | Page 10 of 12
ADP2441-EVALZ User Guide UG-407
NOTES
Rev. 0 | Page 11 of 12
UG-407 ADP2441-EVALZ User Guide
NOTES
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection
circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
Legal Terms and Conditions
By using the evaluation board discussed herein (together with any tools, components documentation or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions
set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you
have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc.
(“ADI”), with its principal place of business at One Technology Way, Norwood, MA 02062, USA. Subject to the terms and conditions of the Agreement, ADI hereby grants to Customer a free, limited, personal,
temporary, non-exclusive, non-sublicensable, non-transferable license to use the Evaluation Board FOR EVALUATION PURPOSES ONLY. Customer understands and agrees that the Evaluation Board is provided
for the sole and exclusive purpose referenced above, and agrees not to use the Evaluation Board for any other purpose. Furthermore, the license granted is expressly made subject to the following additional
limitations: Customer shall not (i) rent, lease, display, sell, transfer, assign, sublicense, or distribute the Evaluation Board; and (ii) permit any Third Party to access the Evaluation Board. As used herein, the term
“Third Party” includes any entity other than ADI, Customer, their employees, affiliates and in-house consultants. The Evaluation Board is NOT sold to Customer; all rights not expressly granted herein, including
ownership of the Evaluation Board, are reserved by ADI. CONFIDENTIALITY. This Agreement and the Evaluation Board shall all be considered the confidential and proprietary information of ADI. Customer may
not disclose or transfer any portion of the Evaluation Board to any other party for any reason. Upon discontinuation of use of the Evaluation Board or termination of this Agreement, Customer agrees to
promptly return the Evaluation Board to ADI. ADDITIONAL RESTRICTIONS. Customer may not disassemble, decompile or reverse engineer chips on the Evaluation Board. Customer shall inform ADI of any
occurred damages or any modifications or alterations it makes to the Evaluation Board, including but not limited to soldering or any other activity that affects the material content of the Evaluation Board.
Modifications to the Evaluation Board must comply with applicable law, including but not limited to the RoHS Directive. TERMINATION. ADI may terminate this Agreement at any time upon giving written notice
to Customer. Customer agrees to return to ADI the Evaluation Board at that time. LIMITATION OF LIABILITY. THE EVALUATION BOARD PROVIDED HEREUNDER IS PROVIDED “AS IS” AND ADI MAKES NO
WARRANTIES OR REPRESENTATIONS OF ANY KIND WITH RESPECT TO IT. ADI SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, ENDORSEMENTS, GUARANTEES, OR WARRANTIES, EXPRESS OR IMPLIED, RELATED
TO THE EVALUATION BOARD INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT OF INTELLECTUAL
PROPERTY RIGHTS. IN NO EVENT WILL ADI AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES RESULTING FROM CUSTOMER’S POSSESSION OR USE OF
THE EVALUATION BOARD, INCLUDING BUT NOT LIMITED TO LOST PROFITS, DELAY COSTS, LABOR COSTS OR LOSS OF GOODWILL. ADI’S TOTAL LIABILITY FROM ANY AND ALL CAUSES SHALL BE LIMITED TO THE
AMOUNT OF ONE HUNDRED US DOLLARS ($100.00). EXPORT. Customer agrees that it will not directly or indirectly export the Evaluation Board to another country, and that it will comply with all applicable
United States federal laws and regulations relating to exports. GOVERNING LAW. This Agreement shall be governed by and construed in accordance with the substantive laws of the Commonwealth of
Massachusetts (excluding conflict of law rules). Any legal action regarding this Agreement will be heard in the state or federal courts having jurisdiction in Suffolk County, Massachusetts, and Customer hereby
submits to the pers onal jurisdiction and venu e of such courts. The United Nations Conventi on on Contracts for the Internation al Sale of Goods shall not apply to this Agreement and is expressly disclaimed.
©2012 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
UG10694-0-6/12(0)
Rev. 0 | Page 12 of 12
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