Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
General Description
The MAXM17544 evaluation kit (EV kit) is a demonstration
circuit of the MAXM17544 high-voltage, high-efficiency,
current-mode scheme, synchronous step-down, DC-DC
switching power module. The EV kit is designed for a 3.3V
output and delivers up to 3.5A load current from a wide
input-voltage range of 4.5V to 42V. The EV kit switches at
an optimal 500kHz switching frequency to allow the use of
small component-sizes, helping to minimize solution-size
while maintaining high-performance. The EV kit provides
a precision-enable input, an open-drain RESET output
signal, and external frequency synchronization to provide
a simple and reliable startup sequence and eliminate beat
frequency between regulators. The EV kit also includes
optional component footprints to program different output
voltages, an adjustable input undervoltage-lockout, and
a soft-start time to control inrush current during startup.
The MAXM17544 IC data sheet provides a complete
description of the part that should be read in conjunction
with this evaluation kit data sheet prior to modifying the
demo circuit.
Features
●Highly Integrated Solution with Integrated Shield
Inductor
●Wide 4.5V to 42V Input Range
●Preset 3.3V Output with a Fixed Resistor-Divider on
FB (Feedback Pin)
●Programmable Output-Voltage Feature (0.9V to 12V)
●Up to 3.5A Output Current
●High 91.2% Efficiency (VIN = 12V, VOUT = 3.3V at 0.74A)
●500kHz Switching Frequency
●Enable/UVLO Input, Resistor-Programmable UVLO
Threshold
●Adjustable Soft-Start Time
●Selectable PWM, PFM, or DCM Mode
●Open-Drain RESET Output
●External Frequency Synchronization
●Overcurrent and Overtemperature Protection
●Low-Profile, Surface-Mount Components
●Lead(Pb)-Free and RoHS Compliant
●Fully Assembled and Tested
19-7625; Rev 0; 5/15
Ordering Information appears at end of data sheet.
PRELIMINARY
Maxim Integrated
│
2
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
Quick Start
Recommended Equipment
●MAXM17544 EV kit
●4.5V to 42V DC power supply (VIN)
●Dummy load capable of sinking 3.5A
●Digital voltmeter (DVM)
●100MHz dual-trace oscilloscope
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation. Caution: Do not turn on
the power supply until all connections are completed.
1) Set the power supply at a voltage between 4.5V and
42V. Disable the power supply.
2) Connect the positive and negative terminals of the
power supply to IN and PGND PCB pads, respectively.
3) Connect the positive and negative terminals of the
3.5A load to OUT and PGND2 PCB pads, respectively,
and set the load to 0A.
4) Connect the DVM across the OUT PCB pad and the
PGND2 PCB pad.
5) Verify that no shunts are installed across pin 1-2 on
jumper JU1 to enable UVLO (see Table 1 for details).
6) Verify that a shunt is installed across JU3 to disable
the external synchronization (see Table 3 for details).
7) Verify that a shunt is installed across JU2 to enable
PWM mode (see Table 2 for details).
8) Enable the input power supply.
9) Verify the DVM displays 3.3V.
10) Increase the load up to 3.5A to verify the DVM continues
displaying 3.3V.
Detailed Description of Hardware
The EV kit is a proven circuit to demonstrate the high-
voltage, high-efficiency, and compact solution-
size of the synchronous step-down, DC-DC power
module. The output voltage is preset for 3.3V to operate
from 4.5V to 42V and provides up to 3.5A load current.
The optimal frequency is set at 500kHz to maximize
efciency and minimize component size. The EV kit includes
jumpers JU1 to enable/disable UVLO of the device, JU2
to congure in PWM, PFM, or DCM mode in advantage
of light-load efciency, and JU3 to enable/disable external
clock synchronize (SYNC). The RESET PCB pad is also
available for monitoring output voltage regulation to
enable/disable the application circuit of the load. The elec-
trolytic capacitor (C8) is required only when the VIN power
supply is situated far from device circuit. When R4 is
open, the device switches at 500kHz switching frequency.
On the bottom layer, additional footprints of optional
components are included to ease board modication for
different input/output congurations.
Soft-Start Input (SS)
The device utilizes an adjustable soft-start function to
limit inrush current during startup. The soft-start time is
programmed by the value of the external capacitor from
SS to GND (C1). The selected output capacitance (CSEL)
and the output voltage (VOUT) determine the minimum
value of C1, as shown by the following equation:
3SEL OUT
C1 28 10 C V
−
≥× × ×
where C1 is in nF and CSEL is in µF
The soft-start time (tSS) is calculated by the equation
below:
SS
t C1/ 5.55=
where tSS is in ms and C1 is in nF.
Programmable Undervoltage Lockout (UVLO)
The EV kit offers an adjustable-input undervoltage-
lockout level by resistor-dividers connected between
IN, EN/UVLO, and GND pins. For normal operation, a
shunt should not be installed across pins 1-2 on JU1
to enable the output through an internal pullup 3.3MΩ
resistor from the EN/UVLO pin to IN pin. To disable the
output, install the shunt across pins 1-2 on JU1 to
pull EN/UVLO pin to GND. See Table 1 for JU1
jumper settings. The EV kit also provides an optional
R3 PCB footprint to program a UVLO threshold voltage
at which an input-voltage level device turns on. The R3
resistor can be calculated by the following equation:
INU
4009.5
R3 (V 1.215)
=
−
where VINU is the input voltage at which the device is
required to turn on, and R3 unit is in kΩ.
Table 1. UVLO Enable/Disable
Configuration (JU1)
*Default position.
SHUNT
POSITION EN PIN MAXM17544_OUTPUT
Installed Connected to GND Disable
Not installed* Connected to VIN Enable
PRELIMINARY
Maxim Integrated
│
3
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
Mode Selection (MODE)
The device’s MODE pin can be used to select among
PWM, PFM, or DCM modes of operation in advance of
constant frequency or high efficiency at light loads. The
logic state of the MODE pin is latched when the VCC
and EN/UVLO voltage exceed the respective UVLO
rising thresholds and all internal voltages are ready
to allow LX switching. The changes on the MODE
pin are ignored during normal operation. Refer to the
MAXM17544 IC data sheet for more information on PWM,
PFM, and DCM modes of operation. Table 2 shows EV kit
jumper settings that can be used to configure the desired
mode of operation.
External Clock Synchronization (SYNC)
The internal oscillator of the device can be synchronized
to an external clock signal to eliminate beat frequency
between regulators through the SYNC pin. The external
synchronization clock frequency must be between 1.1fSW
to 1.4fSW, where fSW is the frequency of operation set
by R5. The minimum external clock high pulse width and
amplitude should be greater than 50ns and 2.1V, respectively.
The minimum external clock low pulse width should be
greater than 160ns, and the maximum external clock
low pulse amplitude should be less than 0.8V. Table 3
describes the connection of the SYNC pin.
Setting VOUT with a Resistive
Voltage Divider at FB
The EV kit is preset for 3.3V and offers an adjustable
output voltage range as low as 0.9V up to 12V at 3.5A
maximum load. The adjustable output voltage can be
programmed by the set of resistor dividers R1 and R2.
Refer to the Table 1 (Selection Component Values) on the
MAXM17544 IC data sheet to select optimal component
values for each specific input voltage range from 4.5V
up to 42V and an output voltage from 0.9V up to 12V. To
obtain a different output voltage other than default setting
outputs in Table 1, only six component (R1, R2, C1–C3,
and C8) values need to be modified by the equation
described in the Setting the Output Voltage section in the
MAXM17544 IC data sheet.
*Default position. *Default position.
SHUNT
POSITION MODE PIN MAXM17544_MODE
Not
installed Unconnected PFM mode of operation
1-2 Connected to VCC DCM mode of operation
2-3* Connected to GND PWM mode of operation
SHUNT
POSITION SYNC PIN MAXM17544_SYNC
1-2* Connected to SGND SYNC feature unused
Not
installed
Connected to test
loop on PCB
Frequency can be
synchronized with an
external clock
Table 2. MODE Description (JU2) Table 3. SYNC Description (JU3)
PRELIMINARY
Maxim Integrated
│
4
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
(VIN = 4.5V - 42V, VOUT = 3.3V, IOUT = 0 – 3.5A, TA = +25°C, unless otherwise noted.)
3
3.1
3.2
3.3
3.4
3.5
3.6
0 1000 2000 3000
VOUT (V)
OUTPUT CURRENT (mA)
LOAD REGULATION
VOUT = 3.3V, PFM MODE toc04
MODE = OPEN
VIN = 5.0V
fSW =500kHz
VIN =12V
fSW =500kHz
VIN =24V
fSW =500kHz
VIN =36V
fSW =500kHz
40
50
60
70
80
90
100
01000 2000 3000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PFM MODE toc01
MODE = OPEN
VIN = 12V
fSW = 500kHz
VIN = 24V
fSW = 500kHz
VIN = 36V
fSW = 500kHz
3
3.1
3.2
3.3
3.4
3.5
3.6
01000 2000 3000
VOUT (V)
OUTPUT CURRENT (mA)
LOAD REGULATION
VOUT = 3.3V, DCM MODE toc06
MODE = VCC
VIN = 5.0V
fSW = 500kHz
VIN = 12V
fSW = 500kHz
VIN = 24V
fSW = 500kHz VIN = 36V
fSW = 500kHz
40
50
60
70
80
90
100
01000 2000 3000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PWM MODE toc02
MODE = SGND
VIN = 12V
fSW = 500kHz
VIN = 24V
fSW = 500kHz
VIN = 36V
fSW = 500kHz
40
50
60
70
80
90
100
0 1000 2000 3000
EFFICIENCY (%)
OUTPUT CURRENT (mA)
EFFICIENCYvs. OUTPUT CURRENT
VOUT = 3.3V, DCM MODE toc03
MODE = VCC
VIN =12V
fSW =500kHz
VIN =24V
fSW =500kHz
VIN =36V
fSW =500kHz
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A TO 1.75A,
MODE = OPEN
2A/div
toc07
200µs/div
IOUT
VOUT
200mV/div
(AC
COUPLED)
3
3.1
3.2
3.3
3.4
3.5
3.6
01000 2000 3000
VOUT (V)
OUTPUT CURRENT (mA)
LOAD REGULATION
VOUT = 3.3V, PWM MODE toc05
MODE = SGND
VIN = 5.0V
fSW = 500kHz
VIN = 12V
fSW = 500kHz
VIN = 24V
fSW = 500kHz
VIN = 36V
fSW = 500kHz
Typical Operating Characteristics
PRELIMINARY
Maxim Integrated
│
5
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
(VIN = 4.5V - 42V, VOUT = 3.3V, IOUT = 0 – 3.5A, TA = +25°C, unless otherwise noted.)
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A TO 1.75A,
MODE = SGND
2A/div
toc08
200µs/div
IOUT
VOUT
200mV/div
(AC
COUPLED)
LOAD CURRENT TRANSIENT RESPONSE
VIN =24V, VOUT = 3.3V, IOUT = 1.75A TO 3.5A,
MODE = SGND
2A/div
toc10
200µs/div
IOUT
VOUT
200mV/div
(AC
COUPLED)
-150.00
-120.00
-90.00
-60.00
-30.00
0.00
30.00
60.00
90.00
120.00
150.00
1k 10k 100k 1Meg
-50
-40
-30
-20
-10
0
10
20
30
40
50
PHASE MARGIN (°)
GAIN (dB)
FREQUENCY (Hz)
CLOSED-LOOP BODE PLOT
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A,
MODE = SGND
GAIN
toc11
PHASE
CROSSOVER FREQUENCY = 52.56kHz
PHASE MARGIN = 66.7◦
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A TO 1.75A,
MODE = VCC
2A/div
toc09
200µs/div
IOUT
VOUT
200mV/div
(AC
COUPLED)
Typical Operating Characteristics (continued)
PRELIMINARY
Maxim Integrated
│
6
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
SUPPLIER WEBSITE
Murata Americas www.murata.com
NEC TOKIN America, Inc. www.nec-tokinamerica.com
Panasonic Corp. www.panasonic.com
SANYO Electric Co., Ltd. www.sanyodevice.com
TDK Corp. www.component.tdk.com
TOKO America, Inc. www.tokoam.com
Note: Indicate that you are using the MAXM17544 when contacting these component suppliers.
Component List and Schematic
Refer to the following files attached to this data sheet for
component information and schematic:
●MAXM17544_EV_BOM.xls
●MAXM17544_EV_Schematic.pdf
Component Suppliers
PRELIMINARY
Maxim Integrated
│
7
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
Figure 1. MAXM17544 EV Kit Component Placement Guide—
Component-Side
Figure 2. MAXM17544 EV Kit Component Placement Guide—
Solder-Side
Figure 3. MAXM17544 EV Kit PCB Layout—Component Side
PRELIMINARY
Maxim Integrated
│
8
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
Figure 4. MAXM17544 EV Kit PCB Layout—PGND Layer 2 Figure 5. MAXM17544 EV Kit PCB Layout—PGND Layer 3
Figure 6. MAXM17544 EV Kit PCB Layout—Solder-Side
PRELIMINARY
Maxim Integrated
│
9
www.maximintegrated.com
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
#Denotes RoHS compliant.
PART TYPE
MAXM17544EVKIT# EV Kit
Ordering Information
PRELIMINARY
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specications without notice at any time.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2015 Maxim Integrated Products, Inc.
│
10
Evaluates: MAXM17544 in 3.3V
Output-Voltage Application
MAXM17544 3.3V Output
Evaluation Kit
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 5/15 Initial release —
Revision History
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
PRELIMINARY
