MAX17504 3.3V Output Evaluation Kit
Evaluates: MAX17504 in
3.3V Output-Voltage Application
General Description
The MAX17504 3.3V output evaluation kit (EV kit) provides
a proven design to evaluate the MAX17504 high-voltage,
high-efficiency, synchronous step-down DC-DC convert-
er. The EV kit is preset for 3.3V output at load currents
up to 3.5A and features a 450kHz switching frequency for
optimum efficiency and component size. The EV kit
features adjustable input undervoltage lockout, adjust-
able soft-start, open-drain
RESET
signal, and external
frequency synchronization.
Features
● Operates from a 5V to 60V Input Supply
● 3.3V Output Voltage
● Up to 3.5A Output Current
● 450kHz Switching Frequency
● Enable/UVLO Input, Resistor-Programmable UVLO
Threshold
● Adjustable Soft-Start Time
● MODE Pin to Select Among PWM, PFM, or DCM
Modes
● Open-Drain RESET Output
● External Frequency Synchronization
● Overcurrent and Overtemperature Protection
● Proven PCB Layout
● Fully Assembled and Tested
Ordering Information
appears at end of data sheet.
Component List
DESIGNATION
C1, C8
QTY
2
DESCRIPTION
2.2µF ±10%, 100V X7R ceramic
capacitors (1210)
Murata GRM32ER72A225KA35
2.2µF ±10%, 10V X7R ceramic
capacitor (0603)
Murata GRM188R71A225K
12000pF ±10%, 16V X7R ceramic
capacitor (0402)
Murata GRM155R71C123K
22µF ±10%, 10V X7R ceramic
capacitors (1210)
Murata GRM32ER71A226K
0.1µF ±10%, 16V X7R ceramic
capacitor (0402)
Murata GRM155R71C104K
Not installed, ceramic capacitor
(0402)
47µF, 80V aluminum electrolytic
capacitor (D = 10mm)
Panasonic EEEFK1K470P
3-pin headers
DESIGNATION
L1
R1
R2
R3
R4
R5
R6
TP1, TP2
U1
—
—
QTY
1
1
1
1
1
1
1
2
1
3
1
DESCRIPTION
6.8µH, 5A inductor
Coilcraft MSS1048-682NL
Cooper Bussmann DR125-6R8-R
3.32MΩ ±1% resistor (0402)
750kΩ ±1% resistor (0402)
82.5kΩ ±1% resistor (0402)
30.9kΩ ±1% resistor (0402)
45.3kΩ ±1% resistor (0402)
10kΩ ±1% resistor (0402)
Test pads
Buck converter (20 TQFN-EP*)
Maxim MAX17504ATP+
Shunts (JU1–JU3)
PCB: MAX17504 – 3.3V Output
EVKIT
C2
1
C3
1
C4, C9
2
C5
C6
C7
JU1–JU3
1
0
1
3
*EP
= Exposed pad.
Note:
C7, R1, and R2 are optional components; R1 and R2
are not needed if the EN/UVLO pin is permanently connected
to VIN. The electrolytic capacitor (C7) is required only when
the VIN power supply is situated far from the MAX17504-based
circuit. When R5 is open, the device switches at 500kHz switch-
ing frequency. The MSS1048 inductor has been used to prepare
the EV kit test report.
19-6888; Rev 1; 2/14
MAX17504 3.3V Output Evaluation Kit
Evaluates: MAX17504 in
3.3V Output-Voltage Application
Component Suppliers
SUPPLIER
Coilcraft, Inc.
Cooper Bussmann
Murata Americas
Panasonic Corp.
PHONE
847-639-6400
636-394-2877
800-241-6574
800-344-2112
www.coilcraft.com
www.cooperindustries.com
www.murataamericas.com
www.panasonic.com
WEBSITE
Note:
Indicate that you are using the MAX17504 when contacting these component suppliers.
Quick Start
Recommended Equipment
● MAX17504 3.3V output EV kit
● 5V to 60V, 7A DC input power supply
● Load capable of sinking 3.5A
● Digital voltmeter (DVM)
Detailed Description
The MAX17504 3.3V output EV kit provides a proven
design to evaluate the MAX17504 high-voltage, high-
efficiency, synchronous step-down DC-DC converter. The
EV kit is preset for 3.3V output from 5V to 60V input at
load currents up to 3.5A and features a 450kHz switching
frequency for optimum efficiency and component size.
The EV kit includes an EN/UVLO PCB pad and jumper
JU1 to enable the output at a desired input voltage. The
SYNC PCB pad and jumper JU3 allow an external clock
to synchronize the device. Jumper JU2 allows the selec-
tion of a particular mode of operation based on light-load
performance requirements. An additional
RESET
PCB
pad is available for monitoring whether the converter out-
put is in regulation.
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify the board operation.
Caution: Do not turn
on power supply until all connections are completed.
1) Set the power supply at a voltage between 5V and
60V. Disable the power supply.
2) Connect the positive terminal of the power supply to
the VIN PCB pad and the negative terminal to the
nearest PGND PCB pad. Connect the positive termi-
nal of the 3.5A load to the VOUT PCB pad and the
negative terminal to the nearest PGND PCB pad.
3) Connect the DVM across the VOUT PCB pad and the
nearest PGND PCB pad.
4) Verify that shunts are installed across pins 1-2 on
jumper JU1 and pins 2-3 on jumper JU3 (see Tables 1
and 3 for details).
5) Select the shunt position on jumper JU2 according
to the intended mode of operation (see
Table 2
for
details).
6) Turn on the DC power supply.
7) Enable the load.
8) Verify that the DVM displays 3.3V.
Soft-Start Input (SS)
The device utilizes an adjustable soft-start function to
limit inrush current during startup. The soft-start time is
adjusted by the value of C3, the external capacitor from
SS to GND. The selected output capacitance (C
SEL
) and
the output voltage (V
OUT
) determine the minimum value
of C3, as shown by the following equation:
C3 ≥ 28 x 10
-6
x C
SEL
x V
OUT
The soft-start time (t
SS
) is related to C3 by the following
equation:
t
SS
= C3/(5.55 x 10
-6
)
For example, to program a 2.2mS soft-start time, C3
should be 12nF.
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2
MAX17504 3.3V Output Evaluation Kit
Evaluates: MAX17504 in
3.3V Output-Voltage Application
changes on the MODE pin are ignored during normal
operation. Refer to the MAX17504 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.
Regulator Enable/Undervoltage-Lockout
Level (EN/UVLO)
The device offers an adjustable input undervoltage-
lockout level. For normal operation, a shunt should be
installed across pins 1-2 on jumper JU1. To disable the
output, install a shunt across pins 2-3 on JU1 and the EN/
UVLO pin is pulled to GND. See Table
1 for JU1 settings.
Set the voltage at which the device turns on with the resis-
tive voltage-divider R1/R2 connected from VIN_ to SGND.
Connect the center node of the divider to EN/UVLO.
Choose R1 to be 3.32MΩ and then calculate R2 as follows:
R2
=
R1
×
1.215
(V
INU
−
1.215)
External Clock Synchronization (SYNC)
The internal oscillator of the device can be synchronized
to an external clock signal on the SYNC pin. The external
synchronization clock frequency must be between 1.1f
SW
and 1.4f
SW
, where f
SW
is the frequency of operation
set by R5. The minimum external clock high pulse width
should be greater than 50ns and the minimum external
clock low pulse width should be greater than 160ns.
where V
INU
is the voltage at which the device is required
to turn on.
Table 2. MODE Description (JU2)
SHUNT
POSITION
Not installed*
1-2
2-3
*Default
position.
MODE PIN
Unconnected
Connected to
SGND
Connected to
VCC
MAX17504_ MODE
PFM mode of
operation
PWM mode of
operation
DCM mode of
operation
MODE Selection (MODE)
The device’s MODE pin can be used to select among
PWM, PFM, or DCM modes of operation. The logic state
of the MODE pin is latched when VCC and EN/UVLO volt-
ages exceed the respective UVLO rising thresholds and
all internal voltages are ready to allow LX switching. State
Table 1. Regulator Enable (EN/UVLO)
Description (JU1)
SHUNT
POSITION
1-2*
Not
installed
2-3
EN/UVLO PIN
Connected to VIN
Connected to the
center node of
resistor-divider R1
and R2
Connected to SGND
MAX17504_ OUTPUT
Enabled
Enabled, UVLO level
set through the R1 and
R2 resistors
Disabled
Table 3. SYNC Description (JU3)
SHUNT
POSITION
1-2
2-3*
*Default
position.
SYNC PIN
Connected to
test loop on PCB
Connected to
SGND
MAX17504_ SYNC
Frequency can be
synchronized with an
external clock
SYNC feature unused
*Default
position.
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MAX17504 3.3V Output Evaluation Kit
Evaluates: MAX17504 in
3.3V Output-Voltage Application
EV Kit Test Report
3.3V OUTPUT, PWM MODE,
3.36
3.35
3.34
OUTPUT VOLTAGE (V)
3.32
3.31
3.30
3.29
3.28
3.27
3.26
0
500
1000
1500
2000
V
IN
= 12V V
IN
= 36V
V
IN
= 24V
MODE = SGND
2500
3000
3500
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
3.33
V
IN
= 48V
LOAD AND LINE REGULATION
figure 1
3.3V OUTPUT, PFM MODE,
3.6
3.5
3.4
3.3
3.2
3.1
3.0
LOAD AND LINE REGULATION
figure 3
V
IN
= 12V
V
IN
= 24V
V
IN
= 36V
V
IN
= 48V
MODE = OPEN
0
500
1000
1500
2000
2500
3000
3500
LOAD CURRENT (mA)
Figure 1. MAX17504 3.3V Output Load and Line Regulation
(PWM Mode)
Figure 3. MAX17504 3.3V Output Load and Line Regulation
(PFM Mode)
3.3V OUTPUT, PWM MODE,
EFFICIENCY VS. LOAD CURRENT
100
90
EFFICIENCY (%)
figure 2
3.3V OUTPUT, PFM MODE,
EFFICIENCY VS. LOAD CURRENT
100
90
80
70
60
50
40
V
IN
= 48V
V
IN
= 24V V
IN
= 36V
V
IN
= 12V
MODE = OPEN
1
10
100
1000
3500
figure 4
70
60
50
40
V
I N
= 12V
V
IN
= 24V V
IN
= 36V
V
IN
= 48V
MODE = SGND
0
500
1000 1500 2000 2500 3000 3500
LOAD CURRENT (mA)
EFFICIENCY (%)
80
30
LOAD CURRENT (mA)
Figure 2. MAX17504 3.3V Output Efficiency (PWM Mode)
Figure 4. MAX17504 3.3V Output Efficiency (PFM Mode)
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Maxim Integrated │
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MAX17504 3.3V Output Evaluation Kit
Evaluates: MAX17504 in
3.3V Output-Voltage Application
EV Kit Test Report (continued)
3.3V OUTPUT, DCM MODE,
EFFICIENCY VS. LOAD CURRENT
100
90
80
70
60
50
40
30
V
IN
= 48V
V
IN
= 36V
V
IN
= 24V
V
IN
= 12V
figure 5
EFFICIENCY (%)
MODE = V
CC
1
10
100
1000
3500
LOAD CURRENT (mA)
Figure 5. MAX17504 3.3V Output Efficiency (DCM Mode)
Figure 6. MAX17504 3.3V Output Full Load Bode Plot
(V
IN
= 24V)
3.3V OUTPUT, PWM MODE
(LOAD CURRENT STEPPED FROM NO LOAD TO 1.75A)
figure 7
V
OUT
(AC)
100mV/div
I
OUT
MODE SGND
MODE ==SGND
100μs/div
1A/div
Figure 7. MAX17504 3.3V Output, No Load to 1.75A Load
Transient (PWM Mode)
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