MAX17572 3.3V Output
Evaluation Kit
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
General Description
The MAX17572 3.3V output evaluation kit (EV kit)
provides a proven design to evaluate the MAX17572
high-voltage, high-efficiency, synchronous step-down
DC-DC converter. The EV kit is preset for 3.3V output at
load currents up to 1A and features a 500kHz switching
frequency for optimum efficiency and component size.
The EV kit features adjustable input undervoltage lockout,
adjustable soft-start, open-drain active-low RESET signal,
and external frequency synchronization.
Quick Start
Recommended Equipment
●
●
●
●
MAX17572 3.3V output EV kit
4.5V to 60V, 2A DC input power supply
Load capable of sinking 1A
Digital voltmeter (DVM)
Procedure
Features
● Operates from a 4.5V to 60V Input Supply
●
3.3V Output Voltage
●
Up to 1A Output Current
● 500kHz Switching Frequency
● Enable/UVLO Input, Resistor-Programmable UVLO
Threshold
● Adjustable Soft-Start Time
●
Open-Drain
RESET
Output
● External Frequency Synchronization
● Overcurrent and Overtemperature Protection
● Proven PCB Layout
● Fully Assembled and Tested
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)
2)
Set the power supply at a voltage between 4.5V and
60V. Disable the power supply.
Connect the positive terminal of the power supply
to the V
IN
PCB pad and the negative terminal to
the nearest PGND PCB pad. Connect the positive
terminal of the 1A load to the V
OUT
PCB pad and the
negative terminal to the nearest PGND PCB pad.
Connect the DVM across the V
OUT
PCB pad and
the nearest PGND PCB pad.
Verify that shunts are installed across pins 1-2 on
jumper JU1 (see
Table 1
for details).
Turn on the DC power supply.
Enable the load.
Verify that the DVM displays 3.3V
3)
4)
5)
6)
7)
Ordering Information
appears at end of data sheet.
19-8651; Rev 1; 6/17
MAX17572 3.3V Output
Evaluation Kit
Detailed Description of Hardware
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
EN/UVLO. Choose R1 to be 3.3MΩ and then calculate
R2 as follows:
R2
=
1.215
×
R1
(V
INU
−
1.215)
The MAX17572 3.3V output EV kit provides a proven
design to evaluate the MAX17572 high-voltage, high
efficiency, synchronous step-down DC-DC converter. The
EV kit is preset for 3.3V output from 4.5V to 60V input at
load currents up to 1A and features a 500kHz 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. An
additional RESET PCB pad is available for monitoring
whether the converter output is in regulation.
where VINU is the voltage at which the device is required
to turn on. Ensure that VINU is higher than 0.8 x V
OUT
.
If the EN/UVLO pin is driven from an external signal source,
a series resistance of minimum 1kΩ is recommended to
be placed between the signal source output and the EN/
UVLO pin, to reduce voltage ringing on the line.
Soft-Start capacitor selection
The device implements adjustable soft-start operation to
reduce inrush current. A capacitor connected from the SS
pin to GND programs the soft-start time. The selected
output capacitance (C
SEL
) and the output voltage (V
OUT
)
determine the minimum required soft-start capacitor
as follows:
C
SS
≥
56
×
10
−
6
×
C
SEL
×
V
OUT
Adjusting Output Voltage
Set the output voltage with a resistive voltage-divider
connected from the positive terminal of the output capacitor
(V
OUT
) to SGND (see
Figure 2).
Connect the center node
of the divider to the FB pin. Use the following procedure to
choose the resistive voltage-divider values:
Calculate resistor R3 from the output to the FB pin as
follows:
R3
=
1850
C
OUT_SEL
The soft-start time (t
SS
) is related to the capacitor con-
nected at SS (C
SS
) by the following equation:
t
SS
=
5.55
×
10
−
6
C
SS
For example, to program a 2ms soft-start time, a 12nF
capacitor should be connected from the SS pin to GND.
Setting the Undervoltage-Lockout Level
Where C
OUT_SEL
(in µF) is the actual derated value of
the output capacitance used and R3 is in kΩ. The minimum
allowable value of R3 is (5.6 x V
OUT
), where R3 is in kΩ.
If the value of R3 calculated using the above equation.
is less than (5.6 x V
OUT
), increase the value of R3 to at
least (5.6 x V
OUT
).
R4
=
R4 is in kΩ.
R3
×
0.9
(V
OUT
−
0.9)
The device offers an adjustable input undervoltage-lockout
level. Set the voltage at which the device turns on with
a resistive voltage-divider connected from V
IN
to SGND
(see
Figure 1).
Connect the center node of the divider to
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
MAX17572_ OUTPUT
Enabled
Enabled, UVLO level set through the
R1 and R2 resistors
Disabled
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2
MAX17572 3.3V Output
Evaluation Kit
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
VIN
R1
EN/UVLO
R2
SGND
R4
SGND
R3
V
OUT
FB
Figure 1. Setting the Input Undervoltage Lockout
Figure 2: Adjusting Output Voltage
EV Kit Performance Report
LOAD AND LINE REGULATION
(3.3V OUTPUT, PWM MODE)
EFFICIENCY vs. LOAD CURRENT
(3.3V OUTPUT, PWM MODE)
100
90
3.50
3.45
toc01
toc02
OUTPUT VOLTAGE (V)
V
IN
= 24V
3.40
3.35
3.30
3.25
3.20
V
IN
= 12V
V
IN
= 48V
80
EFFICIENCY (%)
70
60
50
40
30
MODE = SGND
20
V
IN
= 12V
V
IN
= 36V
V
IN
= 24V
V
IN
= 48V
V
IN
= 36V
0.00
0.20
0.40
0.60
0.80
1.00
0.0
0.2
0.4
0.6
0.8
1.0
LOAD CURRENT (A)
LOAD CURRENT (A)
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3
MAX17572 3.3V Output
Evaluation Kit
EV Kit Performance Report (continued)
BODE PLOT
(3.3V OUTPUT, 1A LOAD CURRENT)
40
30
20
10
GAIN
GAIN
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
LOAD CURRENT STEPPED FROM NO LOAD TO 0.5A
(3.3V OUTPUT, PWM MODE)
toc03
toc04
80
PHASE 60
PHASE
PHASE (°)
V
OUT
(AC)
50mV/div
GAIN (dB)
40
20
0
-10
CROSSOVER FREQUENCY = 42.9kHz,
PHASE MARGIN = 64.5°
CROSSOVER FREQUENCY = 42.9kHz,
-30 PHASE MARGIN = 64.5°
-20
10
3
10
4
FREQUENCY (Hz)
10
5
0
-20
I
LOAD
500mA/div
100μS/div
LOAD CURRENT STEPPED FROM 0.5A TO 1A
(3.3V OUTPUT, PWM MODE)
toc05
V
OUT
(AC)
50mV/div
I
LOAD
500mA/div
100μS/div
Component Suppliers
SUPPLIER
Coilcraft, Inc.
Murata Americas
Panasonic Corp.
Vishay
Onsemi
WEBSITE
www.coilcraft.com
www.murata.com
www.panasonic.com
www.vishay.com
www.onsemi.com
Ordering Information
PART
MAX17572EVKITA#
TYPE
EV KIT
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Maxim Integrated │ 4
MAX17572 3.3V Output
Evaluation Kit
MAX17572 EV System Bill of Materials
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
Description
2.2uF 10%, 100V ,X7R,Ceramic capacitor (1210)
22uF 10%, 10V ,X7R,Ceramic capacitor (1210)
33uF,20%,80V,ELECT,10mm
4.7uF 10%, 10V ,X7R,Ceramic capacitor (0805)
5600pF,10%,50V,X7R,0402,Ceramic capacitor(0402)
0.1uF,10%,50V,X7R, Ceramic capacitor(0402)
47pF,10%,50V,X7R,0402,Ceramic capacitor(0402)
100pF,10%,50V,X7R,0402,Ceramic capacitor(0402)
0.1uF,10%,100V,X7R,0603,Ceramic capacitor(0603)
Diode PIV=20V; IF=0.5A
3-pin header (36-pin header 0.1” centers )
INDUCTOR, 15uH, 2.8A
RES+,3.32MOHM,1%,0402
RES+,604K OHM,1%,0402
RES+,86.6K OHM,1%,0402
RES+, 32.4KOHM,1%,0402
RES+, 4.7OHM,1%,0402
RES+,100K OHM,1%,0402
RES+,40.2K OHM,1%,0402
RES+,1K OHM,1%,0402
Buck Converter
MAX17572ATJ+
3 pin headers
Quantity
1
1
1
1
1
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
Designator
C1
C2
C3
C4
C5
C6,C7
C8
C9
C10
D1
JU1
L1
R1
R2
R3
R4
R5
R6
R7
R8
U1
See Jumper Table1
Part Number
MURATA GRM32ER72A225KA35
MURATA GRM32ER71A226K
TDK C2012X7R1A475K085AC
Murata GRM155R71E562K
MURATA GRM155R71H104KE14
MURATA GRM1555C1H470JA01
MURATA GRM1555C1H101JA01D
MURATA GRM188R72A104KA35
ON SEMICONDUCTOR
NSR05F20NXT5G
PANASONIC EEE-FK1K330P
Sullins: PTC36SAAN
COILCRAFT XAL4040-153ME
MAX17572ATJ+
SULLINS STC02SYAN
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5
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