Maxim Integrated MAX17572 User manual

Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
General Description
The MAX17572 3.3V output evaluation kit (EV kit)
provides a proven design to evaluate the MAX17572
high-voltage, high-efciency, 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 efciency and component size.
The EV kit features adjustable input undervoltage lockout,
adjustable soft-start, open-drain active-low RESET signal,
and external frequency synchronization.
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
19-8651; Rev 1; 6/17
Ordering Information appears at end of data sheet.
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
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 4.5V 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
terminal of the 1A 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 (see Table 1 for details).
5) Turn on the DC power supply.
6) Enable the load.
7) Verify that the DVM displays 3.3V

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
Detailed Description of Hardware
The MAX17572 3.3V output EV kit provides a proven
design to evaluate the MAX17572 high-voltage, high
efciency, 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 efciency 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.
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 (CSEL) and the output voltage (VOUT)
determine the minimum required soft-start capacitor
as follows:
6
SS SEL OUT
C 56 10 C V
−
≥× × ×
The soft-start time (tSS) is related to the capacitor con-
nected at SS (CSS) by the following equation:
SS
SS 6
C
t5.55 10−
=
×
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
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 VIN to SGND
(see Figure 1). Connect the center node of the divider to
EN/UVLO. Choose R1 to be 3.3MΩ and then calculate
R2 as follows:
INU
1.215 R1
R2 (V 1.215)
×
=
−
where VINU is the voltage at which the device is required
to turn on. Ensure that VINU is higher than 0.8 x VOUT.
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.
Adjusting Output Voltage
Set the output voltage with a resistive voltage-divider
connected from the positive terminal of the output capacitor
(VOUT) 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:
OUT_SEL
1850
R3 C =
Where COUT_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 VOUT), where R3 is in kΩ.
If the value of R3 calculated using the above equation.
is less than (5.6 x VOUT), increase the value of R3 to at
least (5.6 x VOUT).
OUT
R3 0.9
R4 (V 0.9)
×
=
−
R4 is in kΩ.
Table 1. Regulator Enable (EN/UVLO) Description (JU1)
SHUNT POSITION EN/UVLO PIN MAX17572_ OUTPUT
1-2* Connected to VIN Enabled
Not installed Connected to the center node of resistor-divider
R1 and R2
Enabled, UVLO level set through the
R1 and R2 resistors
2-3 Connected to SGND Disabled

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
Figure 2: Adjusting Output Voltage
Figure 1. Setting the Input Undervoltage Lockout
EV Kit Performance Report
3.20
3.25
3.30
3.35
3.40
3.45
3.50
0.00 0.20 0.40 0.60 0.80 1.00
OUTPUT VOLTAGE (V)
LOAD CURRENT (A)
LOAD AND LINE REGULATION
(3.3V OUTPUT, PWM MODE)
V
IN
= 36V
V
IN
= 48V
V
IN
= 24V
V
IN
= 12V
toc01
20
30
40
50
60
70
80
90
100
0.0 0.2 0.4 0.6 0.8 1.0
EFFICIENCY (%)
LOAD CURRENT (A)
EFFICIENCY vs. LOAD CURRENT
(3.3V OUTPUT, PWM MODE)
V
IN
= 48V
V
IN
= 36V
V
IN
= 24V
V
IN
= 12V
MODE = SGND
toc02
R1
SGND
VIN
EN/UVLO
R2
R3
SGND
V
OUT
FB
R4

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
100μS/div
50mV/div
LOAD CURRENT STEPPED FROM NO LOAD TO 0.5A
(3.3V OUTPUT, PWM MODE)
V
OUT
(AC)
500mA/div
I
LOAD
toc04
GAIN (dB)
FREQUENCY (Hz)
BODE PLOT
(3.3V OUTPUT, 1A LOAD CURRENT)
CROSSOVER FREQUENCY = 42.9kHz,
PHASE MARGIN = 64.5°
PHASE
GAIN
PHASE (°)
toc03
CROSSOVER FREQUENCY = 42.9kHz,
PHASE MARGIN = 64.5°
PHASE
GAIN
40
-30
-20
-10
0
10
20
30 80
10
3
-20
0
20
40
60
10
5
10
4
100μS/div
50mV/div
LOAD CURRENT STEPPED FROM 0.5A TO 1A
(3.3V OUTPUT, PWM MODE)
V
OUT
(AC)
500mA/div
toc05
I
LOAD
Component Suppliers
Ordering Information
EV Kit Performance Report (continued)
SUPPLIER WEBSITE
Coilcraft, Inc. www.coilcraft.com
Murata Americas www.murata.com
Panasonic Corp. www.panasonic.com
Vishay www.vishay.com
Onsemi www.onsemi.com
PART TYPE
MAX17572EVKITA# EV KIT

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
MAX17572 EV System Bill of Materials
No. Description Quantity Designator
Part Number
12.2uF 10%, 100V ,X7R,Ceramic capacitor (1210) 1C1 MURATA GRM32ER72A225KA35
2
22uF 10%, 10V ,X7R,Ceramic capacitor (1210) 1C2 MURATA GRM32ER71A226K
3
33uF,20%,80V,ELECT,10mm 1C3 PANASONIC EEE-FK1K330P
44.7uF 10%, 10V ,X7R,Ceramic capacitor (0805) 1
C4 TDK C2012X7R1A475K085AC
55600pF,10%,50V,X7R,0402,Ceramic capacitor(0402) 1
C5 Murata GRM155R71E562K
60.1uF,10%,50V,X7R, Ceramic capacitor(0402) 2
C6,C7 MURATA GRM155R71H104KE14
747pF,10%,50V,X7R,0402,Ceramic capacitor(0402) 1
C8 MURATA GRM1555C1H470JA01
8100pF,10%,50V,X7R,0402,Ceramic capacitor(0402) 1
C9 MURATA GRM1555C1H101JA01D
90.1uF,10%,100V,X7R,0603,Ceramic capacitor(0603) 1
C10 MURATA GRM188R72A104KA35
10 Diode PIV=20V; IF=0.5A 1D1
ON SEMICONDUCTOR
NSR05F20NXT5G
11 3-pin header (36-pin header 0.1” centers ) 1JU1
Sullins: PTC36SAAN
12 INDUCTOR, 15uH, 2.8A 1
L1 COILCRAFT XAL4040-153ME
13
RES+,3.32MOHM,1%,0402 1R1
14
RES+,604K OHM,1%,0402 1R2
15
RES+,86.6K OHM,1%,0402 1R3
16
RES+, 32.4KOHM,1%,0402 1R4
17
RES+, 4.7OHM,1%,0402 1R5
18
RES+,100K OHM,1%,0402 1R6
19
RES+,40.2K OHM,1%,0402 1R7
20
RES+,1K OHM,1%,0402 1R8
21
Buck Converter
MAX17572ATJ+
1U1 MAX17572ATJ+
22 3 pin headers 1See Jumper Table1 SULLINS STC02SYAN

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
MAX17572 EV System Schematic
3.3V, 1A
PGND
15UH
10K
C10
C9
R8 D1
3
2
1
JU1
R4 R3
C2
C5
C4
C7
EN/UVLO
R2 R1
RT/SYNC
SGND
RESET
VOUT
21
L1
R6
C8 R7
21
C3 C1
VIN
PGND
5 4 6
12
111 8 7 9
13
210
3
U1
80V
VIN
40.2K
MAX17572
33UF 0.1UF
22UF
0.1UF
5600PF
86.6K 32.4K
3.32M
2.2UF
100PF
1K
VCC604K
VCC
4.7UF
47PF
EP
BST
LX
VCC
GND
SS
FB
RT/SYNC
RESET\
EXTVCC
VIN PGND EN/UVLO
+

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Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
MAX17572 3.3V EV Kit—Top Silkscreen MAX17572 3.3V EV Kit—Top
MAX17572 3.3V EV Kit—Bottom
MAX17572 EV System PCB Layout

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 specications without notice at any time.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2017 Maxim Integrated Products, Inc.
│ 8
Evaluates: MAX17572 in 3.3V
Output-Voltage Application
MAX17572 3.3V Output
Evaluation Kit
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES CHANGED
0 9/16 Initial release —
16/17 Updated Typical Operating Characteristics, Resistor references in Adjusting
Output Voltage section, Bill of Materials, Schematic, and PCB Layout gures. 2–7
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.

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