MAX17575 3.3V Output
Evaluation Kit
Evaluates: MAX17575 in 3.3V
Output-Voltage Application
General Description
The MAX17575 3.3V output evaluation kit (EV kit)
provides a proven design to evaluate the MAX17575
high-voltage, high-efficiency, synchronous step-down
DC-DC converter. The EV kit is preset for 3.3V output at
load currents up to 1.5A 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
●
●
●
●
MAX17575 3.3V output EV kit
4.5V to 60V, 2A DC input power supply
Load capable of sinking 1.5A
Digital voltmeter (DVM)
Procedure
Features
● Operates from a 4.5V to 60V Input Supply
●
3.3V Output Voltage
●
Up to 1.5A 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 1.5A 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.
19-8767; Rev 1; 6/17
MAX17575 3.3V Output
Evaluation Kit
Detailed Description of Hardware
Evaluates: MAX17575 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 MAX17575 3.3V output EV kit provides a proven
design to evaluate the MAX17575 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 1.5A 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 V
INU
is the voltage at which the device is required
to turn on. Ensure that V
INU
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 capaci-
tor (V
OUT
) to SGND (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
(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
MAX17575_ OUTPUT
Enabled
Enabled, UVLO level set through the
R1 and R2 resistors
Disabled
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Maxim Integrated │ 2
MAX17575 3.3V Output
Evaluation Kit
Evaluates: MAX17575 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
MAX17575, 3.3V OUTPUT, PWM MODE,
LOAD AND LINE REGULATION
3.40
100
90
MAX17575, 3.3V OUTPUT, PWM MODE,
EFFICIENCY vs. LOAD CURRENT
toc02
OUTPUT VOLTAGE (V)
3.36
V
IN
= 24V
3.32
V
IN
= 48V
EFFICIENCY (%)
80
70
60
50
40
30
V
IN
= 36V
V
IN
= 24V
V
IN
= 12V
V
IN
= 48V
3.28
V
IN
= 12V
3.24
V
IN
= 36V
3.20
20
MODE = SGND
0
500
1000
1500
0
500
1000
1500
LOAD CURRENT (mA)
LOAD CURRENT (mA)
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Maxim Integrated │
3
MAX17575 3.3V Output
Evaluation Kit
EV Kit Performance Report (continued)
MAX17575, 3.3V OUTPUT,
1.5A LOAD CURRENT, BODE PLOT
40
30
20
10
GAIN
0
-10
-20
-30
10
3
10
4
FREQUENCY (Hz)
10
5
PHASE
140
120
100
80
60
40
CROSSOVER FREQUENCY = 52.6kHz,
PHASE MARGIN = 61.73°
20
0
-20
Evaluates: MAX17575 in 3.3V
Output-Voltage Application
MAX17575, 3.3V OUTPUT, PWM MODE,
(LOAD CURRENT STEPPED FROM NO LOAD TO 0.75A)
toc04
GAIN (dB)
V
OUT
AC
50mV/div
I
LOAD
100μS/div
500mA/div
MAX17575, 3.3V OUTPUT, PWM MODE,
(LOAD CURRENT STEPPED FROM 0.75A TO 1.5A)
toc05
V
OUT
AC
50mV/div
I
LOAD
1A/div
100μS/div
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Maxim Integrated │ 4
MAX17575 3.3V Output
Evaluation Kit
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
Evaluates: MAX17575 in 3.3V
Output-Voltage Application
MAX17575 3.3V Output EV Kit 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
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, 6A
RES+,3.32MOHM,1%,0603
RES+,604K OHM,1%,0603
RES+,69.8K OHM,1%,0402
RES+, 26.1KOHM,1%,0402
RES+, 10KOHM,1%,0402
RES+,40.2K OHM,1%,0402
RES+,1K OHM,1%,0402
VIN, PGND, SGND, VOUT, PGND2, RESET, EN/UVLO,
RT/SYNC
Buck Converter
MAX17575ATC+
Quantity
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
8
1
Designator
C1
C2
C3
C4
C5
C7
C8
C9
C10
D1
JU1
L1
R1
R2
R3
R4
R6
R7
R8
Test Loops
U1
Part Number
MURATA GRM32ER72A225KA35
MURATA GRM32ER71A226K
PANASONIC EEE-FK1K330P
TDK C2012X7R1A475K085AC
KEMET C0402C562K5RAC
MURATA GRM155R71H104KE14
MURATA GRM1555C1H470JA01
KEMET C0402C101K5GAC
MURATA GRM188R72A104KA35
Sullins: PTC36SAAN
COILCRAFT XAL6060-153ME
Any
Any
Any
Any
Any
Any
Any
WEICO WIRE 9020 BUSS
MAX17575ATC+
ON SEMICONDUCTOR
NSR05F20NXT5G
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Maxim Integrated │
5
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