Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
General Description
The MAX17503 3.3V output evaluation kit (EV kit) provides
a proven design to evaluate the MAX17503 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 2.5A 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2.5AOutput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RESETOutput
● ExternalFrequencySynchronization
● OvercurrentandOvertemperatureProtection
● ProvenPCBLayout
● FullyAssembledandTested
19-6815; Rev 0; 9/13
Ordering Information appears at end of data sheet.
*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 MAX17503-based
circuit. When R5 is open, the device switches at 500kHz switch-
ing frequency.
DESIGNATION QTY DESCRIPTION
C1 1
2.2µF±10%,100VX7Rceramic
capacitor (1210)
MurataGRM32ER72A225KA35
C2 1
2.2µF±10%,10VX7Rceramic
capacitor(0603)
MurataGRM188R71A225K
C3 1
5600pF±10%,25VX7Rceramic
capacitor (0402)
MurataGRM155R71E562K
C4 1
47µF±10%,10VX7Rceramic
capacitor (1210)
MurataGRM32ER71A476K
C5 1
0.1µF±10%,16VX7Rceramic
capacitor (0402)
MurataGRM155R71C104K
C6 0Not installed, ceramic capacitor
(0402)
C7 1
47µF,80Valuminumelectrolytic
capacitor (D = 10mm)
PanasonicEEEFK1K470P
JU1,JU2,JU3 3 3-pin headers
DESIGNATION QTY DESCRIPTION
L1 1
6.8µH,5Ainductor
CoilcraftMSS1048-682NL
TaiyoYudenNS10165T6R8NNA
R1 13.32MΩ±1%resistor(0402)
R2 11MΩ±1%resistor(0402)
R3 1127kΩ±1%resistor(0402)
R4 147.5kΩ±1%resistor(0402)
R5 045.3kΩ±1%resistor(0402)
R6 110kΩ±1%resistor(0402)
TP1,TP2 2 Test pads
U1 1Buckconverter(20TQFN-EP*)
MaximMAX17503ATP+
— 3 Shunts(JU1,JU2,JU3)
— 1 PCB:MAX17503–3.3VOutput
EVKIT
Component List
MaximIntegrated
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2
Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
www.maximintegrated.com
Quick Start
Recommended Equipment
● MAX175033.3VoutputEVkit
● 5Vto60V,5ADCinputpowersupply
● Loadcapableofsinking2.5A
● 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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2.5A 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.
Detailed Description
The MAX17503 3.3V output EV kit provides a proven
design to evaluate the MAX17503 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 2.5A 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.
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(CSEL) and
the output voltage (VOUT) determine the minimum value
ofC3,asshownbythefollowingequation:
C3≥28x10-6 x CSEL x VOUT
The soft-start time (tSS) is related to C3 by the following
equation:
tSS=C3/(5.55x10-6)
Forexample,toprograma1mssoft-starttime,C3should
be5.6nF.
Note: Indicate that you are using the MAX17503 when contacting these component suppliers.
SUPPLIER PHONE WEBSITE
Coilcraft,Inc. 847-639-6400 www.coilcraft.com
Murata Americas 800-241-6574 www.murataamericas.com
PanasonicCorp. 800-344-2112 www.panasonic.com
Taiyo Yuden 800-348-2496 www.t-yuden.com
Component Suppliers
MaximIntegrated
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
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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:
INU
R1 1.215
R2 (V 1.215)
×
=
−
where VINU is the voltage at which the device is required
to turn on.
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
changes on the MODE pin are ignored during normal
operation.RefertotheMAX17503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ontheSYNCpin.Theexternal
synchronization clock frequency must be between 1.1fSW
and 1.4fSW, where fSW 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.
*Default position.
*Default position.
*Default position.
SHUNT
POSITION EN/UVLO PIN MAX17503_ 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
SHUNT
POSITION MODE PIN MAX17503_ MODE
Not installed* Unconnected PFMmodeof
operation
1-2 Connected to
SGND
PWMmodeof
operation
2-3 Connected to
VCC
DCM mode of
operation
SHUNT
POSITION SYNC PIN MAX17503_ SYNC
1-2 Connected to
testlooponPCB
Frequencycanbe
synchronized with an
external clock
2-3* Connected to
SGND SYNCfeatureunused
Table 1. Regulator Enable (EN/UVLO)
Description (JU1)
Table 2. MODE Description (JU2)
Table 3. SYNC Description (JU3)
MaximIntegrated
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
www.maximintegrated.com
Figure 1. MAX17503 3.3V Output Load and Line Regulation
(PWM Mode)
Figure 2. MAX17503 3.3V Output Efficiency (PWM Mode)
Figure 3. MAX17503 3.3V Output Load and Line Regulation
(PFM Mode)
Figure 4. MAX17503 3.3V Output Efficiency (PFM Mode)
3.3V OUTPUT, PWM MODE
LOAD AND LINE REGULATION
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
3.27
3.28
3.29
3.30
3.31
3.32
3.33
3.34
3.35
3.25
3.26
VIN = 24V VIN = 48V
MODE = SGND
VIN = 12V VIN = 36V
2000150010005000 2500
3.3V OUTPUT, PWM MODE
EFFICIENCY vs. LOAD CURRENT
LOAD CURRENT (mA)
EFFICIENCY (%)
50
60
70
80
90
100
40
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 48V
2000150010005000 2500
MODE = SGND
3.3V OUTPUT, PFM MODE
LOAD AND LINE REGULATION
LOAD CURRENT (mA)
OUTPUT VOLTAGE (V)
3.1
3.2
3.3
3.4
3.5
3.6
3.0
VIN = 24V
VIN = 36V
2000150010005000 2500
VIN = 12V
VIN = 48V
MODE = OPEN
3.3V OUTPUT, PFM MODE
EFFICIENCY vs. LOAD CURRENT
EFFICIENCY (%)
60
70
75
65
85
80
90
95
100
50
55
VIN = 12V VIN = 24V
VIN = 48V
VIN = 36V
LOAD CURRENT (mA)
100101 1000 2500
MODE = OPEN
EV Kit Test Report
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
www.maximintegrated.com
Figure 5. MAX17503 3.3V Output Efficiency (DCM Mode) Figure 6. MAX17503 3.3V Output Full Load Bode Plot
(VIN = 24V)
Figure 7. MAX17503 3.3V Output, No Load to 1A Load
Transient (PWM Mode)
3.3V OUTPUT, DCM MODE
EFFICIENCY vs. LOAD CURRENT
LOAD CURRENT (mA)
EFFIEIENCY (%)
30
40
50
60
70
80
90
100
20
100100 1000 2500
VIN = 48V
VIN = 36V
VIN = 24V
VIN = 12V
MODE = VCC
3.3V OUTPUT, 2.5A LOAD
CURRENT BODE PLOT
FREQUENCY (Hz)
GAIN (dB)
PHASE (°)
-30
-20
-10
0
10
20
30
40
50
60
-40
-60
-40
-20
0
20
40
60
80
100
120
-80
100k10k1k
CROSSOVER FREQUENCY = 62.5kHz
PHASE MARGIN = 61.2°
GAIN
PHASE
2 4 6 8 1 2 4 6 8 1 2
VOUT (AC)
50mV/div
IOUT
1A/div
40µs/div
3.3V OUTPUT, PWM MODE (LOAD CURRENT
STEPPED FROM NO-LOAD TO 1A)
MODE = SGND
EV Kit Test Report (continued)
MaximIntegrated
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
www.maximintegrated.com
Figure 9. MAX17503 3.3V Output, 50mA to 1A Load Transient
(DCM Mode)
Figure 10. MAX17503 3.3V Output, 1A to 2A Load Transient
Figure 8. MAX17503 3.3V Output, 5mA to 1A Load Transient
(PFM Mode)
VOUT (AC)
100mV/div
IOUT
500mA/div
200µs/div
3.3V OUTPUT, DCM MODE (LOAD CURRENT
STEPPED FROM 50mA TO 1A)
MODE = VCC
VOUT (AC)
50mV/div
IOUT
1A/div
40µs/div
3.3V OUTPUT, PWM MODE (LOAD CURRENT
STEPPED FROM 1A TO 2A)
VOUT (AC)
50mV/div
IOUT
500mA/div
2ms/div
3.3V OUTPUT, PFM MODE (LOAD CURRENT
STEPPED FROM 5mA TO 1A)
MODE = OPEN
EV Kit Test Report (continued)
MaximIntegrated
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
www.maximintegrated.com
Figure 11. MAX17503 3.3V Output EV Kit Schematic
EP
6SYNC
11 MODE
12 VCC
13 SGND
7SS
20
BST
19
LX
18
LX
17
LX
5
RESET
3
VIN
2
VIN
1
VIN
4
EN/UVLO
10
RT
16 PGND
15 PGND
14 PGND
9FB
8CF
U1
MAX17503
R5
1%
45.3k
1
2
3JU3
SYNC
MODE
SGND
C2
2.2uF
C3
5600pF
R6
1%
10k
C5
0.1uF L1
6.8uH
C4
47uF
TP1
TP2
R3
1%
127k
R4
1%
47.5k
VOUT
PGND
C6
OPEN
R2
1%
1M
R1
1%
3.32M
VIN
PGND
C1
2.2uF
+C7
47uF
80V
EN/UVLO
1
2
3JU2
1
2
3
JU1
RESET
VCC
VCC
EN/UVLO
VCC
EN/UVLO
RESET
RESET
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
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Figure 14. MAX17503 3.3V Output EV Kit PCB Layout—
Inner Layer 1
Figure 15. MAX17503 3.3V Output EV Kit PCB Layout—Inner
Layer 2
Figure 12. MAX17503 3.3V Output EV Kit Component
Placement Guide—Component Side
Figure 13. MAX17503 3.3V Output EV Kit Component Side
PCB layout
1.0’’
1.0’’
1.0’’
1.0’’
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
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Figure 17. MAX17503 3.3V Output EV Kit Component
Placement Guide—Top Solder Mask
Figure 18. MAX17503 3.3V Output EV Kit Component
Placement Guide—Bottom Solder Mask
Figure 16. MAX17503 3.3V Output EV Kit PCB Layout—
Solder Side
1.0’’ 1.0’’
1.0’’
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
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#Denotes RoHS compliant.
PART TYPE
MAX17503EVKITA# EVKit
Ordering Information
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. © 2013 MaximIntegratedProducts,Inc.
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Evaluates: MAX17503 in
3.3V Output-Voltage Application
MAX17503 3.3V Output Evaluation Kit
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
09/13 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.
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Authorized Distributor
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