MAX17505ATP+T [MAXIM]
IC REG BUCK ADJ 1.7A SYNC 20TQFN;
| 型号： | MAX17505ATP+T |
| 厂家： | 
MAXIM INTEGRATED PRODUCTS |
| 描述： | IC REG BUCK ADJ 1.7A SYNC 20TQFN 信息通信管理 开关 |
| 文件： | 总26页 (文件大小：1585K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
EVALUATION KIT AVAILABLE
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
General Description
The MAX17505/MAX17505S high-efficiency, high-
voltage, synchronously rectified step-down converter with
dual integrated MOSFETs operates over a 4.5V to 60V
Benefits and Features
●
EliminatesꢀExternalꢀComponentsꢀandꢀReducesꢀTotalꢀ
Cost
• NoꢀSchottky-SynchronousꢀOperationꢀforꢀHighꢀ
EfficiencyꢀandꢀReducedꢀCost
input. It delivers up to 1.7A and 0.9V to 90%V output
IN
voltage. Built-in compensation across the output voltage
range eliminates the need for external components. The
feedback (FB) regulation accuracy over -40NC to +125NC
is ±1.1%. The device is available in a compact (4mm x
4mm) TQFN lead(Pb)-free package with an exposed pad.
Simulation models are available.
• Internal Compensation for Stable Operation at Any
Output Voltage
• All-Ceramic Capacitor Solution: Ultra-Compact
Layout with as Few as Eight External Components
ReducesꢀNumberꢀofꢀDC-DCꢀRegulatorsꢀtoꢀStock
• Wideꢀ4.5Vꢀtoꢀ60VꢀInputꢀVoltageꢀRange
●
• 0.9V to 90%V Output Voltage
IN
The device features a peak-current-mode control
architecture with a MODE feature that can be used to
operate the device in pulse-width modulation (PWM),
pulse-frequency modulation (PFM), or discontinuous-
conduction mode (DCM) control schemes. PWM operation
provides constant frequency operation at all loads, and is
useful in applications sensitive to switching frequency.
PFM operation disables negative inductor current and
additionally skips pulses at light loads for high efficiency.
DCM features constant frequency operation down to
lighter loads than PFM mode, by not skipping pulses but
only disabling negative inductor current at light loads.
DCM operation offers efficiency performance that lies
between PWM and PFM modes. The MAX17505S offers
a lower minimum on-time that allows for higher switching
frequencies and a smaller solution size.
• Delivers Up to 1.7A Over Temperature
• 100kHzꢀtoꢀ2.2MHzꢀAdjustableꢀFrequencyꢀwithꢀ
External Synchronization
• MAX17505SꢀAllowsꢀHigherꢀFrequencyꢀOfꢀOperation
• Available in a 20-Pin, 4mm x 4mm TQFN Package
ReducesꢀPowerꢀDissipation
●
●
• PeakꢀEfficiencyꢀ>ꢀ90%
• PFMꢀandꢀDCMꢀModesꢀforꢀHighꢀLight-LoadꢀEfficiency
• Shutdown Current = 2.8FA (typ)
OperatesꢀReliablyꢀ
• Hiccup-ModeꢀCurrentꢀLimitꢀandꢀAutoretryꢀStartup
• Built-In Output-Voltage Monitoring (Open-Drain
RESET Pin)
• Resistor-ProgrammableꢀEN/UVLOꢀThreshold
• AdjustableꢀSoft-StartꢀandꢀPrebiasedꢀPower-Up
• HighꢀIndustrialꢀ-40°Cꢀtoꢀ+125°CꢀAmbientꢀOperatingꢀ
TemperatureꢀRange/-40°Cꢀtoꢀ+150°CꢀJunctionꢀ
TemperatureꢀRange
A programmable soft-start feature allows users to reduce
input inrush current. The device also incorporates an
output enable/undervoltage lockout pin (EN/UVLO) that
allows the user to turn on the part at the desired input-
voltage level. An open-drain RESET pin provides a
delayed power-good signal to the system upon achieving
successful regulation of the output voltage.
Applications
●ꢀ IndustrialꢀPowerꢀSupplies
Ordering Information appears at end of data sheet.
●ꢀ DistributedꢀSupplyꢀRegulation
●ꢀ BaseꢀStationꢀPowerꢀSupplies
●ꢀ WallꢀTransformerꢀRegulation
●ꢀ High-VoltageꢀSingle-BoardꢀSystems
●ꢀ General-PurposeꢀPoint-of-Load
19-6907; Rev 2; 5/17
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Absolute Maximum Ratings (Note 1)
V
ꢀtoꢀPGND .........................................................-0.3V to +65V
SGNDꢀtoꢀPGND....................................................-0.3V to +0.3V
LXꢀTotalꢀRMSꢀCurrent ...........................................................±4A
Output Short-Circuit Duration....................................Continuous
IN
EN/UVLOꢀtoꢀSGND ...............................................-0.3V to +65V
LXꢀtoꢀPGND................................................-0.3V to (V + 0.3V)
IN
BSTꢀtoꢀPGND........................................................-0.3V to +70V
Continuous Power Dissipation (T = +70ºC) (multilayer board)
A
BST to LX.............................................................-0.3V to +6.5V
TQFN (derate 30.3mW/ºC above T = +70ºC) ......2424.2mW
A
BST to V
FB, CF, RESET, SS, MODE, SYNC,
RTꢀtoꢀSGND .....................................................-0.3V to +6.5V
...........................................................-0.3V to +65V
JunctionꢀTemperature......................................................+150ºC
StorageꢀTemperatureꢀRange.............................-65NC to +160ºC
Lead Temperature (soldering, 10s) .................................+300ºC
Soldering Temperature (reflow).......................................+260ºC
CC
V
ꢀtoꢀSGND.......................................................-0.3V to +6.5V
CC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these
or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect
device reliability.
Package Information
PACKAGE TYPE: 20 TQFN
Package Code
T2044+4
21-0139
90-0409
Outline Number
Land Pattern Number
THERMAL RESISTANCE, FOUR-LAYER BOARD
JunctionꢀtoꢀAmbientꢀ(θ
)
33°C/W
2°C/W
JA
JunctionꢀtoꢀCaseꢀ(θ
)
JC
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”,ꢀorꢀ“-”ꢀinꢀtheꢀpackageꢀcodeꢀindicatesꢀRoHSꢀstatusꢀonly.ꢀPackageꢀdrawingsꢀmayꢀshowꢀaꢀdifferentꢀsuffixꢀcharacter,ꢀbutꢀtheꢀdrawingꢀ
pertainsꢀtoꢀtheꢀpackageꢀregardlessꢀofꢀRoHSꢀstatus.
PackageꢀthermalꢀresistancesꢀwereꢀobtainedꢀusingꢀtheꢀmethodꢀdescribedꢀinꢀJEDECꢀspecificationꢀJESD51-7,ꢀusingꢀaꢀfour-layerꢀboard.ꢀ
For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
Note 1:ꢀ Junctionꢀtemperatureꢀgreaterꢀthanꢀ+125°Cꢀdegradesꢀoperatingꢀlifetimes.
Electrical Characteristics
(V = V
ꢀ=ꢀ24V,ꢀR
= 40.2kIꢀ(500kHz),ꢀC
ꢀ=ꢀ2.2μF,ꢀV
= V
= V
= V
= 0V, LX = SS = RESET =
IN
EN/UVLO
RT
VCC
PGND
SGND
MODE
SYNC
open, V
to V = 5V, V = 1V, T =ꢀ-40°Cꢀtoꢀ+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀ
BST
LX FB A A
referencedꢀtoꢀSGND,ꢀunlessꢀotherwiseꢀnoted.)ꢀ(Noteꢀ2)
PARAMETER
INPUT SUPPLY (V
SYMBOL
CONDITIONS
MIN
TYP MAX UNITS
)
IN
InputꢀVoltageꢀRange
V
4.5
60
V
IN
Input Shutdown Current
I
V
V
V
= 0V (shutdown mode)
2.8
118
162
1.16
4.5
IN-SH
EN/UVLO
ꢀ=ꢀ1V,ꢀMODEꢀ=ꢀRTꢀ=ꢀopen
µA
FB
FB
I
Q_PFM
= 1V, MODE = open
Input Quiescent Current
I
DCM mode, V = 0.1V
LX
1.8
Q-DCM
mA
Normal switching mode, f
= 0.8V
=ꢀ500kHz,ꢀV
FB
SW
I
9.5
Q_PWM
www.maximintegrated.com
Maxim Integrated │ 2
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Electrical Characteristics (continued)
(V = V
ꢀ=ꢀ24V,ꢀR
= 40.2kIꢀ(500kHz),ꢀC
ꢀ=ꢀ2.2μF,ꢀV
= V
= V
= V
= 0V, LX = SS = RESET =
IN
EN/UVLO
RT
VCC
PGND
SGND
MODE
SYNC
open, V
to V = 5V, V = 1V, T =ꢀ-40°Cꢀtoꢀ+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀ
BST
LX FB A A
referencedꢀtoꢀSGND,ꢀunlessꢀotherwiseꢀnoted.)ꢀ(Noteꢀ2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP MAX UNITS
ENABLE/UVLO (EN/UVLO)
V
V
V
V
rising
1.19 1.215 1.24
1.068 1.09 1.111
ENR
EN/UVLO
EN/UVLO
EN/UVLO
EN/UVLO Threshold
V
V
falling
= 0V, T = +25ºC
ENF
EN/UVLO Input Leakage Current
I
-50
0
+50
nA
EN
A
LDO
6V < V < 60V, I
= 1mA
IN
VCC
V
ꢀOutputꢀVoltageꢀRange
V
4.75
5
5.25
100
V
CC
CC
1mAꢀ≤ꢀI
ꢀ≤ꢀ25mA
VCC
V
V
Current Limit
Dropout
I
V
V
V
V
= 4.3V, V = 6V
26.5
4.2
54
mA
V
CC
CC
VCC-MAX
CC
IN
V
= 4.5V, I
= 20mA
CC-DO
IN
VCC
V
rising
falling
4.05
3.65
4.2
3.8
4.3
3.9
CC_UVR
CC
CC
V
UVLO
V
CC
V
CC_UVF
POWER MOSFET AND BST DRIVER
High-SideꢀnMOSꢀOn-Resistance
Low-SideꢀnMOSꢀOn-Resistance
LX Leakage Current
R
I
I
= 0.3A
= 0.3A
165
80
325
150
+2
mI
mI
µA
DS-ONH
LX
LX
R
DS-ONL
I
V
= V - 1V, V = V
+ 1V, T = +25ºC
-2
LX_LKG
LX
IN
LX
PGND
A
SOFT-START (SS)
Charging Current
I
V
= 0.5V
4.7
5
5.3
µA
SS
SS
FEEDBACK (FB)
MODEꢀ=ꢀSGNDꢀonꢀV
0.89
0.9
0.91
CC
FBꢀRegulationꢀVoltage
V
V
FB_REG
MODE = OPEN
0.89 0.915 0.936
FB Input Bias Current
I
0 < V < 1V, T = +25ºC
-50
+50
nA
FB
FB
A
MODE
V
CC
1.6
-
V
MODE = V
(DCM mode)
M-DCM
CC
MODE Threshold
V
V
MODE = open (PFM mode)
V
/ 2
CC
M-PFM
V
MODEꢀ=ꢀGNDꢀ(PWMꢀmode)
1.4
M-PWM
CURRENT LIMIT
Peak Current-Limit Threshold
I
2.4
2.9
2.8
3.4
0
3.25
3.9
A
A
PEAK-LIMIT
I
RUNAWAY-LIMIT
RunawayꢀCurrent-LimitꢀThreshold
Valley Current-Limit Threshold
PFM Current-Limit Threshold
MODE = open/V
MODEꢀ=ꢀGND
MODE = open
-0.16
+0.16
CC
I
A
A
SINK-LIMIT
-1.8
0.75
I
0.6
0.9
PFM
www.maximintegrated.com
Maxim Integrated │ 3
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Electrical Characteristics (continued)
(V = V
ꢀ=ꢀ24V,ꢀR
= 40.2kIꢀ(500kHz),ꢀC
ꢀ=ꢀ2.2μF,ꢀV
= V
= V
= V
= 0V, LX = SS = RESET =
IN
EN/UVLO
RT
VCC
PGND
SGND
MODE
SYNC
open, V
to V = 5V, V = 1V, T =ꢀ-40°Cꢀtoꢀ+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀ
BST
LX FB A A
referencedꢀtoꢀSGND,ꢀunlessꢀotherwiseꢀnoted.)ꢀ(Noteꢀ2)
PARAMETER
RT AND SYNC
SYMBOL
CONDITIONS
MIN
TYP MAX UNITS
R
R
R
R
R
= 210kΩ
= 102kΩ
= 40.2kΩ
= 8.06kΩ
= open
90
100
200
500
110
220
525
RT
RT
RT
RT
RT
180
475
Switching Frequency
f
kHz
SW
1950 2200 2450
460
500
540
1.1 x
1.4 x
f
SW
SYNCꢀFrequencyꢀCaptureꢀRange
SYNC Pulse Width
f
ꢀsetꢀbyꢀR
kHz
ns
V
SW
RT
f
SW
50
V
2.1
IH
SYNC Threshold
V
0.8
0.6
IL
FB Undervoltage Trip Level to
CauseꢀHiccup
V
0.56
0.58
V
FB-HICF
HiccupꢀTimeout
(Note 3)
32,768
Cycles
ns
MAX17505
MAX17505S
135
80
Minimum On-Time
t
ON-MIN
55
5
ns
Minimum Off-Time
LX Dead Time
t
140
160
ns
OFF-MIN
ns
RESET
RESET Output Level Low
I
= 10mA
0.4
V
RESET
RESET Output Leakage Current
T
= T = +25ºC, V
= 5.5V
-0.1
+0.1
µA
A
J
RESET
%V
FB-
FB Threshold for RESET Assertion
V
V
V
falling
FB
90.5
92
95
94
FB-OKF
REG
FB Threshold for RESET
Deassertion
%V
FB-
V
rising
FB
93.8
97.2
FB-OKR
REG
RESET Deassertion Delay After FB
Reachesꢀ95%ꢀRegulation
1024
Cycles
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-ShutdownꢀHysteresis
Temperature rising
165
10
ºC
ºC
Note 2:ꢀ Allꢀlimitsꢀareꢀ100%ꢀtestedꢀatꢀ+25°C.ꢀLimitsꢀoverꢀtemperatureꢀareꢀguaranteedꢀbyꢀdesign.
Note 3: See the Overcurrent Protection/Hiccup Mode section for more details.
www.maximintegrated.com
Maxim Integrated │ 4
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PWM MODE, FIGURE 5 CIRCUIT)
MAX17505 3.3V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PWM MODE, FIGURE 4 CIRCUIT)
toc02
MAX17505 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PWM MODE, FIGURE 3 CIRCUIT)
toc01
toc01a
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
100
90
80
70
60
50
40
30
20
10
0
VIN = 48V
VIN = 36V
VIN = 48V
VIN = 36V
VIN = 48V
VIN = 24V
VIN = 12V
VIN = 36V
VIN = 24V
VIN = 24V
VIN = 12V
VIN = 12V
MODE = SGND
MODE = SGND
1500
MODE = SGND
1500
1700
0
500
1000
0
500
1000
1500
1700
1700
0
500
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PfM MODE, FIGURE 3 CIRCUIT)
MAX17505S 3.3V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PWM MODE, FIGURE 6 CIRCUIT)
toc03
toc02a
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
20
V
IN = 48V
VIN = 36V
VIN = 36V
V
IN = 48V
VIN = 24V
VIN = 24V
VIN = 12V
VIN = 12V
MODE = OPEN
100 1000
MODE = SGND
1000 1500 1700
1700
1
10
0
500
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505 3.3V OUTPUT
EFFICIENCY VS. LOAD CURRENT
(PFM MODE, FIGURE 4 CIRCUIT)
MAX17505S 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(PFM MODE, FIGURE 5 CIRCUIT)
toc03a
toc04
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
20
10
0
VIN = 48V
VIN = 36V
VIN = 48V
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 24V
VIN = 12V
MODE = OPEN
1000
MODE = OPEN
100 1000
1700
10
100
1700
1
10
LOAD CURRENT (mA)
LOAD CURRENT (mA)
www.maximintegrated.com
Maxim Integrated
│
5
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(DCM MODE, FIGURE 5 CIRCUIT)
MAX17505S 3.3V OUTPUT
EFFICIENCY VS. LOAD CURRENT
(PFM MODE, FIGURE 6 CIRCUIT)
MAX17505 5V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(DCM MODE, FIGURE 3 CIRCUIT)
toc04a
toc05
toc05a
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
20
10
VIN = 48V
VIN = 36V
VIN = 48V
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 24V
VIN = 48V
VIN = 36V
VIN = 12V
VIN = 24V
VIN = 12V
MODE = VCC
MODE = OPEN
1000
MODE = VCC
100 1000
1
10
100
1000
1700
1700
10
100
LOAD CURRENT (mA)
1
10
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505S 3.3V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(DCM MODE, FIGURE 6 CIRCUIT)
MAX17505 3.3V OUTPUT
EFFICIENCY vs. LOAD CURRENT
(DCM MODE, FIGURE 4 CIRCUIT)
toc06a
toc06
100
90
80
70
60
50
40
30
20
100
90
80
70
60
50
40
30
20
10
0
VIN = 48V
VIN = 48V
VIN = 36V
VIN = 36V
VIN = 24V
VIN = 24V
VIN = 12V
VIN = 12V
MODE = VCC
1000 1700
MODE = VCC
100 1000 1700
1
10
100
1
10
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505 5V OUTPUT
LOAD AND LINE REGULATION
(PWM MODE, FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
LOAD AND LINE REGULATION
(PWM MODE, FIGURE 5 CIRCUIT)
toc07
toc07a
5.05
5.04
5.03
5.02
5.01
5.00
4.99
4.98
4.97
4.96
4.95
5.02
5.01
5.00
4.99
4.98
4.97
4.96
4.95
4.94
4.93
4.92
VIN = 48V
VIN = 24V
VIN = 12V
VIN = 36V
VIN = 24V
VIN = 48V
VIN = 36V
VIN = 12V
MODE = SGND
1000 1500
MODE = SGND
0
500
1700
0
500
1000
1500 1700
LOAD CURRENT (mA)
LOAD CURRENT (mA)
www.maximintegrated.com
Maxim Integrated │ 6
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S3.3V OUTPUT
LOAD AND LINE REGULATION
(PWM MODE, FIGURE 6 CIRCUIT)
MAX17505 3.3V OUTPUT
LOAD AND LINE REGULATION
(PWM MODE, FIGURE 4 CIRCUIT)
MAX17505 5V OUTPUT
LOAD AND LINE REGULATION
(PFM MODE, FIGURE 3 CIRCUIT)
toc08a
toc08
toc09
3.36
3.35
3.34
3.33
3.32
3.31
3.30
3.29
3.28
3.27
3.26
5.5
5.4
5.3
5.2
5.1
5.0
4.9
4.8
4.7
4.6
4.5
3.50
3.45
3.40
3.35
3.30
3.25
3.20
3.15
3.10
VIN = 36V
VIN = 12V VIN = 24V
VIN = 48V
VIN = 24V
VIN = 48V
VIN = 24V
VIN = 12V
VIN = 36V
VIN = 48V
VIN = 36V
VIN = 12V
MODE = SGND
MODE = SGND
1500 1700
MODE = OPEN
1000 1500
1700
0
500
1000
0
500
LOAD CURRENT (mA)
0
500
1000
1500 1700
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505 3.3V OUTPUT
LOAD AND LINE REGULATION
(PFM MODE, FIGURE 4 CIRCUIT)
MAX17505S5V OUTPUT
LOAD AND LINE REGULATION
(PFM MODE, FIGURE 5 CIRCUIT)
toc10
toc09a
3.37
3.36
3.35
3.34
3.33
3.32
3.31
3.30
3.29
3.28
5.25
5.20
5.15
5.10
5.05
5.00
4.95
4.90
4.85
4.80
4.75
VIN = 48V
VIN = 12V
VIN = 48V
VIN = 12V
VIN = 36V
VIN = 24V
VIN = 24V
VIN = 36V
MODE = OPEN
1000 1500
MODE = OPEN
3.27
0
1700
0
500
500
1000
1500 1700
LOAD CURRENT (mA)
LOAD CURRENT (mA)
MAX17505S3.3V OUTPUT
LOAD AND LINE REGULATION
(PFM MODE, FIGURE 6 CIRCUIT)
SWITCHING FREQUENCY
vs. RT RESISTANCE
toc10a
toc11
3.60
3.50
3.40
3.30
3.20
3.10
3.00
2400
2200
2000
1800
1600
1400
1200
1000
800
V
IN = 48V
VIN = 12V
VIN = 24V
VIN = 36V
600
400
200
MODE = OPEN
1000 1500
0
0
0
500
LOAD CURRENT (mA)
1700
20
40
60
80
100
RRT (kΩ)
www.maximintegrated.com
Maxim Integrated
│
7
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S 5V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(1.7A LOAD CURRENT, FIGURE 5 CIRCUIT)
MAX17505 5V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(1.7A LOAD CURRENT, FIGURE 3 CIRCUIT)
toc12a
toc12
2V/div
2V/div
VEN/UVLO
5V/div
VEN/UVLO
VOUT
VOUT
IOUT
2V/div
1A/div
IOUT
1A/div
5V/div
VRESET
VRESET
5V/div
MODE = SGND
1ms/div
MODE = SGND
1ms/div
MAX17505 3.3V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(1.7A LOAD CURRENT, FIGURE 4 CIRCUIT)
MAX17505S 3.3V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(1.7A LOAD CURRENT, FIGURE 6 CIRCUIT)
toc13
toc13a
VEN/UVLO
2V/div
2V/div
VEN/UVLO
5V/div
2V/div
VOUT
VOUT
IOUT
1A/div
5V/div
IOUT
1A/div
5V/div
VRESET
MODE = SGND
1ms/div
VRESET
MODE = SGND
1mS/div
MAX17505 5V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
MAX17505S 5V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(PFM MODE, 5mA LOAD CURRENT, FIGURE 3 CIRCUIT)
(PFM MODE, 5MA LOAD CURRENT, FIGURE 5 CIRCUIT)
toc14
toc14a
MODE = OPEN
2V/div
1V/div
VEN/UVLO
VEN/UVLO
5V/div
VOUT
VOUT
1V/div
5V/div
MODE = OPEN
2mS/div
VRESET
5V/div
VRESET
2mS/div
www.maximintegrated.com
Maxim Integrated │ 8
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505 3.3V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(PFM MODE, 5mA LOAD CURRENT, FIGURE 4 CIRCUIT)
MAX17505S 3.3V OUTPUT
SOFT-START/SHUTDOWN FROM EN/UVLO
(PFM MODE, 5mA LOAD CURRENT, FIGURE 6 CIRCUIT)
toc15a
toc15
VEN/UVLO
2V/div
1V/div
VEN/UVLO
5/div
VOUT
1V/div
5V/div
VOUT
VRESET
5V/div
VRESET
MODE = OPEN
MODE = OPEN
2ms/div
2mS/div
MAX17505 5V OUTPUT
SOFT-START WITH 2.5V PREBIAS
(PWM MODE, FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
SOFT-START WITH 2.5V PREBIAS
(PWM MODE, FIGURE 5 CIRCUIT)
toc16
toc16a
5V/div
2V/div
2V/div
VEN/UVLO
VEN/UVLO
2V/div
5V/div
VOUT
VOUT
VRESET
5V/div
VRESET
MODE = SGND
MODE = SGND
1mS/div
1mS/div
MAX17505S 3.3V OUTPUT
SOFT-START WITH 2.5V PREBIAS
(PWM MODE, FIGURE 6 CIRCUIT)
MAX17505 3.3V OUTPUT
SOFT-START WITH 2.5V PREBIAS
(PFM MODE, FIGURE 4 CIRCUIT)
toc17a
toc17
2V/div
1V/div
VEN/UVLO
VEN/UVLO
5V/div
1V/div
VOUT
5V/div
VOUT
VRESET
VRESET
5V/div
MODE = OPEN
MODE = OPEN
1ms/div
1mS/div
www.maximintegrated.com
Maxim Integrated │ 9
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(PWM MODE, NO LOAD, FIGURE 3 CIRCUIT)
MAX17505 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(1.7A LOAD CURRENT, FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(1.7A LOAD CURRENT, FIGURE 5 CIRCUIT)
toc19
toc18a
toc18
MODE = SGND
VOUT (AC)
VOUT (AC)
VOUT (AC)
20mV/di
20mV/div
50mV/div
VLX
10V/div
1A/div
10V/div
1A/div
VLX
VLX
10V/div
1A/div
ILX
ILX
ILX
MODE = SGND
MODE = SGND
400nS/div
1μs/div
1μs/div
MAX17505 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(PFM MODE, 25mA LOAD, FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(NO LOAD CURRENT, FIGURE 5 CIRCUIT)
toc20
toc19a
MODE = SGND
100mV/div
VOUT (AC)
VOUT (AC)
50mV/div
VLX
10V/div
VLX
10V/div
ILX
500mA/div
ILX
500mA/div
MODE = OPEN
10μs/div
400ns/div
MAX17505S 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(PFM MODE, 25mA LOAD CURRENT, FIGURE 5 CIRCUIT)
MAX17505 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(DCM MODE, 25mA LOAD, FIGURE 3 CIRCUIT)
toc20a
toc21
VOUT (AC)
100mV/div
20mV/div
VOUT (AC)
MODE = VCC
VLX
VLX
10V/div
10V/div
ILX
ILX
200mA/div
500mA/div
MODE = OPEN
1μs/div
4μs/div
www.maximintegrated.com
Maxim Integrated │ 10
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S 5V OUTPUT
STEADY-STATE SWITCHING WAVEFORMS
(DCM MODE, 25mA LOAD CURRENT, FIGURE 5 CIRCUIT)
MAX17505S 5V OUTPUT
LOAD CURRENT STEPPED FROM 0.85A TO 1A
MAX17505 5V OUTPUT
LOAD CURRENT STEPPED FROM 0.85A TO 1.7A
(PWM MODE, FIGURE 5 CIRCUIT)
(PWM MODE, FIGURE 3 CIRCUIT)
toc21a
toc22a
toc22
VOUT (AC)
20mV/div
VOUT (AC)
100mV/div
MODE = VCC
VOUT (AC)
100mV/div
VLX
10V/div
1A/div
ILX
ILX
IOUT
200mA/div
1A/div
MODE = SGND
MODE = SGND
1μs/div
40μs/div
40μS/div
MAX17505 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 0.85A TO 1.7A
MAX17505S 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 0.85A TO 1.7A
(PWM MODE, FIGURE 6 CIRCUIT)
(PWM MODE, FIGURE 4 CIRCUIT)
toc23
toc23a
VOUT (AC)
50mV/div
VOUT (AC)
50mV/div
IOUT
1A/div
ILX
1A/div
MODE = SGND
MODE = SGND
100μs/div
40μS/div
MAX17505 5V OUTPUT
LOAD CURRENT STEPPED FROM NO LOAD TO 0.85A
MAX17505S 5V OUTPUT
LOAD CURRENT STEPPED FROM NO LOAD TO 0.85A
(PWM MODE, FIGURE 3 CIRCUIT)
(PWM MODE, FIGURE 5 CIRCUIT)
toc24
toc24a
VOUT (AC)
100mV/div
VOUT (AC)
100mV/div
500mA/div
IOUT
500mA/div
ILX
MODE = SGND
MODE = SGND
40μs/div
40μS/div
www.maximintegrated.com
Maxim Integrated │ 11
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505S 3.3V OUTPUT
LOAD CURRENT STEPPED FROM NO LOAD TO 0.85A
MAX17505 3.3V OUTPUT
LOAD CURRENT STEPPED FROM NO LOAD TO 0.85A
(PWM MODE, FIGURE 6 CIRCUIT)
(PWM MODE, FIGURE 4 CIRCUIT)
toc25a
toc25
VOUT (AC)
50mV/div
VOUT (AC)
50mV/div
500mA/div
IOUT
ILX
500mA/div
MODE = SGND
MODE = SGND
100μs/div
40μS/div
MAX17505S 5V OUTPUT
LOAD CURRENT STEPPED FROM 5MA TO 0.85A
MAX17505 5V OUTPUT
LOAD CURRENT STEPPED FROM 5mA TO 0.85A
(PFM MODE, FIGURE 5 CIRCUIT)
(PFM MODE, FIGURE 3 CIRCUIT)
toc26
toc26a
100mV/div
VOUT (AC)
100mV/div
VOUT (AC)
IOUT
500mA/div
ILX
500mA/div
MODE = OPEN
MODE = OPEN
2ms/div
1mS/div
MAX17505 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 5mA TO 0.85A
MAX17505S 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 5mA TO 0.85A
(PFM MODE, FIGURE 4 CIRCUIT)
(PFM MODE, FIGURE 6 CIRCUIT)
toc27a
toc27
VOUT (AC)
100mV/div
VOUT (AC)
50mV/div
500mA/div
ILX
500mA/div
IOUT
MODE = OPEN
MODE = OPEN
2ms/div
2mS/div
www.maximintegrated.com
Maxim Integrated │ 12
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505 5V OUTPUT
MAX17505S 5V OUTPUT
LOAD CURRENT STEPPED FROM 50mA TO 0.85A
LOAD CURRENT STEPPED FROM 50mA TO 0.85A
(DCM MODE, FIGURE 3 CIRCUIT)
(DCM MODE, FIGURE 5 CIRCUIT)
toc28
toc28a
100mV/div
VOUT (AC)
VOUT (AC)
100mV/div
500mA/div
IOUT
IOUT
500mA/div
MODE = VCC
MODE = VCC
200μs/div
200μs/div
MAX17505S 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 50mA TO 0.85A
MAX17505 3.3V OUTPUT
LOAD CURRENT STEPPED FROM 50mA TO 0.85A
(DCM MODE, FIGURE 6 CIRCUIT)
(DCM MODE, FIGURE 4 CIRCUIT)
toc29a
toc29
VOUT (AC)
100mV/div
100mV/div
VOUT (AC)
500mA/div
IOUT
500mA/div
IOUT
MODE = VCC
MODE = VCC
200μs/div
200μs/div
MAX17505 5V OUTPUT
OVERLOAD PROTECTION
(FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
OVERLOAD PROTECTION
(FIGURE 5 CIRCUIT)
toc30a
toc30
VOUT
2V/div
VOUT
200mV/div
IOUT
1A/div
IOUT
1A/div
MODE = VCC
MODE = VCC
20ms/div
10ms/div
www.maximintegrated.com
Maxim Integrated │ 13
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Typical Operating Characteristics (continued)
(V = V
= 24V, V
= V
= 0V, C
= C
= 2.2µF, C
= 0.1µF, C ꢀ=ꢀ5600pF,ꢀRTꢀ=ꢀMODEꢀ=ꢀopen,ꢀT ꢀ=ꢀ-40°Cꢀtoꢀ
IN
EN/UVLO
PGND
SGND
VIN
VCC
BST SS A
+125°C,ꢀunlessꢀotherwiseꢀnoted.ꢀTypicalꢀvaluesꢀareꢀatꢀT ꢀ=ꢀ+25°C.ꢀAllꢀvoltagesꢀareꢀreferencedꢀtoꢀGND,ꢀunlessꢀotherwiseꢀnoted.)
A
MAX17505 5V OUTPUT
APPLICATION OF EXTERNAL CLOCK AT 700kHz
MAX17505S 5V OUTPUT
APPLICATION OF EXTERNAL CLOCK AT 1.2MHz
(FIGURE 3 CIRCUIT)
(FIGURE 5 CIRCUIT)
toc31
toc31a
VLX
10V/div
VLX
10V/div
VSYNC
2V/div
2V/div
VSYNC
MODE = SGND
MODE = SGND
2μs/div
2μs/div
MAX17505 5V OUTPUT
BODE PLOT
(1.7A LOAD CURRENT, FIGURE 3 CIRCUIT)
MAX17505S 5V OUTPUT
BODE PLOT
(1.7A LOAD CURRENT, FIGURE 5 CIRCUIT)
toc32 120
toc32a
50
40
100
40
100
PHASE
GAIN
80
30
20
PHASE
60
50
0
20
0
40
10
0
GAIN
0
-40
-60
-80
-10
-20
CROSSOVER FREQUENCY = 60.7kHz
PHASE MARGIN = 59°
-30
-40
-50
CROSSOVER FREQUENCY = 101kHz
PHASE MARGIN = 58.1°
-50
-100
-120
-20
100K
10K
1K
105
104
103
FREQUENCY (Hz)
FREQUENCY (Hz)
MAX17505S 3.3V OUTPUT
BODE PLOT
MAX17505 3.3V OUTPUT
BODE PLOT
(1.7A LOAD CURRENT, FIGURE 4 CIRCUIT)
(1.7A LOAD CURRENT, FIGURE 6 CIRCUIT)
toc33 120
100
80
toc33a
60
50
40
30
100
40
30
PHASE
PHASE
20
10
0
60
50
20
10
40
GAIN
GAIN
20
0
-10
-20
-30
-40
0
0
-20
-10
-40
CROSSOVER FREQUENCY = 77.7kHz
PHASE MARGIN = 63.2°
CROSSOVER FREQUENCY = 58kHz
PHASE MARGIN = 59°
-60
-80
-20
-30
-50
100K
10K
1K
105
104
FREQUENCY (Hz)
103
FREQUENCY (Hz)
www.maximintegrated.com
Maxim Integrated │ 14
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Pin Configuration
TOP VIEW
15
14
13
12
11
RT
FB
10
9
PGND 16
LX
LX
LX
17
18
19
20
MAX17505/
MAX17505S
8
CF
SS
7
+
6
SYNC
BST
1
2
3
4
5
TQFN
4mm × 4mm
* EXPOSED PAD (CONNECT TO GROUND).
Pin Description
PIN
NAME
FUNCTION
Power-Supply Input. 4.5V to 60V input supply range. Connect the V ꢀpinsꢀtogether.ꢀDecoupleꢀtoꢀPGNDꢀ
IN
1–3
V
with a 2.2µF capacitor; place the capacitor close to the V ꢀandꢀPGNDꢀpins.ꢀReferꢀtoꢀtheꢀMAX17505/
IN
IN
MAX17505S EV kit data sheets for a layout example.
Enable/Undervoltage Lockout. Drive EN/UVLO high to enable the output voltage. Connect to the center
4
5
EN/UVLO of the resistor-divider between V ꢀandꢀSGNDꢀtoꢀsetꢀtheꢀinputꢀvoltageꢀatꢀwhichꢀtheꢀdeviceꢀturnsꢀon.ꢀPullꢀ
IN
up to V for always-on operation.
IN
Open-Drain RESET Output. The RESET output is driven low if FB drops below 92% of its set value.
RESET goes high 1024 clock cycles after FB rises above 95% of its set value.
RESET
The device can be synchronized to an external clock using this pin. See the External Frequency
Synchronization section for more details.
6
7
8
SYNC
SS
Soft-StartꢀInput.ꢀConnectꢀaꢀcapacitorꢀfromꢀSSꢀtoꢀSGNDꢀtoꢀsetꢀtheꢀsoft-startꢀtime.
Atꢀswitchingꢀfrequenciesꢀlowerꢀthanꢀ500kHz,ꢀconnectꢀaꢀcapacitorꢀfromꢀCFꢀtoꢀFB.ꢀLeaveꢀCFꢀopenꢀifꢀ
switchingꢀfrequencyꢀisꢀequalꢀorꢀmoreꢀthanꢀ500kHz.ꢀSeeꢀtheꢀLoop Compensation section for more details.
CF
FeedbackꢀInput.ꢀConnectꢀFBꢀtoꢀtheꢀcenterꢀtapꢀofꢀanꢀexternalꢀresistor-dividerꢀfromꢀtheꢀoutputꢀtoꢀGNDꢀtoꢀ
set the output voltage. See the Adjusting Output Voltage section for more details.
9
FB
ConnectꢀaꢀresistorꢀfromꢀRTꢀtoꢀSGNDꢀtoꢀsetꢀtheꢀregulator’sꢀswitchingꢀfrequency.ꢀLeaveꢀRTꢀopenꢀforꢀtheꢀ
defaultꢀ500kHzꢀfrequency.ꢀSeeꢀtheꢀSetting the Switching Frequency (RT) section for more details.
10
RT
MODEꢀpinꢀconfiguresꢀtheꢀdeviceꢀtoꢀoperateꢀeitherꢀinꢀPWM,ꢀPFM,ꢀorꢀDCMꢀmodesꢀofꢀoperation.ꢀLeaveꢀ
MODEꢀunconnectedꢀforꢀPFMꢀoperationꢀ(pulseꢀskippingꢀatꢀlightꢀloads).ꢀConnectꢀMODEꢀtoꢀSGNDꢀforꢀ
11
MODE
constant-frequency PWM operation at all loads. Connect MODE to V
for DCM operation. See the
CC
MODE Setting section for more details.
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Maxim Integrated
│ 15
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Pin Description (continued)
PIN
12
NAME
FUNCTION
V
5V LDO Output. Bypass V ꢀwithꢀ2.2µFꢀceramicꢀcapacitanceꢀtoꢀSGND.
CC
CC
13
SGND
AnalogꢀGround
PowerꢀGround.ꢀConnectꢀtheꢀPGNDꢀpinsꢀexternallyꢀtoꢀtheꢀpowerꢀgroundꢀplane.ꢀConnectꢀtheꢀSGNDꢀandꢀ
14–16
PGND
PGNDꢀpinsꢀtogetherꢀatꢀtheꢀgroundꢀreturnꢀpathꢀofꢀtheꢀV ꢀbypassꢀcapacitor.ꢀReferꢀtoꢀtheꢀMAX17505/
CC
MAX17505S EV kit data sheets for a layout example.
SwitchingꢀNode.ꢀConnectꢀLXꢀpinsꢀtoꢀtheꢀswitchingꢀsideꢀofꢀtheꢀinductor.ꢀReferꢀtoꢀtheꢀMAX17505/
MAX17505S EV kit data sheets for a layout example.
17–19
20
LX
BST
Boost Flying Capacitor. Connect a 0.1µF ceramic capacitor between BST and LX.
Exposedꢀpad.ꢀConnectꢀtoꢀtheꢀSGNDꢀpin.ꢀConnectꢀtoꢀaꢀlargeꢀcopperꢀplaneꢀbelowꢀtheꢀICꢀtoꢀimproveꢀheatꢀ
dissipationꢀcapability.ꢀAddꢀthermalꢀviasꢀbelowꢀtheꢀexposedꢀpad.ꢀReferꢀtoꢀtheꢀMAX17505/MAX17505SꢀEVꢀ
kit data sheets for a layout example.
—
EP
Block Diagram
MAX17505/MAX17505S
BST
V
5V
CC
LDO
V
IN
SGND
CURRENT-SENSE
LOGIC
PWM/
PFM/
LX
EN/UVLO
HICCUP
LOGIC
AND
DRIVERS
HICCUP
1.215V
RT
PGND
OSCILLATOR
SYNC
CF
FB
MODE
SELECTION
LOGIC
ERROR AMPLIFIER/
LOOP COMPENSATION
MODE
RESET
V
CC
V
BG
= 0.9V
SWITCHOVER
LOGIC
SLOPE
COMPENSATION
5µA
SS
FB
EN/UVLO
RESET
LOGIC
HICCUP
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Maxim Integrated │ 16
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
PFM Mode Operation
Detailed Description
PFM mode of operation disables negative inductor current
and additionally skips pulses at light loads for high
efficiency. In PFM mode, the inductor current is forced to
a fixed peak of 750mA every clock cycle until the output
rises to 102.3% of the nominal voltage. Once the output
reaches 102.3% of the nominal voltage, both the high-side
and low-side FETs are turned off and the device enters
hibernate operation until the load discharges the output to
101.1% of the nominal voltage. Most of the internal blocks
are turned off in hibernate operation to save quiescent
current. After the output falls below 101.1% of the nominal
voltage, the device comes out of hibernate operation,
turns on all internal blocks, and again commences the
process of delivering pulses of energy to the output until it
reaches 102.3% of the nominal output voltage.
The MAX17505/MAX17505S high-efficiency, high-
voltage, synchronously rectified step-down converter with
dual integrated MOSFETs operates over a 4.5V to 60V
input. It delivers up to 1.7A and 0.9V to 90%V output
IN
voltage. Built-in compensation across the output voltage
range eliminates the need for external components. The
feedback (FB) regulation accuracy over -40NC to +125NC
is ±1.1%.
The device features a peak-current-mode control
architecture. An internal transconductance error amplifier
produces an integrated error voltage at an internal node,
which sets the duty cycle using a PWM comparator, a high-
side current-sense amplifier, and a slope-compensation
generator. At each rising edge of the clock, the high-
side MOSFET turns on and remains on until either
the appropriate or maximum duty cycle is reached, or
the peak current limit is detected. During the high-side
MOSFET’sꢀon-time,ꢀtheꢀinductorꢀcurrentꢀrampsꢀup.ꢀDuringꢀ
the second half of the switching cycle, the high-side
MOSFET turns off and the low-side MOSFET turns on.
The inductor releases the stored energy as its current
ramps down and provides current to the output.
The advantage of the PFM mode is higher efficiency at
light loads because of lower quiescent current drawn from
supply. The disadvantage is that the output-voltage ripple
is higher compared to PWM or DCM modes of operation
and switching frequency is not constant at light loads.
DCM Mode Operation
DCM mode of operation features constant frequency
operation down to lighter loads than PFM mode, by not
skipping pulses but only disabling negative inductor cur-
rent at light loads. DCM operation offers efficiency perfor-
mance that lies between PWM and PFM modes.
The device features a MODE pin that can be used to operate
the device in PWM, PFM, or DCN control schemes. The
deviceꢀ integratesꢀ adjustable-inputꢀ undervoltageꢀ lockout,ꢀ
adjustableꢀsoft-start,ꢀopenꢀRESET, and external frequency
synchronization features. The MAX17505S offers a
lower Minimum On-Time that allows for higher switching
frequencies and a smaller solution size.
Linear Regulator (VCC
)
An internal linear regulator (V ) provides a 5V nominal
CC
supply to power the internal blocks and the low-side
Mode Selection (MODE)
The logic state of the MODE pin is latched when V
MOSFET driver. The output of the linear regulator (V
)
CC
CC
should be bypassed with a 2.2µF ceramic capacitor to
SGND.ꢀ Theꢀ deviceꢀ employsꢀ anꢀ undervoltageꢀ lockoutꢀ
and EN/UVLO voltages exceed the respective UVLO
rising thresholds and all internal voltages are ready to
allow LX switching. If the MODE pin is open at power-up,
the device operates in PFM mode at light loads. If the
MODE pin is grounded at power-up, the device operates
in constant-frequency PWM mode at all loads. Finally,
circuit that disables the internal linear regulator when V
falls below 3.8V (typ).
CC
Setting the Switching Frequency (RT)
The switching frequency of the device can be programmed
fromꢀ 100kHzꢀ toꢀ 2.2MHzꢀ byꢀ usingꢀ aꢀ resistorꢀ connectedꢀ
if the MODE pin is connected to V
at power-up, the
CC
device operates in constant-frequency DCM mode at light
loads. State changes on the MODE pin are ignored during
normal operation.
fromꢀtheꢀRTꢀpinꢀtoꢀSGND.ꢀTheꢀswitchingꢀfrequencyꢀ(f
)
SW
isꢀrelatedꢀtoꢀtheꢀresistorꢀconnectedꢀatꢀtheꢀRTꢀpinꢀ(R ) by
RT
the following equation:
3
PWM Mode Operation
21×10
R
≅
−1.7
RT
In PWM mode, the inductor current is allowed to go
negative. PWM operation provides constant frequency
operation at all loads, and is useful in applications
sensitiveꢀ toꢀ switchingꢀ frequency.ꢀ However,ꢀ theꢀ PWMꢀ
mode of operation gives lower efficiency at light loads
compared to PFM and DCM modes of operation.
f
SW
whereꢀR ꢀisꢀinꢀkΩꢀandꢀf ꢀisꢀinꢀkHz.ꢀLeavingꢀtheꢀRTꢀpinꢀ
RT
SW
open causes the device to operate at the default switching
frequencyꢀofꢀ500kHz.ꢀSeeꢀTable 1ꢀforꢀRTꢀresistorꢀvaluesꢀ
for a few common switching frequencies.
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Maxim Integrated │ 17
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
switch current at 3.4A (typ) protects the device under
high input voltage, short-circuit conditions when there is
insufficient output voltage available to restore the inductor
current that was built up during the ON period of the
step-down converter. One occurrence of the runaway
current limit triggers a hiccup mode. In addition, if due to
a fault condition, feedback voltage drops to 0.58V (typ)
any time after soft-start is complete, and hiccup mode
is triggered. In hiccup mode, the converter is protected
by suspending switching for a hiccup timeout period of
32,768 clock cycles. Once the hiccup timeout period
expires, soft-start is attempted again. Note that when soft-
start is attempted under overload condition, if feedback
voltage does not exceed 0.58V, the device switches at
halfꢀtheꢀprogrammedꢀswitchingꢀfrequency.ꢀHiccupꢀmodeꢀ
of operation ensures low power dissipation under output
short-circuit conditions.
Table 1. Switching Frequency vs. RT
Resistor
SWITCHING FREQUENCY (kHz)
RT RESISTOR (kΩ)
500
100
Open
210
200
102
400
49.9
19.1
8.06
1000
2200
Operating Input Voltage Range
The minimum and maximum operating input voltages for
a given output voltage should be calculated as follows:
V
+ (I
× (R
+ 0.15))
OUT
OUT(MAX)
DCR
)
OFF(MAX)
V
=
IN(MIN)
1- (f
× t
SW(MAX)
RESET Output
+ (I
× 0.175)
OUT(MAX)
The device includes a RESET comparator to monitor the
output voltage. The open-drain RESET output requires
an external pullup resistor. RESET goes high (high
impedance) 1024 switching cycles after the regulator
output increases above 95% of the designed nominal
regulated voltage. RESET goes low when the regulator
output voltage drops to below 92% of the nominal
regulated voltage. RESET also goes low during thermal
shutdown.
V
OUT
V
=
IN(MAX)
f
× t
)
ON(MIN)
SW(MAX)
where V
is the steady-state output voltage, I
OUT (MAX)
OUT
isꢀtheꢀmaximumꢀloadꢀcurrent,ꢀR
is the DC resistance
DCR
of the inductor, f
is the maximum switching
is the worst-case minimum switch
SW(MAX)
frequency, t
OFF-MAX
off-time (160ns), and t
switch on-time (135ns for the MAX17505, 80ns for the
MAX17505S).
is the worst-case minimum
Prebiased Output
ON-MIN
When the device starts into a prebiased output, both the
high-side and the low-side switches are turned off so that
theꢀconverterꢀdoesꢀnotꢀsinkꢀcurrentꢀfromꢀtheꢀoutput.ꢀHigh-
side and low-side switches do not start switching until
the PWM comparator commands the first PWM pulse, at
which point switching commences. The output voltage is
then smoothly ramped up to the target value in alignment
with the internal reference.
External Frequency 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 1.1
x f
and 1.4 x f , where f
is the frequency
SW
SW
SW
programmedꢀ byꢀ theꢀ RTꢀ resistor.ꢀ Theꢀ minimumꢀ externalꢀ
clock pulse-width high should be greater than 50ns. See
the RT AND SYNC section in the Electrical Characteristics
table for details.
Thermal-Shutdown Protection
Thermal-shutdown protection limits total power dissipation
inꢀtheꢀdevice.ꢀWhenꢀtheꢀjunctionꢀtemperatureꢀofꢀtheꢀdeviceꢀ
exceeds +165ºC, an on-chip thermal sensor shuts down
the device, allowing the device to cool. The thermal sensor
turnsꢀtheꢀdeviceꢀonꢀagainꢀafterꢀtheꢀjunctionꢀtemperatureꢀ
cools by 10ºC. Soft-start resets during thermal shutdown.
Carefully evaluate the total power dissipation (see the
Power Dissipation section) to avoid unwanted triggering of
the thermal shutdown in normal operation.
Overcurrent Protection/Hiccup Mode
The device is provided with a robust overcurrent protection
scheme that protects the device under overload and
output short-circuit conditions. A cycle-by-cycle peak
current limit turns off the high-side MOSFET whenever
the high-side switch current exceeds an internal limit
of 2.8A (typ). A runaway current limit on the high-side
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Maxim Integrated │ 18
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Select a low-loss inductor closest to the calculated
value with acceptable dimensions and having the lowest
possible DC resistance. The saturation current rating
Applications Information
Input Capacitor Selection
The input filter capacitor reduces peak currents drawn
from the power source and reduces noise and voltage
rippleꢀ onꢀ theꢀ inputꢀ causedꢀ byꢀ theꢀ circuit’sꢀ switching.ꢀ
(I
) of the inductor must be high enough to ensure that
SAT
saturation can occur only above the peak current-limit
value of 2.8A.
Theꢀ inputꢀ capacitorꢀ RMSꢀ currentꢀ requirementꢀ (I
defined by the following equation:
) is
RMS
Output Capacitor Selection
X7Rꢀceramicꢀoutputꢀcapacitorsꢀareꢀpreferredꢀdueꢀtoꢀtheirꢀ
stability over temperature in industrial applications. The
output capacitors are usually sized to support a step load
of 50% of the maximum output current in the application,
so the output voltage deviation is contained to 3% of the
output voltage change. The minimum required output
capacitance can be calculated as follows:
V
×(V - V
)
OUT
OUT
IN
I
= I
×
OUT(MAX)
RMS
V
IN
where, I
is the maximum load current. I
a maximum value when the input voltage equals twice
the output voltage (V = 2 x V ), so I
has
RMS
OUT(MAX)
=
RMS(MAX)ꢀ
IN
OUT
I
/2.
OUT(MAX)
I
× t
1
2
STEP
RESPONSE
∆V
Choose an input capacitor that exhibits less than +10ºC
temperatureꢀ riseꢀ atꢀ theꢀ RMSꢀ inputꢀ currentꢀ forꢀ optimalꢀ
long-termꢀreliability.ꢀUseꢀlow-ESRꢀceramicꢀcapacitorsꢀwithꢀ
high-ripple-currentꢀcapabilityꢀatꢀtheꢀinput.ꢀX7Rꢀcapacitorsꢀ
are recommended in industrial applications for their
temperature stability. Calculate the input capacitance
using the following equation:
C
=
×
OUT
OUT
0.33
1
t
≅ (
+
)
RESPONSE
f
f
sw
C
where I
is the load current step, t
is the
STEP
RESPONSE
response time of the controller, DV
is the allowable
OUT
output-voltage deviation, f is the target closed-loop crossover
C
I
×D ×(1- D)
OUT(MAX)
C
=
frequency, and f
is the switching frequency. For the
IN
SW
η× f
× ∆V
IN
SW
MAX17505, select f to be 1/9th of f
if the switching
C
SW
where D = V
/V is the duty ratio of the controller,
OUT IN
frequencyꢀ isꢀ lessꢀ thanꢀ orꢀ equalꢀ toꢀ 500kHz.ꢀ Ifꢀ theꢀ switchingꢀ
frequencyꢀisꢀmoreꢀthanꢀ500kHz,ꢀselectꢀf ꢀtoꢀbeꢀ55kHz.ꢀForꢀ
f
ꢀisꢀtheꢀswitchingꢀfrequency,ꢀΔV is the allowable input
voltage ripple, and E is the efficiency.
SW
IN
C
the MAX17505S, select f to be 1/10th of f
if the switching
C
SW
In applications where the source is located distant from
the device input, an electrolytic capacitor should be
added in parallel to the ceramic capacitor to provide
necessary damping for potential oscillations caused by
the inductance of the longer input power path and input
ceramic capacitor.
frequencyꢀ isꢀ lessꢀ thanꢀ orꢀ equalꢀ toꢀ 1MHz.ꢀ Ifꢀ theꢀ switchingꢀ
frequencyꢀisꢀmoreꢀthanꢀ1MHz,ꢀselectꢀf ꢀtoꢀbeꢀ100kHz.
C
Derating of ceramic capacitors with DC-voltage must be
considered while selecting the output capacitor. Derating
curvesꢀareꢀavailableꢀfromꢀallꢀmajorꢀceramicꢀcapacitorꢀvendors.
Soft-Start Capacitor Selection
Inductor Selection
Three key inductor parameters must be specified for
operation with the device: inductance value (L), inductor
Theꢀ deviceꢀ implementsꢀ adjustableꢀ soft-startꢀ operationꢀ toꢀ
reduce inrush current. A capacitor connected from the SS pin
toꢀSGNDꢀprogramsꢀtheꢀsoft-startꢀtime.ꢀTheꢀselectedꢀoutputꢀ
saturation current (I
),ꢀandꢀDCꢀresistanceꢀ(R
). The
SAT
DCR
capacitance (C ) and the output voltage (V ) determine
SEL OUT
switching frequency and output voltage determine the
the minimum required soft-start capacitor as follows:
inductor value as follows:
-6
C
≥ 28×10 × C
× V
SEL OUT
SS
V
f
OUT
SW
L =
The soft-start time (t ) is related to the capacitor
SS
connected at SS (C ) by the following equation:
SS
where V
, and f
are nominal values. Select an
C
OUT
SW
SS
t
=
SS
inductor whose value is nearest to the value calculated by
the previous formula.
-6
5.55×10
For example, to program a 1ms soft-start time, a 5.6nF
capacitorꢀshouldꢀbeꢀconnectedꢀfromꢀtheꢀSSꢀpinꢀtoꢀSGND.
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Maxim Integrated │ 19
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
V
IN
V
OUT
R1
R2
R3
EN/UVLO
FB
R4
SGND
SGND
Figure 1. Setting the Input Undervoltage Lockout
Figure 2. Setting the Output Voltage
Setting the Input Undervoltage-Lockout Level
Theꢀdeviceꢀoffersꢀanꢀadjustableꢀinputꢀundervoltage-lockoutꢀ
level. Set the voltage at which the device turns on with
Adjusting Output Voltage
Set the output voltage with a resistive voltage-divider
connected from the positive terminal of the output
a resistive voltage-divider connected from V ꢀ toꢀ SGND.ꢀ
capacitor (V
)ꢀtoꢀSGNDꢀ(seeꢀFigureꢀ2).ꢀConnectꢀtheꢀ
OUT
IN
Connect the center node of the divider to EN/UVLO.
center node of the divider to the FB pin. Use the following
procedure to choose the resistive voltage-divider values:
Calculateꢀ resistorꢀ R3ꢀ fromꢀ theꢀ outputꢀ toꢀ theꢀ FBꢀ pinꢀ asꢀ
follows:
ChooseꢀR1ꢀtoꢀbeꢀ3.3MIꢀandꢀthenꢀcalculateꢀR2ꢀasꢀfollows:
R1×1.215
R2 =
3
(V
-1.215)
216×10
INU
R3 =
f
× C
OUT
C
where V
is the voltage at which the device is required
INU
to turn on. Ensure that V
is higher than 0.8 x V
. If
OUT
whereꢀR3ꢀisꢀinꢀkΩ,ꢀcrossoverꢀfrequencyꢀf ꢀisꢀinꢀkHz,ꢀandꢀ
C
INU
the EN/UVLO pin is driven from an external signal source,
aꢀseriesꢀresistanceꢀofꢀminimumꢀ1kΩꢀisꢀrecommendedꢀtoꢀ
be placed between the signal source output and the EN/
UVLO pin, to reduce voltage ringing on the line.
the output capacitor C
is in µF. For the MAX17505,
OUT
choose f to be 1/9th of the switching frequency, f , if
C
SW
theꢀswitchingꢀfrequencyꢀisꢀlessꢀthanꢀorꢀequalꢀtoꢀ500kHz.ꢀ
Ifꢀtheꢀswitchingꢀfrequencyꢀisꢀmoreꢀthanꢀ500kHz,ꢀselectꢀf
C
toꢀbeꢀ55kHz.ꢀForꢀtheꢀMAX17505S,ꢀselectꢀf to be 1/10th
C
Loop Compensation
of f
if the switching frequency is less than or equal
SW
Theꢀ deviceꢀ isꢀ internallyꢀ loopꢀ compensated.ꢀ However,ꢀ ifꢀ
theꢀswitchingꢀfrequencyꢀisꢀlessꢀthanꢀ500kHz,ꢀconnectꢀaꢀ
0402 capacitor C6 between the CF pin and the FB pin.
Use Table 2 to select the value of C6.
toꢀ1MHz.ꢀIfꢀtheꢀswitchingꢀfrequencyꢀisꢀmoreꢀthanꢀ1MHz,ꢀ
select f ꢀtoꢀbeꢀ100kHz.
C
Table 2. C6 Capacitor Value at Various Switching Frequencies
SWITCHING FREQUENCY RANGE (kHz)
C6 (pF)
2.2
200 to 300
300 to 400
400 to 500
1.2
0.75
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Maxim Integrated │ 20
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
CalculateꢀresistorꢀR4ꢀfromꢀtheꢀFBꢀpinꢀtoꢀSGNDꢀasꢀfollows
Junctionꢀ temperatureꢀ greaterꢀ thanꢀ +125°Cꢀ degradesꢀ
operating lifetimes.
:
R3 × 0.9
R4 =
PCB Layout Guidelines
(V
- 0.9)
OUT
All connections carrying pulsed currents must be very
short and as wide as possible. The inductance of these
connections must be kept to an absolute minimum due to
the high di/dt of the currents. Since inductance of a current
carrying loop is proportional to the area enclosed by the
loop, if the loop area is made very small, inductance is
reduced. Additionally, small-current loop areas reduce
radiated EMI.
Power Dissipation
At a particular operating condition, the power losses that
lead to temperature rise of the part are estimated as
follows:
1
2
P
= (P
×( - 1)) - I
×R
OUT DCR
LOSS
OUT
η
A ceramic input filter capacitor should be placed close
P
= V
×I
OUT
OUT OUT
to the V pins of the IC. This eliminates as much trace
IN
where P
isꢀ theꢀ totalꢀ outputꢀ power,ꢀ ηꢀ isꢀ theꢀ efficiencyꢀ
OUT
inductance effects as possible and gives the IC a cleaner
ofꢀ theꢀ converter,ꢀ andꢀ R
is the DC resistances of the
DCR
voltage supply. A bypass capacitor for the V
pin also
CC
inductor. (See the Typical Operating Characteristics for more
information on efficiency at typical operating conditions.)
For a multilayer board, the thermal performance metrics
for the package are given below:
should be placed close to the pin to reduce effects of trace
impedance.
When routing the circuitry around the IC, the analog
small-signal ground and the power ground for switching
currents must be kept separate. They should be connected
together at a point where switching activity is at a
θ
= 33°C W
= 2°C W
JA
θ
minimum, typically the return terminal of the V
bypass
JC
CC
capacitor. This helps keep the analog ground quiet.
The ground plane should be kept continuous/unbroken
as far as possible. No trace carrying high switching
current should be placed directly over any ground plane
discontinuity.
Theꢀjunctionꢀtemperatureꢀofꢀtheꢀdeviceꢀcanꢀbeꢀestimatedꢀ
at any given maximum ambient temperature (T
from the equation below:
)
A_MAX
T
= T
+ θ ×P
A_MAX JA LOSS
(
)
J_MAX
PCB layout also affects the thermal performance of the
design. A number of thermal vias that connect to a large
ground plane should be provided under the exposed pad
of the part, for efficient heat dissipation.
If the application has a thermal management system that
ensures that the exposed pad of the device is maintained
at a given temperature (T
) by using proper heat
EP_MAX
sinks,ꢀthenꢀtheꢀjunctionꢀtemperatureꢀofꢀtheꢀdeviceꢀcanꢀbeꢀ
estimated at any given maximum ambient temperature
from the equation below:
For a sample layout that ensures first pass success,
refer to the MAX17505 evaluation kit layout available at
www.maximintegrated.com.
T
= T
+ θ ×P
(
)
J_MAX
EP_MAX JC LOSS
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Maxim Integrated │ 21
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Recommended Component Placement for MAX17505/MAX17505S
VOUT
PLANE
PGND PLANE
L1
LX PLANE
C1
C4
C5
LX PLANE
PGND PLANE
VIN PLANE
MAX17505/
MAX17505S
SGND
C2
R1
R2
MODE
R6
C3
C6
R3
R5
SGND PLANE
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Maxim Integrated │ 22
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
V
IN
(6.5V TO 60V)
C1
2.2µF
EN/UVLO
V
IN
V
IN
V
IN
RT
BST
LX
C5
0.1µF
L1
V
OUT
SYNC
10µH
5V, 1.7A
C4
22µF
MAX17505
LX
MODE
R3
178kΩ
LX
FB
V
CC
C2
2.2µF
R4
39kΩ
SGND
CF
RESET
SS
PGND PGND PGND
C3
5.6nF
f
= 500kHz
SW
L1 = 10µH (XAL6060-103ME)
C4 = 22µF (MURATA GRM32ER71A226K)
Figure 3. MAX17505 Typical Application Circuit (5V, 500kHz Switching Frequency)
V
IN
(4.5V TO 60V)
C1
2.2uF
V
IN
EN/UVLO
V
IN
V
IN
V
IN
RT
BST
LX
C5
0.1µF
L1
V
OUT
SYNC
6.8µH
3.3V, 1.7A
C4
47µF
LX
MODE
R3
127kΩ
MAX17505
LX
FB
V
CC
C2
2.2µF
R4
47.5kΩ
SGND
CF
RESET
SS
PGND PGND PGND
C3
5600pF
f
= 500kHz
SW
L1 = 6.8µH (XAL6060-682ME)
C4 = 47µF (MURATA GRM32ER71A476K)
Figure 4. MAX17505 Typical Application Circuit (3.3V, 500kHz Switching Frequency)
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Maxim Integrated │ 23
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
V
IN
C1
2.2µF
R5
EN/UVLO
V
V
IN
IN
V
IN
RT
BST
C5
19.1KΩ
L1
4.7µH
V
OUT
0.1µF
5V,1.7A
SYNC
MODE
LX
LX
C4
10µF
MAX17505S
R3
196KΩ
LX
FB
V
CC
C2
2.2µF
R4
43.2KΩ
SGND
CF
RESET
PGND
SS
PGND
PGND
C3
5.6nF
f
= 1MHz
SW
L1 = 4.7µH (XAL4030, 4mm x 4mm)
C4 = 10µH (MURATA GRM32DR71A106KA01)
Figure 5. MAX17505S Typical Application Circuit (5V Output, 1MHz Switching Frequency)
V
IN
C1
2.2µF
R5
EN/UVLO
V
V
IN
IN
V
IN
RT
BST
C5
19.1KΩ
L1
3.3µH
V
OUT
0.1µF
3.3V,1.7A
SYNC
MODE
LX
LX
C4
22µF
MAX17505S
R3
115KΩ
LX
FB
V
CC
C2
2.2µF
R4
43.2KΩ
SGND
CF
RESET
PGND
SS
PGND
PGND
C3
5.6nF
f
=
1MHz
L1 = 3.3µH (XAL4030, 4mm x 4mm)
C4 = 22µH (MURATA GRM32ER71A226KE20)
SW
Figure 6. MAX17505S Typical Application Circuit (3.3V Output, 1MHz Switching Frequency)
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Maxim Integrated │ 24
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Ordering Information
PART
PIN-PACKAGE
MAX17505ATP+
20 TQFN (4mm x 4mm)
MAX17505SATP+
20 TQFN-EP* (4mm x 4mm)
Note: Device operates over the -40ºC to +125ºC temperature
range, unless otherwise noted.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Chip Information
PROCESS:ꢀBiCMOS
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Maxim Integrated │ 25
MAX17505
4.5V-60V, 1.7A, High-Efficiency,
Synchronous Step-Down DC-DC Converter
With Internal Compensation
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
1
1/14
Initial release
—
10/16
Added MAX17505S to data sheet
1–17
Updated part number in title and TOCs 8a, 12, 12a, 13, 13a, 14a, 15a, 16a, 17a, 18,
18a, 19a, 20a, 21a, 22, 22a, 23, 23a, 24a, 25a, 26a, 27a, 29a, 31, and 31a
2
5/17
1–27
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim
reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Character-
istics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
©
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
2017 Maxim Integrated Products, Inc.
│ 26
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