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MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
General Description
The Himalaya series of voltage regulator ICs. power
modules, and chargers enable cooler, smaller and simpler
power supply solutions. The MAXM17503 is an easy-touse, Himalaya step-down power module that combines
a switching power supply controller, dual n-channel
MOSFET power switches, fully shielded inductor, and the
compensation components in a low-profile, thermally-efficient, system-in-package (SiP). The device operates over
a wide input voltage range of 4.5V to 60V and delivers up to
2.5A continuous output current with excellent line and load
regulation over an output voltage range of 0.9V to 12V.
The device only requires five external components to complete the total power solution. The high level of integration
significantly reduces design complexity, manufacturing
risks, and offers a true plug-and-play power supply solution,
reducing time-to-market.
The device can be operated in the pulse-width modulation
(PWM), pulse-frequency modulation (PFM), or discontinuous
conduction mode (DCM) control schemes.
The MAXM17503 is available in a low-profile, highly
thermal-emissive, compact, 29-pin 9mm x 15mm x
2.8mm SiP package that reduces power dissipation in
the package and enhances efficiency. The package is
easily soldered onto a printed circuit board and suitable
for automated circuit board assembly. The device can
operate over wide industrial temperature range from
-40°C to +125°C.
Benefits and Features
●● Reduces Design Complexity, Manufacturing Risks,
and Time-to-Market
• Integrated Switching Power Supply Controller and
Dual-MOSFET Power Switches
• Integrated Inductor
• Integrated Compensation Components
●● Saves Board Space in Space-Constrained Applications
• Complete Integrated Step-Down Power Supply in a
Single Package
• Small Profile 9mm x 15mm x 2.8mm SiP Package
• Simplified PCB Design with Minimal External BOM
Components
●● Offers Flexibility for Power-Design Optimization
• Wide Input Voltage Range from 4.5V to 60V
• Output-Voltage Adjustable Range from 0.9V to 12V
• Adjustable Frequency with External Frequency
Synchronization (100kHz to 1.8MHz)
• Soft-Start Programmable
• Autoswitch PWM, PFM, or DCM Current-Mode Control
• Optional Programmable EN/UVLO
●● Operates Reliably in Adverse Industrial Environments
• Integrated Thermal Fault Protection
• Hiccup Mode Overload Protection
• RESET Output-Voltage Monitoring
• Wide Industrial Ambient Operating Temperature
Range (-40°C to +125°C)/ Junction Temperature
Range (-40°C to +150°C)
• Complies with CISPR22(EN55022) Class B
Conducted and Radiated Emissions
Typical Application Circuit
Applications
●●
●●
●●
●●
●●
Industrial Power Supplies
Distributed Supply Regulation
FPGA and DSP Point-of-Load Regulator
Base Station Point-of-Load Regulator
HVAC and Building Control
EN
4.5V TO 60V
SYNC
MODE
IN
VIN
CIN
RT
RT
OUT
VCC
OUT
OUT
OPTIONAL
VCC
OUT
MAXM17503
RESET
OUT
Ordering Information appears at end of data sheet.
VOUT
OUT
OUT
SS
COUT
RU
EP3
CSS
FB
CF
EP1
19-7451; Rev 3; 5/20
SGND
PGND
PGND
RB
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Absolute Maximum Ratings (Notes 1, 2)
IN to PGND (Note 2)..............................................-0.3V to +65V
EN to SGND (Note 2).............................................-0.3V to +65V
VCC..............................................-0.3V to min (VIN + 0.3V, 6.5V)
FB, RESET, SS, CF, MODE,
SYNC, RT to SGND..........................................-0.3V to +6.5V
OUT to PGND (VIN < 25V)..........................-0.3V to (VIN + 0.3V)
OUT to PGND (VIN ≥ 25V).....................................-0.3V to +25V
LX to PGND................................................-0.3V to (VIN + 0.3V)
BST to PGND.........................................................-0.3V to +70V
BST to VCC............................................................-0.3V to +65V
BST to LX..............................................................-0.3V to +6.5V
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+125°C
Storage Temperature Range............................. -65°C to +125°C
Lead Temperature (soldering, 10s).................................. +245°C
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
29 SiP
Package Code
L32915+1
Outline Number
21-0879
Land Pattern Number
90-0459
THERMAL RESISTANCE (Note 3)
Junction to Ambient (θJA)
30.8°C/W
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”,
“#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
Note 1: SGND and PGND are internally connected.
Note 2: See the Pin Description for the connection of the backside exposed pad.
Note 3: Data taken using Maxim's evaluation kit, MAXM17503EVKIT#.
Electrical Characteristics
(VIN = VEN = 24V, RRT = 40.2kΩ (500kHz) to SGND, VPGND = VMODE = VSYNC = VSGND = 0V, VCC = LX = SS = RESET = OUT = open,
VBST to VLX = 5V, VFB = 1V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
60
V
13
μA
INPUT SUPPLY (VIN)
IN Input Voltage Range
VIN
Input Shutdown Current
IIN_SH
VEN = 0V
10.5
MODE = RT = open
125
IQ_DCM
MODE = VCC
1.16
IQ_PWM
Normal switching mode, no load
9.5
IQ_PFM_HIB
Input Quiescent Current
www.maximintegrated.com
4.5
μA
1.8
mA
mA
Maxim Integrated │ 2
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Electrical Characteristics (continued)
(VIN = VEN = 24V, RRT = 40.2kΩ (500kHz) to SGND, VPGND = VMODE = VSYNC = VSGND = 0V, VCC = LX = SS = RESET = OUT = open,
VBST to VLX = 5V, VFB = 1V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS
EN Threshold
Enable Pullup Resistor
VENR
VEN rising
1.192
1.215
1.26
VENF
VEN falling
1.068
1.09
1.131
RENP
Pullup resistor between IN and EN pins
3.15
3.3
3.45
MΩ
VCC
6V < VIN < 60V, 1mA < IVCC < 25mA
4.75
5
5.25
V
VIN = 6V, VCC = 4.3V
26.5
60
100
mA
VCC_DO
VIN = 4.5V, IVCC = 20mA
4.2
VCC_UVR
VCC rising
4.05
4.2
4.3
VCC_UVF
VCC falling
3.65
3.8
3.9
V
LDO
VCC Output Voltage Range
VCC Current Limit
VCC Dropout
VCC UVLO
IVCC_MAX
V
V
OUTPUT SPECIFICATIONS
Line Regulation Accuracy
VIN = 6.5V to 60V, VOUT = 5V
0.1
mV/V
Load Regulation Accuracy
Tested with IOUT = 0A and 1A
1
mV/A
FB Regulation Voltage
VFB_REG
FB Input Bias Current
IFB
FB Undervoltage Trip Level to
Cause Hiccup
MODE = SGND
0.887
MODE = open
0.890
0V < VFB < 1V, TA = +25°C
VFB_HICF
0.910
0.915
-50
0.56
Hiccup Timeout
0.58
0.936
V
+50
nA
0.65
V
32,768
Cycles
SOFT-START (SS)
Charging Current
ISS
VSS = 0.5V
4.7
5
5.3
RRT = 210kΩ
90
100
110
μA
RT AND SYNC
Switching Frequency
fSW
RRT = 9.76kΩ
RRT = open
SYNC Pulse Width
www.maximintegrated.com
450
1.1x
fSW
SYNC Frequency Range
SYNC Threshold
1800
500
kHz
550
1.4x
fSW
50
VIH
VIL
kHz
ns
2.1
0.8
V
Maxim Integrated │ 3
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Electrical Characteristics (continued)
(VIN = VEN = 24V, RRT = 40.2kΩ (500kHz) to SGND, VPGND = VMODE = VSYNC = VSGND = 0V, VCC = LX = SS = RESET = OUT = open,
VBST to VLX = 5V, VFB = 1V, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C. All voltages are
referenced to SGND, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MODE
MODE Threshold
VM_DCM
MODE = VCC (DCM mode)
VM_PFM
MODE = open (PFM mode)
VM_PWM
MODE = GND (PWM mode)
VCC - 1.6
V
VCC/2
1.4
CURRENT LIMIT
Average Current-Limit Threshold
RESET
IAVG_LIMIT VOUT = VFB = 0.8V, fSW = 200kHz
3.45
RESET Output Level Low
IRESET = 10mA
RESET Output Leakage Current
VRESET = 5.5V, TA = TJ = +25°C
-0.1
A
0.4
V
+0.1
µA
FB Threshold for RESET
Assertion
VFB_OKF
VFB falling
90.5
92
94.6
%
FB Threshold for RESET
Deassertion
VFB_OKR
VFB rising
93.8
95
97.8
%
RESET Deassertion Delay After
FB Reaches 95% Regulation
1024
Cycles
+165
°C
10
°C
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
Temperature rising
Note 4: All limits are 100% tested at TA = +25°C. Maximum and minimum limits are guaranteed by design and characterized over
temperature.
www.maximintegrated.com
Maxim Integrated │ 4
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 12V, PFM MODE
toc01
100
VIN = 36V,
70
500
1000
2000
VIN = 36V,
2500
0
500
1000
80
70
60
1500
2000
40
2500
fSW = 740kHz
VIN = 24V,
VIN = 48V,
fSW = 740kHz
fSW = 500kHz
MODE = OPEN
0
500
1000
1500
2000
2500
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V, PWM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PFM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PWM MODE
toc05
100
90
80
80
80
VIN = 36V,
VIN = 12V,
fSW = 740kHz fSW = 740kHz
60
VIN = 24V,
VIN = 48V,
fSW = 740kHz
50
fSW = 500kHz
500
1000
1500
2000
60
40
2500
OUTPUT CURRENT (mA)
VIN = 48V,
VIN = 12V,
fSW = 500kHz
0
500
1000
fSW = 366kHz
VIN = 36V,
1500
2000
EFFICIENCY (%)
VIN = 24V,
VIN = 48V,
VIN = 5V,
fSW = 400kHz fSW = 400kHz fSW = 277kHz
MODE = OPEN
0
500
1000
1500
2000
OUTPUT CURRENT (mA)
www.maximintegrated.com
500
2500
1000
1500
2000
2500
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 2.5V, PWM MODE
toc08
100
80
40
0
OUTPUT CURRENT (mA)
80
VIN = 36V,
VIN = 12V,
fSW = 400kHz fSW = 400kHz
VIN = 48V,
fSW = 366kHz
VIN = 36V,
VIN = 12V,
fSW = 500kHz fSW = 500kHz
MODE = SGND
OUTPUT CURRENT (mA)
90
50
60
40
2500
90
60
VIN = 24V,
fSW = 500kHz
MODE = OPEN
toc07
70
70
50
fSW = 500kHz
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 2.5V, PFM MODE
100
EFFICIENCY (%)
VIN = 24V,
fSW = 500kHz
50
MODE = SGND
0
70
EFFICIENCY (%)
90
70
toc06
100
90
40
VIN = 36V,
VIN = 12V,
fSW = 740kHz
50
MODE = SGND
40
toc04
100
fSW = 1.33MHz
fSW = 1.8MHz
50
1500
VIN = 48V,
fSW = 1.8MHz
60
MODE = OPEN
0
VIN = 24V,
EFFICIENCY (%)
fSW = 1.33MHz
fSW = 1.8MHz
50
EFFICIENCY (%)
VIN = 48V,
fSW = 1.8MHz
60
EFFICIENCY (%)
70
80
EFFICIENCY (%)
EFFICIENCY (%)
VIN = 24V,
toc03
90
90
80
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V, PFM MODE
100
toc02
100
90
40
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 12V, PWM MODE
70
VIN = 12V,
fSW = 400kHz
60
50
40
VIN = 5V,
fSW = 400kHz
0
500
VIN = 36V,
fSW = 400kHz
VIN = 48V,
VIN = 24V,
fSW = 400kHz fSW = 277kHz
1000
MODE = SGND
1500
2000
2500
OUTPUT CURRENT (mA)
Maxim Integrated │ 5
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
toc09
VIN = 5V,
fSW = 350kHz
VIN = 24V,
80
70
60
40
VIN = 36V,
VIN = 12V,
50
fSW = 200kHz
fSW = 350kHz
0
500
1000
1500
2000
70
VIN = 24V,
fSW = 285kHz
40
2500
MODE = SGND
0
500
toc12
100
3.6
3.5
70
VIN = 12V,
fSW = 300kHz
60
VIN = 5V,
fSW = 300kHz
50
40
0
500
MODE=SGND
1000
1500
2000
3
2500
LOAD REGULATION
VOUT = 5V, PFM MODE
5.4
VIN = 12V,
fSW = 500kHz
VIN = 36V
1000
fSW = 500kHz fSW = 366kHz
500
1000
1500
2000
VIN = 5.0V
3.4
3.3
2000
3
2500
2500
toc14
VIN = 12V
fSW = 500kHz
VIN = 36V
fSW = 500kHz
VIN = 24V
fSW = 500kHz
3.1
MODE = OPEN
0
500
VIN = 48V
fSW = 366kHz
MODE=SGN
D
1500
2000
2500
1000
OUTPUT CURRENT (mA)
LOAD REGULATION
VOUT = 5V, PWM MODE
5.5
VIN = 12V,
5.3
4.9
1500
fSW = 500kHz
3.2
VIN = 48V
VOUT (V)
VOUT (V)
3.5
VIN = 12V
5.4
5
MODE = OPEN
500
3.6
fSW = 500kHz
toc15
5.1
VIN = 36V,
fSW = 740kHz
5.2
toc16
fSW = 740kHz
5.1
5
4.9
4.8
VIN = 48V,
4.7
fSW = 500kHz
4.6
4.5
toc13
fSW = 740kHz
5.2
0
LOAD REGULATION
VOUT = 3.3V, PWM MODE
VIN = 36V,
fSW = 740kHz
5.3
fSW = 214kHz
LOAD REGULATION
VOUT = 3.3V, PFM MODE
VIN = 24V
0
VIN = 24V,
VIN = 5V,
fSW = 300kHz
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
5.5
40
2500
3.3
3.1
VIN = 12V,
fSW = 300kHz
60
OUTPUT CURRENT (mA)
VIN = 5.0V
3.4
2000
70
OUTPUT CURRENT (mA)
fSW = 500kHz
3.2
VIN = 24V,
fSW = 214kHz
1500
VOUT (V)
80
VOUT (V)
EFFICIENCY (%)
90
1000
80
50
fSW = 200kHz
fSW = 350kHz
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 0.9V, PWM MODE
VIN = 36V,
VIN = 12V,
50
MODE = OPEN
90
80
60
toc11
100
VIN = 5V,
fSW = 350kHz
90
fSW = 285kHz
EFFICIENCY (%)
EFFICIENCY (%)
90
toc10
100
EFFICIENCY (%)
100
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 0.9V, PFM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 1.2V, PWM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 1.2V, PFM MODE
0
500
4.8
VIN = 24V,
MODE = OPEN
1000
1500
2000
OUTPUT CURRENT (mA)
www.maximintegrated.com
VIN = 24V,
4.7
fSW = 740kHz
2500
fSW = 740kHz
4.6
4.5
VIN = 48V,
fSW = 500kHz
MODE = SGND
0
500
1000
1500
2000
2500
OUTPUT CURRENT (mA)
Maxim Integrated │ 6
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
LOAD REGULATION
VOUT = 12V, PFM MODE
13
toc17
VOUT (V)
12.2
12
11.8
fSW = 1.33MHz
11.4
VIN = 36V,
12.20
12.00
0
500
1000
1500
2000
2500
0
500
1000
1500
2000
2µs/div
INPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 5V, IOUT = 2.5A,
MODE = SGND
toc22
INPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 3.3V, IOUT = 2.5A,
MODE = SGND
toc21
toc20
100mV/div
(ACCOUPLED)
VIN
2µs/div
200mV/div
(ACCOUPLED)
VIN
2µs/div
2µs/div
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A - 1.25A,
toc23
MODE = OPEN
IOUT
1A/div
VOUT
200mV/div
(AC
COUPLED)
200µs/div
www.maximintegrated.com
2500
OUTPUT CURRENT (mA)
20mV/div
(ACCOUPLED)
VOUT
VIN = 36V,
MODE = SGND
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 5V, IOUT = 2.5A,
MODE = SGND
fSW = 1.33MHz
fSW = 1.8MHz
11.20
11.00
VIN = 48V,
VIN = 24V,
fSW = 1.8MHz
11.40
MODE = OPEN
20mV/div
(ACCOUPLED)
VOUT
11.60
fSW = 1.8MHz
11.2
11
toc19
12.40
11.80
VIN = 48V,
toc18
12.60
12.4
11.6
OUTPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 3.3V, IOUT = 2.5A,
MODE = SGND
12.80
fSW = 1.8MHz
12.6
VOUT (V)
13.00
VIN = 24V,
12.8
LOAD REGULATION
VOUT = 12V, PWM MODE
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A - 1.25A,
MODE = SGND
toc24
IOUT
1A/div
200mV/div
(AC
COUPLED)
VOUT
100µs/div
Maxim Integrated │ 7
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0.05A - 1.25A,
MODE = VCC
toc25
1A/div
IOUT
200mV/div
(AC
COUPLED)
VOUT
1A/div
IOUT
200mV/div
(AC
COUPLED)
VOUT
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0.05A - 1.25A,
MODE = VCC
toc28
STARTUP THROUGH ENABLE
VIN = 24V, VOUT = 3.3V, IOUT = 0A,
MODE = SGND
STARTUP WITH 2.5V PREBIAS
VIN = 24V, VOUT = 3.3V, IOUT = 0A,
MODE = SGND
toc30
toc29
5V/div
20V/div
LX
1A/div
2V/div
200mV/div
(AC
COUPLED)
VOUT
LX
toc31
5V/div
EN
20V/div
LX
5V/div
RESET
5V/div
1ms/div
SHUTDOWN THROUGH ENABLE
VIN = 24V, VOUT = 3.3V, IOUT = 0A,
MODE = SGND
2V/div
VOUT
2V/div
VOUT
1ms/div
EN
20V/div
LX
RESET
100µs/div
STARTUP WITH 2.5V PREBIAS
VIN = 24V, VOUT = 3.3V, IOUT = 0A,
MODE = OPEN
5V/div
EN
5V/div
RESET
toc32
5V/div
20V/div
2V/div
VOUT
RESET
5V/div
1ms/div
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200mV/div
(AC
COUPLED)
VOUT
100µs/div
EN
VOUT
1A/div
IOUT
200µs/div
100µs/div
IOUT
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0.05A - 1.25A,
toc27
MODE = SGND
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0.05A - 1.25A,
toc26
MODE = OPEN
1ms/div
Maxim Integrated │ 8
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
STARTUP THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 3.3V, IOUT = 2.5A,
MODE = SGND
toc33
SHUTDOWN THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 3.3V, IOUT = 2.5A,
toc34
MODE = SGND
10V/div
VIN
20V/div
LX
VIN
20V/div
LX
20V/div
2V/div
VOUT
5V/div
2V/div
VOUT
5V/div
RESET
RESET
100µs/div
1ms/div
SHUTDOWN THROUGH ENABLE
VIN = 24V, VOUT = 5V, IOUT = 0A, MODE = SGND
STARTUP THROUGH ENABLE
VIN = 24V, VOUT = 5V, IOUT = 0A, MODE = SGND
toc36
toc35
5V/div
EN
20V/div
LX
5V/div
EN
20V/div
LX
2V/div
2V/div
VOUT
5V/div
RESET
VOUT
1ms/div
1ms/div
STARTUP THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 5V, IOUT = 2.5A,
MODE = SGND
toc37
SHUTDOWN THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 5V, IOUT = 2.5A,
toc38
MODE = SGND
10V/div
10V/div
VIN
20V/div
LX
20V/div
VOUT
2V/div
VIN
LX
2V/div
VOUT
5V/div
RESET
5V/div
RESET
5V/div
RESET
1ms/div
www.maximintegrated.com
100µs/div
Maxim Integrated │ 9
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 60V, VOUT = 0.9 to 12V, IOUT = 0A–2.5A, TA = +25°C, unless otherwise noted.)
OUTPUT SHORT IN STEADY STATE
VIN = 24V, VOUT = 3.3V, IOUT = 0A to SHORT
toc39
MODE = SGND
OUTPUT SHORT DURING STARTUP
VIN = 24V, VOUT = 3.3V, IOUT = SHORT,
MODE = SGND
toc40
20V/div
VIN
20V/div
VIN
LX
2V/div
VOUT
IOUT
20V/div
LX
20V/div
10A/div
VOUT
2V/div
IOUT
10A/div
40ms/div
SYNC FREQUENCY AT 740KHZ
VIN = 24V, VOUT = 5V, IOUT = 0A, MODE = GND
toc41
50.00
CLOSED-LOOP BODE PLOT
VIN = 24V, VOUT = 3.3V, IOUT = 2.5A,
MODE = SGND
40.00
SYNC
GAIN (dB)
LX
20V/div
2V/div
90
20.00
60
10.00
30
0.00
0
GAIN
-10.00
VOUT
-30
-20.00
-60
-30.00
-50.00
-90
CROSSOVER FREQUENCY = 54.9kHz
PHASE MARGIN = 53.3◦
-40.00
2µs/div
150
120
PHASE
30.00
5V/div
toc42
1k
10k
100k
PHASE MARGIN (°)
40ms/div
-120
-150
1Meg
FREQUENCY (Hz)
2
1.5
VOUT = 5V
1
0.5
0
VOUT = 12V
70.0
CISPR-22 CLASS B QP LIMIT
60
50
40
30
PEAK EMISSION
20
10
AMBIENT TEMPERATURE (°C)
0.15
10
1
FREQUENCY (MHz)
CONDITION : VIN = 24V, VOUT = 5V, IOUT = 2.5A
FROM MAXM17503EVKITAE#
Final_ScanH
Limit
toc45
50.0
50
40.0
40
CISPR-22 CLASS B QP LIMIT
30
30.0
20.0
20
30
VERTICAL
SCAN
10
10.0
00
AVG EMISSION
0 10 20 30 40 50 60 70 80 90 100110120
Final_ScanV
60.0
60
CISPR-22 CLASS B AVG LIMIT
MAGNITUDE(dBµV/m)
2.5
toc44
70
VOUT = 3.3V
RE 30MHz-1GHz C4=C14=OPEN, L1=SHORT
C7=220pF, C17=C18=150pF
Am p litu d e (d Bu V /m )
OUTOPUT CURRENT (A)
3
CONDUCTED EMISSION PLOT
WITH FILTER:C4=2.2uF, L1=10uH, C14=2.2uF
MAGNITUDE(dBµV)
3.5
OUTPUT CURRENT
vs. AMBIENT TEMPERATURE
VIN = 24V NO AIR FLOW toc43
TUV Rheinland
RADIATED EMISSION PLOT
MaximIC_MAXM17503
HORIZONTAL
SCAN
-10.0 30
30.0M
1000
100
100.0M
1.0G
FREQUENCY (MHz)
Frequency (Hz)
CONDITION : VIN = 24V, VOUT = 5V, IOUT = 2.5A
RE 30MHz-1GHz_0-360 deg_90deg
Height_Quick scan_PI65_Test8.TIL
FROMstep_1-4mtr
MAXM17503EVKITAE#
12:04:29 AM, Tuesday, April 17, 2018
www.maximintegrated.com
Maxim Integrated │ 10
2 column (6.96 in.)
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Pin Configuration
N.C.
SYNC
RESET
EN
29
28
1
IN
PGND
27
26
BST
25
LX
LX
LX
24
23
22
2
21
LX
20
LX
EP2
SS
3
CF
4
FB
5
19
LX
EP1
18
OUT
17
OUT
16
OUT
EP3
RT
6
N.C.
7
11
8
MODE
www.maximintegrated.com
9
VCC
10
SGND
PGND
12
13
14
15
OUT
OUT
OUT
OUT
Maxim Integrated │ 11
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Pin Description
PIN
NAME
1, 7
N.C.
FUNCTION
2
SYNC
3
SS
Soft-Start Input. Connect a capacitor from SS to SGND to set the soft-start.
4
CF
Compensation Filter. Connect capacitor from CF to FB to correct frequency response with
switching frequency below 500kHz. Leave CF open otherwise.
5
FB
Feedback Input. Connect FB to the center tap of an external resistor-divider from the OUT to
SGND to set the output voltage. See the Setting the Output Voltage section for more details.
6
RT
Frequency Set. Connect a resistor from RT to SGND to set the regulator’s switching frequency.
Leave RT open for the default 500kHz frequency.
No Connection
Frequency Synchronization. The device can be synchronized to an external clock using this pin.
See the External Frequency Synchronization section for more details.
Light-Load Mode Selection. The MODE pin configures the MAXM17503 to operate in PWM, PFM,
or DCM mode of operation. Leave MODE unconnected for PFM operation (pulse skipping at light
loads). Connect MODE to SGND for constant-frequency PWM operation at all loads. Connect
MODE to VCC for DCM operation. See the MODE Selection (MODE) section for more details.
8
MODE
9
VCC
10
SGND
Analog Ground. Internally-shorted to PGND. Connect it to PGND through a single point at output
capacitor.
11, 26
PGND
Power Ground. Connect the PGND pins externally to the power ground plane.
12–18
OUT
19–24
LX
25
BST
27
IN
Input Supply Connection. Bypass to PGND with a capacitor; place the capacitor close to the IN
and PGND pins. See Table 1 for more details
28
EN
Enable/Undervoltage-Lockout Input. Default enable through the pullup 3.3MΩ resistor between
EN and IN. Connect a resistor from EN to SGND to set the UVLO threshold. If the EN/UVLO pin
is driven by an external signal, a 50Ω damping resistor in series with the signal line driving EN/
UVLO is required.
29
RESET
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.
EP1
SGND
Analog Ground. Connect this pad to 1in x 1in copper island with a lot of vias for cooling.
EP2
LX
EP3
OUT
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5V LDO Output. No external connection.
Regulator Output Pin. Connect a capacitor from OUT to PGND. See PCB Layout Guidelines
section for more connection details.
Internally Connected to EP2. Please do not connect these pins to external components for any
reason.
Boost Flying Cap Node. No external connection.
Switching Node. Connect this pad to a small copper area of 1in x 1in under the device for thermal
relief.
Connect this pad to the OUT pins and copper area of 1in x 1in.
Maxim Integrated │ 12
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Functional Diagram
MAXM17503
5V
VCC
IN
LDO
0.47µF
2.2µF
SGND
BST
3.3MΩ
VIN
0.1µF
LX
EN
1.215V
HICCUP
RT
OSCILLATOR
PEAK
CURRENT-MODE
CONTROLLER
6.8µH
OUT
4.7µF
SYNC
PGND
CF
MODE
SELECTION
LOGIC
MODE
FB
RESET
SS
www.maximintegrated.com
FB
RESET
LOGIC
Maxim Integrated │ 13
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Design Procedure
where,
VOUT = Steady-state output voltage
Setting the Output Voltage
The MAXM17503 supports an adjustable output voltage range of 0.9V to 12V from an input voltage range of
4.5V to 60V by using a resistive feedback divider from
OUT to FB. Table 1 provides the feedback dividers for
desired input and output voltages. Other adjustable output
voltages can be calculated by following the procedure to
choose the resistive voltage-divider values:
IOUT(MAX) = Maximum load current
Calculate resistor RU from the output to FB as follows:
Input Capacitor Selection
RU =
216 × 1000
f C × C OUT
Where RU is in kΩ, crossover frequency (fC) is in kHz,
and output capacitor (COUT) is in μF. Choose fC to be
1/9th of the switching frequency (fSW) if the switching
frequency is less than or equal to 500kHz. If the switching
frequency is more than 500kHz, select fC to be 55kHz.
R × 0.9
RB = U
kΩ, where R B is in kΩ.
VOUT − 0.9
fSW = Selected operating switching frequency in Hz
tOFF_MIN(MAX) = Worst-case minimum switch off-time
(160ns)
tON_MIN(MAX) = Worst-case minimum switch on-time
(80ns)
The input capacitor serves to reduce the current peaks
drawn from the input power supply and reduces switching
noise to the IC. The input capacitor values in Table 1 are
the minimum recommended values for desired input and
output voltages. Applying capacitor values larger than
those indicated in Table 1 are acceptable to improve the
dynamic response. For further operating conditions, the
total input capacitance must be greater than or equal to
the value given by the following equation in order to keep
the input-voltage ripple within specifications and minimize
the high-frequency ripple current being fed back to the
input source:
Input Voltage Range
CIN =
The minimum and maximum operating input voltages for
a given output voltage should be calculated as follows:
VIN(MIN) =
(
)
VOUT + I OUT(MAX) × 0.22
(
1 − 1.12 × f SW × t OFF_MIN(MAX)
(
)
VIN(MAX) =
)
f SW
53900
VOUT
1.12 × f SW × t ON_MIN(MAX)
∆VIN × fSW
where IIN_AVG is the average input current given by:
+ I OUT(MAX) × 0.175
For D > 0.4, VIN(MIN) =4.26 × VOUT −
IIN_AVG × (1 − D)
IIN_AVG =
POUT
η × VIN
D = Operating duty cycle, which is approximately equal
to VOUT/VIN.
∆VIN = Required input voltage ripple.
fSW = Operating switching frequency.
POUT = Out power, which is equal to VOUT x IOUT.
η = Efficiency.
OUT
VOUT
RU
MAXM17503
FB
RB
Figure 1. Adjustable Output Voltage
www.maximintegrated.com
The input capacitor must meet the ripple-current requirement imposed by the switching currents. The RMS input
ripple current is given by:
IRMS
= I OUT × D × (1 − D)
The worst-case RMS current requirement occurs when
operating with D = 0.5. At this point, the above equation
simplifies to IRMS = 0.5 x IOUT.
For the MAXM17503 system (IN) supply, ceramic
capacitors are preferred due to their resilience to inrush
Maxim Integrated │ 14
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Table 1. Selection Component Values
VIN (V)
VOUT (V)
CIN
COUT
RU (kΩ)
RB (kΩ)
fSW (kHz)
RT (kΩ)
4.5 to 15
0.9
3 x 2.2µF 1206 100V
2 x 100µF 1210 4V
35.7
OPEN
300
68.1
4.5 to 15
1
3 x 2.2µF 1206 100V
2 x 100 µF 1210 4V
35.7
324
300
68.1
4.5 to 15
1.2
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47µF 1210 4V
41.2
124
350
57.6
4.5 to 15
1.5
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47µF 1210 4V
57.6
86.6
350
57.6
4.5 to 15
1.8
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
61.9
61.9
350
57.6
4.5 to 15
2.5
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
53.6
30.1
400
49.9
4.8 to 15
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
OPEN
7.5 to 15
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
12 to 15
8
2 x 2.2µF 1206 100V
1 x 10µF 1210 16V
309
39.2
1200
15.8
4.5 to 28
0.9
3 x 2.2µF 1206 100V
3 x 100µF 1210 4V
35.7
OPEN
214
95.3
4.5 to 28
1
3 x 2.2µF 1206 100V
3 x 100µF 1210 4V
35.7
324
238
86.6
4.5 to 28
1.2
3 x 2.2µF 1206 100V
2 x 100µF 1210 4V
41.2
124
285
71.5
4.5 to 28
1.5
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47µF 1210 4V
57.6
86.6
350
57.6
4.5 to 28
1.8
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
61.9
61.9
350
57.6
4.5 to 28
2.5
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
53.6
30.1
400
49.9
4.8 to 28
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
OPEN
7.5 to 28
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
12 to 28
8
2 x 2.2µF 1206 100V
1 x 10µF 1210 16V
309
39.2
1200
15.8
18.5 to 28
12
2 x 2.2µF 1206 100V
1 x 4.7µF 1210 16V
464
37.4
1800
10.0
4.5 to 40
1.2
3 x 2.2µF 1206 100V
2 x 100µF 1 x 47µF 1210 4V
41.2
124
200
100.00
4.5 to 40
1.5
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47µF 1210 4V
57.6
86.6
250
82.5
4.5 to 40
1.8
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47µF 1210 4V
61.9
61.9
300
68.1
4.5 to 40
2.5
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
53.6
30.1
400
49.90
4.8 to 40
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
OPEN
7.5 to 40
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
12 to 40
8
2 x 2.2µF 1206 100V
1 x 10µF 1210 16V
309
39.2
1200
15.8
18.5 to 40
12
2 x 2.2µF 1206 100V
1 x 4.7µF 1210 16V
464
37.4
1800
10.00
4.5 to 60
1.8
3 x 2.2µF 1206 100V
2 x 100µF 1210 4V
61.9
61.9
200
100.0
5.5 to 60
2.5
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
97.6
54.9
277
73.2
7.5 to 60
3.3
3 x 2.2µF 1206 100V
2 x 47µF 1210 10V
59
22.1
366
54.9
12 to 60
5
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
137
30.1
500
OPEN
18 to 60
8
2 x 2.2µF 1206 100V
1 x 10µF 1210 16V
309
39.2
888
21.5
26.5 to 60
12
2 x 2.2µF 1206 100V
1 x 4.7µF 1210 16V
464
37.4
1333
14.0
www.maximintegrated.com
Maxim Integrated │ 15
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
surge currents typical of systems, and due to their low
parasitic inductance that helps reduce the high-frequency
ringing on the IN supply when the internal MOSFETs are
turned off. Choose an input capacitor that exhibits less
than +10°C temperature rise at the RMS input current for
optimal circuit longevity.
Output Capacitor Selection
The X7R ceramic output capacitors are preferred due to
their stability over temperature in industrial applications.
The minimum recommended output capacitor values
in Table 1 are for desired output voltages to support
a dynamic step load of 50% of the maximum output
current in the application. For additional adjustable output
voltages, the output capacitance value is derived from the
following equation:
I
×t
C OUT = STEP RESPONSE
2 × ∆VOUT
t RESPONSE ≈
0.33
fC
+
1
f SW
where ISTEP is the step load transient, tRESPONSE is the
response time of the controller, ∆VOUT is the allowable
output ripple voltage during load transient, fC is the target
closed-loop crossover frequency, and fSW is the switching
frequency. Select fC to be 1/9th of fSW or 55kHz if the fSW
greater than 500kHz.
Loop Compensation
The MAXM17503 integrates the internal compensation
to stabilize the control loop. Only the device requires a
combination of output capacitors and feedback resistors
to program the closed-loop crossover frequency (fC)
at 1/9th of switching frequency. Use Table 1 to select
component values to compensate with appropriate operating
switching frequency. Connect a 0402 ceramic capacitor
from CF to FB to correct frequency response with switching
frequency below 500kHz. Place a 2.2pF capacitor for
switching frequency below 300kHz, 1.2pF for 300kHz to
500kHz switching frequency range.
www.maximintegrated.com
Setting the Switching Frequency (RT)
The switching frequency range of 100kHz to 1.8MHz are
recommended from Table 1 for desired input and output
voltages. The switching frequency of MAXM17503 can be
programmed by using a single resistor (RRT) connected
from the RT pin to SGND. The calculation of RRT resistor
is given by the following equation:
R RT ≈
21000
− 1.7
f SW
where RRT is in kΩ and fSW is in kHz. Leaving the RT
pin open to operate at the default switching frequency of
500kHz.
Soft-Start Capacitor Selection
The device implements an adjustable soft-start operation to reduce inrush current during startup. A capacitor
(CSS) connected from the SS pin to SGND to program the
soft-start time. The selected output capacitance (CSEL)
and the output voltage (VOUT) determine the minimum
value of CSS, as shown by the following equation:
CSS
SEL
x VOUT
where CSS is in nF and CSEL is in µF.
The value of the soft-start capacitor is calculated from the
desired soft-start time as follows:
t SS ≈
CSS
5.55
where tSS is in ms and CSS is in nF.
Detailed Description
The MAXM17503 is a complete step-down DC-DC power
supply that delivers up to 2.5A output current. The device
provides a programmable output voltage to regulate up
to 12V through external resistor dividers from an input
voltage range of 4.5V to 60V. The recommended input
voltage in Table 1 is selected highly enough to support
the desired output voltage and load current. The device
includes an adjustable frequency feature range from
100kHz to 1.8MHz to reduce sizes of input and output
capacitors. The Functional Diagram shows a complete
internal block diagram of the MAXM17503 power module.
Maxim Integrated │ 16
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Input Undervoltage-Lockout Level
The MAXM17503 contains an internal pullup resistor
(3.3MΩ) from EN to IN to have a default startup voltage.
The device offers an adjustable input undervoltagelockout level to set the voltage at which the device is
turned on by a single resistor connecting from EN/UVLO
to SGND as equation:
R ENU ≈
3.3 × 1215
(VINU − 1.215)
where RENU is in kΩ and VINU is the voltage at which
the device is required to turn on the device. Ensure that
VINU is high enough to support the VOUT. See Table 1
to set the proper VINU voltage greater than or equal the
minimum input voltage for each desired output voltage.
Mode Selection (MODE)
The MAXM17503 features a MODE pin to configure the
device operating in PWM, PFM, or DCM control schemes.
The device operates in PFM mode at light loads if the
MODE pin is open. If the MODE pin connects to ground,
the device operates in constant-frequency PWM mode
at all loads. The device operates in constant-frequency
DCM mode at light loads when the MODE pin connects
to VCC. State changes of the MODE operation are only at
power-up and ignore during normal operation.
PWM Mode Operation
In PWM mode, the step-down controller is switching
a constant-frequency at all loads with a minimum sink
current limit threshold (-1.8A typ) at light load. The
PWM mode of operation gives lower efficiency at light
loads compared to PFM and DCM modes of operation.
However, the PWM mode of operation is useful in applications sensitive to switching frequency.
PFM Mode Operation
In PFM mode, the controller forces the peak inductor
current in order to feed the light loads and maintain high
efficiency. If the load is lighter than the average PFM
value, the output voltage will exceed 102.3% of the feedback threshold and the controller enters into a hibernation
mode, turning off most of the internal blocks. The device
exits hibernation mode, and starts switching again, once
the output voltage is discharged to 101.1% of the feedback
threshold. The device then begins the process of delivering
pulses of energy to the output repeatedly until it reaches
102.3% of the feedback threshold. In this mode, the
behavior resembles PWM operation (with occasional pulse
skipping), where the inductor current does not need to
reach the light-load level.
www.maximintegrated.com
PFM mode offers the advantage of increased efficiency
at light loads due to a lower quiescent current drawn from
the supply. However, the output-voltage ripple is also
increased as compared to the PWM or DCM modes of
operation, and the switching frequency is not constant at
light loads.
DCM Mode Operation
DCM mode features constant frequency operation down
to lighter loads than PFM mode, accomplished by not
skipping pulses. DCM efficiency performance lies between
the PWM and PFM modes.
External Frequency Synchronization (SYNC)
The device can be synchronized by an external clock
signal on the SYNC pin. The external synchronization
clock frequency must be between 1.1 x fSW and 1.4 x fSW,
where fSW is the frequency programmed by the RT
resistor. The minimum external clock high pulse width
and amplitude should be greater than 50ns and 2.1V
respectively. The minimum external clock low pulse width
should be greater than 160ns, and the maximum external
clock low pulse amplitude should be less than 0.8V. Table 1
provides recommended synchronous frequency ranges
for desired output voltages. Connect the SYNC pin to
SGND if it is not used.
RESET Output
The device includes a RESET comparator to monitor the
output for undervoltage and overvoltage conditions. The
open-drain RESET output requires an external pullup
resistor from 10kΩ to 100kΩ to VCC pin or maximum 6V
voltage source. RESET goes high impedance after the
regulator output increases above 95% of the designed
nominal regulated voltage. RESET goes low when the
regulator output voltage drops below 92% of the nominal
regulated voltage. RESET also goes low during thermal
shutdown.
Overcurrent Protection (OCP)
The MAXM17503 is provided with a robust overcurrent
protection (OCP) scheme that protects the module under
overload and output short-circuit conditions. A cycle-bycycle peak current limit turns off the high-side MOSFET
whenever the high-side switch current exceeds an internal limit of 3.7A (typ). The module enters hiccup mode
of operation either after one occurrence of the runaway
current limit 4.3A (typ) or when the FB node goes below
0.58V of its nominal regulation threshold after soft-start
is complete. In hiccup mode, the module is protected by
suspending switching for a hiccup timeout period of 32,768
clock cycles. Once the hiccup timeout period expires, soft-
Maxim Integrated │ 17
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
start is attempted again. Hiccup mode of operation ensures
low power dissipation under output overload or short-circuit
conditions. Note that when soft-start is attempted under
overload condition, if feedback voltage does not exceed
0.58V, the device switches at half the programmed switching frequency.
thermal resistance model (ψJT), measuring thermal
resistance (ψTA), and measuring power dissipation
(PDMAX) on the bench.
The MAXM17503 is designed to support a maximum load
current of 3.5A. The inductor ripple current is calculated
as follows:
T
− TA
PDMAX = JMAX
θ JA
V − VOUT − 0.395 × I OUT
∆I = IN
L × f SW
V
+ 0.220 × I OUT
× OUT
V
−
IN 0.175 × I OUT
The maximum allowable power losses can be calculated
using the following equation:
where:
PDMAX is the maximum allowed power losses with maximum allowed junction temperature.
TJMAX is the maximum allowed junction temperature.
TA is operating ambient temperature.
θJA is the junction to ambient thermal resistance.
where,
VOUT = Steady-state output voltage
VIN = Operating input voltage
fSW = Switching frequency in Hz
L = Power module output inductance (6.8µH ±20%)
IOUT = Required output (load) current
The following condition should be satisfied at the desired
load current (IOUT).
I OUT +
∆I
< 3.2
2
Thermal Fault Protection
The MAXM17503 features a thermal-fault protection
circuit. When the junction temperature rises above +165°C
(typ), a thermal sensor activates the fault latch, pulls down
the RESET output, and shuts down the regulator. The
thermal sensor restarts the controllers after the junction
temperature cools by 10°C (typ). The Soft-start resets
during thermal shutdown.
Power Dissipation and Output-Current Derating
The MAXM17503 output current needs to be derated
if the device needs to be operated in a high ambienttemperature environment. The amount of current-derating
depends upon the input voltage, output voltage, and
ambient temperature. The derating curves in TOC43
from the Typical Operating Characteristics section can be
used as guidelines. The curves are based on simulating
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PCB Layout Guidelines
Careful PCB layout is critical to achieving low switching
losses and clean, stable operation.
Use the following guidelines for good PCB layout:
●●
Keep the input capacitors as close as possible to the
IN and PGND pins.
●●
Keep the output capacitors as close as possible to
the OUT and PGND pins.
●●
Keep the resistive feedback dividers as close as
possible to the FB pin.
●●
Connect all of the PGND connections to as large as
copper plane area as possible on the bottom layer.
●●
Connect EP1 to PGND and GND planes on bottom
layer.
●●
Use multiple vias to connect internal PGND planes
to the top layer PGND plane.
●●
Do not keep any solder mask on EP1, EP2, and EP3
on bottom layer. Keeping solder mask on exposed
pads decreases the heat dissipating capability.
●●
Keep the power traces and load connections short.
This practice is essential for high efficiency.
Using thick copper PCBs (2oz vs. 1oz) can enhance
full-load efficiency. Correctly routing PCB traces is
a difficult task that must be approached in terms of
fractions of centimeters, where a single milliohm of
excess trace resistance causes a measurable
efficiency penalty.
Maxim Integrated │ 18
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Layout Recommendation
PGND
IN
29
28
27
26
25
24
23
22
21
1
2
3
SGND
OUT
20
EP1
19
EP2
4
EP3
5
18
6
17
7
16
8
9
10
PGND
11
12
13
PGND
OUT
14 15
OUT
Ordering Information
Chip Information
PART
TEMP
RANGE
MSL
PINPACKAGE
MAXM17503ALJ+T
-40°C to
+125°C
3
29 SiP
PROCESS: BiCMOS
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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Maxim Integrated │ 19
MAXM17503
4.5V to 60V, 2.5A High-Efficiency, DC-DC
Step-Down Power Module with Integrated Inductor
Revision History
REVISION
NUMBER
REVISION
DATE
0
11/14
Initial release
1
4/15
Added application information to avoid potential latch-up issue on EN pin and added
MSL 3 rating
11, 18
2
11/16
Updated Package Thermal Characteristics and notes sections, updated Pin 4 in the
Pin Description section, and updated the Loop Compensation section
2, 11, 15
5/20
Updated the General Description, Benefits and Features, Pin Description. Pin
Description and Loop Compensation sections, and Table 1; replaced Input-Voltage
Range section; added Overcurrent Protection (OCP) section, and TOC44 and
TOC45
1, 10, 12,
14–18
3
PAGES
CHANGED
DESCRIPTION
—
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
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 specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics 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.
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