MAXM17544 4.5V to 42V, 3.5A High-Efficiency
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
General Description
The Himalaya series of voltage regulator ICs and power
modules enable cooler, smaller, and simpler power supply
solutions. The MAXM17544 is an easy-to-use, 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 42V and delivers up to 3.5A 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 MAXM17544 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 the industrial temperature range from -40°C
to +125°C.
Applications
●●
●●
●●
●●
●●
Industrial Power Supplies
Distributed Supply Regulation
FPGA and DSP Point-of-Load Regulator
Base Station Point-of-Load Regulator
HVAC and Building Control
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
• Integrated Thermal-Fault Protection
• Integrated Peak Current Limit
●● 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 42V
• 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
Typical Application Circuit
RT
4.5V TO 42V
CIN
OPTIONAL
COUT
Ordering Information appears at end of data sheet.
RU
CSS
RB
19-7457; Rev 1; 11/16
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Absolute Maximum Ratings (Notes 1, 2)
IN to PGND (Note 2)..............................................-0.3V to +48V
EN to SGND (Note 2).............................................-0.3V to +48V
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 +53V
BST to VCC............................................................-0.3V to +48V
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
Package Thermal Characteristics (Note 3)
Junction-to-Ambient Thermal Resistance (θJA)............30.8°C/W
Note 1: SGND and PGND are internally connected.
Note 2:See Pin Description for the connection of the backside exposed pad.
Note 3: Data taken using Maxim's evaluation kit, MAXM17544EVKIT#.
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.
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 = .-40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC. All voltages
are referenced to SGND, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
42
V
13
μA
INPUT SUPPLY (VIN)
IN Input Voltage Range
VIN
Input Shutdown Current
IIN_SH
Input Quiescent Current
4.5
VEN = 0V
10.5
IQ_PFM_
MODE = RT = open
125
IQ_DCM
MODE = VCC
1.16
IQ_PWM
Normal switching mode, no load
9.5
HIB
μA
1.8
mA
mA
LOGIC INPUTS
EN Threshold
Enable Pullup Resistor
VENR
VEN rising
1.192
1.215
1.26
V
VENF
VEN falling
1.068
1.09
1.131
V
RENP
Pullup resistor between IN and EN pins
3.15
3.3
3.45
MΩ
VCC
6V < VIN < 42V, 1mA < IVCC < 25mA
4.75
5
5.25
V
60
100
mA
LDO
VCC Output Voltage Range
VCC Current Limit
VCC Dropout
VCC UVLO
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IVCC_MAX
VIN = 6V, VCC = 4.3V
26.5
VCC_DO
VIN = 4.5V, IVCC = 20mA
4.2
VCC_UVR
VCC rising
4.05
4.2
4.3
V
VCC_UVF
VCC falling
3.65
3.8
3.9
V
V
Maxim Integrated │ 2
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown 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 = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC. All voltages
are referenced to SGND, unless otherwise noted.) (Note 4)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OUTPUT SPECIFICATIONS
Line Regulation Accuracy
VIN = 6.5V to 42V, VOUT = 5V
0.1
Load Regulation Accuracy
Tested with IOUT = 0A and 1A
1
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
Hiccup Timeout
mV/A
0.910
0.915
-50
0.56
mV/V
0.58
V
0.936
V
+50
nA
0.65
V
32,768
Cycles
SOFT-START (SS)
Charging Current
ISS
VSS = 0.5V
4.7
RRT = 210kΩ
90
5
5.3
100
110
μA
RT AND SYNC
Switching Frequency
fSW
RRT = 9.76kΩ
RRT = open
450
500
1.1x
fSW
SYNC Frequency Range
SYNC Pulse Width
SYNC Threshold
1800
550
kHz
1.4x
fSW
kHz
50
ns
2.1
VIH
kHz
kHz
0.8
VIL
V
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
4.6
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.
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Maxim Integrated │ 3
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 12V, PWM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 12V, PFM MODE
toc01
90
80
80
VIN = 24V,
fSW = 1.8MHz
60
VIN = 36V,
fSW = 1.8MHz
VIN = 24V,
fSW = 1.8MHz
60
VIN = 36V,
fSW = 1.8MHz
50
0
500
1000
1500
70
40
2000
60
0
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V, PWM MODE
500
1000
1500
40
2000
100
80
VIN = 24V,
fSW = 740kHz
1000
VIN = 12V,
fSW = 500kHz
2000
3000
0
1000
VIN = 36V,
fSW = 500kHz
2000
40
3000
80
VIN = 5V,
fSW = 400kHz
40
VIN = 36V,
fSW = 400kHz
VIN = 24V,
fSW = 400kHz
0
1000
2000
OUTPUT CURRENT (mA)
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1000
3000
2000
3000
toc08
70
VIN = 12V,
fSW = 400kHz
60
VIN = 5V,
fSW = 400kHz
50
MODE = OPEN
MODE = SGND
100
80
50
0
VIN = 36V,
fSW = 500kHz
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 2.5V, PWM MODE
90
60
VIN = 12V,
fSW = 500kHz
OUTPUT CURRENT (mA)
90
VIN = 12V,
fSW = 400kHz
60
OUTPUT CURRENT (mA)
toc07
70
VIN = 24V,
fSW = 500kHz
70
50
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 2.5V, PFM MODE
100
3000
toc06
MODE = OPEN
40
OUTPUT CURRENT (mA)
EFFICIENCY (%)
60
50
MODE = SGND
0
VIN = 24V,
fSW = 500kHz
EFFICIENCY (%)
40
70
EFFICIENCY (%)
80
EFFICIENCY (%)
80
VIN = 36V,
fSW = 740kHz
2000
100
90
50
1000
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PWM MODE
toc05
90
60
0
OUTPUT CURRENT (mA)
90
VIN = 12V,
fSW = 740kHz
MODE = OPEN
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 3.3V, PFM MODE
toc04
70
VIN = 24V,
fSW = 740kHz
OUTPUT CURRENT (mA)
100
VIN = 36V,
fSW = 740kHz
VIN = 12V,
fSW = 740kHz
50
OUTPUT CURRENT (mA)
EFFICIENCY (%)
80
MODE = SGND
MODE = OPEN
40
90
70
50
toc03
100
EFFICIENCY (%)
90
70
toc02
100
EFFICIENCY (%)
EFFICIENCY (%)
100
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 5V, PFM MODE
40
0
1000
VIN = 36V,
fSW = 400kHz
VIN = 24V,
fSW = 400kHz
MODE = SGND
2000
3000
OUTPUT CURRENT (mA)
Maxim Integrated │ 4
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 1.2V, PWM MODE
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 1.2V, PFM MODE
toc09
toc10
100
90
80
80
80
VIN = 5V,
fSW = 350kHz
60
VIN = 36V,
fSW = 200kHz
VIN = 12V,
fSW = 350kHz
50
40
VIN = 24V,
fSW = 285kHz
0
1000
2000
70
VIN = 5V,
fSW = 350kHz
60
40
3000
0
1000
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 0.9V, PWM MODE
70
0
1000
VIN = 5.0V
fSW = 500kHz
3.4
3000
3
OUTPUT CURRENT (mA)
VIN = 12V,
fSW = 740kHz
MODE = OPEN
0
1000
2000
3
3000
VIN = 36V
fSW = 500kHz
MODE = SGND
0
1000
2000
3000
OUTPUT CURRENT (mA)
toc16
5.5
5.4
VIN = 12V,
fSW = 740kHz
5.3
VOUT (V)
VOUT (V)
VIN = 24V
fSW = 500kHz
LOAD REGULATION
VOUT = 5V, PWM MODE
VIN = 36V,
fSW = 740kHz
5.2
5.1
5
5.2
VIN = 36V,
fSW = 740kHz
5.1
5
4.9
4.9
4.8
4.8
VIN = 24V,
fSW = 740kHz
4.7
4.6
4.5
3.3
3.1
toc15
5.3
3.4
VIN = 12V
fSW = 500kHz
3.2
LOAD REGULATION
VOUT = 5V, PFM MODE
5.4
VIN = 5.0V
fSW = 500kHz
OUTPUT CURRENT (mA)
5.5
3000
toc14
3.5
VIN = 12V
fSW = 500kHz
VIN = 36V
fSW = 500kHz
VIN = 24V
fSW = 500kHz
3.1
MODE = SGND
2000
3.6
3.3
3.2
VIN = 24V,
fSW = 214kHz
2000
1000
LOAD REGULATION
VOUT = 3.3V, PWM MODE
VOUT (V)
VOUT (V)
EFFICIENCY (%)
80
40
0
MODE = OPEN
OUTPUT CURRENT (mA)
toc13
3.5
VIN = 5V,
fSW = 300kHz
40
3000
VIN = 24V,
fSW = 214kHz
VIN = 5V,
fSW = 300kHz
50
MODE = SGND
2000
3.6
90
50
VIN = 12V,
fSW = 300kHz
60
LOAD REGULATION
VOUT = 3.3V, PFM MODE
toc12
100
60
VIN = 36V,
fSW = 200kHz
70
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
VIN = 12V,
fSW = 300kHz
VIN = 24V,
fSW = 285kHz
VIN = 12V,
fSW = 350kHz
50
MODE = OPEN
EFFICIENCY (%)
90
70
toc11
100
90
EFFICIENCY (%)
EFFICIENCY (%)
100
EFFICIENCY vs. OUTPUT CURRENT
VOUT = 0.9V, PFM MODE
MODE = OPEN
0
1000
2000
OUTPUT CURRENT (mA)
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VIN = 24V,
fSW = 740kHz
4.7
3000
4.6
4.5
MODE = SGND
0
1000
2000
3000
OUTPUT CURRENT (mA)
Maxim Integrated │ 5
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
LOAD REGULATION
VOUT = 12V, PFM MODE
toc17
13
12.8
12.6
12.4
VOUT (V)
VOUT (V)
12.6
12.2
12
11.8
12.4
12.2
20mV/div
(ACCOUPLED)
VOUT
12
11.8
VIN = 36V,
fSW = 1.8MHz
11.6
11.4
11.2
11
toc19
toc18
13
VIN = 24V,
fSW = 1.8MHz
12.8
OUTPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A, MODE = SGND
LOAD REGULATION
VOUT = 12V, PWM MODE
11.4
MODE = OPEN
0
500
VIN = 24V,
fSW = 1.8MHz
11.6
1000
1500
VIN = 36V,
fSW = 1.8MHz
11.2
11
2000
OUTPUT CURRENT (mA)
MODE = SGND
0
500
1000
INPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 5V, IOUT = 3.5A, MODE = SGND
INPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A, MODE = SGND
toc20
toc21
20mV/div
(ACCOUPLED)
toc22
500mV/div
(ACCOUPLED)
VIN
2µs/div
200mV/div
(ACCOUPLED)
VIN
2µs/div
2µs/div
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0 - 1.75A, MODE =
OPEN
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0 - 1.75A, MODE =
SGND
toc24
toc23
200mV/div
(AC
COUPLED)
VOUT
2A/div
IOUT
200µs/div
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2µs/div
2000
OUTPUT CURRENT (mA)
OUTPUT VOLTAGE RIPPLE
VIN = 24V, VOUT = 5V, IOUT = 3.5A, MODE = SGND
VOUT
1500
200mV/div
(AC
COUPLED)
VOUT
IOUT
2A/div
200µs/div
Maxim Integrated │ 6
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0 - 1.75A, MODE = OPEN
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 3.3V, IOUT = 0 - 1.75A, MODE = VCC
toc25
IOUT
2A/div
2A/div
IOUT
200mV/div
(AC
COUPLED)
VOUT
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0 - 1.75A, MODE = VCC
2A/div
IOUT
VOUT
200mV/div
(AC
COUPLED)
200µs/div
200µs/div
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
200µs/div
toc29
toc28
EN
2A/div
IOUT
toc27
toc26
200mV/div
(AC
COUPLED)
VOUT
LOAD CURRENT TRANSIENT RESPONSE
VIN = 24V, VOUT = 5V, IOUT = 0 - 1.75A, MODE = SGND
LX
toc30
5V/div
EN
20V/div
LX
5V/div
20V/div
2V/div
2V/div
200mV/div
(AC
COUPLED)
VOUT
VOUT
VOUT
5V/div
RESET
200µs/div
5V/div
RESET
1ms/div
1ms/div
SHUTDOWN THROUGH ENABLE
VIN = 24V, VOUT = 3.3V, IOUT = 0A, MODE = SGND
STARTUP WITH 2.5V PREBIAS
VIN = 24V, VOUT = 3.3V, IOUT = 0A, MODE = OPEN
toc32
toc31
EN
LX
5V/div
EN
20V/div
LX
5V/div
20V/div
2V/div
2V/div
VOUT
VOUT
5V/div
RESET
1ms/div
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5V/div
RESET
1ms/div
Maxim Integrated │ 7
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
SHUTDOWN THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A, MODE = SGND
STARTUP THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A, MODE = SGND
toc34
toc33
10V/div
VIN
20V/div
LX
20V/div
VIN
20V/div
LX
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
5V/div
RESET
1ms/div
1ms/div
SHUTDOWN THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 5V, IOUT = 3.5A, MODE = SGND
STARTUP THROUGH INPUT SUPPLY
VIN = 24V, VOUT = 5V, IOUT = 3.5A, MODE = SGND
toc38
toc37
20V/div
VIN
20V/div
LX
2V/div
VOUT
5V/div
RESET
1ms/div
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20V/div
VIN
20V/div
LX
VOUT
2V/div
RESET
5V/div
100µs/div
Maxim Integrated │ 8
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Typical Operating Characteristics (continued)
(VIN = 4.5V to 42V, VOUT = 0.9 to 12V, IOUT = 0A–3.5A, TA = +25°C, unless otherwise noted.)
OUTPUT SHORT IN STEADY STATE
VIN = 24V, VOUT = 3.3V, IOUT = 0A to SHORT MODE =
SGND
toc39
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
40ms/div
CLOSED-LOOP BODE PLOT
VIN = 24V, VOUT = 3.3V, IOUT = 3.5A, MODE = GND
toc41
toc42
50
40
SYNC
30
LX
GAIN (dB)
5V/div
20V/div
90
20
60
10
30
0
0
-10
VOUT
-30
GAIN
-20
2V/div
-30
-50
2µs/div
-60
CROSSOVER FREQUENCY = 49.6kHz
PHASE MARGIN = 72°C
-40
3k
30k
300k
-90
-120
-150
FREQUENCY (Hz)
5
OUTPUT CURRENT
vs. AMBIENT TEMPERATURE
VIN = 24V NO AIR FLOW
4.5
OUTOPUT CURRENT (A)
toc43
VOUT = 3.3V
4
3.5
3
2.5
2
1.5
1
0.5
0
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150
120
PHASE
PHASE MARGIN (°)
SYNC FREQUENCY AT 740 KHZ
VIN = 24V, VOUT = 5V, IOUT = 0A, MODE = GND
VOUT = 5V
VOUT = 12V
0 10 20 30 40 50 60 70 80 90 100 110 120
AMBIENT TEMPERATURE (°C)
Maxim Integrated │ 9
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown 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
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9
VCC
10
SGND
PGND
12
13
14
15
OUT
OUT
OUT
OUT
Maxim Integrated │ 10
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Pin Description
PIN
NAME
1, 7
N.C.
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 Adjusting 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.
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
IC
25
BST
27
IN
Input Supply Connection. Bypass to PGND with a capacitor; place the capacitor close to the IN
and PGND pins. See Selecting Component Tables 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.
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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FUNCTION
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 MAXM17504 to operate in PWM, PFM,
or DCM mode of operation. Leave MODE unconnected for PFM operation (pulse-skipping at lightloads). Connect MODE to SGND for constant-frequency PWM operation at all loads. Connect
MODE to VCC for DCM operation. See the MODE Setting section for more details.
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 │ 11
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Functional Diagram
MAXM17544
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
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FB
RESET
LOGIC
Maxim Integrated │ 12
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Design Procedure
Input Capacitor Selection
Setting the Output Voltage
The MAXM17544 supports an adjustable output
voltage range of 0.9V to 12V from an input voltage range
of 4.5V to 42V 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.
Calculate resistor RU from the output to FB as follows:
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.
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:
CIN =
IIN_AVG × (1 − D)
∆VIN × fSW
where:
IIN_AVG is the average input current given by:
R × 0.9
RB = U
kΩ, where R B is in kΩ.
VOUT − 0.9
IIN_AVG =
POUT
η × VIN
D is the operating duty cycle, which is approximately
equal to VOUT/VIN.
OUT
VOUT
RU
MAXM17544
∆VIN is the required input voltage ripple.
fSW is the operating switching frequency.
POUT is the out power, which is equal to VOUT x IOUT.
η is the efficiency.
FB
RB
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)
Figure 1. Adjustable Output Voltage
Input Voltage Range
Due to the limitation of minimum and maximum duty
cycle, the maximum value (VIN (MAX)) and minimum
value (VIN (MIN)) must accommodate the worst-case
conditions, accounting for the input voltage rises and
drops. To simplify, Table 1 provides operating input
voltage ranges of different desired output voltages.
www.maximintegrated.com
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 MAXM17544 system (IN) supply, ceramic capacitors are preferred due to their resilience to inrush
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.
Maxim Integrated │ 13
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown 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 100µF 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
4.5 to 15
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
Open
6.5 to 15
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
11 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
4.5 to 28
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
Open
6.5 to 28
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
11 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 42
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 42
1.5
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47uF 1210 4V
57.6
86.6
250
82.5
4.5 to 42
1.8
3 x 2.2µF 1206 100V
1 x 100µF 1 x 47uF 1210 4V
61.9
61.9
300
68.1
4.5 to 42
2.5
3 x 2.2µF 1206 100V
1 x 100µF 1210 4V
53.6
30.1
400
49.90
4.5 to 42
3.3
2 x 2.2µF 1206 100V
1 x 47µF 1210 10V
130
48.7
500
Open
6.5 to 42
5
2 x 2.2µF 1206 100V
1 x 22µF 1210 10V
191
42.2
740
26.7
11 to 42
8
2 x 2.2µF 1206 100V
1 x 10µF 1210 16V
309
39.2
1200
15.8
18.5 to 42
12
2 x 2.2µF 1206 100V
1 x 4.7µF 1210 16V
464
37.4
1800
10.00
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Maxim Integrated │ 14
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
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 MAXM17544 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, and 1.2pF for switching
frequency range of 300kHz to 400kHz.
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 MAXM17544 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.
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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 ≥ 28 x 10-3 x CSEL 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 MAXM17544 is a complete step-down DC-DC power
supply that delivers up to 3.5A 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 42V. 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 MAXM17544 power module.
Input Undervoltage-Lockout Level
The MAXM17544 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.
Maxim Integrated │ 15
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Mode Selection (MODE)
The MAXM17544 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 powerup 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.
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
www.maximintegrated.com
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.
Thermal Fault Protection
The MAXM17544 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 MAXM17544 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
thermal resistance model (ΨJT), measuring thermal resistance (ΨTA), and measuring power dissipation (PDMAX)
on the bench.
The maximum allowable power losses can be calculated
using the following equation:
T
− TA
PDMAX = JMAX
θ JA
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.
Maxim Integrated │ 16
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
PCB Layout Guidelines
Careful PCB layout is critical to achieving low switching
losses and clean, stable operation.
●●
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 mW of
excess trace resistance causes a measurable
efficiency penalty.
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 top layer.
●●
Connect EP1 to PGND and GND planes on bottom
layer.
Layout Recommendation
PGND
IN
29
28
27
26
25
24
23
22
21
1
2
3
SGND
OUT
20
EP1
EP2
4
EP3
5
19
18
6
17
7
16
8
9
10
PGND
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11
12
13
PGND
OUT
14 15
OUT
Maxim Integrated │ 17
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Chip Information
Package Information
PROCESS: BiCMOS
Ordering Information
PART
TEMP RANGE
PINPACKAGE
MAXM17544ALJ+T
-40°C to +125°C
29 SiP
+Denotes a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
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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.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
29 SiP
L32915+1
21-0879
90-0459
Maxim Integrated │ 18
MAXM17544
4.5V to 42V, 3.5A High-Efficiency, DC-DC StepDown Power Module with Integrated Inductor
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
12/14
Initial release
1
11/16
Updated Package Thermal Characteristics and notes sections, updated Pin 4 in the
Pin Description section, and updated the Loop Compensation section
DESCRIPTION
—
2, 11, 15
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
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.
© 2016 Maxim Integrated Products, Inc. │ 19
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