19-5240; Rev 2; 7/11
High-Efficiency, 2A, Current-Mode
Synchronous, Step-Down Switching Regulator
General Description
The MAX15053 high-efficiency, current-mode, synchro-
nous step-down switching regulator with integrated
power switches delivers up to 2A of output current.
The device operates from 2.7V to 5.5V and provides an
output voltage from 0.6V up to 94% of the input voltage,
making the device ideal for distributed power systems,
portable devices, and preregulation applications.
The MAX15053 utilizes a current-mode control archi-
tecture with a high gain transconductance error ampli-
fier. The current-mode control architecture facilitates
easy compensation design and ensures cycle-by-cycle
current limit with fast response to line and load transients.
The MAX15053 offers selectable skip-mode functionality
to reduce current consumption and achieve a higher effi-
ciency at light output load. The low R
DS(ON)
integrated
switches ensure high efficiency at heavy loads while min-
imizing critical inductances, making the layout design
a much simpler task with respect to discrete solutions.
Utilizing a simple layout and footprint assures first-pass
success in new designs.
The MAX15053 features a 1MHz, factory-trimmed, fixed-
frequency PWM mode operation. The high switching fre-
quency, along with the PWM current-mode architecture,
allows for a compact, all-ceramic capacitor design.
The MAX15053 offers a capacitor-programmable soft-
start reducing inrush current, startup into PREBIAS
operations, and a PGOOD open-drain output that can be
used as an interrupt and for power sequencing.
The MAX15053 is available in a 9-bump (3 x 3 array),
1.5mm x 1.5mm WLP package and is specified over the
-40NC to +85NC temperature range.
(typ) Low-Side MOSFETs at 5V
TION KIT
EVALUA BLE
AVAILA
Features
S
Internal 30mI (typ) R
DS(ON)
High-Side and 18mI
S
Continuous 2A Output Current Over Temperature
S
96% Efficiency with 3.3V Output at 2A
S
±1% Output Voltage Accuracy Over Load, Line,
MAX15053
and Temperature
S
Operates from 2.7V to 5.5V Supply
S
Cycle-by-Cycle Overcurrent Protection
S
Adjustable Output from 0.6V to Up to 0.94 x V
IN
S
Programmable Soft-Start
S
Factory-Trimmed, 1MHz Switching Frequency
S
Stable with Low-ESR Ceramic Output Capacitors
S
Safe-Startup Into Prebiased Output
S
External Reference Input
S
Skip-Mode Functionality
S
Enable Input/Power-Good Output
S
Fully Protected Against Overcurrent and
Overtemperature
S
Input Undervoltage Lockout
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX15053EWL+
-40°C to +85°C
9 WLP
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
INPUT
2.7V TO 5.5V
OUTPUT
1.8V/2A
Applications
Distributed Power Systems
Preregulators for Linear Regulators
Portable Devices
Notebook Power
Server Power
IP Phones
IN
LX
MAX15053
GND
PGOOD
FB
ENABLE
OFF
ON
EN
SKIP
SS/REFIN
COMP
_______________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
High-Efficiency, 2A, Current-Mode
Synchronous, Step-Down Switching Regulator
MAX15053
ABSOLUTE MAXIMUM RATINGS
IN, PGOOD to GND ................................................-0.3V to +6V
LX to GND ..................................................-0.3V to (V
IN
+ 0.3V)
LX to GND .......................................-1V to (V
IN
+ 0.3V) for 50ns
EN, COMP, FB, SS/REFIN, SKIP to GND ...-0.3V to (V
IN
+ 0.3V)
LX Current (Note 1) ................................................... -5A to +5A
Output Short-Circuit Duration ....................................Continuous
Continuous Power Dissipation (T
A
= +70NC)
9-Bump WLP Multilayer Board
(derate 14.1mW/NC above T
A
= +70NC) ....................1127mW
Operating Temperature Range .......................... -40NC to +85NC
Operating Junction Temperature (Note 2) ......................+105NC
Storage Temperature Range............................ -65NC to +150NC
Soldering Temperature (reflow) ......................................+260NC
Note 1:
LX has internal clamp diodes to GND and IN. Applications that forward bias these diodes should not exceed the IC’s pack-
age power dissipation limits.
Note 2:
Limit the junction temperature to +105NC for continuous operation at maximum output current.
PACKAGE THERMAL CHARACTERISTICS (Note 3)
WLP
Junction-to-Case Thermal Resistance (B
JC
) ...................26NC/W
Junction-to-Ambient Thermal Resistance (B
JA
) ..............71NC/W
Note 3:
Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-
layer board. For detailed information on package thermal considerations, refer to
www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
IN
= 5V, T
A
= -40NC to +85NC, unless otherwise noted, typical values are at T
A
= +25NC.) (Note 4)
PARAMETER
IN Voltage Range
IN Shutdown Supply Current
IN Supply Current
V
IN
Undervoltage Lockout
Threshold
V
IN
Undervoltage Lockout
Hysteresis
ERROR AMPLIFIER
Transconductance
Voltage Gain
FB Set-Point Accuracy
FB Input Bias Current
COMP to Current-Sense
Transconductance
COMP Clamp Low
POWER SWITCHES
LX On-Resistance, High-Side
pMOS
LX On-Resistance, Low-Side
nMOS
High-Side Switch Current-Limit
Threshold
Low-Side Switch Sink Current-
Limit Threshold
I
HSCL
30
18
4
4
mI
mI
A
A
g
MV
A
VEA
V
FB
I
FB
g
MC
V
FB
= 0.65V, V
SS
= 0.6V
Over line, load, and temperature
V
FB
= 0.6V
594
-500
18
0.94
1.5
90
600
606
+500
mS
dB
mV
nA
A/V
V
I
IN
SYMBOL
V
IN
V
EN
= 0V
V
EN
= 5V, V
FB
= 0.65V, no switching
LX starts switching, V
IN
rising
LX stops switching, V
IN
falling
CONDITIONS
MIN
2.7
0.2
1.56
2.6
200
TYP
MAX
5.5
2
2.3
2.7
UNITS
V
FA
mA
V
mV
2
______________________________________________________________________________________
High-Efficiency, 2A, Current-Mode
Synchronous, Step-Down Switching Regulator
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V, T
A
= -40NC to +85NC, unless otherwise noted, typical values are at T
A
= +25NC.) (Note 4)
PARAMETER
Low-Side Switch Source Current-
Limit Threshold
LX Leakage Current
RMS LX Output Current
OSCILLATOR
Switching Frequency
Maximum Duty Cycle
Minimum Controllable On-Time
Slope Compensation Ramp
Valley
Slope Compensation Ramp
Amplitude
ENABLE
EN Input High Threshold Voltage
EN Input Low Threshold Voltage
EN Input Leakage Current
SKIP Input Leakage Current
SOFT-START, PREBIAS, REFIN
Soft-Start Current
SS/REFIN Discharge Resistance
SS/REFIN Prebias Mode Stop
Voltage
External Reference Input Range
HICCUP
Number of Consecutive Current-
Limit Events to Hiccup
Timeout
POWER-GOOD OUTPUT
PGOOD Threshold
PGOOD Threshold Hysteresis
PGOOD V
OL
PGOOD Leakage
THERMAL SHUTDOWN
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
Temperature falling
150
20
NC
NC
V
FB
rising
V
FB
falling
I
PGOOD
= 5mA, V
FB
= 0.5V
V
PGOOD
= 5V, V
FB
= 0.65V
0.535
8
1024
0.555
28
20
0.013
60
0.575
Events
Clock
Cycles
V
mV
mV
FA
I
SS
R
SS
V
SS/REFIN
= 0.45V, sourcing
I
SS/REFIN
= 10mA, sinking
V
SS/REFIN
rising
0
10
8.3
0.58
V
IN
-
1.8
FA
I
V
V
V
EN
rising
V
EN
falling
V
EN
= 5V
V
SKIP
= V
EN
= 5V
1.45
0.4
0.025
25
V
V
FA
FA
V
SLOPE
Extrapolated to 100% duty cycle
f
SW
D
MAX
850
94
1000
95.8
70
1.15
320
1150
kHz
%
ns
V
mV
V
EN
= 0V
2
SYMBOL
CONDITIONS
MIN
TYP
4
10
MAX
UNITS
A
FA
A
MAX15053
3
Note 4:
Specifications are 100% production tested at T
A
= +25NC. Limits over the operating temperature range are guaranteed by
design and characterization.
_______________________________________________________________________________________
High-Efficiency, 2A, Current-Mode
Synchronous, Step-Down Switching Regulator
MAX15053
Typical Operating Characteristics
(V
IN
= 5V, V
OUT
= 1.8V, I
LOAD
= 2A, Circuit of Figure 5, T
A
= +25NC, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(PWM MODE)
MAX15053 toc01
EFFICIENCY vs. OUTPUT CURRENT
(PWM MODE)
MAX15053 toc02
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
400
800
1200
1600
2000
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
50
95
90
EFFICIENCY (%)
85
80
75
70
65
60
V
OUT
= 3.3V
V
OUT
= 3.3V V
OUT
= 1.8V
V
OUT
= 1.2V
V
OUT
= 2.5V V
OUT
= 1.8V
V
OUT
= 1.2V
V
OUT
= 2.5V
V
OUT
= 1.5V
V
OUT
= 1.2V
V
OUT
= 1.5V
V
OUT
= 2.5V V
OUT
= 1.5V
V
OUT
= 1.8V
V
IN
= 5V
2400
V
IN
= 3.3V
0
400
800
1200
1600
2000
2400
55
0
50
V
IN
= 5V
200
400
600
800
1000
1200
1400
1600
1800
2000
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
OUTPUT CURRENT (mA)
EFFICIENCY vs. OUTPUT CURRENT
(SKIP MODE)
MAX15053 toc04
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
1080
SWITCHING FREQUENCY (kHz)
1060
1040
1020
1000
980
960
940
920
900
MAX15053 toc05
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
55
0
50
1100
V
OUT
= 2.5V
V
OUT
= 1.5V
V
OUT
= 1.2V
V
OUT
= 1.8V
V
IN
= 3.3V
200
400
600
800
1000
1200
1400
1600
1800
2000
2.7
3.2
3.7
4.2
4.7
5.2
OUTPUT CURRENT (mA)
INPUT VOLTAGE (V)
OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
MAX15053 toc06
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
1.89
1.87
OUTPUT VOLTAGE (V)
1.85
1.83
1.81
1.79
1.77
MAX15053 toc07
1.89
1.87
OUTPUT VOLTAGE (V)
1.85
1.83
1.81
1.79
1.77
1.75
2.7
V
OUT
= 3.3V
V
OUT
= 5V
I
OUT
= 0.5A
3.2
3.7
4.2
4.7
5.2
1.75
0
0.5
1.0
1.5
2.0
2.5
3.0
SUPPLY VOLTAGE (V)
OUTPUT CURRENT (A)
4
______________________________________________________________________________________
MAX15053 toc03
100
100
EFFICIENCY vs. OUTPUT CURRENT
(SKIP MODE)
100
High-Efficiency, 2A, Current-Mode
Synchronous, Step-Down Switching Regulator
Typical Operating Characteristics (continued)
(V
IN
= 5V, V
OUT
= 1.8V, I
LOAD
= 2A, Circuit of Figure 5, T
A
= +25NC, unless otherwise noted.)
SWITCHING WAVEFORMS
(I
OUT
= 2A)
MAX15053 toc9a
MAX15053
LOAD-TRANSIENT RESPONSE
MAX15053 toc08
V
OUT
100mV/div
AC-COUPLED
V
OUT
50mV/div
AC-COUPLED
I
LX
1A/div
I
OUT
1A/div
0A
0A
V
LX
5V/div
PWM MODE
40
µ
s/div
400
n
s/div
V
IN
= 5V
SWITCHING WAVEFORMS
MAX15053 toc09b
SWITCHING WAVEFORM IN SKIP MODE
(I
OUT
= 10mA)
MAX15053 toc10
V
OUT
50mV/div
AC-COUPLED
I
LX
1A/div
0A
V
LX
5V/div
V
OUT
50mV/div
AC-COUPLED
I
LX
1A/div
V
LX
5V/div
V
IN
= 3.3V
400
n
s/div
10µs/div
INPUT AND OUTPUT RIPPLE VOLTAGE
WAVEFORM (I
OUT
= 2A)
MAX15053 toc11
SHUTDOWN WAVEFORM
MAX15053 toc12
V
ENABLE
5V/div
INPUT
20mV/div
AC-COUPLED
OUTPUT
100mV/div
AC-COUPLED
V
OUT
1V/div
I
LX
1A/div
V
PGOOD
5V/div
400ns/div
10µs/div
_______________________________________________________________________________________
5
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