19-4915; Rev 2; 3/10
KIT
ATION
EVALU
BLE
AVAILA
High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
General Description
The MAX15050/MAX15051 high-efficiency switching reg-
ulators deliver up to 4A load current at output voltages
from 0.6V to (0.9 x V
IN
). The devices operate from 2.9V
to 5.5V, making them ideal for on-board point-of-load
and postregulation applications. Total output-voltage
accuracy is within ±1% over load, line, and temperature.
The MAX15050/MAX15051 feature 1MHz fixed-frequen-
cy PWM operation. The MAX15050 features pulse-skip
mode to improve light-load efficiency. The MAX15050
soft-starts in a monotonic mode and then operates in
the forced PWM mode or pulse-skip mode depending
on the output load current condition. The MAX15051
soft-starts in the monotonic mode and operates in the
forced PWM mode. The high operating frequency
allows for small-size external components.
The low-resistance on-chip nMOS switches ensure high
efficiency at heavy loads while minimizing critical parasitic
inductances, making the layout a much simpler task with
respect to discrete solutions. Following a simple layout
and footprint ensures first-pass success in new designs.
The MAX15050/MAX15051 incorporate a high-bandwidth
(> 26MHz) voltage-error amplifier. The voltage-mode control
architecture and the voltage-error amplifier permit a type III
compensation scheme to achieve maximum loop band-
width, up to 200kHz. High loop bandwidth provides fast
transient response, resulting in less required output capaci-
tance and allowing for all-ceramic capacitor designs.
The MAX15050/MAX15051 feature an output overload
hiccup protection and peak current limit on both high-
side and low-side MOSFETs. These features provide for
ultra-safe operation in the cases of short-circuit condi-
tions, severe overloads, or in converters with bulk elec-
trolytic capacitors.
The MAX15050/MAX15051 feature an adjustable output volt-
age. The output voltage is adjustable by using two external
resistors at the feedback or by applying an external reference
voltage to the REFIN/SS input. The MAX15050/MAX15051
offer programmable soft-start time using one capacitor to
reduce input inrush current. A built-in thermal shutdown pro-
tection assures safe operation under all conditions. The
MAX15050/MAX15051 are available in a 2mm x 2mm,
16-bump (4 x 4 array), 0.5mm pitch WLP package.
Features
o
Internal 18mΩ R
DS(ON)
MOSFETs
o
Pulse-Skip Mode for High-Efficiency Light Load
(MAX15050)
o
Continuous 4A Output Current
o
±1% Output-Voltage Accuracy Over Load, Line,
and Temperature
o
Operates from 2.9V to 5.5V Supply
o
Adjustable Output from 0.6V to (0.9 x V
IN
)
o
Adjustable Soft-Start Reduces Inrush Supply Current
o
Factory-Trimmed 1MHz Switching Frequency
o
Compatible with Ceramic, Polymer, and
Electrolytic Output Capacitors
o
Safe Startup Into Prebias Output
o
Enable Input/Power-Good Output
o
Fully Protected Against Overcurrent and
Overtemperature
o
Overload Hiccup Protection
o
Sink/Source Current for DDR Applications
o
2mm x 2mm, 16-Bump (4 x 4 Array), 0.5mm Pitch
WLP Package
MAX15050/MAX15051
Ordering Information
PART
MAX15050
EWE+
MAX15051
EWE+
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
16 WLP
16 WLP
SKIP
MODE
Yes
No
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
INPUT
2.9V TO 5.5V
IN
EN
V
DD
GND
MAX15050
MAX15051
BST
OUTPUT
LX
Applications
Server Power Supplies
Point-of-Load
ASIC/CPU/DSP Core
and I/O Voltages
DDR Power Supplies
Base-Station Power
Supplies
Telecom and
Networking Power
Supplies
RAID Control Power
Supplies
Portable Applications
REFIN/SS
FB
V
DD
COMP
GND
PWRGD
Pin Configuration appears at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
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, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
MAX15050/MAX15051
ABSOLUTE MAXIMUM RATINGS
IN, PWRGD to GND..................................................-0.3V to +6V
V
DD
to GND ..................-0.3V to the lower of +4V or (V
IN
+ 0.3V)
COMP, FB, REFIN/SS to GND ....................-0.3V to (V
DD
+ 0.3V)
EN to GND................................................................-0.3V to +6V
BST to LX..................................................................-0.3V to +6V
BST to GND ............................................................-0.3V to +12V
LX to GND ....................-0.3V to the lower of +6V or (V
IN
+ 0.3V)
LX to GND (Note 1) ..-1V to the lower of +6V or (V
IN
+ 1V) for 50ns
I
LX(RMS)
....................................................................................6A
V
DD
Output Short-Circuit Duration .............................Continuous
Converter Output Short-Circuit Duration ....................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Bump (4 x 4 Array), 0.5mm Pitch WLP
(derate 20.4mW/°C above +70°C) ..............................1000mW
Thermal Resistance (Note 2)
θ
JA
.................................................................................49°C/W
θ
JC
...................................................................................9°C/W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Operating Junction Temperature
at Maximum Current (Note 3)........................................+105°C
Storage Temperature Range .............................-65°C to +150°C
Soldering Temperature (soldering, 10s) ..........................+260°C
Note 1:
LX has internal clamp diodes to GND and IN. Applications that forward bias these diodes should take care not to exceed
the IC’s power dissipation limit of the device.
Note 2:
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.
Note 3:
Operating the junction temperature above +105°C will degrade the life of the device.
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
(V
IN
= V
EN
= 5V, C
VDD
= 2.2µF, T
A
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 4)
PARAMETER
IN Voltage Range
IN Supply Current
Total Shutdown Current from IN
V
DD
Undervoltage Lockout
Threshold
V
DD
Undervoltage Deglitching
V
DD
Output Voltage
V
DD
Dropout
V
DD
Current Limit
BST
MAX15050, V
BST
= 5V, V
LX
= 0V, no switching
BST Supply Current
IN to BST On-Resistance
PWM COMPARATOR
PWM Comparator Propagation
Delay
PWM Peak-to-Peak Ramp
Amplitude
PWM Valley Amplitude
10mV overdrive
20
1
0.76
ns
V
V
MAX15051, V
IN
= V
LX
= 3.3V, V
BST
= 6.6V,
no switching
V
IN
= 3.3V, I
IN
= 0.16A
10
µA
250
4
I
VDD
= 0 to 10mA
V
IN
= 2.9V, I
VDD
= 10mA
V
DD
= 0V
20
37
3.1
No load, no switching
V
IN
= 3.3V
V
IN
= 5V
V
DD
rising
V
DD
falling
2.35
CONDITIONS
MIN
2.9
4.8
5.3
10
2.6
2.55
10
3.3
3.5
0.09
TYP
MAX
5.5
8
8.5
20
2.8
UNITS
V
mA
µA
V
µs
V
V
mA
V
IN
= V
BST
- V
LX
= 5V, V
EN
= 0V
LX starts/stops switching,
no load
2
_______________________________________________________________________________________
High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
EN
= 5V, C
VDD
= 2.2µF, T
A
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 4)
PARAMETER
COMP
COMP Clamp Voltage High
COMP Clamp Voltage Low
COMP Slew Rate
COMP Shutdown Resistance
ERROR AMPLIFIER
FB Regulation Accuracy Using
External Resistors
Open-Loop Voltage Gain
Error-Amplifier Unity-Gain
Bandwidth
Error-Amplifier Common-Mode
Input Range
Error-Amplifier Maximum Output
Current
FB Input Bias Current
REFIN/SS
REFIN/SS Common-Mode Range
REFIN/SS Charging Current
REFIN/SS Offset Voltage
REFIN/SS Pulldown Resistance
LX (ALL BUMPS COMBINED)
LX On-Resistance, High Side
LX On-Resistance, Low Side
I
LX
= -500mA
I
LX
= 500mA
V
IN
= V
BST
- V
LX
= 3.3V
V
IN
= 3.3V
High-side sourcing
Low-side sourcing
LX Current-Limit Thresholds
V
IN
= 3.3V
Low-side sinking
Zero-crossing current threshold
Skip high-side sourcing
Sink current-limit DAC steps
LX Leakage Current
LX Switching Frequency
LX Maximum Duty Cycle
LX Minimum On-Time
RMS LX Output Current
ENABLE
EN Input Logic-Low Threshold
(Falling)
0.7
V
V
EN
= 0V
V
IN
= 3.3V
V
IN
= 3.3V
V
IN
= 3.3V
4
V
LX
= 0V
V
LX
= 5V
0.9
90
5.4
24
18
8
7
7
0.2
0.58
4
-10
10
1
96
80
1.1
Steps
µA
MHz
%
ns
A
A
54
50
m
m
V
DD
= 2.9V to 3.5V
V
REFIN/SS
= 0.45V
V
REFIN/SS
= 0.9V, FB shorted to COMP
V
IN
= V
DD
= 3.3V, V
REFIN/SS
= 0.1V
0
6
-4.5
300
8
V
DD
- 2
10
+4.5
V
µA
mV
V
DD
= 2.9V to 3.5V
V
COMP
= 1V, no switching, V
FB
= 0.7V, sink
V
REFIN/SS
= 0.6V
V
FB
= 0.5V, source
V
FB
= 0.7V
0
1
-1
70
0.594
0.6
115
26
V
DD
- 2
0.606
V
dB
MHz
V
mA
nA
V
DD
= 2.9V to 5V, V
FB
= 0.5V, V
REFIN/SS
= 0.6V
V
DD
= 2.9V to 5V, V
FB
= 0.7V, V
REFIN/SS
= 0.6V
V
FB
= 0.7V to 0.5V, V
REFIN/SS
= 0.6V
From COMP to GND, V
IN
= 3.3V, V
COMP
= 100mV,
V
EN
= V
REFIN/SS
= 0V
2
0.68
1.4
6
V
V
V/µs
CONDITIONS
MIN
TYP
MAX
UNITS
MAX15050/MAX15051
3
_______________________________________________________________________________________
High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
MAX15050/MAX15051
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= V
EN
= 5V, C
VDD
= 2.2µF, T
A
= -40°C to +85°C, typical values are at T
A
= +25°C, unless otherwise noted.) (Note 4)
PARAMETER
EN Input Logic-High Threshold
(Rising)
EN Input Current
THERMAL SHUTDOWN
Thermal-Shutdown Threshold
Thermal-Shutdown Hysteresis
POWER-GOOD (PWRGD)
Power-Good Threshold Voltage
Power-Good Edge Deglitch
PWRGD Output-Voltage Low
PWRGD Leakage Current
V
FB
falling, V
REFIN/SS
= 0.6V
V
FB
rising, V
REFIN/SS
= 0.6V
V
FB
falling or rising
I
PWRGD
= 4mA
V
PWRGD
= 5V, V
FB
= 0.9V, V
REFIN/SS
= 0.6V
87
90
92.5
48
0.03
0.1
0.15
1
93
% of
V
REFIN/SS
Clock
cycles
V
µA
Clock
cycles
Clock
cycles
% of
V
REFIN/SS
µs
+165
20
°C
°C
V
EN
= 0 or 5V
CONDITIONS
MIN
1.5
0.01
1
TYP
MAX
UNITS
V
µA
OVERCURRENT LIMIT (HICCUP MODE)
Current-Limit Startup Blanking
Autoretry Restart Time
FB Hiccup Threshold
Hiccup Threshold Blanking Time
V
FB
falling
V
FB
falling
112
896
70
36
Note 4:
Specifications are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by
design and characterization.
Typical Operating Characteristics
(V
IN
= 5V, output voltage = 1.8V, I
LOAD
= 4A, and T
A
= +25°C, circuit of Figure 1, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 5V) (MAX15050)
MAX15050
toc01
EFFICIENCY vs. LOAD CURRENT
V
IN
= 5V (MAX15051)
MAX15050 toc01b
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 3.3V) (MAX15050)
MAX15050
toc02
100
90
EFFICIENCY (%)
80
70
V
OUT
= 1.8V
60
50
40
0.01
0.1
1
V
OUT
= 2.5V
V
OUT
= 1.2V
V
OUT
= 3.3V
100
90
EFFICIENCY (%)
80
V
OUT
= 2.5V
70
V
OUT
= 3.3V
60
50
40
V
OUT
= 1.8V
V
OUT
= 1.2V
100
90
EFFICIENCY (%)
80
70
60
50
40
V
OUT
= 2.5V
V
OUT
= 1.8V
V
OUT
= 1.2V
10
0.1
1
LOAD CURRENT (A)
10
0.01
0.1
1
10
LOAD CURRENT (A)
LOAD CURRENT (A)
4
_______________________________________________________________________________________
High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package
Typical Operating Characteristics (continued)
(V
IN
= 5V, output voltage = 1.8V, I
LOAD
= 4A, and T
A
= +25°C, circuit of Figure 1, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
V
IN
= 3.3V (MAX15051)
MAX15050 toc02b
MAX15050/MAX15051
FREQUENCY vs. INPUT VOLTAGE
MAX15050
toc03
LINE REGULATION
(I
LOAD
= 4A)
0.8
% OUTPUT FROM NORMAL
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
MAX15050 toc04
100
90
EFFICIENCY (%)
80
70
V
OUT
= 1.2V
60
50
40
0.1
1
LOAD CURRENT (A)
V
OUT
= 2.5V
V
OUT
= 1.8V
1.20
1.15
1.10
FREQUENCY (MHz)
1.05
1.00
0.95
0.90
0.85
0.80
T
A
= +25NC
T
A
= -40NC
T
A
= +85NC
1.0
10
2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE (V)
2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
INPUT VOLTAGE (V)
LOAD REGULATION
0.8
% OUTPUT FROM NORMAL
0.6
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
MAX15050 toc05
LOAD-TRANSIENT RESPONSE
MAX15050 toc06
LOAD-TRANSIENT RESPONSE
MAX15050 toc07
1.0
V
OUT
AC-COUPLED
200mV/div
V
OUT
AC-COUPLED
100mV/div
4A
I
OUT
2A/div
1A
4A
I
OUT
2A/div
2A
40µs/div
40µs/div
LOAD CURRENT (A)
SWITCHING WAVEFORMS
MAX15050 toc08
SHUTDOWN WAVEFORM
MAX15050 toc09
V
OUT
AC-COUPLED
50mV/div
V
EN
5V/div
I
LX
1A/div
V
OUT
1V/div
V
LX
2V/div
0V
400ns/div
10µs/div
_______________________________________________________________________________________
5
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