19-5918; Rev 1; 8/11
TION KIT
EVALUA BLE
AVAILA
High-Efficiency, 8A, Current-Mode Synchronous
Step-Down Switching Regulator with VID Control
General Description
The MAX15109 high-efficiency, current-mode, synchro-
nous step-down switching regulator with integrated
power switches deliver up to 8A of output current. This
regulator operates from 2.7V to 5.5V and provides four
output voltages using two VID control inputs.
This IC utilizes a current-mode control architecture
with a high gain transconductance error amplifier.
The current-mode control architecture facilitates easy
compensation design and ensures cycle-by-cycle
current limit with fast response to line and load transients.
This regulator offers skip-mode functionality to reduce
current consumption and achieve a higher efficiency at
light loads. The low R
DS(ON)
integrated switches ensure
high efficiency at heavy loads while minimizing critical
inductance, making the layout design a much simpler
task with respect to discrete solutions. The high switching
frequency (1MHz), along with the PWM current-mode archi-
tecture allows for a compact, all-ceramic capacitor design.
The IC features a capacitor-programmable slew-rate
control to reduce input current at the startup and when
the output changes state under VID control. Internal
control circuitry ensures safe-startup into a prebiased
output. Power sequencing is controlled with the enable
input and power-good output.
The IC is available in a 20-bump (4 x 5 array), 2.5mm x
2mm, WLP package and is fully specified over the -40NC
to +85NC temperature range.
Features
S
Continuous 8A Output Current
S
Efficiency Over 90%
S
±
1% Accuracy Over Load, Line, and Temperature
S
Operates from a 2.7V to 5.5V Supply
S
VID Control Inputs for Selecting Output Voltage
S
Programmable Slew-Rate Control
S
Safe Startup into Prebiased Output
S
1MHz Switching Frequency
S
Stable with Low-ESR Ceramic Output Capacitors
S
Enable Input and Power-Good Output for Power-
Supply Sequencing
S
Cycle-by-Cycle Overcurrent Protection Faults
S
Fully Protected Against Overcurrent and
Overtemperature
S
Input Undervoltage Lockout
S
20-Bump (4 x 5 Array), 2.5mm x 2mm, WLP
Package
MAX15109
Ordering Information
PART
MAX15109EWP+
TEMP RANGE
-40NC to +85NC
PIN-PACKAGE
20 WLP
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Applications
Distributed Power Systems
DDR Memory
Notebook Power
2.7V TO
5.5V
VID0
VID1
Typical Operating Circuit
OUTPUT
VID0
VID1
IN
LX
FB
PGND
MAX15109
INX
COMP
PGOOD
SS
_______________________________________________________________
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, 8A, Current-Mode Synchronous
Step-Down Switching Regulator with VID Control
MAX15109
ABSOLUTE MAXIMUM RATINGS
IN, PGOOD to PGND ..............................................-0.3V to +6V
LX to PGND ................................................-0.3V to (V
IN
+ 0.3V)
LX to PGND .....................................-1V to (V
IN
+ 0.3V) for 50ns
EN, COMP, FB, SS, VID0,
VID1 to PGND.........................................-0.3V to (V
IN
+ 0.3V)
Continuous LX Current (Note 1) ............................ -12A to +12A
Output Short-Circuit Duration ....................................Continuous
Continuous Power Dissipation (T
BOARD
= +70NC)
WLP (derate 31.7mW/NC above T
BOARD
= +70NC) ......1.27W
Operating Temperature Range .......................... -40NC to +85NC
Operating Junction Temperature (Note 2) ......................+110NC
Storage Temperature Range............................ -65NC to +150NC
Soldering Temperature (reflow) (Note 3) ........................+260NC
Note 1:
LX has internal clamp diodes to PGND and IN. Do not exceed the power dissipation limits of the device when forward
biasing these diodes.
Note 2:
Limit the junction temperature to +110NC for continuous operation at full current.
Note 3:
The WLP package is constructed using a unique set of package techniques that impose a limit on the thermal profile the
device can be exposed to during board-level solder attach and rework. This limit permits only the use of the solder pro-
files recommended in the industry-standard specification JEDEC 020A, paragraph 7.6, Table 3 for IR/VPR and convection
reflow. Preheating is required. Hand or wave soldering is not allowed.
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
= 5V, C
SS
= 4.7nF, T
A
= T
J
= -40NC to +85NC. Typical values are at T
A
= +25NC, unless otherwise noted.) (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
Output Voltage Accuracy
FB Input Bias Current
COMP to Current-Sense
Transconductance
COMP Clamp Low
Compensation RAMP Valley
POWER SWITCHES
High-Side Switch Current-Limit
Threshold
Low-Side Switch Sink
Current-Limit Threshold
Low-Side Switch Source
Current-Limit Threshold
I
HSCL
14
14
14
A
A
A
g
MV
A
VEA
V
FB
I
FB
G
MOD
V
FB
= 1V
Over line, load, and temperature
-1
-100
25
0.93
1
1.4
90
+1
+100
mS
dB
%
nA
A/V
V
V
I
IN
SYMBOL
V
IN
V
EN
= 0V
V
EN
= 5V, V
FB
= 1V, not switching
LX starts switching, V
IN
rising
LX stops switching, V
IN
falling
CONDITIONS
MIN
2.7
0.3
3.4
2.6
200
TYP
MAX
5.5
3
6
2.7
UNITS
V
FA
mA
V
mV
2
______________________________________________________________________________________
High-Efficiency, 8A, Current-Mode Synchronous
Step-Down Switching Regulator with VID Control
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 5V, C
SS
= 4.7nF, T
A
= T
J
= -40NC to +85NC. Typical values are at T
A
= +25NC, unless otherwise noted.) (Note 4)
PARAMETER
LX Leakage Current
RMS LX Output Current
OSCILLATOR
Switching Frequency
Maximum Duty Cycle
Minimum Controllable On-Time
ENABLE
EN Input High Threshold Voltage
EN Input Low Threshold Voltage
EN Input Leakage Current
VID CONTROL INPUTS
VID_ High Threshold Voltage
VID_ Low Threshold Voltage
VID1 Input Leakage Current
VID0 Input Leakage Current
SOFT-START, PREBIAS
Soft-Start Current
SS Discharge Resistance
SS Prebias Mode Stop Voltage
HICCUP
Number of Consecutive
Current-Limit Events to Hiccup
Timeout
POWER-GOOD OUTPUT
VID0
0
0
1
1
VID1
0
1
0
1
824
705
654
580
559
853
729
677
602
578
22
884
755
701
624
600
100
1
+160
Temperature falling
25
8
1024
Events
Clock
Cycles
I
SS
R
SS
V
SS
= 0.45V, sourcing
I
SS
= 10mA, sinking
SS rising
10
8.5
0.58
FA
I
V
V
VID_
rising
V
VID_
falling
V
VID1
= 5V
V
VID0
= 5V
0.67
0.33
30
1
V
V
FA
FA
V
EN
rising
V
EN
falling
V
EN
= 5V
1.3
0.4
1
V
V
FA
f
SW
D
MAX
850
1000
94
100
1150
kHz
%
ns
SYMBOL
V
EN
= 0V
8
CONDITIONS
MIN
TYP
MAX
10
UNITS
FA
A
MAX15109
PGOOD Threshold
PGT
FB rising
mV
FB falling
PGOOD V
OL
PGOOD Leakage
THERMAL SHUTDOWN
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
I
PGOOD
= 5mA, V
FB
= 0.5V
V
PGOOD
= 5V, V
FB
= 1V
mV
mV
FA
NC
NC
Note 4:
Specifications are 100% production tested at T
A
= +25NC. Limits over the operating temperature range are guaranteed by
design and characterization.
_______________________________________________________________________________________
3
High-Efficiency, 8A, Current-Mode Synchronous
Step-Down Switching Regulator with VID Control
MAX15109
Typical Operating Characteristics
(Circuit of
Typical Application Circuit,
T
A
= +25NC, unless otherwise noted.)
EFFICIENCY vs. OUTPUT CURRENT
(V
IN
= 5V)
MAX15109 toc01
EFFICIENCY vs. OUTPUT CURRENT
(V
IN
= 3.3V)
MAX15109 toc02
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
(V
OUT
= 0.9V)
MAX15109 toc03a
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
1
2
3
4
5
V
OUT
= 0.9V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
OUT
= 0.9V
0.915
0.910
OUTPUT VOLTAGE (V)
0.905
0.900
0.895
0.890
0.885
V
OUT
= 0.675V
V
OUT
= 0.725V
V
OUT
= 0.8V
V
OUT
= 0.675V
V
OUT
= 0.725V
V
OUT
= 0.8V
4A LOAD
8A LOAD
6
7
8
0
1
2
3
4
5
6
7
8
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
SUPPLY VOLTAGE (V)
OUTPUT VOLTAGE vs. SUPPLY VOLTAGE
(V
OUT
= 0.675V)
MAX15109 toc03b
OUTPUT VOLTAGE vs. OUTPUT CURRENT
(V
OUT
= 0.9V)
MAX15109 toc04a
0.690
0.685
OUTPUT VOLTAGE (V)
0.680
0.675
0.670
0.665
0.660
2.7
3.1
3.5
3.9
4.3
4.7
5.1
0.915
0.910
OUTPUT VOLTAGE (V)
0.905
0.900
0.895
0.890
0.885
4A LOAD
V
IN
= 5V
8A LOAD
V
IN
= 3.3V
5.5
0
1
2
3
4
5
6
7
8
SUPPLY VOLTAGE (V)
OUTPUT CURRENT (A)
OUTPUT VOLTAGE vs. OUTPUT CURRENT
(V
OUT
= 0.675V)
MAX15109 toc04b
OUTPUT VOLTAGE ERROR
vs. SUPPLY VOLTAGE
MAX15109 toc05
0.690
0.685
OUTPUT VOLTAGE (V)
0.680
0.675
0.670
0.665
0.660
0
1
2
3
4
5
6
7
0
-0.10
-0.20
-0.30
-0.40
-0.50
OUTPUT VOLTAGE ERROR (%)
V
IN
= 5V
V
OUT
= 0.675V
V
IN
= 3.3V
V
OUT
= 0.9V
8
-0.60
2.7
3.1
3.5
3.9
4.3
I
LOAD
= 8A
4.7
5.1
5.5
OUTPUT CURRENT (A)
SUPPLY VOLTAGE (V)
4
______________________________________________________________________________________
High-Efficiency, 8A, Current-Mode Synchronous
Step-Down Switching Regulator with VID Control
Typical Operating Characteristics (continued)
(Circuit of
Typical Application Circuit,
T
A
= +25NC, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
(V
IN
= 5V, V
OUT
= 0.9V)
SWITCHING WAVEFORMS
(I
OUT
= 8A, V
IN
= 5V)
MAX15109
MAX15109 toc06
MAX15109 toc07
V
OUT
10mV/div
AC-COUPLED
V
OUT
10mV/div
AC-COUPLED
I
LX
5A/div
4A
I
OUT
2A
40µs/div
400ns/div
V
LX
5V/div
SWITCHING WAVEFORM IN SKIP MODE
(I
OUT
= 10mA, V
IN
= 5V)
MAX15109 toc08
SHUTDOWN WAVEFORM
(I
LOAD
= 8A)
MAX15109 toc09
V
OUT
10mV/div
AC-COUPLED
I
LX
2A/div
V
LX
5V/div
V
EN
2V/div
V
LX
5V/div
I
LX
5A/div
V
OUT
500mV/div
V
PGOOD
2V/div
10µs/div
40µs/div
SOFT-START WAVEFORMS
(NO LOAD, SKIP MODE)
MAX15109 toc10a
SOFT-START WAVEFORMS
(I
LOAD
= 8A)
V
EN
2V/div
V
LX
5V/div
MAX15109 toc10b
V
EN
2V/div
V
LX
5V/div
V
OUT
500mV/div
V
PGOOD
5V/div
200µs/div
200µs/div
V
OUT
500mV/div
V
PGOOD
5V/div
_______________________________________________________________________________________
5
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