EVALUATION KIT AVAILABLE
MAX15048/MAX15049
Triple-Output Buck Controllers
with Tracking/Sequencing
General Description
The MAX15048/MAX15049 are triple-output pulse-width
modulated (PWM), step-down, DC-DC controllers with
tracking (MAX15048) and sequencing (MAX15049)
options. The devices operate over the 4.7V to 23V input-
voltage range. Each PWM controller provides an adjustable
output down to 0.6V and delivers up to 15A of load current
with excellent load and line regulation. The MAX15049 can
start into prebiased outputs. The MAX15048/MAX15049
are optimized for high-performance, small-size power-
management solutions.
The options of coincident or ratiometric tracking (MAX15048)
or output sequencing (MAX15049) allow the tailoring of
the power-up/power-down sequence depending on the
system requirements. Each of the MAX15048/MAX15049
PWM sections utilizes a voltage-mode control scheme with
external compensation, allowing for good noise immunity
and maximum flexibility with a wide selection of inductor
values and capacitor types. Each PWM section operates at
the same fixed switching frequency that is programmable
from 200kHz to 1.2MHz. Each converter, operating at up to
1.2MHz with 120N out-of-phase, increases the input capaci-
tor ripple frequency up to 3.6MHz, reducing the RMS input
ripple current and thus the size of the input bypass capaci-
tor significantly. The MAX15048/MAX15049 integrate boost
diodes for additional system cost savings.
The MAX15048/MAX15049 include internal undervolt-
age lockout (UVLO) with hysteresis and digital soft-start
(MAX15048/MAX15049)/soft-stop (MAX15048) for glitch-
free power-up and power-down of the converter. The
power-good circuitry (PGOOD) monitors all three outputs
and provides a power-good signal to the system control/
processor when all outputs are within regulation. Protection
features include lossless valley-mode current limit, hiccup
mode output short-circuit protection, and thermal shutdown.
The MAX15048/MAX15049 are available in space-saving,
5mm x 5mm, lead-free, 32-pin TQFN-EP packages and
are specified for operation over the -40NC to +85NC
extended temperature range.
Features
S
4.7V to 23V or 5V ±10% Input Voltage Range
S
Triple-Output Synchronous Buck Controllers with
120° Out-of-Phase Operation
S
Prebias Power-Up (MAX15049)
S
Output Voltage Adjustable Down to 0.6V
S
Coincident/Ratiometric Tracking (MAX15048)
S
Accurate Sequencing Through Enable Threshold
(MAX15049)
S
External Compensation for Maximum Flexibility
S
Digital Soft-Start (MAX15048/MAX15049) and Soft-
Stop (MAX15048)
S
Lossless Valley-Mode Current Sensing Using
R
DS(ON)
of the Low-Side MOSFET
S
PGOOD Output
S
Integrated Bootstrap Diodes
S
Programmable Switching Frequency from 200kHz
to 1.2MHz
S
Thermal Shutdown and Hiccup Mode Short-Circuit
Protection
S
Space-Saving (5mm x 5mm), 32-Pin TQFN
Package
PART
MAX15048ETJ+
MAX15049ETJ+
TEMP RANGE
-40
N
C to +85
N
C
-40
N
C
to
+85
N
C
PIN-PACKAGE
32 TQFN-EP*
32 TQFN-EP*
Ordering Information
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Simplified Typical Operating
Circuit (Coincident Tracking)
V
OUT2
IN
IN
COMP2
PGND2
BST2
DH2
DL2
EN2
EN1
IN
DH1
DH3
V
OUT3
LX3
BST3
DL3
PGND3
FB3
V
OUT1
COMP3
LX1
LX2
FB2
IN
V
OUT1
Applications
Point-of-Load DC-DC Converters
ASIC/CPU/DSP Core and I/O Voltages
DDR Power Supply
Base-Station Power Supplies
Telecom and Networking Power Supplies
RAID Control Power Supplies
Set-Top Boxes
MAX15048
BST1
DL1
PGND1
FB1
PGOOD
SGND
RT
V
REG
V
OUT1
V
OUT2
V
OUT3
SOFT-START
SOFT-STOP
COINCIDENT TRACKING OUTPUTS
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
REG
EN3
COMP1
19-5110; Rev 0; 1/10
MAX15048/MAX15049
Triple-Output Buck Controllers
with Tracking/Sequencing
ABSOLUTE MAXIMUM RATINGS
IN, LX_ to SGND ...................................................-0.3V to +30V
BST_ to SGND .......................................................-0.3V to +30V
BST_ to LX_ .............................................................-0.3V to +6V
REG, DREG_, EN_, RT to SGND .............................-0.3V to +6V
PGOOD, FB_, COMP_ to SGND .............................-0.3V to +6V
DL_ to PGND_ .....................................-0.3V to (V
DREG_
+ 0.3V)
DH_ to LX_ .............................................-0.3V to (V
BST_
+ 0.3V)
PGND to SGND, PGND_
to Any Other PGND_ .........................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70NC)
32-Pin TQFN (derate 34.5mW/NC above +70NC) ...2758.6mW
Junction-to-Case Thermal Resistance (B
JC
)
(Note 1) .....................................................................2NC/W
Junction-to-Ambient Thermal Resistance (B
JA
)
(Note 1) ...................................................................29NC/W
Operating Junction Temperature Range ........... -40NC to +85NC
Maximum Junction Temperature.....................................+150NC
Storage Temperature Range............................ -60NC to +150NC
Lead Temperature (soldering, 10s) ..... ………….………+300NC
Soldering (reflow) ................................. ………….………+260NC
Note 1:
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.maximintegrated.com/thermal-tutorial.
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
= 12V or V
IN
= V
REG
= 5V, V
DREG_
= V
REG
, V
PGND_
= 0V, C
REG
= 2.2FF, R
RT
= 39.2kI, T
A
= -40NC to +85NC, unless otherwise
noted. Typical values are at T
A
= T
J
= +25NC.) (Note 2)
PARAMETER
SYSTEM SPECIFICATIONS
Input Voltage Range
Input Undervoltage-Lockout
Threshold
Input Undervoltage-Lockout
Hysteresis
Operating Supply Current
Shutdown Supply Current
VOLTAGE REGULATOR (REG)
Output-Voltage Set Point
Load Regulation
BOOTSTRAP SWITCH
Internal Boost Switch Resistance
FB_ Input Bias Current
FB_ Voltage Set Point
FB_ to COMP_ Transconductance
COMP_ Output Swing
Open-Loop Gain
Unity-Gain Bandwidth
Soft-Start/-Stop Duration
Reference Voltage Steps
0.75
80
10
2048
64
V
FB_
V
BST,LX
= 5V
-1
0.594
0.600
2.0
3.5
3
+1
0.606
I
FA
V
mS
V
dB
MHz
Clocks
Steps
TRANSCONDUCTANCE ERROR AMPLIFIER/DIGITAL SOFT-START/-STOP
V
REG
V
IN
= 6V to 23V
I
REG
= 0 to 60mA, V
IN
= 6V
4.75
5.25
0.2
V
V
V
IN
= 12V, V
FB_
= 0.8V
V
IN
= 12V, EN_ = 0, PGOOD unconnected
V
IN
V
UVLO
4.7
V
IN
= V
REG
= V
DREG
_ (Note 3)
V
IN
rising
4.5
4.0
4.2
0.3
6
100
9
200
23
5.5
4.4
V
V
V
mA
FA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
Maxim Integrated
MAX15048/MAX15049
Triple-Output Buck Controllers
with Tracking/Sequencing
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V or V
IN
= V
REG
= 5V, V
DREG_
= V
REG
, V
PGND_
= 0V, C
REG
= 2.2FF, R
RT
= 39.2kI, T
A
= -40NC to +85NC, unless otherwise
noted. Typical values are at T
A
= T
J
= +25NC.) (Note 2)
PARAMETER
OSCILLATOR
Switching Frequency Range
(Each Converter)
Switching Frequency Accuracy
(Each Converter)
Phase Delay
RT Current
Minimum Controllable On-Time
Minimum Off-Time
PWM Ramp Amplitude (
P-P
)
PWM Ramp Valley
DRIVERS
DL_, DH_
Break-Before-Make Time
DH1 On-Resistance
DH2 On-Resistance
DH3 On-Resistance
DL1 On-Resistance
DL2 On-Resistance
DL3 On-Resistance
CURRENT-LIMIT AND HICCUP MODE
Cycle-by-Cycle Valley
Current-Limit Threshold
Threshold Temperature
Coefficient
Number of Cumulative
Current-Limit Events to Hiccup
Number of Consecutive
Noncurrent-Limit Cycles to
Clear N
CL
Hiccup Timeout
N
CL
N
CLR
N
HT
V
LIM
T
A
= T
J
= +25NC
69
3333
8
3
4096
mV
ppm/NC
Events
Events
Clock
periods
C
LOAD
= 2nF
Low, sinking 100mA
High, sourcing 100mA
Low, sinking 100mA
High, sourcing 100mA
Low, sinking 100mA
High, sourcing 100mA
Low, sinking 100mA
High, sourcing 100mA
Low, sinking 100mA
High, sourcing 100mA
Low, sinking 100mA
High, sourcing 100mA
35
0.8
2.4
0.8
2.4
0.8
2.4
0.6
2.4
0.6
2.4
0.6
2.4
ns
I
I
I
I
I
I
t
ON(MIN)
t
OFF(MIN)
f
SW
f
SW
minimum, V
RT
= 0.5V
f
SW
maximum, V
RT
= 3V
f
SW
= 500kHz
DH1 rising to DH2 rising and DH2 rising to
DH3 rising
V
RT
= 0.5V to 3V
31.5
-4
120
32
75
300
1.0
1.2
32.5
200
1200
+4
kHz
%
Degrees
FA
ns
ns
V
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Maxim Integrated
3
MAX15048/MAX15049
Triple-Output Buck Controllers
with Tracking/Sequencing
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V or V
IN
= V
REG
= 5V, V
DREG_
= V
REG
, V
PGND_
= 0V, C
REG
= 2.2FF, R
RT
= 39.2kI, T
A
= -40NC to +85NC, unless otherwise
noted. Typical values are at T
A
= T
J
= +25NC.) (Note 2)
PARAMETER
ENABLE/PGOOD
EN_ Threshold
EN_ Threshold Hysteresis
EN_ Input Bias Current
PGOOD Threshold
PGOOD Hysteresis
PGOOD Output Low Level
PGOOD Leakage
THERMAL SHUTDOWN
Thermal-Shutdown Temperature
Thermal-Shutdown Hysteresis
Temperature rising
+160
20
NC
NC
Sinking 3mA
V
PGOOD
= 5V
-1
FB_ rising
-1
0.545
0.550
30
0.1
+1
V
EN-TH
EN_ rising
0.57
0.60
46
+1
0.555
0.63
V
mV
FA
V
mV
V
FA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 2:
100% production tested at T
A
= T
J
= +25NC and T
A
= T
J
= +85NC. Limits at other temperatures are guaranteed by
design.
Note 3:
For 5V applications, connect REG directly to IN.
Typical Operating Characteristics
(V
IN
= 12V, V
DREG_
= V
REG
, V
PGND_
= 0V, C
REG
= 2.2FF, R
RT
= 39.2kI, T
A
= +25NC, unless otherwise noted. See Figure 10.)
CONVERTER 1 EFFICIENCY
vs. LOAD CURRENT
MAX15048 toc01
CONVERTER 2 EFFICIENCY
vs. LOAD CURRENT
MAX15048 toc02
CONVERTER 3 EFFICIENCY
vs. LOAD CURRENT
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
1
2
3
4
LOAD CURRENT (A)
V
IN
= 12V
V
IN
= 5V
MAX15048 toc03
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
V
OUT1
= 3.3V
2.5
V
IN
= 12V
V
IN
= 5V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
V
OUT2
= 1.8V
2.5
V
IN
= 12V
V
IN
= 5V
100
V
OUT3
= 1.2V
5
6
3.0
3.0
4
Maxim Integrated
MAX15048/MAX15049
Triple-Output Buck Controllers
with Tracking/Sequencing
Typical Operating Characteristics (continued)
(V
IN
= 12V, V
DREG_
= V
REG
, V
PGND_
= 0V, C
REG
= 2.2FF, R
RT
= 39.2kI, T
A
= +25NC, unless otherwise noted. See Figure 10.)
CONVERTER 1 OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX15048 toc04
CONVERTER 2 OUTPUT VOLTAGE
vs. LOAD CURRENT
MAX15048 toc05
CONVERTER 3 OUTPUT VOLTAGE
vs. LOAD CURRENT
1.199
1.198
OUTPUT VOLTAGE (V)
1.197
1.196
1.195
1.194
1.193
1.192
1.191
1.190
0
1
2
3
4
LOAD CURRENT (A)
V
IN
= 5V
V
IN
= 12V
MAX15048 toc06
3.330
3.328
3.325
OUTPUT VOLTAGE (V)
3.323
3.320
3.318
3.315
3.313
3.310
3.308
3.305
3.303
3.300
0
0.5
1.0
V
IN
= 5V
1.810
1.809
1.808
OUTPUT VOLTAGE (V)
1.807
1.806
1.805
1.804
1.803
1.802
1.801
1.800
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
V
IN
= 12V
V
IN
= 5V
1.200
V
IN
= 12V
V
OUT1
= 3.3V
1.5
2.0
2.5
3.0
LOAD CURRENT (A)
V
OUT2
= 1.8V
2.5
3.0
V
OUT3
= 1.2V
5
6
SWITCHING FREQUENCY vs. R
RT
MAX15048 toc07
SWITCHING-FREQUENCY ACCURACY
vs. TEMPERATURE
MAX15048 toc08
REG OUTPUT VOLTAGE
vs. INPUT VOLTAGE
5.05
5.00
REG OUTPUT VOLTAGE (V)
4.95
4.90
4.85
4.80
4.75
4.70
4.65
4.60
4.55
4.50
4.70
8.36
12.02
15.68
INPUT VOLTAGE (V)
I
REG
= 60mA
19.34
23.00
MAX15048 toc09
1200
1100
SWITCHING FREQUENCY (kHz)
1000
900
800
700
600
500
400
300
200
15.60
31.22
46.84
62.46
V
IN
= 12V
78.08
0.5
SWITCHING-FREQUENCY ACCURACY (%)
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
f
SW
= 500kHz
5.10
93.70
R
RT
(kI)
-40 -28 -15 -3 10 23 35 48 60 73 85
TEMPERATURE (°C)
ERROR AMP TRANSCONDUCTANCE
vs. TEMPERATURE
MAX15048 toc10
VALLEY CURRENT LIMIT
vs. TEMPERATURE
90
VALLEY CURRENT LIMIT (mV)
85
80
75
70
65
60
55
50
45
40
DL1 AND DH1 PEAK
SOURCE-AND-SINK CURRENT
MAX15048 toc12
MAX15048 toc11
3.0
ERROR AMP TRANSCONDUCTANCE (mS)
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
V
COMP_
= 2V
V
FB_
= 0.6V ± 0.02V
95
V
IN
= 12V
C
LOAD
= 10nF
I
DL1
(1A/div)
I
DH1
(1A/div)
-40 -28 -15 -3 10 23 35 48 60 73 85
TEMPERATURE (°C)
-40 -28 -15 -3 10 23 35 48 60 73 85
TEMPERATURE (°C)
200ns/div
Maxim Integrated
5
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