19-4219; Rev 2; 3/11
KIT
ATION
EVALU
BLE
AVAILA
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
General Description
Features
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5.5V to 28V or 5V ±10% Input Supply Range
0.6V to (0.85 x V
IN
) Adjustable Outputs
Adjustable 200kHz to 1MHz Switching Frequency
Guaranteed Monotonic Startup into a Prebiased
Load
Lossless, Cycle-by-Cycle, Low-Side, Source Peak
Current Limit with Adjustable, Temperature-
Compensated Threshold
Cycle-by-Cycle, Low-Side, Sink Peak Current-
Limit Protection
Proprietary Adaptive Internal Digital Soft-Start
±1% Accurate Voltage Reference
Internal Boost Diodes
Adaptive Synchronous Rectification Eliminates
External Freewheeling Schottky Diodes
Hiccup-Mode Short-Circuit Protection and
Thermal Shutdown
Power-Good Outputs and Analog Enable Inputs
for Power Sequencing
MAX15023
The MAX15023 dual, synchronous step-down controller
operates from a 5.5V to 28V or 5V ±10% input voltage
range and generates two independent output voltages.
Each output is adjustable from 85% of the input voltage
down to 0.6V and supports loads of 12A or higher. Input
voltage ripple and total RMS input ripple current are
reduced by interleaved 180° out-of-phase operation.
The MAX15023 offers the ability to adjust the switching
frequency from 200kHz to 1MHz with an external resistor.
The MAX15023’s adaptive synchronous rectification elimi-
nates the need for external freewheeling Schottky diodes.
The device also utilizes the external low-side MOSFET’s
on-resistance as a current-sense element, eliminating the
need for a current-sense resistor. This protects the DC-
DC components from damage during output overloaded
conditions or output short-circuit faults without requiring a
current-sense resistor. Hiccup-mode current limit reduces
power dissipation during short-circuit conditions. The
MAX15023 includes two independent power-good out-
puts and two independent enable inputs with precise
turn-on/turn-off thresholds, which can be used for supply
monitoring and for power sequencing.
Additional protection features include cycle-by-cycle,
low-side, sink peak current limit, and thermal shutdown.
Cycle-by-cycle, low-side, sink peak current limit prevents
reverse inductor current from reaching dangerous levels
when the device is sinking current from the output. The
MAX15023 also allows prebiased startup without dis-
charging the output and features adaptive internal digital
soft-start. This new proprietary feature enables monoton-
ic charging of externally large output capacitors at start-
up, and achieves good control of the peak inductor
current during hiccup-mode short-circuit protection.
The MAX15023 is available in a space-saving and ther-
mally enhanced 4mm x 4mm, 24-pin TQFN-EP pack-
age. The device operates over the -40°C to +85°C
extended temperature range.
Ordering Information
PART
MAX15023ETG+
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
24 TQFN-EP*
-40°C to +85°C
MAX15023ETG/V+
24 TQFN-EP*
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
Pin Configuration
COMP2
PGND2
13
12
11
10
LX2
BST2
DH2
DH1
BST1
LX1
9
*EP
8
7
1
FB1
2
EN1
3
EN2
4
PGOOD1
5
DL1
6
PGND1
TOP VIEW
PGOOD2
15
18
RT 19
SGND 20
IN 21
LIM2 22
LIM1 23
COMP1 24
17
16
14
Applications
Point-of-Load Regulators
Set-Top Boxes
LCD TV Secondary Supplies
Switches/Routers
Power Modules
DSP Power Supplies
MAX15023
+
TQFN
*EXPOSED PAD (CONNECT TO GROUND).
________________________________________________________________
Maxim Integrated Products
DL2
V
CC
FB2
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.
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
MAX15023
ABSOLUTE MAXIMUM RATINGS
IN to SGND.............................................................-0.3V to +30V
BST_ to V
CC
............................................................-0.3V to +30V
LX_ to SGND .............................................................-1V to +30V
EN_ to SGND............................................................-0.3V to +6V
PGOOD_ to SGND .................................................-0.3V to +30V
BST_ to LX_ ..............................................................-0.3V to +6V
DH_ to LX_ ..........................................….-0.3V to (V
BST_
+ 0.3V)
DL_ to PGND_ ............................................-0.3V to (V
CC
+ 0.3V)
SGND to PGND_ .................................................. -0.3V to +0.3V
V
CC
to SGND................-0.3V to the lower of +6V or (V
IN
+ 0.3V)
All Other Pins to SGND...............................-0.3V to (V
CC
+ 0.3V)
V
CC
Short Circuit to SGND.........................................Continuous
V
CC
Input Current (IN = V
CC
, internal LDO not used) ......600mA
PGOOD_ Sink Current ........................................................20mA
Continuous Power Dissipation (T
A
= +70°C)(Note 1)
24-Pin TQFN-EP (derate 27.8mW/°C above +70°C)......2222.2mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
Note 1:
These power limits are due to the thermal characteristics of the package, absolute maximum junction temperature (150°C),
and the JEDEC 51-7 defined setup. Maximum power dissipation could be lower, limited by the thermal shutdown protection
included in this IC.
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.
PACKAGE THERMAL CHARACTERISTICS (Note 2)
24 TQFN-EP
Junction-to-Ambient Thermal Resistance (θ
JA
)...............+36°C/W
Junction-to-Case Thermal Resistance (θ
JC
)......................+8°C/W
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
http://www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
IN
= 12V, R
T
= 33kΩ, C
VCC
= 4.7µF, C
IN
= 1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 3)
PARAMETER
GENERAL
Input Voltage Range
Quiescent Supply Current
Standby Supply Current
V
CC
REGULATOR
Output Voltage
V
CC
Regulator Dropout
V
CC
Short-Circuit Output Current
V
CC
Undervoltage Lockout
V
CC
Undervoltage Lockout
Hysteresis
ERROR AMPLIFIER (FB_, COMP_)
FB_ Input Voltage Set-Point
FB_ Input Bias Current
V
FB_
I
FB_
V
FB_
= 0.6V
594
-250
600
606
+250
mV
nA
V
CC
6V < V
IN
< 28V, I
LOAD
= 5mA
V
IN
= 6V, 1mA < I
LOAD
< 100mA
I
LOAD
= 100mA
V
IN
= 5V
V
CC_UVLO
V
CC
falling
150
3.6
5.00
5.2
0.07
250
3.8
430
4
5.50
V
V
mA
V
mV
V
IN
I
IN
I
IN_SBY
5.5
V
IN
= V
CC
V
FB1
= V
FB2
= 0.9V, no switching
V
EN1
= V
EN2
= V
SGND
4.5
4.5
0.21
28
5.5
6
0.35
V
mA
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V, R
T
= 33kΩ, C
VCC
= 4.7µF, C
IN
= 1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 3)
PARAMETER
FB_ to COMP_
Transconductance
Amplifier Open-Loop Gain
Amplifier Unity-Gain Bandwidth
COMP_ Swing (High)
COMP_ Swing (Low)
COMP_ Source/Sink Current
ENABLE (EN_)
EN_ Input High
EN_ Input Hysteresis
EN_ Input Leakage Current
OSCILLATOR
Switching Frequency
Switching Frequency
Adjustment Range
PWM Ramp Peak-to-Peak
Amplitude
PWM Ramp Valley
Phase Shift Between
Channels
Minimum Controllable On-Time
Maximum Duty Cycle
OUTPUT DRIVERS
DH_ On-Resistance
DL_ On-Resistance
DH_ Peak Current
DL_ Peak Current
DH_, DL_ Break-Before-Make
Time (Dead Time)
SOFT-START
Soft-Start Duration
Reference Voltage Steps
2048
64
Switching
cycles
Steps
Low, sinking 100mA, V
BST_
- V
LX_
= 5V
High, sourcing 100mA, V
BST_
- V
LX_
= 5V
Low, sinking 100mA, V
CC
= 5.2V
High, sourcing 100mA, V
CC
= 5.2V
C
LOAD
= 10nF
C
LOAD
= 10nF
Sinking
Sourcing
Sinking
Sourcing
1
1.2
0.75
1.4
3
2
3
2
15
Ω
Ω
A
A
ns
86
V
RAMP
V
VALLEY
From DH1 to DH2 rising edges
f
SW
Each converter
(Note 4)
460
200
1.42
0.72
180
60
87.5
100
500
540
1000
kHz
kHz
V
V
Degrees
ns
%
V
EN_H
V
EN_HYS
I
LEAK_EN_
-250
EN_ rising
1.15
1.20
150
+250
1.25
V
mV
nA
I
COMP_
No load at COMP_
| I
COMP_
|, V
COMP_
= 1.5V
45
SYMBOL
g
m
CONDITIONS
I
COMP
= ±40µA
No load
MIN
650
TYP
1200
80
10
2.4
0.6
80
120
MAX
1900
UNITS
µS
dB
MHz
V
V
µA
MAX15023
_______________________________________________________________________________________
3
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
MAX15023
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 12V, R
T
= 33kΩ, C
VCC
= 4.7µF, C
IN
= 1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 3)
PARAMETER
CURRENT LIMIT/HICCUP
Cycle-by-Cycle, Low-Side,
Source Peak Current-Limit
Threshold Adjustment Range
LIM_ Reference Current
LIM_ Reference Current TC
Number of Consecutive Current-
Limit Events to Hiccup
Hiccup Timeout
Cycle-by-Cycle, Low-Side,
Sink Peak Current-Limit Sense
Voltage
BOOST
Boost Switch Resistance
POWER-GOOD OUTPUTS
PGOOD_ Threshold
PGOOD_ Output Leakage
PGOOD_ Output Low Voltage
THERMAL SHUTDOWN
Thermal Shutdown Threshold
Thermal Shutdown Hysteresis
Temperature falling
+150
20
°C
°C
V
FB_
rising
V
FB_
falling
I
LEAK_PGD
V
PGOOD_
= 28V, V
EN_
= 5V, V
FB_
= 0.8V
V
PGOOD_L
I
PGOOD_
= 2mA, EN_ = SGND
88.5
85.5
92.5
89.5
96.5
93.5
1
0.4
%
V
FB(NOMINAL)
µA
V
V
IN
= V
CC
= 5.2V, I
BST_
= 10mA
4.5
8
Ω
Out of soft-start
I
LIM_
Source peak limit = V
LIM_
/10
V
LIM_
= 0.3V to 3V, T
A
= +25°C
V
LIM_
= 0.3V
30
45
50
2400
7
7936
V
LIM_
/
20
300
55
mV
µA
ppm/°C
Events
Switching
cycles
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 3:
All
Electrical Characteristics
limits over temperature are 100% tested at room temperature and guaranteed by design over
the specified temperature range.
Note 4:
Select R
T
as
R
T
(k
Ω
)
=
24806
(f
SW
(kHz))
1.0663
(24806 has a
1
unit).
farad
4
_______________________________________________________________________________________
Wide 4.5V to 28V Input, Dual-Output
Synchronous Buck Controller
Typical Operating Characteristics
(Supply = IN = 12V, unless otherwise noted. See
Typical Application Circuit
of Figure 6.)
MAX15023
EFFICIENCY
vs. LOAD CURRENT
95
90
85
80
75
70
65
60
55
50
45
40
35
30
0.1
V
OUT1
= 3.3V
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
0.1
MAX15023 toc01
EFFICIENCY
vs. LOAD CURRENT
V
OUT1
= 3.3V
MAX15023 toc02
OUTPUT VOLTAGE CHANGE
vs. LOAD CURRENT
100.8
OUTPUT VOLTAGE CHANGE (%)
100.6
100.4
100.2
100.0
99.8
99.6
99.4
99.2
99.0
0
2
4
6
8
10
12
LOAD CURRENT (A)
OUT1
MAX15023 toc03
101.0
EFFICIENCY (%)
EFFICIENCY (%)
V
OUT1
= 1.2V
V
OUT1
= 1.2V
V
IN
= 12V
1
10
100
V
IN
= V
CC
= 5V
1
10
100
LOAD CURRENT (A)
LOAD CURRENT (A)
V
CC
VOLTAGE
vs. LOAD CURRENT
MAX15023 toc04
V
CC
VOLTAGE
vs. IN VOLTAGE
MAX15023 toc05
V
CC
VOLTAGE
vs. TEMPERATURE
5.45
5.40
SUPPLY VOLTAGE (V)
5.35
5.30
5.25
5.20
5.15
5.10
5.05
5.00
I
LOAD
= 5mA
MAX15023 toc06
5.40
5.35
SUPPLY VOLTAGE (V)
5.30
5.50
5.35
5.20
V
CC
VOLTAGE (V)
5.05
4.90
4.75
4.60
4.45
4.30
I
LOAD
= 50mA
I
LOAD
= 5mA
5.50
5.25
5.20
5.15
5.10
5.05
5.00
0
15 30 45 60 75 90 105 120 135 150
LOAD CURRENT (mA)
4.15
4.00
4
8
12
16
20
24
28
IN VOLTAGE (V)
-40
-15
10
35
30
85
TEMPERATURE (°C)
SWITCHING FREQUENCY
vs. R
T
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
10
20
30
40
50
R
T
(kΩ)
60
70
80
90
800
750
700
650
600
550
500
450
400
350
300
250
200
-40
MAX15023 toc07
SWITCHING FREQUENCY
vs. TEMPERATURE
MAX15023 toc08
I
IN
CURRENT
vs. SWITCHING FREQUENCY
V
IN
= 12V
180
I
IN
CURRENT (mA)
150
120
90
60
C
DL
= C
DH
= 1nF
C
DL
= C
DH
= 10nF
C
DL
= C
DH
= 4.7nF
MAX15023 toc09
210
R
T
= 22.1kΩ
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
R
T
= 33.2kΩ
R
T
= 66.5kΩ
30
0
C
DL
= C
DH
= 0nF
-15
10
35
60
85
200 300 400 500 600 700 800 900 1000
SWITCHING FREQUENCY (kHz)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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