19-4107; Rev 1; 7/11
KIT
ATION
EVALU
BLE
AVAILA
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers
General Description
The MAX15022 is a dual-output, pulse-width-modulated
(PWM), step-down DC-DC regulator with dual LDO con-
trollers. The device operates from 2.5V to 5.5V and
each output can be adjusted from 0.6V to the input
supply (V
AVIN
). The MAX15022 delivers up to 4A (regu-
lator 1) and 2A (regulator 2) of output current with two
LDO controllers that can be used to drive two external
PNP transistors to provide two additional outputs. This
device offers the ability to adjust the switching frequen-
cy from 500kHz to 4MHz and provides the capability of
optimizing the design in terms of size and performance.
The MAX15022 utilizes a voltage-mode control scheme
with external compensation to provide good noise
immunity and maximum flexibility in selecting inductor
values and capacitor types. The dual switching regula-
tors operate 180° out-of-phase, thereby reducing the
RMS input ripple current and thus the size of the input
bypass capacitor significantly.
The MAX15022 offers the ability to track (coincident or
ratiometric) or sequence during power-up and power-
down operation. When sequencing, it powers up glitch-
free into a prebiased output.
Additional features include an internal undervoltage
lockout with hysteresis and a digital soft-start/soft-stop
for glitch-free power-up and power-down. Protection
features include lossless cycle-by-cycle current limit,
hiccup-mode output short-circuit protection, and ther-
mal shutdown.
The MAX15022 is available in a space-saving, 5mm x
5mm, 28-pin TQFN-EP package and is specified for
operation from -40°C to +125°C temperature range.
Features
o
2.5V to 5.5V Input-Voltage Range
o
Dual-Output Synchronous Buck Regulators
o
Integrated Switches for 4A and 2A Output
Currents
o
180° Out-Of-Phase Operation
o
Output Voltage Adjustable from 0.6V to V
AVIN
o
Two LDO Controllers
o
Lossless, Cycle-by-Cycle Current Sensing
o
External Compensation for Maximum Flexibility
o
Digital Soft-Start and Soft-Stop for Tracking
Applications
o
Digital Soft-Start into a Prebiased Load for
Sequencing Applications
o
Sequencing or Coincident/Ratiometric Tracking
o
Programmable Switching Frequency from 500kHz
to 4MHz
o
Thermal Shutdown and Hiccup-Mode Short-
Circuit Protection
o
30µA Shutdown Current
o
100% Maximum Duty Cycle
o
Space-Saving (5mm x 5mm) 28-Pin TQFN
Package
MAX15022
Pin Configuration
PGND2
PVIN2
EN4
EN3
15
14
13
12
FB3
B3
COMP1
FB1
EN1
DVDD1
PGND1
11
10
9
8
2
PGND1
3
LX1
4
PVIN1
5
PVIN1
6
LX1
7
PGND1
FB4
LX2
TOP VIEW
Applications
RFID Reader Cards
Power-over-Ethernet (PoE) IP Phones
Automotive Multimedia
Multivoltage Supplies
Networking/Telecom
B4 22
COMP2 23
FB2 24
EN2 25
SGND 26
AVIN 27
21
20
19
18
17
16
MAX15022
Ordering Information
PART
MAX15022ATI+
MAX15022ATI/V+
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
28 TQFN-EP*
28 TQFN-EP*
RT 28
1
+
*EP
+Denotes
a lead(Pb)-free/RoHS-compliant package.
*EP
= Exposed pad.
/V denotes an automotive qualified part.
SEL
THIN QFN
(5mm x 5mm)
*EP = EXPOSED PAD.
________________________________________________________________
Maxim Integrated Products
DVDD2
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.
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers
MAX15022
ABSOLUTE MAXIMUM RATINGS
AVIN, PVIN_, B_, DVDD_, EN_, FB_, RT,
SEL to SGND .........................................................-0.3V to +6V
COMP_ to SGND .....................................-0.3V to (V
AVIN
+ 0.3V)
PGND_ to SGND ...................................................-0.3V to +0.3V
LX Current (Note 1)
Regulator 1...............................................................................6A
Regulator 2...............................................................................3A
Current into Any Pin Other than PVIN_,
LX_ and PGND_.............................................................±50mA
Continuous Power Dissipation (T
A
= +70°C)
TQFN (derate 34.5mW/°C above +70°C) ................2758.6mW
Operating Temperature Range .........................-40°C to +125°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:
LX has internal diodes to PGND_ and PVIN_. Applications that forward bias these diodes should take care not to exceed
the IC’s package power dissipation limits.
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)
TQFN
Junction-to-Ambient Thermal Resistance (θ
JA
)...............29°C/W
Junction-to-Case Thermal Resistance (θ
JC
)......................2°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
www.maxim-ic.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(V
AVIN
= V
PVIN_
= V
DVDD_
= 3.3V, V
PGND_
= V
SGND
= 0V, R
T
= 25kΩ, and T
A
= T
J
= -40°C to +125°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
SYSTEM SPECIFICATIONS
Input-Voltage Range
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
Operating Supply Current
Shutdown Supply Current
PWM DIGITAL SOFT-START/SOFT-STOP
Soft-Start/Soft-Stop Duration
Reference Voltage Steps
PWM ERROR AMPLIFIERS
FB1, FB2 Input Bias Current
FB1, FB2 Voltage Set-Point
COMP1, COMP2 Voltage Range
Error-Amplifier Open-Loop Gain
Error-Amplifier Unity-Gain
Bandwidth
I
COMP
_ = -250µA to +250µA
-1
0.593
0.3
80
12
0.599
+1
0.605
V
AVIN
- 0.5
µA
V
V
dB
MHz
4096
64
Clock
Cycles
Steps
V
EN_
= 1.3V, V
FB_
= 0.8V
V
EN_
= 0V
V
AVIN
= V
PVIN1
= V
PVIN2
= V
DVDD1
=
V
DVDD2
AVIN rising
2.5
2.1
2.2
0.12
3.5
30
6
65
5.5
2.3
V
V
V
mA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers
MAX15022
ELECTRICAL CHARACTERISTICS (continued)
(V
AVIN
= V
PVIN_
= V
DVDD_
= 3.3V, V
PGND_
= V
SGND
= 0V, R
T
= 25kΩ, and T
A
= T
J
= -40°C to +125°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
LDO CONTROLLERS
FB3, FB4 Input Bias Current
FB3, FB4 Voltage Set-point
FB3, FB4 to B3, B4
Transconductance
B3, B4 Driver Sink Current
LDO Soft-Start Duration
LDO Reference Voltage Steps
POWER MOSFETS
Regulator 1 p-Channel MOSFET
R
DSON
Regulator 1 n-Channel MOSFET
R
DSON
Regulator 1 Gate Charge
Maximum LX1 RMS Current
Regulator 2 p-Channel MOSFET
R
DSON
Regulator 2 n-Channel MOSFET
R
DSON
Regulator 2 Gate Charge
Maximum LX2 RMS Current
PWM CURRENT LIMIT AND HICCUP MODE
Regulator 1 Peak Current Limit
Regulator 1 Valley Current Limit
Regulator 2 Peak Current Limit
Regulator 2 Valley Current Limit
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
PVIN
= V
AVIN
= 3.3V
V
PVIN
= V
AVIN
= 2.5V
V
PVIN
= V
AVIN
= 3.3V
V
PVIN
= V
AVIN
= 2.5V
V
PVIN
= V
AVIN
= 3.3V
V
PVIN
= V
AVIN
= 2.5V
V
PVIN
= V
AVIN
= 3.3V
V
PVIN
= V
AVIN
= 2.5V
4.5
3.40
4.0
3.0
2.25
1.70
2.0
1.5
4.9
3.65
5.0
3.7
2.45
1.85
2.5
1.85
4
3
8192
5.3
3.95
5.65
4.25
2.65
1.98
2.83
2.13
A
A
A
A
Clock
Cycles
Clock
Cycles
Clock
Cycles
V
DVDD2
= 5V
V
DVDD2
= 5V
V
DVDD2
= 5V
V
DVDD1
= 5V
V
DVDD1
= 5V
V
DVDD1
= 5V
50
30
8
4
100
60
4
2
180
100
90
50
mΩ
mΩ
nC
A
mΩ
mΩ
nC
A
5mA sink current, V
B_
= 0.5V to 5.5V
2.5mA to 10mA sink current,
V
B_
= 0.5V to 5.5V
V
FB3,
V
FB4
= 0V, V
B_
= 0.5V to 5.5V
-250
0.585
0.56
20
512
64
0.600
1.20
+250
0.615
2.30
nA
V
S
mA
Clock
Cycles
Steps
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
_______________________________________________________________________________________
3
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers
MAX15022
ELECTRICAL CHARACTERISTICS (continued)
(V
AVIN
= V
PVIN_
= V
DVDD_
= 3.3V, V
PGND_
= V
SGND
= 0V, R
T
= 25kΩ, and T
A
= T
J
= -40°C to +125°C, unless otherwise noted.
Typical values are at T
A
= +25°C.) (Note 3)
PARAMETER
ENABLE/SEL
EN_ Threshold
EN_ Hysteresis
EN_ Input Current
SEL High Threshold
SEL Low Threshold
SEL Input Bias Current
OSCILLATOR
Switching Frequency Range
Oscillator Accuracy
Phase Shift Between Regulators
RT Current
RT Voltage Range
Minimum Controllable On-Time
Minimum Controllable Off-Time
PWM Ramp Amplitude
PWM Ramp Valley
THERMAL SHUTDOWN
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Temperature rising
+160
15
°C
°C
V
RT
0 < V
RT
< 1.067V
31.30
0.130
60
60
V
AVIN
/4
0.3
f
SW
f
SW
= 4MHz x [V
RT
(V)/1.067(V)] (Note 4)
f
SW
≤
1500kHz
f
SW
> 1500kHz
-6
-10
180
32.00
32.58
1.067
4000
+6
+10
kHz
%
Degrees
µA
V
ns
ns
V
V
Present only during startup
-100
-2.5
0.85 x V
AVIN
0.2 x V
AVIN
+100
V
EN_
rising
1.207
1.225
0.12
+2.5
1.243
V
V
µA
V
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 3:
Specifications are 100% production tested at T
A
= +25°C and T
A
= +125°C. Maximum and minimum specifications over
temperature are guaranteed by design.
Note 4:
When operating with V
AVIN
= 2.5V, the maximum operating frequency should be derated to 3MHz.
4
_______________________________________________________________________________________
Dual, 4A/2A, 4MHz, Step-Down DC-DC
Regulator with Dual LDO Controllers
MAX15022
Typical Operating Characteristics
(V
AVIN
= V
DVDD1
= V
DVDD2
= V
PVIN1
= V
PVIN2
= 5V, V
OUT1
= 3.3V, V
OUT2
= 1.5V, V
PGND_
= 0V, R
T
= 16.5kΩ. T
A
= +25°C, unless
otherwise noted.)
CHANNEL 1 EFFICIENCY
vs. LOAD CURRENT
MAX15022 toc01
CHANNEL 1 EFFICIENCY
vs. LOAD CURRENT
MAX15022 toc02
CHANNEL 2 EFFICIENCY
vs. LOAD CURRENT
90
80
EFFICIENCY (%)
70
60
50
40
30
P
VIN2
= 5V
P
VIN2
= 3.3V
MAX15022 toc03
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
100
1000
LOAD CURRENT (mA)
V
OUT1
= 1.8V
f
SW
= 2MHz
EN2 = 0V
V
PVIN1
= 5V
V
PVIN1
= 3.3V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
PVIN1
= 5V
f
SW
= 2MHz
EN2 = 0V
100
1000
LOAD CURRENT (mA)
V
OUT1
= 3.3V
V
OUT1
= 1.8V
V
OUT1
= 1.0V
100
20
10
0
5000
100
V
OUT2
= 1.5V
f
SW
= 2MHz
EN1 = 0V
1000
LOAD CURRENT (mA)
3000
5000
CHANNEL 2 EFFICIENCY
vs. LOAD CURRENT
MAX15022 toc04
CHANNEL 1
LOAD REGULATION
MAX15022 toc05
CHANNEL 2
LOAD REGULATION
1.5065
1.5060
1.5055
V
OUT2
(V)
1.5050
1.5045
1.5040
1.5035
1.5030
V
PVIN2
= 3.3V
V
PVIN2
= 5V
MAX15022 toc06
100
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
100
1000
LOAD CURRENT (mA)
V
PVIN2
= 5V
f
SW
= 2MHz
EN1 = 0V
V
OUT2
= 1.0V
V
OUT2
= 1.5V
V
OUT2
= 2.5V
3.320
3.318
3.316
3.314
V
OUT1
(V)
3.312
3.310
3.308
3.306
3.304
3.302
3.300
0
0.5
1.0
V
PVIN1
= 5V
f
SW
= 2MHz
1.5 2.0 2.5 3.0
LOAD CURRENT (A)
3.5
1.5070
1.5025
1.5020
4.0
0
LOAD CURRENT (A)
f
SW
= 2MHz
0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
3000
SWITCHING FREQUENCY
vs. RT RESISTANCE
MAX15022 toc07
SWITCHING FREQUENCY
vs. TEMPERATURE
CHANGE IN SWITCHING FREQUENCY (%)
0.4
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
-0.4
-0.5
f
SW
= 2MHz
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX15022 toc08
4.5
4.0
SWITCHING FREQUENCY (MHz)
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0
5
10
15
20
25
30
0.5
35
RT RESISTANCE (kΩ)
_______________________________________________________________________________________
5
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