MAX20429CAFNA [MAXIM]
Dual 6A High-Efficiency Low Voltage Buck Converter;型号: | MAX20429CAFNA |
厂家: | MAXIM INTEGRATED PRODUCTS |
描述: | Dual 6A High-Efficiency Low Voltage Buck Converter |
文件: | 总18页 (文件大小:715K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
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MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
General Description
Benefits and Features
The MAX20429 is a high-efficiency dual switching regula-
tor that delivers up to 6A (peak) load current per output
from 0.5V to 1.5875V in 12.5mV steps and 1.6V to 3.8V
in 50mV steps. The IC operates from 3V to 5.5V, making
it ideal for on-board point-of-load and post-regulation ap-
plications. Total output error is less than ±1.0% over load,
line, and temperature.
● High-Feature Set in an Ultra-Small Footprint
• High-Efficiency DC-DC Converter
• Two Independent Outputs, up to 6A per Output
• 3.0V to 5.5V Operating Supply Voltage
• Resistor-Adjustable Output Voltage
• Optional Factory-Preset Output Voltage
• 2.1MHz/3.2MHz Options
• Enable Input
• Individual RESET Outputs
• Spread-Spectrum Option
• Peak Current-Mode Architecture
• 3mm x 3.5mm FCQFN
The MAX20429 features fixed-frequency PWM mode op-
eration with a switching frequency of 2.1MHz or 3.2MHz.
High-frequency operation allows for an all-ceramic capac-
itor design with small external components.
The low-resistance on-chip switches ensure high efficien-
cy at heavy loads while minimizing critical inductances,
making the layout a much simpler task with respect to dis-
crete solutions. Following a simple layout and footprint en-
sures first-pass success in new designs.
● High-Precision
• 108/92% OV/UV Monitor
• ±3% OV/UV Accuracy
• ±1% Output Voltage Accuracy
• Excellent Load-Transient Performance
The device features the MAXQ™ technology, which pro-
vides precision transient performance and phase margin.
This allows obtaining the maximum power, performance,
and precision from the converter over a very wide range of
configurations.
• PWM and SKIP Mode Operation
TM
• MAXQ
Power Architecture
● High Efficiency
• Up to 96% Efficiency 5V to 3.3V
• Up to 90% Efficiency 5V to 1V
The MAX20429 has separate enable inputs and status
outputs for each buck converter. The output voltage is
preset at the factory to allow customers to achieve ±1%
output-voltage accuracy without using expensive 0.1% re-
sistors. The devices offer factory programmable soft-start
and RESET times.
● -40°C to +125°C Operating Temperature Range
● AEC-Q100 Qualified
Ordering Information appears at end of data sheet.
The devices include over-temperature shutdown and over-
current limiting. All devices are designed to operate from
–40 °C to +125 °C ambient temperature range.
Applications
● Secondary Regulator for SoC / MCU Supply
19-100842; Rev 1; 12/20
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Simplified Block Diagram
VIN
PV1,PV2
OUT1
CIN
L
LX1
V
OUT1
SYNC
VDD
COUT
VIN
PGND1
MAX20429
GND
OUT2
L
LX2
V
COUT
OUT2
ENABLE 1
ENABLE 2
EN1
EN2
PGND2
VIO
PGND
RESET1
RESET2
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Maxim Integrated | 2
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
TABLE OF CONTENTS
General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Benefits and Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Simplified Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Absolute Maximum Ratings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
FC2QFN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Pin Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
MAX20429 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Functional Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Internal Block Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
MAXQ Power Architecture (No Wasted Performance). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Enable Input (EN1, EN2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
RESET Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Internal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Synchronization (SYNC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Soft-Start and Soft-Shutdown. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Current Limit / Short-Circuit Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
PWM/SKIP Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Overtemperature Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Spread Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Resistor-Adjustable Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Inductor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Output Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Typical Application Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Typical Application Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
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Maxim Integrated | 3
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
LIST OF TABLES
Table 1. Slope Compensation Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 2. Output Capacitor Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
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Maxim Integrated | 4
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Absolute Maximum Ratings
PV1, PV2 to GND....................................................... -0.3V to 6V
LX Continuous RMS Current (15000hr lifespan) ......................6A
Output Short-Circuit Duration......................................Continuous
Continuous Power Dissipation (4-Layer Board) (T A = +70°C,
derate 51.8 mW/°C above +70°C. ) .......................... to 4145mW
Ambient Operating Temperature ........................-40°C to +125°C
Operating Junction Temperature ........................-40°C to +150°C
Storage Temperature Range ..............................-65°C to +150°C
Lead Temperature Range.................................................+300°C
V
DD
to GND................................................................ -0.3V to 6V
OUT1, OUT2 to GND ..................................... -0.3V to V +0.3V
DD
LX1, LX2 to GND............................................... -0.3 to PV_ + 0.3
EN1, EN2, RESET1, RESET2 to GND ...................... -0.3V to 6V
SYNC to GND................................................. -0.3V to V +0.3V
DD
PGND_ to GND ..................................................... -0.3V to +0.3V
LX Continuous RMS Current (95000hr lifespan)...................... 4A
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 Information
FC2QFN
Package Code
F183A3FY+1
21-100428
90-100155
Outline Number
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ
)
19.3°C/W
5.0°C/W
JA
Junction to Case (θ
)
JC
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates
RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
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.
Electrical Characteristics
°
°
°
(PV1 = PV2 = 5V, T = -40 C to +150 C, unless otherwise noted. Typical values are at T = 25 C under normal conditions unless
J
A
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
5.5
5
UNITS
PV Supply Voltage
Range
V
PV
3.0
V
V
V
= V
= low, T = +25°C
3
EN1
EN2
A
Supply Current
I
µA
VDD
= high, V
= low, no load
440
2.6
2.7
2.1
3.2
EN1
EN2
V
DD
UVLO
V
V
Falling
Rising
2.4
V
V
UVLO
VDD UVLO
2.9
2.3
3.6
UVLO
f
f
= 2.1MHz
= 3.2MHz
1.9
2.9
SW
Oscillator Frequency
f
MHz
%
SW
SW
Spread Spectrum
Range
+3
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Maxim Integrated | 5
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Electrical Characteristics (continued)
°
°
°
(PV1 = PV2 = 5V, T = -40 C to +150 C, unless otherwise noted. Typical values are at T = 25 C under normal conditions unless
J
A
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
OUT
Programmable voltage range, 3.0 V ≤
0.5
3.8
V
V
PV
≤ 5.5V (Note 4)
Output Voltage
V
Step size, 0.5 V ≤ V
4)
≤ 1.5875 V (Note
≤ 3.8 V (Note 4)
OUT
OUT
OUT
12.5
mV
Step size, 1.6 V ≤ V
Option 1
50
0.825
1.1
0.7
0.9
1
1.3
1.65
2
Option 2
Skip Mode Peak Current
I
A
SKIP
Option 3
1.15
1.3
1.4
Option 4
1.69
PWM mode, 0A ≤ I
≤ I
,
MAX
LOAD
MAX(3.0V,V
+ 0.5V) ≤ V ≤ 5.5V,
≥ 3.8V
-1
-7
1
%
OUT
IN
0.6V ≥ V
OUT
PWM mode, 0A ≤ I
≤ I
, 0.5V ≤
LOAD
MAX
+7
mV
Voltage Accuracy
V
OUT
≤ 0.5875V
PWM mode, 0A ≤ I
MAX(3.0V,V
≤ I
,
LOAD
MAX
+ 0.5V) ≤ V ≤ 5.5V,
OUT
IN
-1
+1
%
V
OUT
= 0.6V. ADJ variant
MAX20429CAFNA/VY+
DC Load Regulation
DC Line Regulation
0A ≤ I ≤ I (PWM mode)
0.1
0.05
18
%
LOAD
MAX
PV_ from 3V to 5.5V
Including metal and package
Intrinsic
%/V
R
50
50
High-Side On-
Resistance
ON-H
mΩ
16
R
Including metal and package
Intrinsic
12
Low-Side On-
Resistance
ON-L
mΩ
%
10
V
IN
= 5V, V
= 1.8V, L = 220nH, DCR
OUT
Efficiency
92.4
= 13mΩ
Option 1 (2.0A DC)
Option 2 (3.0A DC)
Option 3 (4.0A DC)
Option 4 (6.0A DC)
2.6
3.9
5.2
7.8
3.5
4.7
6.0
10
Current-Limit Threshold
I
A
LIM
nMOS Zero-Crossing
Threshold
I
100
mA
ZX
LX_ Rise/Fall Time
Dead Time
PV = 3.3V, I
PV = 3.3V, I
= 2A (Note 4)
= 2A (Note 4)
1
3
ns
ns
µA
%
OUT
OUT
t
DEAD
LX_ Leakage Current
Max Duty Cycle
Minimum On-Time
0.01
D
Effective
100
MAX
t
35
50
60
ns
ON
LX_ Discharge
Resistance
R
Ω
DIS
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Maxim Integrated | 6
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Electrical Characteristics (continued)
°
°
°
(PV1 = PV2 = 5V, T = -40 C to +150 C, unless otherwise noted. Typical values are at T = 25 C under normal conditions unless
J
A
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LX_ Switching Phase
LX1 rising to LX2 rising (Note 4)
180
°
Option 1 (step = 12.5mV for V
1.6V, otherwise 50mV)
<
<
<
<
OUT
OUT
OUT
OUT
32
16
8
Option 2 (step = 12.5mV for V
1.6V, otherwise 50mV)
Soft-Start Rate
clks/step
Option 3 (step = 12.5mV for V
1.6V, otherwise 50mV)
Option 4 (step = 12.5mV for V
1.6V, otherwise 50mV)
4
Option 1
Hi-Z
32
Soft-Shutdown Rate
Voltage Accuracy
t
SHDN
Option 2 (step = 12.5mV for V
1.6V, otherwise 50mV)
<
OUT
clks/step
mV
PWM mode, 0A ≤ I
≤ I
, 0.5V ≤
MAX
LOAD
-7
+7
V
OUT
≤ 0.5875V
RESET
OV Threshold Range
UV Threshold Range
V
V
Rising
Falling
104
89
108
92
112
95
%
%
OUT
OUT
Option 1 (15.6ms@2.1MHz,
10.2ms@3.2MHz)
32768
16384
8192
Option 2 (7.8ms@2.1MHz,
5.1ms@3.2MHz)
Active Timeout Period
Output Low Level
t
clks
HOLD
Option 3 (3.9ms@2.1MHz,
2.5ms@3.2MHz)
Option 4 (488μs@2.1MHz,
320μs@3.2MHz)
1024
0.1
ISINK = 3mA
(Note 4)
0.2
V
Thermal Shutdown
Temperature
T
165
ºC
SHDN
Thermal Shutdown
Hysteresis
T
(Note 4)
15
ºC
HYS
Leakage Current
OV/UV Filter
0.1
10
µA
μs
ENABLE INPUT (EN)
Input High
Rising
Falling
1.5
1.8
V
V
Input Low
0.5
0.4
Hysteresis
0.05
0.1
V
Leakage Current
SYNCHRONIZATION (SYNC)
Input High
µA
V
V
Input Low
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Maxim Integrated | 7
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Electrical Characteristics (continued)
°
°
°
(PV1 = PV2 = 5V, T = -40 C to +150 C, unless otherwise noted. Typical values are at T = 25 C under normal conditions unless
J
A
otherwise noted.)
PARAMETER
SYMBOL
CONDITIONS
MIN
1.8
TYP
MAX
2.5
UNITS
MHz
kΩ
f
f
= 2.1MHz
= 3.2MHz
SYNC Input Frequency
Range
SW
f
SYNC
2.8
3.6
SW
Pulldown Resistance
100
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a 4-layer
board. For detailed information on package thermal considerations see http://www.maxim-ic.com/thermal-tutorial.
Note 2: All units are 100% production tested at +25˚C. All temperature limits are guaranteed by design.
Note 3: The device is designed for continuous operation up to T = +125°C for 95,000 hours and T = +150°C for 5,000 hours.
J
J
Note 4: Guaranteed by design. Not production tested.
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Maxim Integrated | 8
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Typical Operating Characteristics
(V
= V
= 5V; T = +25°C unless otherwise noted)
PV2 A
PV1
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Maxim Integrated | 9
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Typical Operating Characteristics (continued)
(V
= V
= 5V; T = +25°C unless otherwise noted)
PV2 A
PV1
Pin Configuration
MAX20429
TOP VIEW
17
16
15
18
14
13
EN2
RESET2
PV2
EN1
1
2
3
12
11
RESET1
PV1
LX2
4
10
LX1
9
6
7
8
5
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Maxim Integrated | 10
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Pin Description
PIN
NAME
FUNCTION
OUT2 Active-High Enable Input. Drive EN2 HIGH for normal operation. The device enters soft-start
on the rising edge enters soft-shutdown on the falling edge.
1
EN2
2
3
RESET2
PV2
OUT2 Active-Low Open Drain RESET Output. External pullup resistor required if used.
OUT2 Power Input Supply. Connect a 10μF or larger ceramic capacitor from PV2 to PGND2.
OUT2 Inductor Connection. Connect LX2 to the switched side of the inductor.
OUT2 Power Ground
4
LX2
5,6
7
PGND2
PGND
PGND1
LX1
Power Ground
8,9
10
11
12
OUT1 Power Ground
OUT1 Inductor Connection. Connect LX1 to the switched side of the inductor.
OUT1 Power Input Supply. Connect a 10μF or larger ceramic capacitor from PV1 to PGND1.
OUT1 Active-Low Open Drain RESET Output. External pullup resistor required if used.
PV1
RESET1
OUT1 Active-High Enable Input. Drive EN1 HIGH for normal operation. The device enters soft-start
on the rising edge enters soft-shutdown on the falling edge.
13
14
15
EN1
OUT1
SYNC
OUT1 Feedback Input. Connect to the output capacitor of Output 1.
SYNC Input. Connect SYNC to GND or leave unconnected to enable skip-mode operation under
light loads. Connect SYNC to PV or an external clock to enable fixed-frequency FPWM operation.
16
17
18
V
Internal Analog Supply. Connect a 2.2µF capacitor between this pin and GND.
Analog Ground
DD
GND
OUT2
OUT2 Feedback Input. Connect to the output capacitor of Output 2.
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Maxim Integrated | 11
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Functional Diagrams
Internal Block Diagram
x2
I-SENSE
AMP
PV1,
PV2
SKIP CURRENT
COMP
CLK
PV_
PV_
PEAK CURRENT
COMP
RAMP
GENERATOR
LX1,
LX2
∑
CONTROL
LOGIC
PWM
COMP
COMP
PGND1
I-SENSE
AMP
VID[7:0]
V
REF
EAMP
FPWM CLK
V
REF
8-BIT DAC
ZX
COMP
OV
UV
OV[x]
UV[x]
PGND1,
PGND2
OUT1,
OUT2
VREF
MAXQTM
TEST LOGIC
OTP
CLK
CLK180
FPWM
OSC
SYNC
PGND
UVLO
VDD
GND
AGND
UV/OV
BANDGAP
RESET1
RESET2
V
REF
RESET1
RESET2
RESET1
RESET2
VID[7:0]
EN1
EN2
CONTROL
LOGIC
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Maxim Integrated | 12
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Detailed Description
MAXQ Power Architecture (No Wasted Performance)
The MAXQ power architecture allows the MAX20429 to achieve the maximum dynamic performance under all worst-case
conditions. Without the MAXQ power architecture, typical AC performance must be lowered below the device capabilities
to guarantee that the device will be stable under all worst-case application conditions. The MAXQ power architecture
keeps the device operating at peak performance.
Enable Input (EN1, EN2)
The enable control input EN1/EN2 activates the device channel from its low-power shutdown state. EN1/EN2 have an
input-high threshold of 1.5V (typ), an input-low threshold of 0.5V, and a hysteresis of 50mV (typ). When an enable input
goes high, the output voltage ramps up with the soft-start time. When an enable input goes low, the output voltage ramps
down with the soft-start time or enters a Hi-Z state depending on the factory programmed setting of the device. See Soft-
Start and Soft-Shutdown section for more detail.
RESET Output
The device features open-drain reset outputs that assert low when the corresponding output voltage is outside of the OV/
UV window. The OV/UV comparators run from a separate reference to provide drift detection on the outputs. RESET_
remains asserted for a fixed timeout period after the corresponding output returns to its regulated voltage. The fixed
timeout period for 2.1 MHz is selectable between 0.5ms, 3.9ms, 7.8ms, or 15.6ms. The fixed timeout period for 3.2 MHz
is selectable between 0.3ms, 2.5ms, 5.1ms, or 10.2ms. To obtain a logic signal, place a pullup resistor between the
RESET_ pins to the system I/O voltage.
Internal Oscillator
The device has a spread-spectrum oscillator that varies the internal operating frequency by ±3% relative to the internally
generated operating frequency of 2.1MHz/3.2MHz (typ). This function does not apply to externally applied oscillation
frequency on the SYNC pin.
Synchronization (SYNC)
A logic-high on SYNC enables fixed-frequency, forced-PWM mode. Apply an external clock on the SYNC input to
synchronize the internal oscillator to an external clock. The SYNC input accepts signal frequencies in the range of
1.9MHz < f
< 2.3MHz when f
= 2.1MHz, and 2.9MHz < f
< 3.6MHz when f
= 3.2MHz. When the pin is
SYNC
SW
SYNC
SW
open-circuited or logic-low, the SYNC input enables the device to enter a low-power skip mode under light-load conditions
if the IC is configured to allow that behavior.
Soft-Start and Soft-Shutdown
The device includes a factory-programmable fixed soft-start time. Soft-start time limits startup inrush current by forcing
the output voltage to ramp up towards its regulation point. The soft-start ramp rate can be factory programmed with four
different options: 32, 16, 8, or 4 clocks per step, where step size = 12.5mV for V
> 1.6V).
≤ 1.6V (50mV step size when V
OUT
OUT
When an EN pin goes low, the associated output enters shutdown. There are factory programmable options available that
will either simply disable switching and activate a 50Ω (typ) discharge resistor, or perform a soft-shutdown by ramping
down the reference at a fixed rate until a minimum on-time of 20ns is reached, at which point the switching stops and the
discharge resistor is activated. The soft-shutdown ramp rate is fixed at 32 clocks per step, where step size = 12.5mV for
V
OUT
≤ 1.6V (50mV step size when V
> 1.6V) when not configured as a simple discharge resistor.
OUT
Current Limit / Short-Circuit Protection
The device features a current limit that protects the device against short-circuit and overload conditions at the output. In
the event of a short-circuit or overload condition, the high-side MOSFET remains on until the inductor current reaches
www.maximintegrated.com
Maxim Integrated | 13
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
the high-side MOSFET’s current-limit threshold. The converter then turns on the low-side MOSFET to allow the inductor
current to ramp down. Once the inductor current crosses below the low-side MOSFET current-limit threshold, the
converter turns on the high-side MOSFET again. This cycle repeats until the short or overload condition is removed.
If the device crosses the current limit with the output voltage below 50% of the target, hiccup mode will be enabled and
the output will turn off for 10ms, then the channel will attempt to power up through soft-start.
PWM/SKIP Modes
The device features an input (SYNC) that puts the converter either in SKIP mode or forced-PWM mode of operation.
See Pin Descriptions for mode detail. In FPWM mode of operation, the converter switches at a constant frequency with
variable on-time. In SKIP mode, the converter’s switching frequency is load-dependent until the output load reaches a
set threshold. At higher load current, the switching frequency does not change, and the operating mode is similar to the
FPWM mode. SKIP mode helps improve efficiency in light-load applications by allowing the converter to turn on the high-
side switch only when the output voltage falls below a set threshold. As such, the converter does not switch MOSFETs
on and off, as is often the case in the PWM mode. Consequently, the gate charge and switching losses are much lower
in SKIP mode.
Overtemperature Protection
Thermal overload protection limits the total power dissipation in the MAX20429. When the junction temperature exceeds
165°C (typ), an internal thermal sensor shuts down both outputs, allowing the IC to cool. The thermal sensor turns on the
outputs again after the junction temperature cools by 15°C.
Spread Spectrum
The spread-spectrum option is enabled/disabled based on the part number. See the ordering table. If the spread
spectrum is enabled and an external clock is applied to the SYNC pin, then the spread-spectrum circuit is bypassed,
effectively disabling the option.
Resistor-Adjustable Output
MAX20429 output voltage can be set by external resistors in addition to the factory programmed V
options. See the
OUT
Typical Application Diagram for placement of R1 and R2 external resistors. Desired output voltage can be calculated
using the following method:
R1 + R2
R2
V
=
* V
REF
OUT
where V
= 0.6V when using the device specified for adjustable output voltage.
REF
Fixed output voltage devices can use external resistors to achieve output voltages higher than the factory setting. When
using a fixed output voltage device, use the factory preset output voltage as V
to calculate the resistor values.
REF
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Maxim Integrated | 14
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Applications Information
Input Capacitor Selection
An input filter capacitor reduces peak currents drawn from the upstream power source and reduces noise and voltage
ripple on the input (caused by the circuit's switching behavior). One 10µF X7R ceramic capacitor each is recommended
for the PV1 and PV2 pins. The V
pin is the input to the analog circuitry and should be connected to the same supply
DD
as PV1/2 through a series 2Ω resistor IC to a 2.2µF X7R bypass capacitor.
Inductor Selection
Three key inductor parameters must be specified for operation with the MAX20429: inductance value (L), peak inductor
current (I
), and inductor saturation current (I
). The minimum required inductance is a function of operating
PEAK
SAT
frequency, input-to-output voltage differential, and the maximum output current capability of the output. A lower inductor
value minimizes size and cost, improves large-signal and transient response, but reduces efficiency due to higher
peak currents and higher peak-to-peak output-voltage ripple for the same output capacitor. On the other hand, higher
inductance increases efficiency by reducing the ripple current. Resistive losses due to extra wire turns can exceed the
benefit gained from lower ripple current levels especially when the inductance is increased without also allowing for larger
inductor dimensions.
Soft-saturating inductors are recommended for use with the MAX20429. The gradual decrease in inductance means that
the IC will respond to overcurrent conditions before the LX current reaches dangerously high levels that might otherwise
result in damage to the IC. If a hard-saturating inductor is used, its saturation current must be above the maximum LX
current limit. For a soft-saturation inductor, only the current limit for temperature must be above the maximum LX current
limit.
The MAX20429 is designed for nominal ΔI
equal to approximately 33% of the full load current. Use the following
PK-PK
equation to calculate the typical inductance with respect to ripple current:
V
− V
OUT
× V
(
)
IN
OUT
× Δ
L =
V
× f
× I
IN SW MAX
PK−PK
The V and V
terms are typical values to optimize inductor selection for expected operating conditions. The
IN
OUT
switching frequency f
is 2.1MHz, 3.2MHz, or a different value if the synchronization function is utilized. The maximum
SW
current I
is the channel's rated output current (2A, 3A, 4A, or 6A), not the expected application maximum load current.
MAX
Calculate the minimum inductance L
with Δ
= 40%, and the typical inductance L
with Δ
= 30%.
MIN1
PK-PK
TYP1
PK-PK
The second bound on minimum inductance is with respect to slope compensation. This applies only to peak current
control, not to adaptive COT control. The absolute minimum inductance allowable must ensure that the inductor current
downslope is less than twice the downslope of the compensation ramp:
m2
− m ≥
2
Table 1. Slope Compensation Terms
TERM
VALUE
V
OUT
L
m2
-m
Inductor current downslope:
× R
CS
Compensating ramp: OTP_SLP * 0.680 V / µsec
1/2, 2/3, 4/3 (factory programmed)
0.330Ω for 2A channel
OTP_SLP
0.240Ω for 3A channel
R
CS
0.185Ω for 4A channel
0.133Ω for 6A channel
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Maxim Integrated | 15
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
For margin of error, the worst-case inductance (largest derating for current and temperature, plus lowest value for percent
tolerance) should result in the inductor downslope being 25% greater than half the slope compensation ramp:
R
CS
L
= V
×
× 1.25
MIN2
OUT
2 × m
Nominally, the inductor current down-slope should be approximately equal to the compensating ramp. Equal down-slopes
will result in current waveform perturbations being eliminated in a single switching cycle:
R
CS
L
= V
×
OUT
m
TYP2
Two equations must therefore be fulfilled: one equation for minimum worst-case inductance (required) and one for typical
inductance (recommended): L > max ( L , L ) and L > max ( L , L ). The maximum inductance
MIN
MIN1
MIN2
TYP
TYP1
TYP2
should be less than 2 x L
to avoid degrading the control performance.
TYP2
Output Capacitors
The MAX20429 is designed to be stable with low-ESR ceramic capacitors. Other capacitor types are not recommended
as the ESR zero can affect stability of the device. The output capacitor calculations below are guidelines based on
nominal conditions. The phase margin must be measured on the final circuit to verify proper stability is achieved.
Conditions:
● Feed-forward zero enabled, GMZ = 116μS, FFR = 300kΩ
● Nominal inductor value based on the Inductor Selection section
For V
For V
< 1.6V
OUT
R
COMP
COUT
= 11.5μsec × I
×
×
MIN
TYP
MAX
140kΩ
R
COMP
140kΩ
COUT
= 24.5μsec × I
MAX
≥ 1.6V
OUT
R
COMP
COUT
= 8.0μsec × I
×
MIN
TYP
MAX
140kΩ
R
COMP
COUT
= 21.0μsec × I
×
MAX
140kΩ
Table 2. Output Capacitor Terms
TERM
DESCRIPTION
COUT
COUT
Minimum fully-derated capacitance necessary for phase margin of approximately 45 degrees
Nominal output capacitance for a UGBW of 200kHz
MIN
TYP
I
The IC channel's maximum DC current capability: 2A, 3A, 4A, or 6A
Nominal output voltage
MAX
V
OUT
R
COMP
Compensation Resistor setting. Default = 140kΩ. Can be factory set from 35kΩ to 297.5kΩ in 17.5kΩ increments.
www.maximintegrated.com
Maxim Integrated | 16
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Typical Application Circuits
Typical Application Diagram
VIN
PV1,PV2
2x10µF
OUT1
RESISTOR ADJUSTABLE OUTPUT OPTION
220nH
R2
LX1
V
OUT1
SYNC
2x47μF
VIN
2Ω
V
R1
OUT1
PGND1
OUT1
VDD
2.2µF
MAX20429
220nH
GND
LX1
OUT2
2x47μF
220nH
PGND1
LX2
V
OUT2
2x47μF
EN1
EN2
PGND2
VIO
PGND
RESET1
RESET2
Ordering Information
V
I
V
I
SPREAD
SPECTRUM (MHz)
f
t
OUT1
(V)
OUT1
(A)
(2)
OUT2 OUT2
SW
HOLD
(ms)
(5)
Soft-
Shutdown
RCOMP
(kΩ)
PART
(V)
(A)
Soft-Start
(1)
(2)
(3)
(4)
(1)
MAX20429AAFNA/VY+
MAX20429CAFNA/VY+
0.85
3
0.72
6
6
ON
2.1
15.6
3.9
1.64 mv/us
0.82 mv/us
122.5
140
ADJ
(6)
ADJ
(6)
730 us
(fixed)
6
ON
2.1
730 us (fixed)
For variants with different options, contact the factory
/V Denotes an AEC-Q100 automotive-qualified part.
+ Denotes lead(Pb)-free/RoHS-compliant package.
T Denotes tape-and-reel.
Y Denotes side-wettable package.
(1)
Fixed factory setting, 0.5V to 1.5875V in 12.5mV steps or 1.6V to 3.8V in 50mV steps.
(2)
(3)
(4)
(5)
(6)
2, 3, 4, or 6
ON or OFF
2.1 or 3.2
0.5, 3.9, 7.8, 15.6 for f
= 2.1MHz or 0.3, 2.5, 5.1, 10.2 for f
= 3.2MHz.
SW
SW
ADJ (adjustable externally)
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Maxim Integrated | 17
MAX20429
Dual 6A High-Efficiency Low Voltage Buck
Converter
Revision History
REVISION REVISION
PAGES
DESCRIPTION
CHANGED
NUMBER
DATE
0
6/20
Initial release
—
Updated General Description, Benefits and Features, Absolute Maximum Ratings,
Electrical Characteristics, Detailed Description, and Ordering Information
1
12/20
1, 4, 5, 12, 13, 16
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max
limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2020 Maxim Integrated Products, Inc.
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