MAX20429EVKIT [MAXIM]

Single Supply Operation with 3.0V to 5.5V Input Supply Range;


型号：	MAX20429EVKIT
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	Single Supply Operation with 3.0V to 5.5V Input Supply Range
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

• 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

C_IN

LX1

OUT1

SYNC

VDD

C_OUT

VIN

PGND1

MAX20429

GND

OUT2

LX2

C_OUT

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

to GND................................................................ -0.3V to 6V

OUT1, OUT2 to GND ..................................... -0.3V to V +0.3V

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

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

Junction to Case (θ

)

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

otherwise noted.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

5.5

UNITS

PV Supply Voltage

Range

3.0

= V

= low, T = +25°C

EN1

EN2

Supply Current

µA

VDD

= high, V

= low, no load

440

2.6

2.7

2.1

3.2

EN1

EN2

UVLO

Falling

Rising

2.4

UVLO

VDD UVLO

2.9

2.3

3.6

UVLO

= 2.1MHz

= 3.2MHz

1.9

2.9

Oscillator Frequency

MHz

Spread Spectrum

Range

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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

otherwise noted.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

OUT

Programmable voltage range, 3.0 V ≤

0.5

3.8

≤ 5.5V (Note 4)

Output Voltage

Step size, 0.5 V ≤ V

≤ 1.5875 V (Note

≤ 3.8 V (Note 4)

OUT

12.5

Step size, 1.6 V ≤ V

Option 1

0.825

1.1

0.7

0.9

1.3

1.65

Option 2

Skip Mode Peak Current

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

OUT

0.6V ≥ V

OUT

PWM mode, 0A ≤ I

≤ I

, 0.5V ≤

LOAD

MAX

Voltage Accuracy

OUT

≤ 0.5875V

PWM mode, 0A ≤ I

MAX(3.0V,V

≤ I

LOAD

MAX

+ 0.5V) ≤ V ≤ 5.5V,

OUT

-1

OUT

= 0.6V. ADJ variant

MAX20429CAFNA/VY+

DC Load Regulation

DC Line Regulation

0A ≤ I ≤ I (PWM mode)

0.1

0.05

LOAD

MAX

PV_ from 3V to 5.5V

Including metal and package

Intrinsic

%/V

High-Side On-

Resistance

ON-H

mΩ

Including metal and package

Intrinsic

Low-Side On-

Resistance

ON-L

mΩ

= 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

Current-Limit Threshold

LIM

nMOS Zero-Crossing

Threshold

100

LX_ Rise/Fall Time

Dead Time

PV = 3.3V, I

= 2A (Note 4)

µA

OUT

DEAD

LX_ Leakage Current

Max Duty Cycle

Minimum On-Time

0.01

Effective

100

MAX

LX_ Discharge

Resistance

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

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

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)

Option 1

Hi-Z

Soft-Shutdown Rate

Voltage Accuracy

SHDN

Option 2 (step = 12.5mV for V

1.6V, otherwise 50mV)

OUT

clks/step

PWM mode, 0A ≤ I

≤ I

, 0.5V ≤

MAX

LOAD

-7

OUT

≤ 0.5875V

RESET

OV Threshold Range

UV Threshold Range

Rising

Falling

104

108

112

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

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

Thermal Shutdown

Temperature

165

ºC

SHDN

Thermal Shutdown

Hysteresis

(Note 4)

ºC

HYS

Leakage Current

OV/UV Filter

0.1

µA

μs

ENABLE INPUT (EN)

Input High

Rising

Falling

1.5

1.8

Input Low

0.5

0.4

Hysteresis

0.05

0.1

Leakage Current

SYNCHRONIZATION (SYNC)

Input High

µA

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

otherwise noted.)

PARAMETER

SYMBOL

CONDITIONS

MIN

1.8

TYP

MAX

2.5

UNITS

MHz

kΩ

= 2.1MHz

= 3.2MHz

SYNC Input Frequency

Range

SYNC

2.8

3.6

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.

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

= 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

= 5V; T = +25°C unless otherwise noted)

PV2 A

PV1

Pin Configuration

MAX20429

TOP VIEW

EN2

RESET2

PV2

EN1

RESET1

PV1

LX2

LX1

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Maxim Integrated | 10

MAX20429

Dual 6A High-Efficiency Low Voltage Buck

Converter

Pin Description

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.

EN2

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

LX2

5,6

PGND2

PGND

PGND1

LX1

Power Ground

8,9

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.

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.

Internal Analog Supply. Connect a 2.2µF capacitor between this pin and GND.

Analog Ground

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

I-SENSE

AMP

PV1,

PV2

SKIP CURRENT

COMP

CLK

PV_

PEAK CURRENT

COMP

RAMP

GENERATOR

LX1,

LX2

∑

CONTROL

LOGIC

PWM

COMP

PGND1

I-SENSE

AMP

VID[7:0]

REF

EAMP

FPWM CLK

REF

8-BIT DAC

COMP

OV[x]

UV[x]

PGND1,

PGND2

OUT1,

OUT2

V_REF

MAXQ^TM

TEST LOGIC

OTP

CLK

CLK180

FPWM

OSC

SYNC

PGND

UVLO

VDD

GND

AGND

UV/OV

BANDGAP

RESET1

RESET2

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

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

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

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

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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

* 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

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

OUT

× V

(

)

OUT

× Δ

L =

× f

× I

IN SW MAX

PK−PK

The V and V

terms are typical values to optimize inductor selection for expected operating conditions. The

OUT

switching frequency f

is 2.1MHz, 3.2MHz, or a different value if the synchronization function is utilized. The maximum

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:

− m ≥

Table 1. Slope Compensation Terms

TERM

VALUE

OUT

-m

Inductor current downslope:

× R

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

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:

= 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:

= V

OUT

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

< 1.6V

OUT

COMP

COUT

= 11.5μsec × I

MIN

TYP

MAX

140kΩ

COMP

140kΩ

COUT

= 24.5μsec × I

MAX

≥ 1.6V

OUT

COMP

COUT

= 8.0μsec × I

MIN

TYP

MAX

140kΩ

COMP

COUT

= 21.0μsec × I

MAX

140kΩ

Table 2. Output Capacitor Terms

TERM

DESCRIPTION

COUT

Minimum fully-derated capacitance necessary for phase margin of approximately 45 degrees

Nominal output capacitance for a UGBW of 200kHz

MIN

TYP

The IC channel's maximum DC current capability: 2A, 3A, 4A, or 6A

Nominal output voltage

MAX

OUT

COMP

Compensation Resistor setting. Default = 140kΩ. Can be factory set from 35kΩ to 297.5kΩ in 17.5kΩ increments.

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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

LX1

OUT1

SYNC

2x47μF

VIN

2Ω

OUT1

PGND1

OUT1

VDD

2.2µF

MAX20429

220nH

GND

LX1

OUT2

2x47μF

220nH

PGND1

LX2

OUT2

2x47μF

EN1

EN2

PGND2

VIO

PGND

RESET1

RESET2

Ordering Information

SPREAD

SPECTRUM (MHz)

OUT1

(V)

OUT1

(A)

(2)

OUT2 OUT2

HOLD

(ms)

(5)

Soft-

Shutdown

RCOMP

(kΩ)

PART

(V)

(A)

Soft-Start

(1)

(2)

(3)

(4)

(1)

MAX20429AAFNA/VY+

MAX20429CAFNA/VY+

0.85

0.72

2.1

15.6

3.9

1.64 mv/us

0.82 mv/us

122.5

140

ADJ

(6)

ADJ

(6)

730 us

(fixed)

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.

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

6/20

Initial release

—

Updated General Description, Benefits and Features, Absolute Maximum Ratings,

Electrical Characteristics, Detailed Description, and Ordering Information

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.

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