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MAX20021/MAX20022 Automotive Quad, Low-Voltage

Step-Down DC-DC Converters

General Description

The MAX20021/MAX20022 power-management ICs

(PMICs) integrate four low-voltage, high-efficiency, step-

down DC-DC converters. Each of the four outputs is

factory or resistor programmable between 1.0V to 4.0V

and can deliver up to 1.0A of current. The PMICs operate

from 3.0V to 5.5V, making them ideal for automotive point-

of-load and post-regulation applications.

The PMICs feature fixed-frequency PWM-mode operation

with a switching frequency of 2.2MHz or 3.2MHz. High-

frequency operation allows for an all-ceramic capacitor

design and small-size external components. The low-

resistance on-chip switches ensure high efficiency at

heavy loads while minimizing critical inductances, making

the layout a much simpler task with respect to discrete

solutions. Internal current sensing and loop compensation

reduce board space and system cost.

The PMICs offer a spread-spectrum option to reduce

radiated emissions. Two of the four buck converters oper-

ate 180º out-of-phase with the internal clock. This feature

reduces the necessary input capacitance and improves

EMI as well. All four buck converters operate in constant-

PWM mode outside the AM band. The PMICs offer a

SYNC input to synchronize to an external clock.

The PMICs provide individual enable inputs and power-

good/reset outputs, as well as factory-programmable

RESET times.

The PMICs offer several important protection features

including: input overvoltage protection, input undervoltage

monitoring, input undervoltage lockout, cycle-by-cycle

current limiting, and overtemperature shutdown. The

input undervoltage monitor indicates a brownout condition

by driving PG_ low when the input falls below the UVM

threshold.

The MAX20021/MAX20022 PMICs are available in a

28-pin TQFN package with an exposed pad and are

specified for operation over the -40ºC to +125ºC automo-

tive temperature range.

Applications

● Automotive

● Industrial

Benets and Features

● Quad Step-Down DC-DC Converters with Integrated

FETs

● Operate from 3.0V to 5.5V Supply Voltage

● 1.0V to 4.0V Fixed or Adjustable Output Voltage

● 2.2MHz (MAX20022) or 3.2MHz (MAX20021)

Switching Frequency

● Four Channels Capable of Delivering Up to 1A Each

● Designed to Improve Automotive EMI Performance

• Forced-PWM Operation

• Two Channels 180º Out-of-Phase

• SYNC Input

• Spread-Spectrum Option

● Soft-Start and Supply Sequencing Reduces Inrush

Current

● Individual Enable Inputs and Power-Good Outputs to

Simplify Sequencing

● OV/UV Input-Voltage Monitoring

● Overtemperature and Short-Circuit Protection

● 28-Pin (5mm x 5mm x 0.8mm) TQFN-EP Package

● -40ºC to +125ºC Operating Temperature Range

19-6628; Rev 3; 8/14

Ordering Information/Selector Guide appear at end of data

sheet.

For related parts and recommended products to use with this part, refer

to www.maximintegrated.com/MAX20021.related.

Simplied Block Diagram

EVALUATION KIT AVAILABLE

PGND_

LX_

SYNC

OUTS_

CONTROL

OUT1

10µF

1.5µH

OUT

MAX20021

2.2µF

1µF

EN_

PG_

GND

SEL

STEP-DOWN

PWM OUT_

1.0V TO 4.0V

UP TO

0.5A OR 1A

SS OSC

4 CHANNELS

PV_

10kΩ

Summary of content (16 pages)

PAGE 1
EVALUATION KIT AVAILABLE MAX20021/MAX20022 General Description The MAX20021/ MAX20022 power-management ICs (PMICs) integrate four low-voltage, high-efficiency, stepdown DC-DC converters. Each of the four outputs is factory or resistor programmable between 1.0V to 4.0V and can deliver up to 1.0A of current. The PMICs operate from 3.0V to 5.5V, making them ideal for automotive pointof-load and post-regulation applications.
PAGE 2
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Absolute Maximum Ratings PV_ to PGND_......................................................-0.3V to +6.0V VA to GND.............................................................-0.3V to +6.0V OUTS_, EN_, PG_, SYNC, SEL to GND.......-0.3V to VA + 0.3V PV_ to PV_............................................................-0.3V to +0.3V PGND_ to GND.....................................................-0.3V to +0.3V LX_ to PGND..........
PAGE 3
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Electrical Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYNC Input Frequency Range SYMBOL fSYNC CONDITIONS MIN TYP MAX PWM switching frequency = 2.2MHz (see the Selector Guide) 1.7 2.5 PWM switching frequency = 3.2MHz (see the Selector Guide) 2.
PAGE 4
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Electrical Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = TJ = -40ºC to +125ºC, unless otherwise noted. Typical values are at TA = +25ºC under normal conditions, unless otherwise noted.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNIT UV/OV Propagation Delay 15 µs PG_ Output High Leakage Current 0.1 µA PG_ Output Low Level VPV_= 3.0V, sinking 3mA 0.22 V 1.
PAGE 5
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) VOUT1 = 3.3V 70 50 80 VOUT3 = 2.65V VOUT4 = 1.8V 40 30 20 VOUT1 = 3.3V 70 60 50 VOUT3 = 2.65V 40 VOUT4 = 1.8V 30 VOUT2 = 1.2V 20 VOUT2 = 1.2V 10 0 0.0001 fSW = 2.2MHz, VPV_ = 5V 0.0100 0.1000 0 0.0001 1.0000 LOAD CURRENT (A) 0.0010 0.0100 0.
PAGE 6
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) SHORT-CIRCUIT BEHAVIOR LOAD TRANSIENT, (VOUT1 = 3.3V) MAX20021 toc08 MAX20021 toc09 VOUT3 2V/div IOUT1 500mA/div VLX3 2V/div VOUT1 100mV/div IOUT3 1A/div 400ns/div 10µs/div LINE TRANSIENT, (VOUT1 = 3.3V) SWITCHING FREQUENCY vs. TEMPERATURE MAX20021 toc10 VPV1 = 3.
PAGE 7
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Typical Operating Characteristics (continued) (VA = VPV1 = VPV2 = VPV3 = VPV4 = 5.0V; TA = +25ºC, unless otherwise noted.) 0 MAX20021 toc15 MAX20021 toc14 45 PHASE MARGIN vs. FREQUENCY 200 150 PHASE MARGIN (°) MAGNITUDE (dB) 90 SMALL-SIGNAL GAIN vs. FREQUENCY 100 50 0 -50 1E+4 1E+5 PSRR (dB) 1E+4 1E+5 1E+6 PSRR vs. FREQUENCY OUTPUT VOLTAGE-NOISE DENSITY vs. FREQUENCY -30 NO LOAD -50 -60 150mA LOAD -70 0.001 0.
PAGE 8
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters PV4 LX4 PGND4 PGND3 LX3 PV3 TOP VIEW EN4 Pin Configuration 21 20 19 18 17 16 15 OUTS4 22 14 OUTS3 PG4 23 13 EN3 12 PG3 11 SEL 10 PG2 9 EN2 8 OUTS2 GND 24 MAX20021 SYNC 25 VA 26 PG1 27 EP = GND PV1 LX1 4 5 6 7 PV2 3 LX2 2 PGND2 1 EN1 OUTS1 28 PGND1 + TQFN Pin Description PIN NAME 1 EN1 Active-High Digital Enable Input for Buck 1. Driving EN1 high enables Buck 1.
PAGE 9
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Pin Description (continued) PIN NAME FUNCTION PV3 Buck 3 Voltage Input. Connect a 2.2µF or larger ceramic capacitor from PV3 to PGND3 as close as possible to the device. 16 LX3 Buck 3 Switching Node. LX3 is high impedance when the device is off. 17 PGND3 Power Ground for Buck 3 18 PGND4 Power Ground for Buck 4 19 LX4 Buck 4 Switching Node. LX4 is high impedance when the device is off. 20 PV4 Buck 4 Voltage Input.
PAGE 10
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters CURRENT-SENSE AMP PV1—PV4 VREF PEAK CURRENT COMP RAMP GENERATOR PV1 ∑ PWM COMP PGND1 CONTROL LOGIC PV1 VREF PGND1 SOFT-START GENERATOR OUTS1— OUTS4 LX1—LX4 CLK180 CLK PGND1 —PGND4 VALLEY CURRENT LIM COMP P1-OK FEEDBACK SELECT SEL VREF SYNC OSC P-OK[1:4] OTP CLK VOLTAGE REFERENCE MAX20021 EN1 TRIMBITS CLK180 VREF UVLO VA VA PG1 PG2 EN2 EN3 EN4 MAIN CONTROL LOGIC PG3 PG4 SEL GND Figure 1.
PAGE 11
MAX20021/MAX20022 Detailed Description The MAX20021/MAX20022 PMICs offer four, highefficiency, synchronous step-down converters that operate with a 3.0V to 5.5V input voltage range and provide a 1.0V to 4.0V output voltage range. The PMICs deliver up to 1.0A of load current per output. The PMICs achieve ±3% output error over load, line, and temperature ranges. The PMICs feature fixed-frequency PWM-mode operation with a 2.2MHz or 3.2MHz switching frequency.
PAGE 12
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Output 3 Voltage Select (SEL) The MAX20021 offers a SEL input to allow selection of the OUT3 voltage. For fixed output versions, connect SEL to PGND_ for a 1.8V output or to PV_ for a 2.65V output. There is no soft transition between the two output-voltage settings, so SEL should not be toggled during normal operation. For the MAX20022, connect SEL to PGND_ or leave unconnected.
PAGE 13
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters The external feedback resistive divider must be frequency compensated for proper operation. Place a capacitor across R1 in the resistive divider network. Use the following equation to determine the value of the capacitor: R2  R2  > 1, C1 = C  R1  R1  else C1 C, where C 15pF = = If Connect OUTS_ to VOUT_ for a fixed 1.0V output voltage. Inductor Selection The PMICs are optimized for use with a 1.5µH inductor for 2.
PAGE 14
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters 3) Keep the power traces and load connections short. This practice is essential for high efficiency. Use thick copper PCBs (2oz vs. 1oz) to enhance full-load efficiency. 4) Use a single ground plane to reduce the chance of ground potential differences. With a single ground plane, enough isolation between analog return signals and high-power signals must be maintained.
PAGE 15
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Ordering Information FREQUENCY TEMP RANGE MAX20021ATI_ / V+ PART 3.2MHz -40ºC to +125ºC PIN-PACKAGE 28 TQFN-EP* MAX20022ATI_ / V+ 2.2MHz -40ºC to +125ºC 28 TQFN-EP* Note: Insert the desired suffix letter (from the Selector Guide) into the blank area "_" to indicate factory-selectable features. /V denotes an automotive qualified part that conforms to AEC-Q100. +Denotes a lead(Pb)-free/RoHS-compliant package.
PAGE 16
MAX20021/MAX20022 Automotive Quad, Low-Voltage Step-Down DC-DC Converters Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 3/13 Initial release — 1 4/13 Removed future product reference for the MAX20022 15 2 12/13 Added AEC-Q100 reference to Ordering Information 15 3 8/14 Added two new MAX20021 options to Selector Guide 15 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product.