Rainbow Electronics MAX15041 User Manual

General Description

The MAX15041 low-cost, synchronous DC-DC convert­er with internal switches delivers an output current up to
3A. The MAX15041 operates from an input voltage of

4.5V to 28V and provides an adjustable output voltage
from 0.6V to 90% of V

IN

, set with two external resistors.
The MAX15041 is ideal for distributed power systems,
preregulation, set-top boxes, television, and other con­sumer applications.

The MAX15041 features a peak-current-mode PWM con­troller with internally fixed 350kHz switching frequency
and a 90% maximum duty cycle. The current-mode con­trol architecture simplifies compensation design, and
ensures a cycle-by-cycle current limit and fast response
to line and load transients. A high-gain transconductance
error amplifier allows flexibility in setting the external com­pensation by using a type III compensation scheme,
thereby allowing the use of all ceramic capacitors.

This synchronous buck regulator features internal
MOSFETs that provide better efficiency than asynchro­nous solutions, while simplifying the design relative to
discrete controller solutions. In addition to simplifying
the design, the integrated MOSFETs minimize EMI,
reduce board space, and provide higher reliability by
minimizing the number of external components.

The MAX15041 also features thermal shutdown and
overcurrent protection (high-side sourcing and low-side
sinking), and an internal 5V LDO with undervoltage
lockout. In addition, this device ensures safe startup
when powering into a prebiased output.

Other features include an externally adjustable soft-start
that gradually ramps up the output voltage and reduces
inrush current. Independent enable control and power­good signals allow for flexible power sequencing.

The MAX15041 is available in a space-saving, high­power, 3mm x 3mm, 16-pin TQFN-EP package and is
fully specified from -40°C to +85°C.

Applications

Distributed Power Systems

Wall Adapters

Preregulators

Set-Top Boxes

Televisions

xDSL Modems

Consumer Products

Features

o Up to 3A of Continuous Output Current
o ±1% Output Accuracy Over Temperature
o 4.5V to 28V Input Voltage Range
o Adjustable Output Voltage Range from 0.606V to

0.9 x V

IN

o Internal 170mΩ R

DS-ON

High-Side and 105mΩ

R

DS-ON

Low-Side Power Switches

o Fixed 350kHz Switching Frequency
o Up to 93% Efficiency
o Cycle-By-Cycle Overcurrent Protection
o Programmable Soft-Start
o Stable with Low-ESR Ceramic Output Capacitors
o Safe Startup into Prebiased Output
o Enable Input and Power-Good Output
o Fully Protected Against Overcurrent and

Overtemperature

o V

DD

LDO Undervoltage Lockout

o Space-Saving, Thermally Enhanced, 3mm x 3mm

Package

MAX15041

Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM

Step-Down DC-DC Regulator with Internal Switches

________________________________________________________________

Maxim Integrated Products

1

Typical Operating Circuit

Ordering Information

19-4815; Rev 0; 7/09

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.

EVALUATION KIT

AVAILABLE

PART

TEMP RANGE

PIN-

TOP

MARK

MAX15041ETE+

AGV

+

Denotes a lead(Pb)-free/RoHS-compliant package.

*

EP = Exposed pad.

Pin Configuration appears at end of data sheet.

PACKAGE

-40°C to +85°C 16 TQFN-EP*

INPUT

12V

PGOOD

IN

EN

V

DD

PGOOD

SS

MAX15041

SGND

BST

PGND

COMP

OUTPUT

1.8V AT 3A

LX

FB

MAX15041

Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= 12V, C

VDD

= 1µF, CIN= 22µF, TA= TJ= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 3)

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.

Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed

the IC’s package power dissipation.

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

.

IN to SGND.............................................................-0.3V to +30V

EN to SGND.................................................-0.3V to (V

IN

+ 0.3V)

LX to PGND ................................-0.3V to min (+30V, V

IN

+ 0.3V)

LX to PGND .....................-1V to min (+30V, V

IN

+ 0.3V) for 50ns

PGOOD to SGND .....................................................-0.3V to +6V

V

DD

to SGND............................................................-0.3V to +6V

COMP, FB, SS to SGND..............-0.3V to min (+6V, V

DD

+ 0.3V)

BST to LX .................................................................-0.3V to +6V

BST to SGND .........................................................-0.3V to +36V

SGND to PGND ....................................................-0.3V to +0.3V

LX Current (Note 1) ....................................................-5A to +8A

Converter Output Short-Circuit Duration ...................Continuous

Continuous Power Dissipation (T

A

= +70°C)
16-Pin TQFN-EP (derate 14.7mW/°C above +70°C)

Multilayer Board .........................................................1666mW

Package Thermal Resistance (Note 2)

θ

JA

................................................................................48°C/W

θ

JC

..................................................................................7°C/W

Operating Temperature Range ..........................-40°C to +85°C

Junction Temperature .....................................................+150°C

Storage Temperature Range ............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

STEP-DOWN CONVERTER

Input-Voltage Range V

Input Supply Current I

Shutdown Input Supply Current

ENABLE INPUT

EN Shutdown Threshold Voltage V

EN Shutdown Voltage Hysteresis V

EN Lockout Threshold Voltage

EN Input Current I

POWER-GOOD OUTPUT

PGOOD Threshold V

PGOOD Threshold Hysteresis V

PGOOD Output Low Voltage V

PGOOD Leakage Current I

ERROR AMPLIFIER

Error Amplifier
Transconductance

Error Amplifier Voltage Gain A

FB Set-Point Accuracy V

FB Input Bias Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN

IN

EN_SHDN

EN_HYST

V

EN_LOCK

V

EN_LOCK_HYSTVEN

EN

PGOOD_THVFB

PGOOD_HYST

PGOOD_OLIPGOOD

PGOOD

g

MV

VEA

FB

FB

Switching 2.1 4 mA

VEN = 0V, V

V

= 0V, VIN = V

EN

VEN rising 1.4 V

VEN rising 1.7 1.95 2.15 V

falling 100 mV

VEN = 2.9V 2 5.3 9 µA

rising 540 560 584 mV

V

PGOOD

VFB = 0.5V -100 +100

VFB = 0.7V -100 +100

regulated by internal

DD

= 5V 18 28

DD

= 5mA, VFB = 0.5V 35 100 mV

= 5V, VFB = 0.7V 10 nA

4.5 28 V

212

100 mV

15 mV

1.6 mS

90 dB

600 606 612 mV

µA

nA

MAX15041

Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM

Step-Down DC-DC Regulator with Internal Switches

_______________________________________________________________________________________ 3

Note 3: Specifications are 100% production tested at TA= +25°C. Limits over the operating temperature range are guaranteed by

design and characterization.

ELECTRICAL CHARACTERISTICS (continued)

(VIN= 12V, C

VDD

= 1µF, CIN= 22µF, TA= TJ= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 3)

SS Current I

SS Discharge Resistance R

SS Prebiased Mode Stop Voltage 0.65 V

Current Sense to COMP
Transconductance

COMP Clamp Low VFB = 0.7V 0.68 V

PWM Compensation Ramp Valley 830 mV

PWM CLOCK

Switching Frequency f

Maximum Duty Cycle D 90 %

Minimum Controllable On-Time 150 ns

INTERNAL LDO OUTPUT (VDD)

VDD Output Voltage V

VDD Short-Circuit Current VIN = 6.5V 30 80 mA

LDO Dropout Voltage I

V

Undervoltage Lockout

DD

Threshold

V

Undervoltage Lockout

DD

Hysteresis

POWER SWITCH

LX On-Resistance

High-Side Switch Source
Current-Limit Threshold

Low-Side Switch Sink
Current-Limit Threshold

LX Leakage Current

BST Leakage Current V

THERMAL SHUTDOWN

Thermal-Shutdown Threshold Rising +155 °C

Thermal-Shutdown Hysteresis 20 °C

HICCUP PROTECTION

Blanking Time

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SS

SS

G

MOD

SW

DD

V

UVLO_TH

V

UVLO_HYST

VSS = 0.45V, sourcing 4.5 5 5.5 µA

ISS = 10mA, sinking, VEN = 1.6V 6 Ω

9S

315 350 385 kHz

I

= 1mA to 25mA, VIN = 6.5V 4.75 5.1 5.5 V

VDD

= 25mA, VDD drops by -2% 50 600 mV

VDD

V

rising 4 4.25 V

DD

150 mV

High-side switch, ILX = 1A 170 305

Low-side switch, I

V

= 33V, VIN = V

BST

= 5V, VIN = 28V, V

V

BST

= 33V, VIN = VLX = 28V 10 nA

BST

= 1A 105 175

LX

5 6 7.2 A

-3 A

= 28V 10

LX

= 0V 10

LX

16 x Soft-

Start Time

mΩ

nA

MAX15041

Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM
Step-Down DC-DC Regulator with Internal Switches

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VIN= 12V, V

OUT

= 3.3V, C

VDD

= 1µF, CIN= 22µF, TA= +25°C, circuit of Figure 3 (see Table 1 for values), unless otherwise specified.)

EFFICIENCY vs. LOAD CURRENT

100

VIN = 12V

95

90

85

80

75

70

EFFICIENCY (%)

65

60

55

50

V

= 5.0V

OUT

V

= 3.3V

OUT

V

= 2.5V

OUT

V

= 1.8V

OUT

V

= 1.2V

OUT

0 3.0

LOAD CURRENT (A)

LOAD-TRANSIENT WAVEFORMS

200µs/div

2.52.01.51.00.5

MAX15041 toc04

MAX15041 toc01

I

LOAD

2A/div

V

OUT

AC-COUPLED
200mV/div

V

PGOOD

5V/div

EFFICIENCY vs. LOAD CURRENT

100

VIN = 5V

95

90

85

80

75

70

EFFICIENCY (%)

65

60

55

50

V

= 3.3V

OUT

V

= 2.5V

OUT

V

= 1.8V

OUT

V

= 1.2V

OUT

0 3.0

LOAD CURRENT (A)

NORMALIZED OUTPUT VOLTAGE

vs. TEMPERATURE

1.002
I

= 0A

LOAD

1.001

1.000

0.999

0.998

0.997

NORMALIZED OUTPUT VOLTAGE

0.996

0.995

-40 85
TEMPERATURE (NC)

OUTPUT-VOLTAGE REGULATION

vs. LOAD CURRENT

0.2

MAX15041 toc02

2.52.01.51.00.5

0

-0.2

-0.4

-0.6

-0.8

OUTPUT-VOLTAGE REGULATION (%)

-1.0

-1.2

03.0
LOAD CURRENT (A)

MAX15041 toc03

2.52.01.51.00.5

NORMALIZED OUTPUT VOLTAGE

vs. TEMPERATURE

1.004

I

= 2A

LOAD

1.002

MAX15041 toc05

1.000

0.998

0.996

NORMALIZED OUTPUT VOLTAGE

0.994

0.992

603510-15

-40 85

TEMPERATURE (NC)

603510-15

MAX15041 toc06

FB SET POINT vs.TEMPERATURE

610

608

606

604

FB SET POINT (mV)

602

600

-40 85
TEMPERATURE (NC)

385

MAX15041 toc07

603510-15

375

365

355

345

FREQUENCY (kHz)

335

325

315

vs. INPUT VOLTAGE

INPUT VOLTAGE (V)

SWITCHING FREQUENCY

MAX15041 toc08

TA = +85NC

TA = +25NC

TA = -40NC

2520151050

MAX15041

Low-Cost, 3A, 4.5V to 28V Input, 350kHz, PWM

Step-Down DC-DC Regulator with Internal Switches

_______________________________________________________________________________________

5

Typical Operating Characteristics (continued)

(VIN= 12V, V

OUT

= 3.3V, C

VDD

= 1µF, CIN= 22µF, TA= +25°C, circuit of Figure 3 (see Table 1 for values), unless otherwise specified.)

INPUT SUPPLY CURRENT (mA)

16

L = 4.7FH
I

LOAD

15

14

13

12

11

10

0

INPUT SUPPLY CURRENT

vs. INPUT VOLTAGE

= 0A

INPUT VOLTAGE (V)

SHUTDOWN WAVEFORMS

252015105

MAX15041 toc12

SHUTDOWN CURRENT

vs. TEMPERATURE

TEMPERATURE (NC)

MAX15041 toc13

V
2V/div

I

IN

5A/div

I

L

5A/div

V
2V/div

MAX15041 toc09

V

EN

5V/div

V

OUT

2V/div

I

L

2A/div

V

PGOOD

5V/div

SHUTDOWN CURRENT

vs. INPUT VOLTAGE

MAX15041 toc10

4.0

3.5

3.0

2.5

2.0

SHUTDOWN CURRENT (FA)

1.5

1.0

-40 85

10

9

8

7

6

5

4

3

SHUTDOWN CURRENT (FA)

2

1

0

INPUT VOLTAGE (V)

2520151050

OUTPUT SHORT-CIRCUIT WAVEFORMS

MAX15041 toc11

603510-15

OUT

SS

100µs/div

SWITCHING WAVEFORMS

1µs/div

MAX15041 toc14

V

LX

10V/div

I

L

2A/div

V

OUT

AC-COUPLED
50mV/div

SOFT-START WAVEFORMS

10µs/div

400µs/div

MAX15041 toc15

V

EN

5V/div

V

OUT

2V/div

I

L

2A/div

V

PGOOD

5V/div