Rainbow Electronics MAX15051 User Manual

General Description

The MAX15050/MAX15051 high-efficiency switching reg­ulators deliver up to 4A load current at output voltages
from 0.6V to (0.9 x V

IN

). The devices operate from 2.9V
to 5.5V, making them ideal for on-board point-of-load
and postregulation applications. Total output-voltage
accuracy is within ±1% over load, line, and temperature.

The MAX15050/MAX15051 feature 1MHz fixed-frequen­cy PWM operation. The MAX15050 features pulse-skip
mode to improve light-load efficiency. The MAX15050
soft-starts in a monotonic mode and then operates in
the forced PWM mode or pulse-skip mode depending
on the output load current condition. The MAX15051
soft-starts in the monotonic mode and operates in the
forced PWM mode. The high operating frequency
allows for small-size external components.

The low-resistance on-chip nMOS switches ensure high
efficiency at heavy loads while minimizing critical parasitic
inductances, making the layout a much simpler task with
respect to discrete solutions. Following a simple layout
and footprint ensures first-pass success in new designs.

The MAX15050/MAX15051 incorporate a high-bandwidth
(> 26MHz) voltage-error amplifier. The voltage-mode control
architecture and the voltage-error amplifier permit a type III
compensation scheme to achieve maximum loop band­width, up to 200kHz. High loop bandwidth provides fast
transient response, resulting in less required output capaci­tance and allowing for all-ceramic capacitor designs.

The MAX15050/MAX15051 feature an output overload
hiccup protection and peak current limit on both high­side and low-side MOSFETs. These features provide for
ultra-safe operation in the cases of short-circuit condi­tions, severe overloads, or in converters with bulk elec­trolytic capacitors.

The MAX15050/MAX15051 feature an adjustable output volt­age. The output voltage is adjustable by using two external
resistors at the feedback or by applying an external reference
voltage to the REFIN/SS input. The MAX15050/MAX15051
offer programmable soft-start time using one capacitor to
reduce input inrush current. A built-in thermal shutdown pro­tection assures safe operation under all conditions. The
MAX15050/MAX15051 are available in a 2mm x 2mm,
16-bump (4 x 4 array), 0.5mm pitch WLP package.

Applications

Features

o Internal 18mΩ R

DS(ON)

MOSFETs

o Pulse-Skip Mode for High-Efficiency Light Load

(MAX15050)

o Continuous 4A Output Current
o ±1% Output-Voltage Accuracy Over Load, Line,

and Temperature

o Operates from 2.9V to 5.5V Supply
o Adjustable Output from 0.6V to (0.9 x V

IN

)

o Adjustable Soft-Start Reduces Inrush Supply Current
o Factory-Trimmed 1MHz Switching Frequency
o Compatible with Ceramic, Polymer, and

Electrolytic Output Capacitors

o Safe Startup Into Prebias Output
o Enable Input/Power-Good Output
o Fully Protected Against Overcurrent and

Overtemperature

o Overload Hiccup Protection
o Sink/Source Current for DDR Applications
o 2mm x 2mm, 16-Bump (4 x 4 Array), 0.5mm Pitch

WLP Package

MAX15050/MAX15051

High-Efficiency, 4A, 1MHz, Step-Down Regulators

with Integrated Switches in 2mm x 2mm Package

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-4915; Rev 2; 3/10

EVALUATION KIT

AVAILABLE

+

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

Pin Configuration appears at end of data sheet.

OUTPUT

INPUT

2.9V TO 5.5V
BST

LX

IN

EN

V

DD

GND

FB

V

DD

COMP

PWRGD

REFIN/SS

GND

MAX15050
MAX15051

Typical Operating Circuit

Server Power Supplies
Point-of-Load
ASIC/CPU/DSP Core

and I/O Voltages
DDR Power Supplies
Base-Station Power

Supplies

Telecom and
Networking Power
Supplies

RAID Control Power
Supplies

Portable Applications

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.

PART TEMP RANGE

M A X1 5 0 5 0 E WE + - 40°C to + 85°C 16 WLP Yes

M A X1 5 0 5 1 E WE + - 40°C to + 85°C 16 WLP No

PIN­PACKAGE

SKIP

MODE

MAX15050/MAX15051

High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VIN= VEN= 5V, C

VDD

= 2.2µF, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 4)

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.

IN, PWRGD to GND..................................................-0.3V to +6V

V

DD

to GND..................-0.3V to the lower of +4V or (VIN+ 0.3V)

COMP, FB, REFIN/SS to GND....................-0.3V to (V

DD

+ 0.3V)

EN to GND................................................................-0.3V to +6V

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

BST to GND ............................................................-0.3V to +12V

LX to GND ....................-0.3V to the lower of +6V or (V

IN

+ 0.3V)
LX to GND (Note 1) ..-1V to the lower of +6V or (V

IN

+ 1V) for 50ns

I

LX(RMS)

....................................................................................6A

V

DD

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

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

Continuous Power Dissipation (T

A

= +70°C)
16-Bump (4 x 4 Array), 0.5mm Pitch WLP

(derate 20.4mW/°C above +70°C)..............................1000mW

Thermal Resistance (Note 2)

θ

JA

.................................................................................49°C/W

θ

JC

...................................................................................9°C/W

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

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

Operating Junction Temperature

at Maximum Current (Note 3)........................................+105°C

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

Soldering Temperature (soldering, 10s) ..........................+260°C

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

the IC’s power dissipation limit of the device.

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

.

Note 3: Operating the junction temperature above +105°C will degrade the life of the device.

PARAMETER CONDITIONS MIN TYP MAX UNITS

IN Voltage Range 2.9 5.5 V

IN Supply Current No load, no switching

Total Shutdown Current from IN VIN = V

VDD Undervoltage Lockout
Threshold

VDD Undervoltage Deglitching 10 µs

VDD Output Voltage I

VDD Dropout VIN = 2.9V, I

VDD Current Limit VDD = 0V 20 37 mA

BST

BST Supply Current

IN to BST On-Resistance VIN = 3.3V, IIN = 0.16A 4 

PWM COMPARATOR

PWM Comparator Propagation
Delay

PWM Peak-to-Peak Ramp
Ampl itude

PWM Valley Amplitude 0.76 V

VIN = 3.3V 4.8 8

= 5V 5.3 8.5

V

IN

- VLX = 5V, VEN = 0V 10 20 µA

BST

LX starts/stops switching,
no load

= 0 to 10mA 3.1 3.3 3.5 V

VDD

= 10mA 0.09 V

VDD

MAX15050, V

MAX15051, V
no switching

10mV overdrive 20 ns

1 V

BST

IN

= 5V, V

= V

LX

= 3.3V, V

VDD ris ing 2.6 2.8

falling 2.35 2.55

V

DD

= 0V, no switching 10

LX

= 6.6V,

BST

250

mA

V

µA

MAX15050/MAX15051

High-Efficiency, 4A, 1MHz, Step-Down Regulators

with Integrated Switches in 2mm x 2mm Package

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VIN= VEN= 5V, C

VDD

= 2.2µF, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 4)

PARAMETER CONDITIONS MIN TYP MAX UNITS

COMP

COMP Clamp Voltage High V

COMP Clamp Voltage Low V

COMP Slew Rate V

COMP Shutdown Res istance

ERROR AMPLIFIER

FB Regulation Accuracy Using
External Resistors

Open-Loop Voltage Gain 115 dB

Error-Amplifier Unity-Gain
Bandwidth

Error-Amplifier Common-Mode
Input Range

Error-Amplifier Maximum Output
Current

FB Input Bias Current VFB = 0.7V 70 nA

REFIN/SS

REFIN/SS Common-Mode Range V

REFIN/SS Charging Current V

REFIN/SS Offset Voltage V

REFIN/SS Pulldown Resistance VIN= V

LX (ALL BUMPS COMBINED)

LX On-Resistance, High Side ILX = -500mA VIN = V

LX On-Resistance, Low Side ILX = 500mA VIN = 3.3V 18 50 m

LX Current-Limit Thresholds VIN= 3.3V

LX Leakage Current V

LX Switching Frequenc y VIN= 3.3V 0.9 1 1.1 MHz

LX Maximum Duty Cycle VIN= 3.3V 90 96 %

LX Minimum On-Time VIN= 3.3V 80 ns

RMS LX Output Current 4 A

ENABLE

EN Input Logic-Low Threshold
(Falling)

= 2.9V to 5V, V

DD

= 2.9V to 5V, V

DD

= 0.7V to 0.5V, V

FB

From COMP to GND, V

= V

V

EN

REFIN/SS

0.594 0.6 0.606 V

26 MHz

= 2.9V to 3.5V 0 VDD - 2 V

V

DD

V

= 1V, no sw itching,

COMP

V

REFIN/SS

DD

REFIN/SS

REFIN/SS

EN

0.7 V

= 0.6V

= 2.9V to 3.5V 0 V

= 0.45V 6 8 10 µA

= 0.9V, FB shorted to COMP -4.5 +4.5 mV

= 3.3V, V

DD

= 0V

= 0.5V, V

FB

FB

= 0V

REFIN/SS

= 0.7V, V

REFIN/SS

IN

REFIN/SS

REFIN/SS

= 0.6V 1.4 V/µs

= 3.3V, V

V

FB

V

FB

= 0.1V 300 

BST

High-side sourcing 5.4 8

Low-side sourcing 7

Low-side sink ing 7

Zero-crossing current threshold 0.2

Skip h igh-side sourcing 0.58

Sink current-limit DAC steps 4 Steps

V

= 0V -10

LX

= 5V 10

V

LX

= 0.6V 2 V

= 0.6V 0.68 V

= 100mV,

COMP

= 0.7V, sink 1

= 0.5V, source -1

- V

= 3.3V 24 54 m

LX

6 

- 2 V

DD

mA

A

µA

MAX15050/MAX15051

High-Efficiency, 4A, 1MHz, Step-Down Regulators
with Integrated Switches in 2mm x 2mm Package

4 _______________________________________________________________________________________

Note 4: 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= VEN= 5V, C

VDD

= 2.2µF, TA= -40°C to +85°C, typical values are at TA= +25°C, unless otherwise noted.) (Note 4)

Typical Operating Characteristics

(VIN= 5V, output voltage = 1.8V, I

LOAD

= 4A, and TA = +25°C, circuit of Figure 1, unless otherwise noted.)

PARAMETER CONDITIONS MIN TYP MAX UNITS

EN Input Logic-High Threshold
(Rising)

EN Input Current VEN = 0 or 5V 0.01 1 µA

THERMAL SHUTDOWN

Thermal-Shutdown Threshold +165 °C

Thermal-Shutdown Hysteresis 20 °C

POWER-GOOD (PWRGD)

Power-Good Threshold Voltage

Power-Good Edge Deglitch VFB falling or rising 48

PWRGD Output-Voltage Low I

PWRGD Leakage Current V

OVERCURRENT LIMIT (HICCUP MODE)

Current-Limit Startup Blan king 112

Autoretr y Restart Time 896

FB Hiccup Threshold VFB falling 70

Hiccup Threshold B lank ing Time VFB falling 36 µs

1.5 V

VFB falling, V

rising, V

V

FB

= 4mA 0.03 0.15 V

PWRGD

= 5V, V

PWRGD

REFIN/SS

REFIN/SS

= 0.6V 87 90 93

= 0.6V 92.5

= 0.9V, V

FB

REFIN/SS

= 0.6V 0.1 1 µA

% of

V

REFIN/SS

Clock

cycles

Clock

cycles

Clock

cycles

% of

V

REFIN/SS

EFFICIENCY vs. LOAD CURRENT

(V

= 5V) (MAX15050)

100

90

80

70

EFFICIENCY (%)

60

50

40

0.01 10

IN

V

= 2.5V

OUT

V

= 3.3V

OUT

V

= 1.8V

OUT

LOAD CURRENT (A)

V

OUT

10.1

EFFICIENCY vs. LOAD CURRENT

VIN = 5V (MAX15051)

100

MAX15050 toc01

= 1.2V

90

80

V

= 2.5V

70

EFFICIENCY (%)

60

50

40

0.1 1 10

V

= 3.3V

OUT

LOAD CURRENT (A)

OUT

V

= 1.8V

OUT

MAX15050 toc01b

V

= 1.2V

OUT

EFFICIENCY vs. LOAD CURRENT

(V

= 3.3V) (MAX15050)

V

OUT

IN

V

OUT

= 1.2V

LOAD CURRENT (A)

= 1.8V

V

= 2.5V

OUT

10.1

100

90

80

70

EFFICIENCY (%)

60

50

40

0.01 10

MAX15050 toc02

MAX15050/MAX15051

High-Efficiency, 4A, 1MHz, Step-Down Regulators

with Integrated Switches in 2mm x 2mm Package

_______________________________________________________________________________________

5

Typical Operating Characteristics (continued)

(VIN= 5V, output voltage = 1.8V, I

LOAD

= 4A, and TA = +25°C, circuit of Figure 1, unless otherwise noted.)

EFFICIENCY vs. LOAD CURRENT

= 3.3V (MAX15051)

V

V

= 1.2V

OUT

IN

V

= 1.8V

OUT

LOAD CURRENT (A)

V

= 2.5V

OUT

100

90

80

70

EFFICIENCY (%)

60

50

40

0.1 1 10

LOAD REGULATION

1.0

0.8

0.6

0.4

0.2

0

-0.2

-0.4

% OUTPUT FROM NORMAL

-0.6

-0.8

-1.0

LOAD CURRENT (A)

FREQUENCY vs. INPUT VOLTAGE

1.20

1.15

MAX15050 toc02b

1.10

1.05

1.00

0.95

FREQUENCY (MHz)

0.90

0.85

0.80

TA = +25NC

TA = -40NC

2.9 5.5

INPUT VOLTAGE (V)

LOAD-TRANSIENT RESPONSE

MAX15050 toc05

3.0 3.52.52.01.51.00.504.0

40µs/div

TA = +85NC

MAX15050 toc06

5.35.13.1 3.3 3.5 3.9 4.1 4.3 4.5 4.73.7 4.9

MAX15050 toc03

V

OUT

AC-COUPLED
200mV/div

4A
I

OUT

2A/div
1A

LINE REGULATION

(I

= 4A)

1.0

0.8

0.6

0.4

0.2

0

-0.2

-0.4

% OUTPUT FROM NORMAL

-0.6

-0.8

-1.0

2.9 5.5

LOAD

INPUT VOLTAGE (V)

LOAD-TRANSIENT RESPONSE

40µs/div

5.35.14.7 4.93.5 3.7 3.9 4.1 4.3 4.53.1 3.3

MAX15050 toc07

MAX15050 toc04

V

OUT

AC-COUPLED
100mV/div

4A
I

OUT

2A/div
2A

SWITCHING WAVEFORMS

400ns/div

MAX15050 toc08

V

OUT

AC-COUPLED
50mV/div

I

LX

1A/div

V

LX

2V/div
0V

SHUTDOWN WAVEFORM

10µs/div

MAX15050 toc09

V

EN

5V/div

V

OUT

1V/div