Rainbow Electronics MAX17083 User Manual

General Description

The MAX17083 is a fixed-frequency, current-mode,
step-down regulator optimized for low-voltage, low­power applications. This regulator features dual internal
n-channel MOSFET power switches for high efficiency
and reduced component count. External Schottky
diodes are not required. An integrated boost switch
eliminates the need for an external boost diode. The
internal 25mΩ low-side power MOSFET easily supports
continuous load currents up to 5A. The MAX17083 pro­duces an adjustable 0.75V to 2.7V output voltage from
the system’s 3.3V or 5V input supply.

This step-down regulator uses a peak current-mode
control scheme to eliminate the additional external
compensation required by voltage-mode architectures,
providing an easy-to-implement architecture without
sacrificing fast transient response. The MAX17083 pro­vides peak current-limit protection and operates in
light-load pulse-skipping mode to maintain high effi­ciency under light-load conditions.

Independent enable input and open-drain power-good
output allow flexible system power sequencing. The volt­age soft-start gradually ramps up the output voltage
within a predictable time period, effectively limiting the
inrush current. The MAX17083 features output undervolt­age, output overvoltage, and thermal-fault protection.

The MAX17083 is available in a 24-pin 4mm x 4mm x

0.75mm TQFN package. The exposed backside pad
improves thermal characteristics.

Features

o Fixed-Frequency, Current-Mode Controller

o 2.4V to 5.5V Input Range

o Internal 5A Step-Down Regulator

o Internal BST Switch

o Fault Protection: Undervoltage, Overvoltage,

Thermal, Peak Current Limit

o Enable Input and Power-Good Output

o Voltage-Controlled Soft-Start

o High-Impedance Shutdown

o < 1µA (typ) Shutdown Current

MAX17083

Low-Voltage, Internal Switch,

Step-Down Regulator

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

19-4458; Rev 0; 2/09

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.

Ordering Information

PART TEMP RANGE PIN-PACKAGE

MAX17083ETG+ -40°C to +85°C 24 TQFN

+

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

Applications

Low-Power Architectures

Ultra-Mobile PCs

Netbook and Nettop PCs

Portable Gaming

Notebook and Subnotebook Computers

PDAs and Mobile Communicators

TOP VIEW

19

N.C.

20

PGND

21

PGND

PGND

22

PGND

23

N.C.

24

CC

BST

MAX17083

IN

TQFN

EN

V

IN

FREQ

LX

LX

18 17 16 15 14 13

+

12 3456

LX

LX

4mm x 4mm

SET

POK

12

FB

11

N.C.

10

GND

GND

9

GND

8

REF

7

MAX17083

Low-Voltage, Internal Switch,
Step-Down Regulator

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V

IN

= V

FREQ

= VCC= VEN= 5V, I

REF

= no load, TA= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.)

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 to PGND...............................................................-0.3V to +6V

V

CC

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

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

REF, FB, SET, FREQ, POK to GND ............-0.3V to (V

CC

+ 0.3V)

LX to GND (Notes 1, 2)................................-0.6V to (V

IN

+ 0.3V)

BST to GND.........................................(V

CC

- 0.3V) to (VLX+ 6V)

GND to PGND (Note 2) .........................................-0.3V to +0.3V

REF Short-Circuit Current......................................................1mA

Continuous Power Dissipation, Multilayer PCB (T

A

= +70°C)

24-Pin, 4mm x 4mm TQFN

(derate 27.8mW/°C above +70°C) ........................2222mW

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IN Input Voltage Range V

IN

2.4 5.5 V

VCC Input Voltage Range V

CC

4.5 5.5 V

IN Undervoltage Threshold No hy steresis 2.1 2.4 V

Vcc Undervoltage Threshold Rising edge, 160mV hysteresis 4.2 4.5 V

Shutdown Supply C urrent EN = GND, measured at VCC, TA = +25°C 0.1 1.0 μA

Supply Current Regulator enabled 65 95 μA

REFERENCE

Reference Output Voltage V

REF

No load 1.24 1.25 1.26 V

Reference Load Regulation -1μA < I

REF

< +50μA 3 10 mV

OSCILLATOR

Oscillator Frequency f

OSC

FREQ = GND 0.45 0.50 0.55 MHz

FREQ = VCC 1.50

FREQ = open 1.00

FREQ = REF 0.75

FREQ Settings

FREQ = GND 0.50

MHz

INTERNAL 5A STEP-DOWN CONVERTER

SET = GND 0.754 0.765 0.774

SET = REF 1.107 1.122 1.136

SET = open 1.51 1.53 1.55

FB Regulation Voltage
(No Load)

V

FB

No load

SET = 5V 1.812 1.836 1.86

V

SET = GND 0.72 0.774

SET = REF 1.07 1.136

SET = open 1.45 1.55

FB Regulation Voltage
(Full Load)

V

FB

I

OUT

= 4A

SET = 5V 1.76 1.86

V

Note 1: LX has clamp diodes to PGND and IN. If continuous current is applied through these diodes, thermal limits must be observed.
Note 2: Measurements valid using 20MHz bandwidth limit.

MAX17083

Low-Voltage, Internal Switch,

Step-Down Regulator

_______________________________________________________________________________________ 3

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

FB Load Regulation SET = GND -4 mV/A

FB Line Regulation
(Slope Compensation)

V

FB

SET = GND, 0 to 100% duty cycle,
V

CC

= 4.5V to 5.5V

10 15 20 mV

FB Input Current IFB SET = GND, TA= +25°C -100 -5 +100 nA

High-side n-channe l RDH 32 50

Internal MOSFET On-Resistance
(Note 3)

Low-side n-channel R

DL

17 30

m

Internal BST On-Resistance 2 

LX Peak Current Limit 5 6 8 A

LX Idle Mode™ Trip Leve l 1.5 A

LX Zero-Crossing Trip Level 100 mA

Soft-Start Ramp Time T

SS

1939/

f

SW

ms

Soft-Start Fault Blanking Time T

SSLT

3232/

f

SW

ms

POK Upper Trip Threshold and
Overvoltage Fault Threshold

Rising edge, 50mV h ysteresi s 9 12 14 %

POK Lower Trip Threshold Fal ling edge, 50mV hysteresis -14 -12 -9 %

POK Pr opagation Dela y Time t

POK

FB forced 50mV beyond POK trip threshold 5 μs

Overvoltage Fault Latch
Delay Time

FB forced 50mV above POK upper trip
threshold

5 μs

Undervoltage Fault Latch
Delay Time

FB forced 50mV below POK lower trip
threshold, TUV

1534/

f

SW

ms

POK Output Low Voltage I

SINK

= 3mA 0.4 V

POK Leakage Current I

POK

SET = GND, FB = 1V (POK high impedance),
POK forced to 5.5V, T

A

= +25°C

1 μA

Thermal-Shutdown Threshold T

SHDN

Hysteresis = 15°C +160 °C

LOGIC INPUTS

EN Input High Threshold Rising, hysteresi s = 220mV (typ) 1.0 1.4 1.6 V

EN Input Bias Current TA = +25°C 0.1 1 μA

V

CC

VCC -

0.5

Open 3 3.2

REF 1.2 2.2

FREQ and SET Input Voltage
Levels

GND 0.5

V

FREQ and SET Input Bias
Currents

T

A

= +25°C -2 +0.1 +2 μA

ELECTRICAL CHARACTERISTICS (continued)

(Circuit of Figure 1, V

IN

= V

FREQ

= VCC= VEN= 5V, I

REF

= no load, TA= 0°C to +85°C, unless otherwise noted. Typical values are at

T

A

= +25°C.)

Idle Mode is a trademark of Maxim Integrated Products, Inc.

Typical Operating Characteristics

(Circuit of Figure 1, V

IN

= 5V, V

OUT

= 1.1V, FREQ = open. TA= +25°C, unless otherwise noted.)

MAX17083

Low-Voltage, Internal Switch,
Step-Down Regulator

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(Circuit of Figure 1, V

IN

= V

FREQ

= VCC= VEN= 5V, I

REF

= no load, TA= -40°C to +85°C, unless otherwise noted. Typical values are

at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS MIN MAX UNITS

Shutdown Supply C urrent EN = GND, measured at VCC, TA = +25°C 10 μA

Supply Current
Regulator Enabled

Does not inc lude switching losses, measured
from V

CC

120 μA

REFERENCE

Reference Output Voltage V

REF

No load 1.145 1.265 V

INTERNAL 5A STEP-DOWN CONVERTER

LX Peak Current Limit 4.35 8 A

Note 3: Limits are 100% production tested at TA= +25°C. Maximum and minimum limits are guaranteed by design and

characterization.

EFFICIENCY vs. LOAD CURRENT

100

V

= 1.8V

OUT

90

80

70

EFFICIENCY (%)

60

50

0.001 10

= 5V, 1MHz)

(V

IN

V

= 0.75V

OUT

0.01 0.1 1
LOAD CURRENT (A)

V

= 1.5V

OUT

V

= 1.1V

OUT

EFFICIENCY vs. LOAD CURRENT

= 3.3V, 1MHz)

(V

IN

V

= 1.5V

= 1.8V

V

0.01 0.1 1

OUT

= 0.75V

OUT

LOAD CURRENT (A)

MAX17083 toc02

V

= 1.1V

OUT

EFFICIENCY (%)

MAX17083 toc01

100

V

OUT

90

80

70

EFFICIENCY (%)

60

50

0.001 10

EFFICIENCY vs. LOAD CURRENT

= 5V, 750kHz)

(V

100

V

OUT

90

80

70

60

50

0.001 10

IN

V

= 1.5V

= 1.8V

0.01 0.1 1

OUT

V

= 0.75V

OUT

LOAD CURRENT (A)

V

= 1.1V

OUT

MAX17083 toc03

MAX17083

Low-Voltage, Internal Switch,

Step-Down Regulator

_______________________________________________________________________________________ 5

Typical Operating Characteristics (continued)

(Circuit of Figure 1, V

IN

= 5V, V

OUT

= 1.1V, FREQ = open. TA= +25°C, unless otherwise noted.)

100

EFFICIENCY (%)

EFFICIENCY vs. LOAD CURRENT

V

OUT

90

80

70

60

50

0.001 10

REGULATOR STARTUP WAVEFORM

EN

= 3.3V, 750kHz)

(V

IN

= 1.8V

V

= 1.5V

OUT

V

OUT

V

= 0.75V

OUT

0.01 0.1 1
LOAD CURRENT (A)

(HEAVY LOAD)

= 1.1V

MAX17083 toc06

MAX17083 toc04

SMPS OUTPUT VOLTAGE

vs. LOAD CURRENT (1MHz)

0.78

0.77

VIN = 5V

0.76

OUTPUT VOLTAGE (V)

0.75

0.74

VIN = 3.3V

06

LOAD CURRENT (A)

42315

MAX17083 toc05

REGULATOR STARTUP WAVEFORM

(NO LOAD)

EN

MAX17083 toc07

POK

OUT

IL

LX

f

= 750kHz, VIN = 5V,

SW

= 1.1V

V

OUT

EN: 5V/div
OUT: 1V/div

400μs/div

R

= 0.22Ω

LOAD

POK: 2V/div

: 5A/div

I

L

LX: 5V/div

POK

OUT

IL

LX

= 1MHz, VIN = 5V,

f

SW

= 1.1V

V

OUT

EN: 5V/div
OUT: 1V/div

400μs/div

POK: 2V/div

: 5A/div

I

L

LX: 5V/div