19-4458; Rev 0; 2/09
Low-Voltage, Internal Switch,
Step-Down Regulator
General Description
The MAX17083 is a fixed-frequency, current-mode,
step-down regulator optimized for low-voltage, low-
power 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 pro-
duces 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 pro-
vides peak current-limit protection and operates in
light-load pulse-skipping mode to maintain high effi-
ciency under light-load conditions.
Independent enable input and open-drain power-good
output allow flexible system power sequencing. The volt-
age soft-start gradually ramps up the output voltage
within a predictable time period, effectively limiting the
inrush current. The MAX17083 features output undervolt-
age, 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
Applications
Low-Power Architectures
Ultra-Mobile PCs
Netbook and Nettop PCs
Portable Gaming
Notebook and Subnotebook Computers
PDAs and Mobile Communicators
Ordering Information
PART
MAX17083ETG+
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
24 TQFN
+Denotes
a lead(Pb)-free/RoHS-compliant package.
Pin Configuration
BST
V
CC
14
SET
13
12 FB
11 N.C.
10 GND
LX
LX
EN
15
TOP VIEW
18
N.C. 19
PGND 20
PGND 21
PGND 22
PGND 23
N.C. 24
17
16
MAX17083
9
8
GND
GND
REF
+
1
LX
2
LX
3
IN
4
IN
5
FREQ
6
POK
7
TQFN
4mm x 4mm
________________________________________________________________
Maxim Integrated Products
1
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.
Low-Voltage, Internal Switch,
Step-Down Regulator
MAX17083
ABSOLUTE MAXIMUM RATINGS
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 (V
LX
+ 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
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.
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.
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= V
FREQ
= V
CC
= V
EN
= 5V, I
REF
= no load,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
IN Input Voltage Range
V
CC
Input Voltage Range
IN Undervoltage Threshold
Vcc Undervoltage Threshold
Shutdown Supply Current
Supply Current
REFERENCE
Reference Output Voltage
Reference Load Regulation
OSCILLATOR
Oscillator Frequency
f
OSC
FREQ = GND
FREQ = V
CC
FREQ Settings
FREQ = open
FREQ = REF
FREQ = GND
INTERNAL 5A STEP-DOWN CONVERTER
SET = GND
FB Regulation Voltage
(No Load)
V
FB
No load
SET = REF
SET = open
SET = 5V
SET = GND
FB Regulation Voltage
(Full Load)
V
FB
I
OUT
= 4A
SET = REF
SET = open
SET = 5V
0.754
1.107
1.51
1.812
0.72
1.07
1.45
1.76
0.765
1.122
1.53
1.836
0.774
1.136
1.55
1.86
0.774
1.136
1.55
1.86
V
V
0.45
0.50
1.50
1.00
0.75
0.50
MHz
0.55
MHz
V
REF
No load
-1μA < I
REF
< +50μA
1.24
1.25
3
1.26
10
V
mV
SYMBOL
V
IN
V
CC
No hysteresis
Rising edge, 160mV hysteresis
EN = GND, measured at V
CC
, T
A
= +25°C
Regulator enabled
CONDITIONS
MIN
2.4
4.5
2.1
4.2
0.1
65
TYP
MAX
5.5
5.5
2.4
4.5
1.0
95
UNITS
V
V
V
V
μA
μA
2
_______________________________________________________________________________________
Low-Voltage, Internal Switch,
Step-Down Regulator
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, V
IN
= V
FREQ
= V
CC
= V
EN
= 5V, I
REF
= no load,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at
T
A
= +25°C.)
PARAMETER
FB Load Regulation
FB Line Regulation
(Slope Compensation)
FB Input Current
Internal MOSFET On-Resistance
(Note 3)
Internal BST On-Resistance
LX Peak Current Limit
LX Idle Mode™ Trip Level
LX Zero-Crossing Trip Level
Soft-Start Ramp Time
Soft-Start Fault Blanking Time
POK Upper Trip Threshold and
Overvoltage Fault Threshold
POK Lower Trip Threshold
POK Propagation Delay Time
Overvoltage Fault Latch
Delay Time
Undervoltage Fault Latch
Delay Time
POK Output Low Voltage
POK Leakage Current
Thermal-Shutdown Threshold
LOGIC INPUTS
EN Input High Threshold
EN Input Bias Current
Rising, hysteresis = 220mV (typ)
T
A
= +25°C
V
CC
FREQ and SET Input Voltage
Levels
Open
REF
GND
FREQ and SET Input Bias
Currents
T
A
= +25°C
-2
+0.1
V
CC
-
0.5
3
1.2
3.2
2.2
0.5
+2
μA
V
1.0
1.4
0.1
1.6
1
V
μA
I
POK
T
SHDN
t
POK
T
SS
T
SSLT
Rising edge, 50mV hysteresis
Falling edge, 50mV hysteresis
FB forced 50mV beyond POK trip threshold
FB forced 50mV above POK upper trip
threshold
FB forced 50mV below POK lower trip
threshold, TUV
I
SINK
= 3mA
SET = GND, FB = 1V (POK high impedance),
POK forced to 5.5V, T
A
= +25°C
Hysteresis = 15°C
+160
9
-14
5
V
FB
I
FB
SYMBOL
SET = GND
SET = GND, 0 to 100% duty cycle,
V
CC
= 4.5V to 5.5V
SET = GND, T
A
= +25°C
High-side n-channel R
DH
Low-side n-channel R
DL
10
-100
CONDITIONS
MIN
TYP
-4
15
-5
32
17
2
6
1.5
100
1939/
f
SW
3232/
f
SW
12
-12
5
5
1534/
f
SW
0.4
1
14
-9
8
A
A
mA
ms
ms
%
%
μs
μs
ms
V
μA
°C
20
+100
50
30
MAX
UNITS
mV/A
mV
nA
m
MAX17083
Idle Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
Low-Voltage, Internal Switch,
Step-Down Regulator
MAX17083
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, V
IN
= V
FREQ
= V
CC
= V
EN
= 5V, I
REF
= no load,
T
A
= -40°C to +85°C,
unless otherwise noted. Typical values are
at T
A
= +25°C.)
PARAMETER
Shutdown Supply Current
Supply Current
Regulator Enabled
REFERENCE
Reference Output Voltage
LX Peak Current Limit
V
REF
No load
1.145
4.35
1.265
8
V
A
INTERNAL 5A STEP-DOWN CONVERTER
SYMBOL
CONDITIONS
EN = GND, measured at V
CC
, T
A
= +25°C
Does not include switching losses, measured
from V
CC
MIN
MAX
10
120
UNITS
μA
μA
Note 3:
Limits are 100% production tested at T
A
= +25°C. Maximum and minimum limits are guaranteed by design and
characterization.
Typical Operating Characteristics
(Circuit of Figure 1, V
IN
= 5V, V
OUT
= 1.1V, FREQ = open. T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 5V, 1MHz)
MAX17083 toc01
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 3.3V, 1MHz)
V
OUT
= 1.8V
90
EFFICIENCY (%)
V
OUT
= 1.5V
MAX17083 toc02
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 5V, 750kHz)
V
OUT
= 1.8V
90
EFFICIENCY (%)
V
OUT
= 1.5V
MAX17083 toc03
100
V
OUT
= 1.8V
90
EFFICIENCY (%)
V
OUT
= 1.5V
100
100
80
V
OUT
= 1.1V
70
V
OUT
= 0.75V
60
80
V
OUT
= 1.1V
70
V
OUT
= 0.75V
60
80
V
OUT
= 1.1V
70
V
OUT
= 0.75V
60
50
0.001
0.01
0.1
LOAD CURRENT (A)
1
10
50
0.001
0.01
0.1
LOAD CURRENT (A)
1
10
50
0.001
0.01
0.1
LOAD CURRENT (A)
1
10
4
_______________________________________________________________________________________
Low-Voltage, Internal Switch,
Step-Down Regulator
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= 5V, V
OUT
= 1.1V, FREQ = open. T
A
= +25°C, unless otherwise noted.)
MAX17083
EFFICIENCY vs. LOAD CURRENT
(V
IN
= 3.3V, 750kHz)
V
OUT
= 1.8V
90
EFFICIENCY (%)
V
OUT
= 1.5V
MAX17083 toc04
SMPS OUTPUT VOLTAGE
vs. LOAD CURRENT (1MHz)
MAX17083 toc05
100
0.78
80
OUTPUT VOLTAGE (V)
0.77
V
IN
= 5V
0.76
V
OUT
= 1.1V
70
V
OUT
= 0.75V
60
0.75
V
IN
= 3.3V
50
0.001
0.74
0.01
0.1
LOAD CURRENT (A)
1
10
0
1
2
3
4
5
6
LOAD CURRENT (A)
REGULATOR STARTUP WAVEFORM
(HEAVY LOAD)
MAX17083 toc06
REGULATOR STARTUP WAVEFORM
(NO LOAD)
MAX17083 toc07
EN
POK
OUT
EN
POK
OUT
IL
LX
400μs/div
f
SW
= 750kHz, V
IN
= 5V,
V
OUT
= 1.1V
EN: 5V/div
OUT: 1V/div
R
LOAD
= 0.22Ω
POK: 2V/div
I
L
: 5A/div
LX: 5V/div
IL
LX
400μs/div
f
SW
= 1MHz, V
IN
= 5V,
V
OUT
= 1.1V
EN: 5V/div
OUT: 1V/div
POK: 2V/div
I
L
: 5A/div
LX: 5V/div
_______________________________________________________________________________________
5
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