19-3106; Rev 0; 1/08
KIT
ATION
EVALU
BLE
AVAILA
Low-Noise Step-Up DC-DC Converter
General Description
Features
o
90% Efficiency
o
Adjustable Output from V
IN
to 18V
o
2.4A, 0.15Ω, 22V Power MOSFET
o
+2.6V to +4.0V Input Range
o
Pin-Selectable 640kHz or 1.2MHz Switching
Frequency
o
Programmable Soft-Start
o
Small 8-Pin µMAX Package
o
Integrated Input Voltage Clamp Circuit
MAX17067
The MAX17067 boost converter incorporates high-
performance (at 1.2MHz), current-mode, fixed-frequency,
pulse-width modulation (PWM) circuitry with a built-in
0.15Ω n-channel MOSFET to provide a highly efficient
regulator with fast response.
High switching frequency (640kHz or 1.2MHz selectable)
allows for easy filtering and faster loop performance. An
external compensation pin provides the user flexibility in
determining loop dynamics, allowing the use of small,
low equivalent-series-resistance (ESR) ceramic output
capacitors. The device can produce an output voltage
as high as 18V.
Soft-start is programmed with an external capacitor, which
sets the input-current ramp rate. The MAX17067 is avail-
able in a space-saving 8-pin μMAX
®
package. The ultra-
small package and high switching frequency allow the
total solution to be less than 1.1mm high.
Application
LCD Displays
PART
MAX17067EUA+
Ordering Information
TEMP RANGE
-40°C to +85°C
PIN-
PACKAGE
8 μMAX
PKG
CODE
U8+1
Typical Operating Circuit
V
IN
2.6V TO 4V
+
Denotes a lead-free package.
Pin Configuration
TOP VIEW
IN
V
OUT
LX
COMP
1
FB
2
SHDN
3
GND
4
SS
FB
ON/OFF
SHDN
8
7
SS
FREQ
IN
LX
MAX17067
FREQ
GND
MAX17067
6
5
COMP
μMAX
μMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________
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-Noise Step-Up DC-DC Converter
MAX17067
ABSOLUTE MAXIMUM RATINGS
LX to GND ..............................................................-0.3V to +22V
SHDN,
FREQ to GND ............................................-0.3V to +7.5V
IN to GND (Note 1) ...................................................-0.3V to +6V
SS, COMP, FB to GND ................................-0.3V to (V
IN
+ 0.3V)
RMS LX Pin Current ..............................................................1.2A
Continuous Power Dissipation (T
A
= +70°C)
8-Pin μMAX (derate 4.1mW/°C above +70°C) ............330mW
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
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
(V
IN
=
SHDN
= 3V, FREQ = 3V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
Input Supply Range
Output Voltage
Input Supply Clamp Voltage
V
IN
Undervoltage Lockout
Quiescent Current
Shutdown Supply Current
ERROR AMPLIFIER
Feedback Voltage
FB Input Bias Current
Feedback-Voltage Line
Regulation
Transconductance
Voltage Gain
OSCILLATOR
Frequency
Maximum Duty Cycle
n-CHANNEL SWITCH
Current Limit
On-Resistance
Leakage Current
Current-Sense Transresistance
SOFT-START
Reset Switch Resistance
Charge Current
V
SS
= 1.2V
2.5
4.5
100
6.5
μA
I
LIM
R
ON
I
LXOFF
R
CS
V
LX
= 20V
0.2
V
FB
= 1V, duty cycle = 68% (Note 4)
1.8
2.4
150
10
0.3
3.4
275
20
0.4
A
m
μA
V/A
f
OSC
DC
FREQ = GND
FREQ = IN
FREQ = GND, FREQ = IN
500
1000
89
640
1200
92
780
1400
95
kHz
%
g
m
A
V
V
FB
I
FB
Level to produce V
COMP
= 1.24V
V
FB
= 1.24V
Level to produce V
COMP
= 1.24V,
2.6V < V
IN
< 5.5V
I = 5μA
100
1.23
50
1.24
125
0.05
240
3800
1.25
200
0.15
440
V
nA
%/V
μS
V/V
UVLO
I
IN
I
IN
Use external limiting resistor; R
IN
= 100 ,
V
IN
= 10V (Note 3)
V
IN
rising, typical hysteresis is 50mV, LX
remains off below this level
V
FB
= 1.3V, not switching
V
FB
= 1.0V, switching
SHDN
= GND, T
A
= +25°C
SHDN
= GND, T
A
= +85°C
6.05
2.30
6.40
2.45
0.3
1.5
30
30
SYMBOL
V
IN
V
OUT
< 18V
CONDITIONS
MIN
2.6
TYP
MAX
4.0
18
6.60
2.57
0.6
2.5
60
UNITS
V
V
V
V
mA
μA
2
_______________________________________________________________________________________
Low-Noise Step-Up DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
=
SHDN
= 3V, FREQ = 3V,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 2)
PARAMETER
CONTROL INPUTS
Input Low Voltage
Input High Voltage
Hysteresis
FREQ Pulldown Current
SHDN
Input Current
Thermal Shutdown
I
FREQ
I
SHDN
SHDN
= GND, T
A
= +25°C
SHDN
= GND, T
A
= +85°C
Temperature rising
Hysteresis
V
IL
V
IH
SHDN,
FREQ, V
IN
= 2.6V to 4.0V
SHDN,
FREQ, V
IN
= 2.6V to 4.0V
SHDN,
FREQ
3
-1
0
160
20
0.7 x
V
IN
0.1 x
V
IN
6
9
+1
0.3 x
V
IN
V
V
V
μA
μA
°C
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX17067
ELECTRICAL CHARACTERISTICS
(V
IN
=
SHDN
= 3V, FREQ = 3V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 2)
PARAMETER
Input Supply Range
Output Voltage Range
Input Supply Clamp Voltage
VIN Undervoltage Lockout
Quiescent Current
ERROR AMPLIFIER
Feedback Voltage
FB Input Bias Current
Feedback-Voltage Line
Regulation
Transconductance
OSCILLATOR
Frequency
Maximum Duty Cycle
f
OSC
DC
FREQ = GND
FREQ = IN
FREQ = GND, FREQ = V
IN
450
950
89
830
1500
95
kHz
%
g
m
V
FB
I
FB
Level to produce V
COMP
= 1.24V
V
FB
= 1.24V
Level to produce V
COMP
= 1.24V,
2.6V < V
IN
< 4.0V
I = 5μA
100
1.227
1.253
200
0.15
440
V
nA
%/V
μS
UVLO
I
IN
Use external limiting resistor;
R
IN
= 100 , V
IN
= 10V (Note 3)
V
IN
rising, typical hysteresis is 80mV, LX
remains off below this level
V
FB
= 1.3V, not switching
V
FB
= 1.0V, switching
6.03
2.30
SYMBOL
V
IN
V
OUT
< 18V
CONDITIONS
MIN
2.6
TYP
MAX
4.0
18
6.60
2.57
0.6
2.5
UNITS
V
V
V
V
mA
_______________________________________________________________________________________
3
Low-Noise Step-Up DC-DC Converter
MAX17067
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
=
SHDN
= 3V, FREQ = 3V,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
n-CHANNEL SWITCH
Current Limit
On-Resistance
Current-Sense Transresistance
SOFT-START
Reset Switch Resistance
Charge Current
CONTROL INPUTS
Input Low Voltage
Input High Voltage
V
IL
V
IH
SHDN,
FREQ, V
IN
= 2.6V to 4.0V
SHDN,
FREQ, V
IN
= 2.6V to 4.0V
0.7 x
V
IN
0.3 x
V
IN
V
V
V
SS
= 1.2V
2.5
100
6.5
μA
I
LIM
R
ON
R
CS
V
FB
= 1V, duty cycle = 68% (Note 4)
V
IN
= 3V
0.19
1.8
3.4
275
0.40
V/A
A
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Note 1:
Limit on IN absolute maximum ratings is for operation without the use of an external resistor for the internal clamp circuit.
See the
IN Supply Clamp Circuit
section for IN voltage limits during clamping circuit operation.
Note 2:
Limits are 100% production tested at T
A
= +25°C. Maximum and minimum limits over temperature are guaranteed by design
and characterization.
Note 3:
See the
IN Supply Clamp Circuit
section to properly size the external resistor.
Note 4:
Current limit varies with duty-cycle slope compensation. See the
Output-Current Capability
section.
Typical Operating Characteristics
(Circuit of Figure 1, V
IN
= 3.3V, f
OSC
= 640kHz, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. L0AD CURRENT
(V
IN
= 3.3V, V
OUT
= 9V)
MAX17067 toc01
STEP-UP CONVERTER
LOAD REGULATION
MAX17067 toc02
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
1300
SWITCHING FREQUENCY (kHz)
1200
FREQ = IN
1100
1000
900
800
700
600
FREQ = GND
MAX17067 toc03
100
1.0
1400
90
EFFICIENCY (%)
f
OSC
= 640kHz
L = 4.7μH
REGULATION (%)
0.5
L = 3.3μH
0
80
f
OSC
= 1.2MHz
L = 3.3μH
70
60
50
1
10
100
1000
LOAD CURRENT (mA)
-0.5
1
10
100
1000
LOAD CURRENT (mA)
500
2.5
3.0
3.5
4.0
4.5
5.0
5.5
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
Low-Noise Step-Up DC-DC Converter
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= 3.3V, f
OSC
= 640kHz, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX17067 toc04
MAX17067
SOFT-START
(R
LOAD
= 18Ω)
MAX17067 toc05
4.0
3.5
SUPPLY CURRENT (mA)
3.0
2.5
2.0
1.5
1.0
0.5
0
2.5
2.7
2.9
3.1
3.3
3.5
3.7
3.9
SUPPLY VOLTAGE (V)
NONSWITCHING
SWITCHING
V
OUT
5V/div
0V
INDUCTOR
CURRENT
1A/div
0A
2ms/div
LOAD-TRANSIENT RESPONSE
(I
LOAD
= 10mA TO 200mA)
MAX17067 toc06
PULSED LOAD-TRANSIENT RESPONSE
(I
LOAD
= 40mA TO 1.1A)
MAX17067 toc07
I
OUT
200mA/div
10mA
V
OUT
500mA/div
AC-COUPLED
0V
I
OUT
1A/div
0.1A
9V
V
OUT
200mV/div
AC-COUPLED
0V
INDUCTOR
CURRENT
500mA/div
0A
100μs/div
L = 3.3μH
R
COMP
= 39kΩ
C
COMP1
= 620pF
L = 3.3μH
R
COMP
= 39kΩ
C
COMP1
= 620pF
10μs/div
INDUCTOR
CURRENT
1A/div
0A
SWITCHING WAVEFORMS
(I
LOAD
= 500mA)
MAX17067 toc08
LX
5V/div
0V
INDUCTOR
CURRENT
1A/div
0A
1μs/div
_______________________________________________________________________________________
5
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