Rainbow Electronics MAX17067 User Manual
General Description
The MAX17067 boost converter incorporates highperformance (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 available in a space-saving 8-pin μMAX
®
package. The ultrasmall package and high switching frequency allow the
total solution to be less than 1.1mm high.
Application
LCD Displays
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
Low-Noise Step-Up DC-DC Converter
________________________________________________________________
Maxim Integrated Products
1
Typical Operating Circuit
19-3106; Rev 0; 1/08
Pin Configuration
Ordering Information
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
μMAX is a registered trademark of Maxim Integrated Products, Inc.
+
Denotes a lead-free package.
PART TEMP RANGE
MAX17067EUA+ -40°C to +85°C 8 μMAX
PINPACKAGE
PKG
CODE
U8+1
V
IN
2.6V TO 4V
IN
ON/OFF
SHDN
MAX17067
FREQ
SS
LX
GND
FB
COMP
V
OUT
TOP VIEW
1
COMP
2
3
SHDN
4
8
SS
FREQFB
7
MAX17067
μMAX
6
IN
5
LXGND
MAX17067
Low-Noise Step-Up DC-DC Converter
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VIN= SHDN = 3V, FREQ = 3V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
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.
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
Input Supply Range VIN V
Output Voltage 18 V
Input Supply Clamp Voltage
VIN Undervoltage Lockout UVLO
Quiescent Current I
Shutdown Supply Current I
ERROR AMPLIFIER
Feedback Voltage VFB Level to produce V
FB Input Bias Current IFB VFB = 1.24V 50 125 200 nA
Feedback-Voltage Line
Regulation
Transconductance g
Voltage Gain AV 3800 V/V
OSCILLATOR
Frequency f
Max imum Dut y C ycle DC FREQ = GND, FREQ = IN 89 92 95 %
n-CHANNEL SWITCH
Current Lim it I
On-Resistance RON 150 275 m
Leakage Current I
Current-Sense Tran sres is tance RCS 0.2 0.3 0.4 V/A
SOFT-START
Reset Switch Res is tance 100
Charge Current VSS = 1.2V 2.5 4.5 6.5 μA
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
< 18V 2.6 4.0 V
OUT
Use external limiting resistor; R
= 10V (Note 3)
V
IN
V
rising, typical hysteresis is 50mV, LX
IN
remains off below this level
VFB = 1.3V, not switching 0.3 0.6
IN
VFB = 1.0V, switching 1.5 2.5
SHDN = GND, TA = +25°C 30 60
IN
SHDN = GND, TA = +85°C 30
= 1.24V 1.23 1.24 1.25 V
COMP
Level to produce V
2.6V < V
I = 5μA 100 240 440 μS
m
OSC
LXOFF
FREQ = GND
FREQ = IN 1000 1200 1400
VFB = 1V, duty cyc le = 68% (Note 4) 1.8 2.4 3.4 A
LIM
VLX = 20V 10 20 μA
< 5.5V
IN
COMP
= 1.24V,
= 100,
IN
6.05 6.40 6.60 V
2.30 2.45 2.57 V
0.05 0.15 %/V
500 640 780
mA
μA
kHz
MAX17067
Low-Noise Step-Up DC-DC Converter
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS
(VIN= SHDN = 3V, FREQ = 3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 2)
ELECTRICAL CHARACTERISTICS (continued)
(VIN= SHDN = 3V, FREQ = 3V, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 2)
CONTROL INPUTS
Input Low Voltage V
Input High Voltage V
Hysteresis SHDN, FREQ
FREQ Pulldown Current I
SHDN Input Current I
Thermal Shutdown
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SHDN, FREQ, VIN = 2.6V to 4.0V
IL
SHDN, FREQ, VIN = 2.6V to 4.0V
IH
3 6 9 μA
FREQ
SHDN
SHDN = GND, TA = +25°C -1 +1
SHDN = GND, TA = +85°C 0
Temperature rising 160
Hysteresis 20
0.7 x
V
IN
V
0.1 x
V
IN
0.3 x
V
IN
V
V
μA
°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Supply Range VIN V
Output Voltage Range 18 V
Input Supply Clamp Voltage
VIN Undervoltage Lockout UVLO
Quiescent Current I
ERROR AMPLIFIER
Feedback Voltage VFB Level to produce V
FB Input Bias Current IFB VFB = 1.24V 200 nA
Feedback-Voltage Line
Regulation
Transconductance g
OSCILLATOR
Frequency f
Maximum Duty Cycle DC FREQ = GND, FREQ = VIN 89 95 %
IN
m
OSC
< 18V 2.6 4.0 V
OUT
Use external limiting resistor;
R
= 100, VIN = 10V (Note 3)
IN
V
rising, typical hysteresis is 80mV, LX
IN
remains off below this level
VFB = 1.3V, not switching 0.6
VFB = 1.0V, switching 2.5
= 1.24V 1.227 1.253 V
COMP
Level to produce V
2.6V < V
I = 5μA 100 440 μS
FREQ = GND
FREQ = IN 950 1500
< 4.0V
IN
COMP
= 1.24V,
6.03 6.60 V
2.30 2.57 V
mA
0.15 %/V
450 830
kHz
Low-Noise Step-Up DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(VIN= SHDN = 3V, FREQ = 3V, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
n-CHANNEL SWITCH
Current Lim it I
On-Resistance RON VIN = 3V 275
Current-Sense Tran sres is tance RCS 0.19 0.40 V/A
SOFT-START
MAX17067
Reset Switch Res is tance 100
Charge Current VSS = 1.2V 2.5 6.5 μA
CONTROL INPUTS
Input Low Voltage V
Input High Voltage V
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
Note 2: Limits are 100% production tested at TA= +25°C. Maximum and minimum limits over temperature are guaranteed by design
and characterization.
Note 3: See the
IN Supply Clamp Circuit
Note 4: Current limit varies with duty-cycle slope compensation. See the
VFB = 1V, duty cyc le = 68% (Note 4) 1.8 3.4 A
LIM
SHDN, FREQ, VIN = 2.6V to 4.0V
IL
SHDN, FREQ, VIN = 2.6V to 4.0V
IH
0.7 x
V
IN
0.3 x
V
IN
V
section for IN voltage limits during clamping circuit operation.
section to properly size the external resistor.
Output-Current Capability
section.
V
Typical Operating Characteristics
(Circuit of Figure 1, VIN= 3.3V, f
EFFICIENCY vs. L0AD CURRENT
100
90
80
70
EFFICIENCY (%)
60
50
1 100010010
IN
f
= 640kHz
OSC
= 4.7μH
L
LOAD CURRENT (mA)
f
OSC
= 3.3μH
L
OUT
= 1.2MHz
(V
= 3.3V, V
4 _______________________________________________________________________________________
= 640kHz, TA= +25°C, unless otherwise noted.)
OSC
STEP-UP CONVERTER
= 9V)
MAX17067 toc01
0.5
REGULATION (%)
-0.5
1.0
0
1 100010010
LOAD REGULATION
L = 3.3μH
LOAD CURRENT (mA)
1400
1300
MAX17067 toc02
1200
1100
1000
900
800
SWITCHING FREQUENCY (kHz)
700
600
500
2.5 5.54.53.5 5.04.03.0
SWITCHING FREQUENCY
vs. INPUT VOLTAGE
INPUT VOLTAGE (V)
FREQ = IN
MAX17067 toc03
FREQ = GND
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