19-1794 Rev 0; 10/00
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
General Description
The MAX1817 is a compact, high-efficiency, dual-out-
put step-up converter for portable devices that pro-
vides both the main logic supply and the LCD bias. The
device operates from an input voltage of +1.5V to
+5.5V, allowing the use of 2- or 3-cell alkaline batteries,
or 1-cell lithium-ion (Li+) batteries.
The MAX1817’s main regulator supplies 125mA at
either a preset 3.3V or an adjustable 2.5V to 5.5V out-
put voltage with up to 88% efficiency. A 0.1µA shut-
down state also minimizes battery drain. The
MAX1817’s secondary step-up converter provides the
LCD bias voltage and is adjustable up to +28V.
Other features include a fast switching frequency to
reduce the size of external components and a low qui-
escent current to maximize battery life. Both outputs can
be independently shut down for improved flexibility.
The MAX1817 is supplied in a compact 10-pin µMAX
package. The MAX1817 evaluation kit (MAX1817EVKIT)
is available to speed up design.
Features
o
Dual Step-Up Converter in a Tiny 10-Pin µMAX
Package
o
Main Output
Up to 125mA Load Current
Fixed 3.3V or Adjustable 2.5V to 5.5V
Up to 88% Efficiency
Internal Switch
o
LCD Output
Up to 28V for LCD Bias
Internal Switch
o
Input Voltage Range +1.5V to +5.5V
o
Minimal External Components Required
o
0.1µA Logic-Controlled Shutdown
o
Low 15µA Quiescent Supply Current
MAX1817
________________________Applications
Organizers/Translators
PDAs
MP3 Players
GPS Receivers
PART
MAX1817EUB
Ordering Information
TEMP. RANGE
-40°C to +85°C
PIN-PACKAGE
10 µMAX
Typical Operating Circuit
+1.5V
TO +5.5V
Pin Configuration
TOP VIEW
FB
1
LCD
LX
LXLCD
FBLCD
ON
ONLCD
FBLCD
AGND
2
3
4
5
10
OUT
9
LX
GND
LXLCD
N.C.
MAX1817
8
7
6
LCD ON/OFF
ONLCD
MAX1817
MAIN ON/OFF
ON
AGND
OUT
FB
GND
MAIN
µMAX
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
MAX1817
ABSOLUTE MAXIMUM RATINGS
OUT to GND .............................................................-0.3V to +6V
ON, ONLCD, FB, FBLCD, LX to GND ......-0.3V to (V
OUT
+ 0.3V)
LXLCD to GND .......................................................-0.3V to +30V
AGND to GND .......................................................-0.3V to +0.3V
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW
LXLCD, LX Maximum Current ........................................0.5A
RMS
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
ON
= V
ONLCD
= V
OUT
= +3.3V, FB = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
GENERAL
Input Voltage Range
Startup Voltage
Quiescent Current from OUT
(Main Only)
Quiescent Current from OUT
Shutdown Quiescent Current
MAIN OUTPUT
OUT Undervoltage Lockout
Fixed-Mode Output Voltage
Adjustable-Mode FB Regulation
Voltage
FB Input Bias Current
FB Dual Mode
TM
Threshold
Output Voltage Adjustment
Range
Maximum LX On-Time
Zero Crossing Comparator
Threshold (V
LX
- V
OUT
)
Zero Crossing Comparator
Backup Timer
Line Regulation
Load Regulation
LX On-Resistance
LX Current Limit
V
FB
= +0.5V
I
OUT
= 100mA,
V
IN
= +2V to +3V
V
IN
= +2.5V,
I
LOAD
= 10mA to 100mA
V
OUT
= 3.3V, I
LX
= 100mA
0.5
V
FB
= 0.5V
V
FB
= 1.35V
45
2.5
2.4
0
22
5
20
45
1.6
1.6
0.35
0.75
0.65
1.05
75
V
OUT
rising, V
FB
= 1.35V
V
OUT
falling, V
FB
= 1.35V
V
FB
≤
45mV
1.95
3.14
1.20
2.2
2.15
3.3
1.25
3.47
1.30
50
105
5.5
7.5
40
70
2.4
V
V
V
nA
mV
V
µs
mV
µs
%
%
Ω
A
R
LOAD
= 35Ω
R
LOAD
=
∞,
V
FB
= 1.35V
V
FB
= V
FBLCD
= 1.35V,
V
ONLCD
= 0
V
FB
= V
FBLCD
= 1.35V
V
ON
= V
ONLCD
= 0
1.5
1.5
1.2
5
15
0.1
1.55
10
30
1
5.5
V
V
µA
µA
µA
CONDITIONS
MIN
TYP
MAX
UNITS
Dual Mode is a trademark of Maxim Integrated Products.
2
_______________________________________________________________________________________
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
ELECTRICAL CHARACTERISTICS (continued)
(V
ON
= V
ONLCD
= V
OUT
= +3.3V, FB = GND,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
LX Leakage Current
ON Input Low Voltage
ON Input High Voltage
ON Input Bias Current
LCD OUTPUT
LXLCD Voltage
LXLCD On-Resistance
LXLCD Current Limit
LXLCD Leakage Current
FBLCD Regulation Voltage
FBLCD Input Bias Current
LCD Line Regulation
LCD Load Regulation
Maximum LXLCD On-Time
Minimum LXLCD Off-Time
ONLCD Input Low Voltage
ONLCD Input High Voltage
ONLCD Input Bias Current
V
FBLCD
≥
1.2V
V
FBLCD
≤
0.7V
2.5V < V
OUT
< 5.5V
2.5V < V
OUT
< 5.5V
1.6
1
V
FBLCD
= 1.35V
I
LOAD
= 5mA, V
IN
= +2V to +3V
I
LOAD
= 1mA to 5mA, V
IN
= +2.5V
4
0.5
2.4
0.1
0.5
9
1
5
14
1.5
7.5
400
V
LXLCD
= 28V, V
ONLCD
= 0
1.20
V
OUT
= 3.3V, I
LXLCD
= 100mA
0.28
1.1
0.5
0.1
1.25
28
2.0
0.7
1
1.30
50
V
Ω
A
µA
V
nA
%
%
µs
µs
mV
V
µA
CONDITIONS
V
ON
= GND, V
LX
= 5.5V
1.8V < V
OUT
< 5.5V, V
FB
= 0.5V
1.8V < V
OUT
< 5.5V, V
FB
= 0.5V
1.6
1
MIN
TYP
0.1
MAX
1
400
UNITS
µA
mV
V
µA
MAX1817
ELECTRICAL CHARACTERISTICS
(V
ON
= V
ONLCD
= V
OUT
= +3.3V, FB = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
GENERAL
Input Voltage Range
Startup Voltage
Quiescent Current from OUT
(Main Only)
Quiescent Current from OUT
Shutdown Quiescent Current
MAIN OUTPUT
OUT Undervoltage Lockout
Fixed-Mode Output Voltage
Adjustable-Mode FB Regulation
Voltage
FB Input Bias Current
V
FB
= 1.35V
V
OUT
rising, V
FB
= 1.35V
V
OUT
falling, V
FB
= 1.35V
V
FB
≤
45mV
1.95
3.14
1.20
3.47
1.30
50
2.4
V
V
V
nA
R
LOAD
=
∞,
V
FB
= 1.35V
V
FB
= V
FBLCD
= 1.35V, V
ONLCD
= 0
V
FB
= V
FBLCD
= 1.35V
V
ON
= V
ONLCD
= 0
1.5
5.5
1.7
10
30
1
V
V
µA
µA
µA
CONDITIONS
MIN
MAX
UNITS
_______________________________________________________________________________________
3
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
MAX1817
ELECTRICAL CHARACTERISTICS (continued)
(V
ON
= V
ONLCD
= V
OUT
= +3.3V, FB = GND,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 1)
PARAMETER
FB Dual Mode Threshold
Output Voltage Adjustment Range
Maximum LX On-Time
Zero Crossing Comparator
Threshold (V
LX
- V
OUT
)
Zero Crossing Comparator
Backup Timer
LX On-Resistance
LX Current Limit
LX Leakage Current
ON Input Low Voltage
ON Input High Voltage
ON Input Bias Current
LCD OUTPUT
LXLCD Voltage
LXLCD On-Resistance
LXLCD Current Limit
LXLCD Leakage Current
FBLCD Regulation Voltage
FBLCD Input Bias Current
Maximum LXLCD On-Time
Minimum LXLCD Off-Time
ONLCD Input Low Voltage
ONLCD Input High Voltage
ONLCD Input Bias Current
V
FBLCD
≥
1.2V
V
FBLCD
≤
0.7V
2.5V < V
OUT
< 5.5V
2.5V < V
OUT
< 5.5V
1.6
1
V
FBLCD
= 1.35V
4
0.5
2.2
V
LXLCD
= 28V, V
ONLCD
= 0
1.20
V
OUT
= 3.3V, I
LXLCD
= 100mA
0.25
28
2
0.7
1
1.30
70
14
1.5
7.5
400
V
Ω
A
µA
V
nA
µs
µs
mV
V
µA
V
ON
= GND, V
LX
= 5.5V
1.8V < V
OUT
< 5.5V, V
FB
= 0.5V
1.8V < V
OUT
< 5.5V, V
FB
= 0.5V
1.6
1
V
FB
= 0.5V
V
OUT
= 3.3V, I
LX
= 100mA
0.42
V
FB
= 0.5V
CONDITIONS
MIN
45
2.5
2.4
0
22
MAX
105
5.5
7.5
40
70
0.65
1.05
1
400
UNITS
mV
V
µs
mV
µs
Ω
A
µA
mV
V
µA
Note 1:
Specifications to -40°C are guaranteed by design and not production tested.
4
_______________________________________________________________________________________
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
Typical Operating Characteristics
(Circuit of Figure 3, T
A
= +25°C, unless otherwise noted.)
MAIN OUTPUT EFFICIENCY
vs. LOAD CURRENT
MAX1817-01
MAX1817
LCD OUTPUT EFFICIENCY
vs. LOAD CURRENT
MAX1817-02
STARTUP VOLTAGE vs. LOAD CURRENT
A
140
LOAD CURRENT (mA)
120
100
80
60
40
20
0
100
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
STARTUP VOLTAGE (V)
RESISTIVE LOAD
LCD OFF
MAX1817 toc03
95
A: V
IN
= 3.3V,
V
OUT
= 5V
B: V
IN
= 2.4V,
V
OUT
= 5V
75
70
65
EFFICIENCY (%)
60
55
50
45
40
35
30
V
OUT
= 3.3V,
NO LOAD
0.1
1
10
C
B
160
90
EFFICIENCY (%)
D
F E
A: V
IN
= +2.4V, V
LCD
= 12V
B: V
IN
= +2.4V, V
LCD
= 18V
C: V
IN
= +2.4V, V
LCD
= 24V
D: V
IN
= +1.8V, V
LCD
= 12V
E: V
IN
= +1.8V, V
LCD
= 18V
F: V
IN
= +1.8V, V
LCD
= 24V
85
80
C: V
IN
= 2.4V,
V
OUT
= 3.3V
D: V
IN
= 1.8V,
V
OUT
= 5V
75
E: V
IN
= 1.8V,
V
OUT
= 3.3V
CIRCUIT OF FIGURE 2
0.1
1
10
100
1000
LOAD CURRENT (mA)
70
25
0.01
LOAD CURRENT (mA)
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE (LCD OFF)
MAX1817 toc04
NO-LOAD SUPPLY CURRENT
vs. INPUT VOLTAGE
400
SUPPLY CURRENT (µA)
350
300
250
200
150
100
50
0
V
OUT
= 3.3V
V
LCD
= 18V, NO LOAD
R1 = 1MΩ, R2 = 75kΩ
MAX1817-05
18
16
SUPPLY CURRENT (µA)
14
12
10
8
6
4
2
0
1.0
1.5
2.0
2.5
3.0
3.5
450
4.0
0
1
2
3
4
5
6
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
MAIN CONVERTER
SWITCHING WAVEFORM
MAX1817-06
LCD CONVERTER
SWITCHING WAVEFORM
MAX1817-07
A
0
0
A
B
B
C
0
10µs/div
A: I
LX
, 500mA/div
B: V
OUT
, 50mV/div, AC-COUPLED
C: V
LX
, 5V/div
V
IN
= 2.4V, V
OUT
= 3.3V, I
LOAD,OUT
= 50mA, V
ONLCD
= 0
0
4µs/div
A: I
LXLCD
, 500mA/div
B: V
LCD
, 100mV/div, AC-COUPLED
C: V
LXLCD
, 10V/div
V
IN
= 2.4V, V
OUT
= 3.3V, I
LOAD,OUT
= 0,
V
LCD
= 18V, I
LOAD,LCD
= 5mA
C
_______________________________________________________________________________________
5
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