Rainbow Electronics MAX1817 User Manual
General Description
The MAX1817 is a compact, high-efficiency, dual-output step-up converter for portable devices that provides 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 output voltage with up to 88% efficiency. A 0.1µA shutdown 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 quiescent 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.
________________________Applications
Organizers/Translators
PDAs
MP3 Players
GPS Receivers
Features
♦ Dual Step-Up Converter in a Tiny 10-Pin µMAX
Package
♦ Main Output
Up to 125mA Load Current
Fixed 3.3V or Adjustable 2.5V to 5.5V
Up to 88% Efficiency
Internal Switch
♦ LCD Output
Up to 28V for LCD Bias
Internal Switch
♦ Input Voltage Range +1.5V to +5.5V
♦ Minimal External Components Required
♦ 0.1µA Logic-Controlled Shutdown
♦ Low 15µA Quiescent Supply Current
MAX1817
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
MAX1817
LX
ONLCD
ON
FB
OUT
FBLCDLCD ON/OFF
+1.5V
TO +5.5V
MAIN ON/OFF MAIN
LCD
AGND GND
LXLCD
Typical Operating Circuit
19-1794 Rev 0; 10/00
Ordering Information
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.
PART
MAX1817EUB -40°C to +85°C 10 µMAX
TEMP. RANGE
PIN-PACKAGE
TOP VIEW
ONLCD
1
FB
2
ON
MAX1817
3
4
5
MAX
µ
10
OUT
9
LX
8
GND
7
LXLCDFBLCD
N.C.AGND
6
MAX1817
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VON= V
ONLCD =VOUT
= +3.3V, FB = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +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.
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
Dual Mode is a trademark of Maxim Integrated Products.
PARAMETER CONDITIONS MIN TYP MAX UNITS
GENERAL
Input Voltage Range 1.5 5.5 V
Startup Voltage
Quiescent Current from OUT
(Main Only)
Quiescent Current from OUT VFB = V
Shutdown Quiescent Current VON = V
MAIN OUTPUT
OUT Undervoltage Lockout
Fixed-Mode Output Voltage VFB ≤ 45mV 3.14 3.3 3.47 V
Adjustable-Mode FB Regulation
Voltage
FB Input Bias Current VFB = 1.35V 50 nA
FB Dual Mode
Output Voltage Adjustment
Range
Maximum LX On-Time VFB = 0.5V 2.4 5 7.5 µs
Zero Crossing Comparator
Threshold (V
Zero Crossing Comparator
Backup Timer
Line Regulation
Load Regulation
LX On-Resistance V
LX Current Limit 0.5 0.75 1.05 A
TM
LX
R
= 35Ω 1.5
LOAD
= ∞, VFB = 1.35V 1.2 1.55
R
LOAD
VFB = V
V
ONLCD
V
rising, VFB = 1.35V 2.2 2.4
OUT
falling, V
V
OUT
Threshold 45 75 105 mV
- V
)
OUT
= +0.5V 22 45 70 µs
V
FB
I
= 100mA,
OUT
= +2V to +3V
V
IN
V
= +2.5V,
IN
= 10mA to 100mA
I
LOAD
= 3.3V, ILX = 100mA 0.35 0.65 Ω
OUT
= 1.35V,
FBLCD
= 0
= 1.35V 15 30 µA
FBLCD
= 0 0.1 1 µA
ONLCD
= 1.35V 1.95 2.15
FB
510µA
1.20 1.25 1.30 V
2.5 5.5 V
02040mV
1.6 %
1.6 %
V
V
MAX1817
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VON= V
ONLCD
= V
OUT
= +3.3V, FB = GND, TA= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
ELECTRICAL CHARACTERISTICS
(VON= V
ONLCD
= V
OUT
= +3.3V, FB = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)
LX Leakage Current VON = GND, VLX = 5.5V 0.1 1 µA
ON Input Low Voltage 1.8V < V
ON Input High Voltage 1.8V < V
ON Input Bias Current 1µA
LCD OUTPUT
LXLCD Voltage 28 V
LXLCD On-Resistance V
LXLCD Current Limit 0.28 0.5 0.7 A
LXLCD Leakage Current V
FBLCD Regulation Voltage 1.20 1.25 1.30 V
FBLCD Input Bias Current V
LCD Line Regulation I
LCD Load Regulation I
Maximum LXLCD On-Time 4 9 14 µs
Minimum LXLCD Off-Time
ONLCD Input Low Voltage 2.5V < V
ONLCD Input High Voltage 2.5V < V
ONLCD Input Bias Current 1µA
PARAMETER CONDITIONS MIN TYP MAX UNITS
< 5.5V, VFB = 0.5V 400 mV
OUT
< 5.5V, VFB = 0.5V 1.6 V
OUT
= 3.3V, I
OUT
= 28V, V
LXLCD
= 1.35V 50 nA
FBLCD
= 5mA, VIN = +2V to +3V 0.1 %
LOAD
= 1mA to 5mA, VIN = +2.5V 0.5 %
LOAD
V
≥ 1.2V 0.5 1 1.5
FBLCD
V
≤ 0.7V 2.4 5 7.5
FBLCD
OUT
OUT
= 100mA 1.1 2.0 Ω
LXLCD
= 0 0.1 1 µA
ONLCD
< 5.5V 400 mV
< 5.5V 1.6 V
µs
GENERAL
Input Voltage Range 1.5 5.5 V
Startup Voltage R
Quiescent Current from OUT
(Main Only)
Quiescent Current from OUT VFB = V
Shutdown Quiescent Current VON = V
MAIN OUTPUT
OUT Undervoltage Lockout
Fixed-Mode Output Voltage VFB ≤ 45mV 3.14 3.47 V
Adjustable-Mode FB Regulation
Voltage
FB Input Bias Current VFB = 1.35V 50 nA
PARAMETER CONDITIONS MIN MAX UNITS
= ∞, VFB = 1.35V 1.7 V
LOAD
V
= V
FB
V
rising, VFB = 1.35V 2.4
OUT
falling, VFB = 1.35V 1.95
V
OUT
= 1.35V, V
FBLCD
= 1.35V 30 µA
FBLCD
= 0 1 µA
ONLCD
= 0 10 µA
ONLCD
1.20 1.30 V
V
MAX1817
Compact, High-Efficiency, Dual-Output
Step-Up DC-DC Converter
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VON= V
ONLCD
= V
OUT
= +3.3V, FB = GND, TA= -40°C to +85°C, unless otherwise noted.) (Note 1)
Note 1: Specifications to -40°C are guaranteed by design and not production tested.
FB Dual Mode Threshold 45 105 mV
Outp ut V ol tag e Ad j ustm ent Rang e 2.5 5.5 V
Maximum LX On-Time VFB = 0.5V 2.4 7.5 µs
Zero Crossing Comparator
Threshold (V
Zero Crossing Comparator
Backup Timer
LX On-Resistance V
LX Current Limit 0.42 1.05 A
LX Leakage Current VON = GND, VLX = 5.5V 1 µA
ON Input Low Voltage 1.8V < V
ON Input High Voltage 1.8V < V
ON Input Bias Current 1µA
LCD OUTPUT
LXLCD Voltage 28 V
LXLCD On-Resistance V
LXLCD Current Limit 0.25 0.7 A
LXLCD Leakage Current V
FBLCD Regulation Voltage 1.20 1.30 V
FBLCD Input Bias Current V
Maximum LXLCD On-Time 4 14 µs
Minimum LXLCD Off-Time
ONLCD Input Low Voltage 2.5V < V
ONLCD Input High Voltage 2.5V < V
ONLCD Input Bias Current 1µA
PARAMETER CONDITIONS MIN MAX UNITS
LX
- V
)
OUT
V
= 0.5V 22 70 µs
FB
= 3.3V, ILX = 100mA 0.65 Ω
OUT
< 5.5V, VFB = 0.5V 400 mV
OUT
< 5.5V, VFB = 0.5V 1.6 V
OUT
= 3.3V, I
OUT
= 28V, V
LXLCD
= 1.35V 70 nA
FBLCD
V
≥ 1.2V 0.5 1.5
FBLCD
V
≤ 0.7V 2.2 7.5
FBLCD
OUT
OUT
= 100mA 2 Ω
LXLCD
= 0 1 µA
ONLCD
< 5.5V 400 mV
< 5.5V 1.6 V
040mV
µs
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