MAX1554ETA ,High-Efficiency / 40V Step-Up Converters for 2 to 10 White LEDsFeaturesThe MAX1553/MAX1554 drive white LEDs in series with Constant-Current Regulation for Even ..
MAX1554ETA+ ,High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDsEVALUATION KIT AVAILABLEHigh-Efficiency, 40V Step-UpMAX1553/MAX1554Converters for 2 to 10 White LEDs
MAX1554ETA+ ,High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDsGeneral Description Benefits and
MAX1554ETA+T ,High-Efficiency, 40V Step-Up Converters for 2 to 10 White LEDsElectrical Characteristics(V = 3.3V, V = 0V, C = 1µF, R = 10Ω, T = 0°C to +85°C, unless otherwise n ..
MAX1555EZK+ ,SOT23, Dual-Input, USB/AC Adapter, 1-Cell Li+ Battery Chargersfeatures aOrdering InformationCHG output to indicate charging status.With USB connected, but withou ..
MAX1555EZK+T ,SOT23, Dual-Input, USB/AC Adapter, 1-Cell Li+ Battery ChargersApplicationsMAX1551EZK ADRT POK OutputPDAsMAX1555EZK ADRU CHG OutputWireless AppliancesCell PhonesD ..
MAX4211FETE ,+2.7 V to +5.5 V, High-side power and current monitorApplications SENSE4V TO +28V - LOADRS+ RS-Overpower Circuit BreakersVCC+2.7V TOSmart Battery Packs/ ..
MAX4211FETE+ ,High-Side Power and Current Monitorsapplications.(3mm x 3mm)Both the MAX4210/MAX4211 feature three different cur-MAX4210AEUA -40°C to + ..
MAX4211FETE+T ,High-Side Power and Current MonitorsApplications SENSE4V TO +28V - LOADRS+ RS-Overpower Circuit BreakersVCC+2.7V TOSmart Battery Packs/ ..
MAX4212EUK ,Miniature, 300MHz, Single-Supply, Rail-to-Rail Op Amps with Enableapplications.' Space-Saving SOT23-5, µMAX, or QSOP PackagesThe MAX4212 comes in a miniature 5-pin S ..
MAX4212EUK ,Miniature, 300MHz, Single-Supply, Rail-to-Rail Op Amps with EnableELECTRICAL CHARACTERISTICS (V = +5V, V = 0V, EN_ = +5V, R = 2kW to V / 2, V = V / 2, T = T to T , u ..
MAX4212EUK+T ,Miniature, 300MHz, Single-Supply, Rail-to-Rail Op Amps with Enableapplications).♦ Rail-to-Rail OutputsThese devices require only 5.5mA of quiescent supply♦ Input Com ..
MAX1554ETA
High-Efficiency / 40V Step-Up Converters for 2 to 10 White LEDs
General DescriptionThe MAX1553/MAX1554 drive white LEDs in series with
a constant current to provide efficient display backlight-
ing in cellular phones, PDAs, and other hand-held
devices. The step-up converter includes an internal
40V, low RDSON, N-channel MOSFET switch for high
efficiency and maximum battery life. The MAX1553 has
a current limit of 480mA for driving two to six white
LEDs, while the MAX1554 has a current limit of 970mA
for driving up to 10 white LEDs.
A single analog/PWM Dual Modeinput provides two
simple means of brightness adjustment. A separate
enable input provides on/off control. Soft-start minimizes
inrush current during startup.
The MAX1553/MAX1554 are available in space-saving
8-pin TDFN 3mm x 3mm packages.
ApplicationsCellular Phones
PDA, Palmtop, and Wireless Handhelds
Color Display Backlight
FeaturesConstant-Current Regulation for Even LED
IlluminationInternal 40V MOSFET Switch Capable of Driving
10 LEDsSmall, Low-Profile External Components2.7V to 5.5V Input RangeUp to 88% Efficiency Driving 6 LEDsUp to 82% Efficiency Driving 9 LEDs
(20mA, VCC= 3.6V)Analog or PWM Control of LED IntensityOptimized for Low Input RippleSoft-Start to Minimize Inrush Current3mm x 3mm 8-Pin TDFN Package
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
Pin Configuration
Ordering Information
Typical Operating Circuit19-2875; Rev 0; 6/03
Dual Mode is a trademark of Maxim Integrated Products, Inc.
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICSStresses 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.
VCC, FB, OV to GND..............................................-0.3V to +6.0V
LX to GND..............................................................-0.3V to +45V
EN, BRT, SS to GND...................................-0.3V to (VCC+ 0.3V)
ILX...................................................................................0.9ARMS
Continuous Power Dissipation (TA= +70°C)
8-Pin 3mm x 3mm TDFN
(derate 24.4mW/°C above +70°C).............................1951mW
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
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
ELECTRICAL CHARACTERISTICS(VCC= 3.3V, VOV= 0V, COUT= 1µF, RSENSE= 10Ω, TA
= -40°C to +85°C, unless otherwise noted.) (Note 1)
ELECTRICAL CHARACTERISTICS (continued)(VCC= 3.3V, VOV= 0V, COUT= 1µF, RSENSE= 10Ω, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
Typical Operating Characteristics(MAX1553 driving six white LEDs, VCC= VEN= 3.6V, Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
Typical Operating Characteristics (continued)(MAX1553 driving six white LEDs, VCC= VEN= 3.6V, Circuit of Figure 1, TA = +25°C, unless otherwise noted.)
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
Detailed Description
Control SchemeThe MAX1553/MAX1554 utilize a minimum off-time, cur-
rent-limited control scheme. If the voltage at FB drops
below the regulation threshold, the internal low-side
MOSFET turns on and the inductor current ramps up to
the current limit. Once the current-limit comparator
trips, the low-side MOSFET turns off for the minimum
off-time (250ns). After 250ns, if the voltage at FB is
above the regulation threshold, the low-side MOSFET
stays off. If the voltage at FB is below the regulation
point, the low-side MOSFET turns back on and the
cycle repeats. By using a regulation control scheme
that is not fixed frequency and that can skip pulses, the
MAX1553/MAX1554 operate with very high efficiency.
Soft-StartSoft-start is provided on the MAX1553/MAX1554 to min-
imize inrush current. The soft-start time is set with an
external capacitor, C3 (Figures 1, 2, and 3). Use the fol-
lowing equation to solve for C3:
where tSSis the soft-start time. A value of 0.1µF pro-
vides a soft-start time of 20ms.
ShutdownThe MAX1553/MAX1554 feature a low-current shut-
down feature. When EN is low, the IC turns off, reduc-
ing its supply current to approximately 0.1µA. For
normal operation, drive EN high or connect to VCC.
Overvoltage ProtectionThe MAX1553/MAX1554 have an adjustable overvoltage-
protection circuit. When the voltage at OV reaches the
overvoltage threshold (1.25V typ), the protection circuitry
prevents the internal MOSFET from switching, allowing
the output voltage to decay.
The peak output voltage in an overvoltage-protection
event is set with a resistor-divider from the output con-
nected to OV (R2 and R3 in Figures 1, 2, and 3). Select
a value for R3 (10kΩis recommended), then solve for
R2 using the following equation:
where VOVis the overvoltage threshold (1.25V typ), and
VOUT(PEAK)is the desired peak output voltage.
