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CAT4237
White LED Driver, CMOS Boost Converter, High Voltage
CAT4237
High Voltage CMOS Boost
White LED Driver
Description
The CAT4237 is a DC/DC stepïup converter that delivers an
accurate constant current ideal for driving LEDs. Operation at a
constant switching frequency of 1 MHz allows the device to be used
with small value external ceramic capacitors and inductor. LEDs
connected in series are driven with a regulated current set by the
external resistor R1. LED currents up to 40 mA can be supported over
a wide range of input supply voltages from 2.8 V to 5.5 V , making the
device ideal for batteryïpowered applications. The CAT4237
highïvoltage output stage is perfect for driving six, seven or eight
white LEDs in series with inherent current matching in LCD backlight
applications.
LED dimming can be done by using a DC voltage, a logic signal, or pulse width modulation (PWM) signal. The shutdown input pin
allows the device to be placed in powerïdown mode with zero
quiescent current.
In addition to thermal protection and overload current limiting, the
device also enters a very low power operating mode during Open
LED fault conditions. The device is housed in a low profile (1 mm
max height) 5ïlead thin SOT23 package for space critical
applications.
Features Drives 6 to 8 White LEDs in Series from 3 V Up to 87% Efficiency Low Quiescent Ground Current 0.6 mA Adjustable Output Current (up to 40 mA) High Frequency 1 MHz Operation High V oltage Power Switch Shutdown Current Less than 1 A Open LED Low Power Mode Automatic Shutdown at 1.9 V (UVLO) Thermal Shutdown Protection Thin SOT23 5ïlead (1 mm Max Height) These Devices are PbïFree, Halogen Free/BFR Free and are RoHS
Compliant
Applications Color LCD and Keypad Backlighting Cellular Phones Handheld Devices Digital Cameras PDAs Portable Game Machine
http://
TSOTï23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
UDYM
MARKING DIAGRAMS
Device Package Shipping (Note 4)
ORDERING INFORMATION (Note 3)
CAT4237TDïT3
(Note 1)
TSOTï23
(PbïFree)
3,000/
Tape & Reel
LT = CAT4237TDïT3
UD = CAT4237TDïGT3
Y = Production Year (Last Digit)
M = Production Month (1ï9, A, B, C)
(Top View)
VIN
SHDN
GND
LTYM
CAT4237TDïGT3
(Note 2)
TSOTï23
(PbïFree)
3,000/
Tape & Reel MatteïTin Plated Finish (RoHSïcompliant). NiPdAu Plated Finish (RoHSïcompliant) For detailed information and a breakdown of
device nomenclature and numbering systems,
please see the ON Semiconductor Device No-
menclature document, TND310/D, available at
www. For information on tape and reel specifications, in-
cluding part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifica-
