CAT4237 Datasheet, PDF (1/13 Pages) Catalyst Semiconductor – High Voltage CMOS Boost White LED Driver

CAT4237
High Voltage CMOS Boost
White LED Driver
Description
The CAT4237 is a DC/DC step−up 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 battery−powered applications. The CAT4237
high−voltage 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
a pulse width modulation (PWM) signal. The shutdown input pin
allows the device to be placed in power−down 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) 5−lead 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 Voltage Power Switch
• Shutdown Current Less than 1 mA
• Open LED Low Power Mode
• Automatic Shutdown at 1.9 V (UVLO)
• Thermal Shutdown Protection
• Thin SOT23 5−lead (1 mm Max Height)
• These Devices are Pb−Free, 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://onsemi.com
5
1
TSOT−23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
1
SW
VIN
GND
FB
SHDN
(Top View)
MARKING DIAGRAMS
LTYM
UDYM
LT = CAT4237TD−T3
UD = CAT4237TD−GT3
Y = Production Year (Last Digit)
M = Production Month (1−9, A, B, C)
ORDERING INFORMATION
Device
CAT4237TD−T3
(Note 1)
Package
TSOT−23
(Pb−Free)
Shipping
3,000/
Tape & Reel
CAT4237TD−GT3
(Note 2)
TSOT−23
(Pb−Free)
3,000/
Tape & Reel
1. Matte−Tin Plated Finish (RoHS−compliant).
2. NiPdAu Plated Finish (RoHS−compliant)
© Semiconductor Components Industries, LLC, 2010
1
February, 2010 − Rev. 2
Publication Order Number:
CAT4237/D