CAT37 Datasheet, PDF (1/11 Pages) Catalyst Semiconductor – CMOS White LED Driver Boost Converter

CAT37
CMOS White LED Driver
Boost Converter
Description
The CAT37 is a DC/DC step up converter that delivers a regulated
output current. Operation at a constant switching frequency of
1.2 MHz allows the device to be used with very small value external
inductor and ceramic capacitors.
The CAT37 is targeted to drive multiple white light−emitting diodes
(LEDs) connected in series and provides the necessary regulated current
to control the brightness and the color purity. An external resistor R1
controls the output current level. LED currents of up to 40 mA can be
supported over a wide range of input supply voltages from 2.5 V to 7 V,
making the device ideal for battery−powered applications.
A high voltage output stage allows up to 4 White LEDs to be driven
in series. Series drive provides inherent current matching.
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 “near zero”
quiescent current.
In addition to overcurrent limiting protection, the device also
includes detection circuitry to ensure protection against open−circuit
load fault conditions.
The device is available in a low profile (1 mm max height) 5−lead
TSOT−23 package.
Features
• Low Quiescent Ground Current (0.5 mA Typical)
• Power Efficiency Over 80%
• Compatible Pinout with LT1937
• Adjustable Output Current (up to 40 mA)
• High Frequency 1.2 MHz Operation
• Input Voltage Operation down to 2.5 V
• Low Resistance (0.5 W) Power Switch
• Drives up to 4 White LEDs in Series
• Shutdown Current Less than 1 mA
• Load Fault Protection Against Open−circuits
• Low Value External Components
• Low Profile (1 mm) TSOT−23 5−lead Package
• These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Applications
• Color LCD and Keypad Backlighting
• Cellular Phones
• Handheld Terminals
• Digital Cameras
• PDAs/Games
• Portable MP3 Players
© Semiconductor Components Industries, LLC, 2010
1
February, 2010 − Rev. 21
http://onsemi.com
5
1
TSOT−23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
1
SW
VIN
GND
FB
SHDN
(Top View)
1 mm Maximum Height
q_JA = 250°C/W (free air)
MARKING DIAGRAM
LMYM
ULYM
LM = CAT37TDI−T3
UL = CAT37TDI−GT3
Y = Production Year (Last Digit)
M = Production Month (1−9, A, B, C)
ORDERING INFORMATION
Device
CAT37TDI−T3
(Note 1)
Package
TSOT−23
(Pb−Free)
Shipping
3,000/
Tape & Reel
CAT37TDI−GT3
(Note 2)
TSOT−23
3,000/
(Pb−Free) Tape & Reel
1. Matte−Tin Plated Finish (RoHS−compliant).
2. NiPdAu Plated Finish (RoHS−compliant).
Publication Order Number:
CAT37/D