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

CAT4237
High Voltage CMOS Boost White LED Driver
Features
• Drives 6 to 8 White LEDs in series from 3V
• Up to 87% Efficiency
• Low Quiescent Ground Current 0.6mA
• Adjustable Output Current (up to 40mA)
• High Frequency 1MHz Operation
• High Voltage Power Switch
• Shutdown current less than 1µA
• Open LED low power mode
• Automatic Shutdown at 1.9V (UVLO)
• Thermal shutdown protection
• Thin SOT23 5-Lead (1mm max height)
Applications
• Color LCD and keypad Backlighting
• Cellular Phones
• Handheld Devices
• Digital Cameras
• PDAs
• Portable Game Machine
Ordering Information
Part
Package
Number
CAT4237TS TSOT23-5
CAT4237TD TSOT23-5
Lead Free¹
Note 1: NiPdAu Lead Plating
Quantity
per Reel
3000
3000
Package
Marking
LS
LT
Product 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 1MHz 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 40mA can be
supported over a wide range of input supply
voltages from 2.8V to 5.5V, 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
(1mm max height) 5-lead thin SOT23 package for
space critical applications.
Pin Configuration
Typical Application Circuit
Top View
5-Lead Thin SOT23
1mm max height
L: Sumida CDRH3D16-330
D: Central CMDSH05-4 (rated 40V)
C2: Taiyo Yuden UMK212BJ224 (rated 50V)
© 2005 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
1 of 13
Doc. No. 5013, Rev. A