CAT4240 Datasheet, PDF (1/14 Pages) Catalyst Semiconductor – 6 Watt Boost LED Driver

6 Watt Boost LED Driver
CAT4240
FEATURES
„ Switch Current Limit 750mA
„ Drives High Voltage LED strings (38V)
„ Up to 94% Efficiency
„ Low Quiescent Ground Current 0.6mA
„ 1MHz Fixed Frequency Low noise Operation
„ Soft start “in-rush” current limiting
„ Shutdown current less than 1μA
„ Open LED Overvoltage Protection
„ Automatic Shutdown at 1.9V (UVLO)
„ Thermal overload protection
„ Thin SOT23 5-Lead (1mm max height)
APPLICATIONS
„ GPS Navigation Systems
„ Portable Media Players
„ Handheld Devices, Digital Cameras
DESCRIPTION
The CAT4240 is a DC/DC step-up converter that delivers
an accurate constant current ideal for driving LEDs.
Operation at a fixed 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. The CAT4240 high-voltage output stage is perfect for
driving mid-size and large panel displays containing up to
ten white LEDs in series.
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.
ORDERING INFORMATION
Part Number
CAT4240TD-GT3
Package
TSOT23-5
Green*
Quantity Package
per Reel Marking
3000
TG
* NiPdAu Plated Finish
For Ordering Information details, see page 13.
Pin Configuration
5-Lead Thin SOT23
(1mm max height)
SW 1
GND 2
FB 3
5 VIN
4 SHDN
Typical Application Circuit
V_L
8V to C1
16V
VIN
5V _C3
1µF
L1
D1
47µH
4.7µF/16V
SW
VIN
C2
1µF/50V
VOUT
CAT4240
SHDN
FB ^{(300mV) R2}
GND
1kΩ
300mA
R1
1Ω
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
L1: Sumida CDRH6D28-470
D1: Central CMSH1-40 (rated 40V)
1
Doc. No. MD-5026 Rev. B