CAT4238
High Efficiency 10 LED Boost Converter
FEATURES
Drives High Voltage LED strings (38V)
Up to 87% Efficiency
Low Quiescent Ground Current 0.6mA
Adjustable Output Current
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)
DESCRIPTION
The CAT4238 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. LED currents up to 40mA can be supported over a
wide range of input supply voltages up to 5.5V, making
the device ideal for battery-powered applications. The
CAT4238 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.
APPLICATIONS
GPS Navigation Systems
Portable Media Players
Handheld Devices, Digital Cameras
Portable Game Machines
ORDERING INFORMATION
Part Number
CAT4238TD-GT3
* Lead Finish NiPdAu
Package
TSOT23-5
Green*
Quantity Package
per Reel Marking
3000
MU
PIN CONFIGURATION
TSOT23 5-Lead
(1mm max height)
SW
GND
FB
1
2
3
4
SHDN
5
VIN
TYPICAL APPLICATION CIRCUIT
L
VIN
C1
4.7µF
VIN
SW
47µH
C2
0.22µF
D
VOUT
CAT4238
OFF ON
SHDN
GND
FB
(300mV)
R1
15Ω
20mA
Top View
L: Sumida CDC5D23B-470
D: Central CMDSH05-4
C2: Taiyo Yuden UMK212BJ224 (rated 50V)
© 2008 SCILLC. All rights reserved.
Characteristics subject to change without notice
1
Doc. No. MD-5019 Rev. E
ONSEMI [ ON SEMICONDUCTOR ]
