CAT4237TD-T3 Datasheet, PDF (1/14 Pages) ON Semiconductor – High Voltage CMOS Boost White LED Driver

High Voltage CMOS Boost White LED Driver
CAT4237
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
„ RoHS-compliant
„ 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
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.
Part Number
Package
CAT4237TD-T3 TSOT23-5 ⁽¹⁾
CAT4237TD-GT3 TSOT23-5 ⁽²⁾
Quantity
per Reel
3000
3000
Package
Marking
LT
UD
Notes: (1) Matte-Tin Plated Finish (RoHS-compliant).
(2) NiPdAu Plated Finish (RoHS-compliant).
PIN CONFIGURATION
5-Lead Thin SOT23
(1mm max height)
SW 1
GND 2
5 VIN
FB 3
4 SHDN
Top View
For Ordering Information details, see page 13.
TYPICAL APPLICATION CIRCUIT
V_IN
L
D
V_OUT
3V to
4.2V ^C1
33µH
C₂
4.7µF
SW ^0.22µF
VIN
OFF ON
CAT4237
SHDN
FB ^{VFB = 300mV}
GND
R1
15Ω
L: Sumida CDRH3D16-330
D: Central CMDSH05-4 (rated 40V)
C2: Taiyo Yuden UMK212BJ224 (rated 50V)
20mA
2008 SCILLC. All rights reserved.
1
Characteristics subject to change without notice
Doc. No. MD-5013, Rev. C