CAT4137 Datasheet, PDF (1/16 Pages) Catalyst Semiconductor – CMOS Boost Converter - White LED Driver

CMOS Boost Converter – White LED Driver
CAT4137
FEATURES
„ Drives up to 5 White LEDs from 3V
„ Power Efficiency up to 87%
„ Low Quiescent Ground Current 0.1mA
„ Adjustable Output Current (up to 30mA)
„ High Frequency 1MHz Operation
„ “Zero” current shutdown mode
„ Operates down to 2V (from two AA batteries)
„ Soft start power-up
„ Open LED low power mode
„ Automatic shutdown at 1.9V (UVLO)
„ Thermal shutdown protection
„ Thin SOT23 5-Lead (1mm max height)
APPLICATIONS
„ LCD Backlighting
„ Cellular Phones
„ Handheld Devices
„ Digital Cameras
ORDERING INFORMATION
Part Number
CAT4137TD-T3
CAT4137TD-GT3
Package
TSOT23-5⁽¹⁾
TSOT23-5⁽²⁾
Quantity
per Reel
3000
3000
Package
Marking
LX
UE
Notes: (1) Matte-Tin Plated Finish (RoHS-compliant).
(2) NiPdAu Plated Finish (RoHS-compliant).
PIN CONFIGURATION
TSOT-23 5-Lead
1mm max height
SW 1
GND 2
FB 3
5 VIN
4 SHDN
(Top View)
DESCRIPTION
The CAT4137 is a DC/DC step-up converter that
delivers a regulated output current. Operation at a
constant switching frequency of 1MHz allows the
device to be used with small value external ceramic
capacitors and inductor.
The device drives a string of white LEDs connected
in series and provides the regulated current to control
the LEDs with inherent uniform brightness and
matching. An external resistor R1 sets the output
current and allows up to 30mA current to be
supported over a wide range of input supply voltages
from 2.2V to 5.5V, making the device ideal for
battery-powered applications.
LED dimming can be done by using a DC voltage, a
logic signal, or a pulse width modulation (PWM)
signal. The shutdown control 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.
For Ordering Information details see page 15.
TYPICAL APPLICATION CIRCUIT
V_IN
2.2 to
5.5V
C1
1µF
L
D
22µH
C2
SW _0.22µF
VIN
V_OUT
CAT4137
OFF ON SHDN FB
GND
V_FB = 300mV
R1
15Ω
L: Murata LQH32CN220
D: Central CMDSH2-3 (rated 30V)
© Catalyst Semiconductor, Inc.
1
Characteristics subject to change without notice
Doc. No. MD-5012 Rev. B