CAT4237 Driver Datasheet

CAT4237 Datasheet PDF, Equivalent


Part Number

CAT4237

Description

High Voltage CMOS Boost White LED Driver

Manufacture

Catalyst Semiconductor

Total Page 13 Pages
Datasheet
Download CAT4237 Datasheet


CAT4237
www.DataSheet4U.com
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

CAT4237
ABSOLUTE MAXIMUM RATINGS
Parameter
VIN, FB voltage
SHDN* voltage
SW voltage
Storage Temperature Range
Junction Temperature Range
Lead Temperature
Rating
-0.3 to +7
-0.3 to +7
-0.3 to 60
-65 to +160
-40 to +125
300
Unit
V
V
V
°C
°C
°C
RECOMMENDED OPERATING CONDITIONS
Typical application circuit with external components are shown on page 1.
Parameter
Range
Unit
VIN
2.8 to 5.5
V
SW pin voltage
0 to 30
V
Ambient Temperature Range
-40 to +85
°C
6, 7 or 8 LEDs
1 to 40
mA
CAT4237
ELECTRICAL OPERATING CHARACTERISTICS
VIN = 3.6V, ambient temperature of 25ºC (over recommended operating conditions unless specified
otherwise)
Symbol Parameter
Conditions
Min Typ Max Unit
IQ Operating Current
ISD Shutdown Current
VFB FB Pin Voltage
IFB FB pin input leakage
VFB = 0.2V
VFB = 0.4V (not switching)
VSHDN* = 0V
8 LEDs with ILED=20mA
0.6 1.5 mA
0.1 0.6
0.1 1 µA
285 300 315 mV
1 µA
R1 = 10
ILED Programmed LED Current R1 = 15
R1 = 20
28.5 30 31.5
19 20 21 mA
14.25 15 15.75
VIH SHDN* Logic High
VIL SHDN* Logic Low
Enable Threshold Level
Shutdown Threshold Level
0.8 1.5
0.4 0.7
V
V
FSW Switching Frequency
0.8 1.0 1.3 MHz
ILIM Switch Current Limit
350 450 600 mA
RSW Switch “On” Resistance
ISW = 100mA
1.0 2.0
ILEAK Switch Leakage Current
Switch Off, VSW = 5V
1 5 µA
Thermal Shutdown
150 ºC
Thermal Hysteresis
20 ºC
VUVLO
VOV-SW
Undervoltage Lockout
(UVLO) Threshold
Overvoltage Threshold
1.9 V
35 V
© 2005 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
2 of 13
Doc. No. 5013, Rev. A


Features www.DataSheet4U.com CAT4237 High Volta ge CMOS Boost White LED Driver Features • • • • • • • • • • Drives 6 to 8 White LEDs in serie s from 3V Up to 87% Efficiency Low Quie scent Ground Current 0.6mA Adjustable O utput Current (up to 40mA) High Frequen cy 1MHz Operation High Voltage Power Sw itch Shutdown current less than 1µA Op en LED low power mode Automatic Shutdow n at 1.9V (UVLO) Thermal shutdown prote ction Thin SOT23 5-Lead (1mm max height ) 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 s witching frequency of 1MHz allows the d evice to be used with small value exter nal ceramic capacitors and inductor. LE Ds connected in series are driven with a regulated current set by the external resistor R1. LED currents up to 40mA c an be supported over a wide range of in put supply voltages from 2.8V to 5.5V, making the device ideal for battery-powered applications. The CAT4237 high-voltage out.
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