CAT4237 Datasheet PDF - Catalyst Semiconductor
| Part Number | CAT4237 | |
| Description | High Voltage CMOS Boost White LED Driver | |
| Manufacturers | Catalyst Semiconductor | |
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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
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CAT4237
Typical Characteristics
VIN = 3.6V, CIN = 4.7uF, COUT = 0.22µF, L = 33µH with 8 LEDs at 20mA, TAMB=25ºC, unless otherwise specified.
Quiescent Current vs. VIN (Not Switching)
140
120
100
80
60
40 VFB =0.4V
20 (not switching)
0
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8
INPUT VOLTAGE [V]
Quiescent Current vs. VIN (Switching)
2.0
1.5
1.0
0.5
0.0
2.5
3.0 3.5 4.0 4.5
INPUT VOLTAGE [V]
5.0
FB Pin Voltage vs. Supply Voltage
315
8LEDs at 20mA
310 VOUT= 26V
305
300
295
290
285
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8
INPUT VOLTAGE [V]
FB Pin Voltage vs. Output Current
315
310
8 LEDs
305
300
295
290
285
0
5 10 15 20 25 30
OUTPUT CURRENT [mA]
Switching Frequency vs. Supply Voltage
1040
Switching Waveforms
1020
1000
980
960
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8
INPUT VOLTAGE [V]
© 2005 Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
5 of 13
Doc. No. 5013, Rev. A
Preview 5 Page |
Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for CAT4237 electronic component. |
| Information | Total 13 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ CAT4237.PDF Datasheet ] | |
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