CAT4237 Datasheet PDF - ON Semiconductor
| Part Number | CAT4237 | |
| Description | High Voltage CMOS Boost White LED Driver | |
| Manufacturers | ON Semiconductor | |
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CAT4237
High Voltage CMOS Boost
White LED Driver
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 1 MHz 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 40 mA can be supported over
a wide range of input supply voltages from 2.8 V to 5.5 V, 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 (1 mm
max height) 5−lead thin SOT23 package for space critical
applications.
Features
• Drives 6 to 8 White LEDs in Series from 3 V
• Up to 87% Efficiency
• Low Quiescent Ground Current 0.6 mA
• Adjustable Output Current (up to 40 mA)
• High Frequency 1 MHz Operation
• High Voltage Power Switch
• Shutdown Current Less than 1 mA
• Open LED Low Power Mode
• Automatic Shutdown at 1.9 V (UVLO)
• Thermal Shutdown Protection
• Thin SOT23 5−lead (1 mm Max Height)
• These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS
Compliant
Applications
• Color LCD and Keypad Backlighting
• Cellular Phones
• Handheld Devices
• Digital Cameras
• PDAs
• Portable Game Machine
http://onsemi.com
5
1
TSOT−23
TD SUFFIX
CASE 419AE
PIN CONNECTIONS
1
SW VIN
GND
FB SHDN
(Top View)
MARKING DIAGRAMS
LTYM
UDYM
LT = CAT4237TD−T3
UD = CAT4237TD−GT3
Y = Production Year (Last Digit)
M = Production Month (1−9, A, B, C)
ORDERING INFORMATION (Note 3)
Device
CAT4237TD−T3
(Note 1)
Package Shipping (Note 4)
TSOT−23
(Pb−Free)
3,000/
Tape & Reel
CAT4237TD−GT3 TSOT−23
(Note 2)
(Pb−Free)
3,000/
Tape & Reel
1. Matte−Tin Plated Finish (RoHS−compliant).
2. NiPdAu Plated Finish (RoHS−compliant)
3. For detailed information and a breakdown of
device nomenclature and numbering systems,
please see the ON Semiconductor Device No-
menclature document, TND310/D, available at
www.onsemi.com
4. For information on tape and reel specifications, in-
cluding part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifica-
tions Brochure, BRD8011/D.
© Semiconductor Components Industries, LLC, 2011
November, 2011 − Rev. 3
1
Publication Order Number:
CAT4237/D
|
| |
 
CAT4237
TYPICAL CHARACTERISTICS
(VIN = 3.6 V, CIN = 4.7 mF, COUT = 0.22 mF, L = 33 mH with 8 LEDs at 20 mA, TAMB = 25°C, unless otherwise specified.)
140 2.0
120
100 1.5
80
60
40
20
0
2.7
VFB = 0.4 V
(not switching)
3.0 3.3 3.6 3.9 4.2 4.5
INPUT VOLTAGE (V)
Figure 4. Quiescent Current vs. VIN
(Not Switching)
4.8
1.0
0.5
0
2.5
3.0 3.5 4.0 4.5
INPUT VOLTAGE (V)
Figure 5. Quiescent Current vs. VIN
(Switching)
315
310
8 LEDs at 20 mA
VOUT = 26 V
305
315
310
8 LEDs
305
5.0
300 300
295 295
290
285
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8
INPUT VOLTAGE (V)
Figure 6. FB Pin Voltage vs. Supply Voltage
290
285
0 5 10 15 20 25 30
OUTPUT CURRENT (mA)
Figure 7. FB Pin Voltage vs. Output Current
1040
1020
1000
SW pin
20V/div
Inductor
Current
100mA/div
980
VOUT
AC coupled
200mV/div
960
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8
INPUT VOLTAGE (V)
Figure 8. Switching Frequency vs. Supply
Voltage
0.5 msec/div
Figure 9. Switching Waveforms
http://onsemi.com
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for CAT4237 electronic component. |
| Information | Total 12 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ CAT4237.PDF Datasheet ] | |
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| Part Number | Description | MFRS |
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