CAT4137 datasheet(8/14 Pages) CATALYST

部品番号	CAT4137

部品情報	CMOS Boost Converter - White LED Driver

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メーカー	CATALYST [Catalyst Semiconductor]

ホームページ	http://www.catalyst-semiconductor.com

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CAT4137

Doc. No. MD-5012 Rev. B

8

Characteristics subject to change without notice

DEVICE OPERATION

The CAT4137 is a fixed frequency (1MHz), low

noise, inductive boost converter providing constant

current to the load. A high voltage internal CMOS

power switch is used to energize the external

inductor. When the power switch is then turned off,

the stored energy inductor is released into the load

via the external Schottky diode.

The on/off duty cycle of the power switch is internally

adjusted and controlled to maintain a constant

regulated voltage of 0.3V across the external

feedback resistor connected to the feedback pin

(FB). The value of external resistor will accurately set

the LED bias current accordingly (0.3V/R1).

During the initial power-up stage, the duty cycle of

the internal power switch is limited to prevent

excessive in-rush currents and thereby provide a

“soft-start” mode of operation.

While in normal operation, the device will comfortably

deliver up to 30mA of bias current into a string of up to

5 white LEDs.

In the event of a “Open-Led” fault condition, where

the feedback control loop becomes open, the output

voltage will continue to increase. Once this voltage

exceeds 24V, an internal protection circuit will

become active and place the device into a very low

power safe operating mode. In addition, an internal

clamping circuit will limit the peak output voltage to

29V. If this fault condition is repaired, the device will

automatically resume normal operation.

Thermal overload protection circuitry has been

included to prevent the device from operating at

unsafe junction temperatures above 150ºC.

In the

event of a thermal overload condition the device will

automatically shutdown and wait till the junction

temperatures cools to 130ºC before normal operation

is resumed.

BLOCK DIAGRAM

VREF

Enable

VIN

VOUT

Current

Sense

300mV

ILED

C1

RS

SHDN

Thermal

Shutdown

& UVLO

1MHz

Oscillator

Over Voltage

Protection

PWM

&

Logic

Driver

C2

GND

FB

SW

+

–

A1

N1

A2

RC

CC

R1

15Ω

同様の部品番号 - CAT4137

メーカー	部品番号	データシート	部品情報
Catalyst Semiconductor	CAT4137	867Kb / 28P	Catalyst Semiconductor
ON Semiconductor	CAT4137	179Kb / 16P	CMOS Boost Converter - White LED Driver February, 2010 ??Rev. 2
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	CAT4137TD-GT3	251Kb / 16P	CMOS Boost Converter - White LED Driver Doc. No. MD-5012 Rev. C
	CAT4137TD-GT3	179Kb / 16P	CMOS Boost Converter - White LED Driver February, 2010 ??Rev. 2

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