L3012

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

4 of 5

www.unisonic.com.tw

QW-R125-025.D

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FUNCTION DESCRIPTION

The UTC L3012 is a current mode and fixed frequency (280kHz) LED driver.

1. Output current setting

100mV).

S

SENSE

IN

OUT

R

V

V

I





=100mV/Rs

2. Current limiting

UTC L3012 has internal current limiting function, and the voltage on COMP is clamped at about 2V, the output

current of the power MOSFET is limited at about 2A by current comparator.

3. Diode Selection

UTC L3012 driver LED need a Schottky diode. If output current is 700mA or smaller then SS14W (1N5819) is ok.

4. PWM dimming

UTC L3012 has internal PWM dimming function. When PWM voltage is connects to high level, the chip is working

normally, when PWM voltage is open or connects to low level, the COMP pin voltage will keep normal state, so can

improve the startup speed of the chip. Adjust the output current by control the duty of external PWM signal.

The minimum setup time of UTC L3012 PWM dimming is less than 20μS, and the maximum PWM dimming ratio

is up to 500:1. When high dimming ratio is needed, the dimming frequency is recommended 500Hz below, or else

the dimming frequency can be up to 2KHz. When PWM pin is low, output is shutdown.

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TYPICAL APPLICATION CIRCUI

1

2

3

4

8

7

6

5

SW

GND

SENSE

ADJ

PWM

COMP

SBD

Rs

Cout

L

10µF

1µF

100nF