USL1601

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

4 of 6

www.unisonic.com.tw

QW-R125-033.a



FUNCTION DESCRIPTION

The UTC USL1601 is a constant current controller, designed for driving non-isolated buck LED power supply.

UTC USL1601 integrates 600V power MOSFET, and it uses patent constant current control method and source

driver structure, excellent constant current characteristic is achieved with low counts components. Low cost and high

efficiency of system is realized.

Start up

clamped to 12.5V by internal Zener diode.

Line Compensation

The UTC USL1601 integrates line compensation function. The line voltage is sensed by the voltage difference

sensed line voltage. The excellent line regulation is achieved.

The line compensation coefficient is given by the following equation：

=

V

Constant Current Control and Output Current Setting

The UTC USL1601 uses patent constant current control method, excellent constant current is achieved with low

counts components. The UTC USL1601 senses the peak current in inductor cycle by cycle. The CS Pin is connected

to the input of internal current comparator, and compared with the internal 300mV reference voltage. The external

power MOSFET will be turned off when the CS pin voltage reaches the voltage threshold. The comparator has a

650ns LEB timer to avoid mis-trigger.

The peak current in the inductor is given by:

）

A

m

(

R

400

=

I

CS

PK

The current in LED can be calculated by the following equation:

2

I

=

I

PK

LED

Source Driver Structure

The UTC USL1601 uses the patent source driver structure. The typical operation current is as low as 3mA, the

auxiliary winding is not need. So the system design is simple and the cost is low.