UCL2310

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

5 of 7

www.unisonic.com.tw

QW-R125-061.a



APPLICATION INFORMATION

The UTC UCL2310 is a high precision primary-side regulation single stage Active PFC controller for constant

current LED lighting, Operating in critical conduction mode, the controller achieves high power factor, low THD and

high efficiency.

Start Up

reaches the turn on threshold, the internal circuits start working. The COMP pin voltage is pulled up to 1.5V quickly,

then the UTC UCL2310 starts the MOSFET driver. The system works at 10kHz frequency at the beginning, the

COMP voltage rises up gradually, and the transformer primary peak current also rises up. The LED current hence

winding.

Constant Current Control

The UTC UCL2310 adopts proprietary primary side current sensing scheme. It can precisely control the LED

current without secondary side sense and feedback circuit. The current in LED can be calculated by the equation:

S

P

CS

REF

OUT

N

N

R

V

I







2

Where,

NP: Primary winding turns of transformer

NS: Secondary winding turns of transformer

Rcs: The current sensing resistor value

Feedback Network

The UTC UCL2310 senses the output current zero crossing information through the feedback network, the

FB falling threshold voltage is set to 0.1V with 0.08V hysteresis. The FB pin is also used to detect output OVP,

the threshold voltage is 1.6V. The ratio of FB upper resistor to lower resistor can be set as:

A

S

FB

OVP

FBH

FBL

FBL

N

N

V

V

R

R

R







_

6

.

1

Where,

NS: Secondary winding turns of transformer

NA: Auxiliary winding turns of transformer

The FB upper resistor can be set to around 330kΩ to improve the system efficiency. It is also used for fine tuning

the LED current line compensation.

Thermal Regulation

The UTC UCL2310 integrates thermal regulation function. When the system is over temperature, the output

current is gradually reduced; the output power and thermal dissipation are also reduced. The system temperature is

regulated and the system reliability is improved. The thermal regulation temperature is set to 150℃ internally.