Temperature Compensation

When the interior temperature of the LED lamp is over high, there will be strong light failure and the life span of the LED will be

decreased. The FC2082G integrates temperature compensation, when the interior Tj of the chip exceeds 130℃, the output current will

be decreased automatically to lower down the interior temperature of the LED.

System Scheme Design

Rext

Power

Supply

Vin

GND

LED2

LEDn

LED1

1

2

3

OUT

GND

REXT

Diagram 4. FC2082G Application Circuit Schematic Diagram



Theory of Efficiency Design

The operating efficiency of the application circuit shown in Diagram 4 is given by:

IN

LED

LED

IN

LED

LED

IN

LED

V

V

*

n

I

*

V

I

*

V

*

n

P

P

η

=

=

=

bigger the number (n) of the cascaded LEDs is, the higher the operating efficiency is.

During the design of the system, the OUT operating voltage of the FC2082G needs to be adjusted in accordance with the

application environment to optimize η.



Design of Number of Cascaded LEDs

Two aspects need to be considered in the design of the number of cascaded LEDs:

VOUT > VOUT_MIN needs to be guaranteed;

2) The lower the OUT voltage is, the higher the operating efficiency of the system is.

In conclusion, the OUT operating voltage range is: V

LED

OUT_MIN

LED

OUT_MAX

V

V

Vin

n

V

V

Vin

-

<

<

-

2018. 07. 09

5/12

Revision No : 1

FC2082G

OUT_MIN