Application Description



Single-chip Application

Diagram 5 is the FC2082G application circuit diagram, the LED lamps in the LED tube can be connected in cascade or in

parallel or in combination of both; C1 is high-voltage ceramic capacitor, which is used to low down voltage of Vin; C2 is electrolytic

capacitor, which is used to lower down voltage ripple of Vin; Rext is used to set the operating current of LED tube.

Rext

Vin

LED Tube Lamp

C1

AC~

LED2

LEDn

LED1

1

2

3

OUT

GND

REXT

C2

Diagram 5. Typical Application Circuit— AC Power Input

The value of C1 is determined by the AC voltage and the number of the cascaded LEDs in the LED tube lamp, and normally

it’s0uF ~ 4.7uF. When the number of the cascaded LEDs is big enough, C1 is not needed.

The higher C2 is, the lower the Vin ripple and the OUT voltage ripple are. The value of C2 is determined by the summed

operating current of the LED tube lamp: the higher the current is, the bigger the value of C2 is, normally it’s 4.7uF/400V~22uF/400V,

and the specific value is given by:

V

t

I

C

LED

Δ

=

*

2

ILED is the constant current of the whole scheme, t (time): (1/4)*(1/fAC)= 5ms (at 50Hz), ΔV is the OUT voltage ripple.



Parallel-chip Application

Rext1

IC1

IC2

ICN

Rext2

RextN

AC~

LED1-1

LED1-n

LED2-1

LED2-n

C1

1

2

3

OUT

GND

REXT

1

2

3

OUT

GND

REXT

1

2

3

OUT

GND

REXT

Diagram 6. Circuit Schematic Diagram of Parallel Application

Select the number of the parallel chips basing on the number of the LED lamps and the LED lamp operating current, and the

resistance of Rext1~RextN in the diagram can be set to be the same or different.

In the parallel-chip application, the system constant current threshold voltage is the maximal threshold voltage of the parallel

2018. 07. 09

6/12

Revision No : 1

FC2082G