8

Date: 3/31/06 RevG

SP6683 1X/1.5X Charge Pump LED Driver for Flash or Backlight

© Copyright 2006 Sipex Corporation

Configuring the SP6683 as Voltage or

Current Source

The white LED load configuration used by

customers can be discrete white LEDs or a white

LED module. Inside the white LED module,

there may or may not be resistors in series with

the white LEDs. According to the different

application requirements, the SP6683 can be

configured as either a voltage source or a current

source to provide solutions for these different

applications, as shown below. The figure shows

the SP6683 driving discrete white LEDs as a

current source.

The current in one white LED current is set by

the ratio of the feedback pin voltage (315mV)

The current of the remaining white LEDs is set

according to the similarity of the white LEDs.

3-wire white LED modules with internal series

resistors (as shown in figure below) can also be

driven in this way.

APPLICATION INFORMATION

1

8

5

Rb

SP6683

Rb

2.2uF

GND

FB

V

OUT

Driving discrete white LEDs as current source

In the figure above, the SP6683 was used to

drive a 2-wire white LED module (without

internal series resistors) as a current source. The

current of the white LED module instead of the

current of a single LED as in the figure showing

the 3 wire white LED module.

3-wire white LED module

Driving 2-wire white LED module as current source

Driving 2-wire white LED module as voltage source

3-wire W-LED module

Anode

FB

GND

GND

V

OUT

Anode

5

V

FB

Rb

SP6683

Cathode

8

2-wire W-LED module

1

Anode

5

8

SP6683

Cathode

V

OUT

R6

1

R5

2.2uF

V

FB

2-wire W-LED

module

GND